nih-gov/pubmed.ncbi.nlm.nih.gov/20157491/index.html

4929 lines
No EOL
158 KiB
HTML
Raw Permalink Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

<!DOCTYPE html>
<html lang="en" >
<head itemscope itemtype="http://schema.org/WebPage" prefix="og: http://ogp.me/ns#" >
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<!-- Mobile properties -->
<meta name="HandheldFriendly" content="True">
<meta name="MobileOptimized" content="320">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<link rel="preconnect" href="https://cdn.ncbi.nlm.nih.gov">
<link rel="preconnect" href="https://www.ncbi.nlm.nih.gov">
<link rel="preconnect" href="https://www.google-analytics.com">
<link rel="stylesheet" href="https://cdn.ncbi.nlm.nih.gov/pubmed/277eb475-38df-4990-a0ee-0080b04e86fc/CACHE/css/output.ba8099dd2df4.css" type="text/css">
<link rel="stylesheet" href="https://cdn.ncbi.nlm.nih.gov/pubmed/277eb475-38df-4990-a0ee-0080b04e86fc/CACHE/css/output.452c70ce66f7.css" type="text/css">
<link rel="stylesheet" href="https://cdn.ncbi.nlm.nih.gov/pubmed/277eb475-38df-4990-a0ee-0080b04e86fc/CACHE/css/output.7bf600913d6e.css" type="text/css">
<link rel="stylesheet" href="https://cdn.ncbi.nlm.nih.gov/pubmed/277eb475-38df-4990-a0ee-0080b04e86fc/CACHE/css/output.0bfa59184c7a.css" type="text/css">
<link rel="stylesheet" href="https://cdn.ncbi.nlm.nih.gov/pubmed/277eb475-38df-4990-a0ee-0080b04e86fc/CACHE/css/output.b576742ffc3e.css" type="text/css">
<title>Understanding PubMed user search behavior through log analysis - PubMed</title>
<link rel="preload" as="font" href="https://cdn.ncbi.nlm.nih.gov/pubmed/277eb475-38df-4990-a0ee-0080b04e86fc/uswds/dist/fonts/merriweather-bold-webfont.woff2" type="font/woff2" crossorigin />
<!-- Favicons -->
<link rel="shortcut icon" type="image/ico" href="https://cdn.ncbi.nlm.nih.gov/coreutils/nwds/img/favicons/favicon.ico" />
<link rel="icon" type="image/png" href="https://cdn.ncbi.nlm.nih.gov/coreutils/nwds/img/favicons/favicon.png" />
<!-- 192x192, as recommended for Android
http://updates.html5rocks.com/2014/11/Support-for-theme-color-in-Chrome-39-for-Android
-->
<link rel="icon" type="image/png" sizes="192x192" href="https://cdn.ncbi.nlm.nih.gov/coreutils/nwds/img/favicons/favicon-192.png" />
<!-- 57x57 (precomposed) for iPhone 3GS, pre-2011 iPod Touch and older Android devices -->
<link rel="apple-touch-icon-precomposed" href="https://cdn.ncbi.nlm.nih.gov/coreutils/nwds/img/favicons/favicon-57.png">
<!-- 72x72 (precomposed) for 1st generation iPad, iPad 2 and iPad mini -->
<link rel="apple-touch-icon-precomposed" sizes="72x72" href="https://cdn.ncbi.nlm.nih.gov/coreutils/nwds/img/favicons/favicon-72.png">
<!-- 114x114 (precomposed) for iPhone 4, 4S, 5 and post-2011 iPod Touch -->
<link rel="apple-touch-icon-precomposed" sizes="114x114" href="https://cdn.ncbi.nlm.nih.gov/coreutils/nwds/img/favicons/favicon-114.png">
<!-- 144x144 (precomposed) for iPad 3rd and 4th generation -->
<link rel="apple-touch-icon-precomposed" sizes="144x144" href="https://cdn.ncbi.nlm.nih.gov/coreutils/nwds/img/favicons/favicon-144.png">
<!-- For Pinger + Google Optimize integration (NS-820) -->
<meta name="ncbi_sg_optimize_id" content="">
<!-- Mobile browser address bar color -->
<meta name="theme-color" content="#20558a">
<!-- Preserve the Referrer when going from HTTPS to HTTP -->
<meta name="referrer" content="origin-when-cross-origin">
<meta name="ncbi_pinger_gtm_track" content="true"/>
<!-- Logging params: Pinger defaults -->
<meta name="ncbi_app" content="pubmed" />
<meta name="ncbi_db" content="pubmed" />
<meta name="ncbi_phid" content="BA3600017CB8DF0500002D80F3BC54B8.1.m_6" />
<meta name="ncbi_pinger_stat_url" content="https://www.ncbi.nlm.nih.gov/stat" />
<meta name="log_category" content="literature" />
<meta name="ncbi_cost_center" content="pubmed" />
<!-- Logging params: Pinger custom -->
<meta name="ncbi_pdid" content="abstract" />
<meta name="log_op" content="retrieve" />
<meta name="uid" content="20157491" />
<meta name="ncbi_uid" content="20157491" />
<meta name="log_displayeduids" content="20157491" />
<meta name="log_source_db" content="pubmed,pmc" />
<meta name="log_icons_present" content="true" />
<meta name="ncbi_search_id" content="baKULWJvIKEmjmzpBLKMtQ:647ff15141af266103a93759ef71cd80" />
<meta name="ncbi_adj_nav_search_id" content="O76G0u_mXSrhAito6o4KYg:647ff15141af266103a93759ef71cd80" />
<!-- Social meta tags for unfurling urls -->
<meta name="description" content="This article reports on a detailed investigation of PubMed users&#x27; needs and behavior as a step toward improving biomedical information retrieval. PubMed is providing free service to researchers with access to more than 19 million citations for biomedical articles from MEDLINE and life science journa …"><meta name="keywords" content="pmid:20157491, PMC2797455, doi:10.1093/database/bap018, Rezarta Islamaj Dogan, G Craig Murray, Zhiyong Lu, PubMed Abstract, NIH, NLM, NCBI, National Institutes of Health, National Center for Biotechnology Information, National Library of Medicine, MEDLINE"><meta name="robots" content="index,nofollow,noarchive"><meta property="og:title" content="Understanding PubMed user search behavior through log analysis - PubMed"><meta property="og:url" content="https://pubmed.ncbi.nlm.nih.gov/20157491/"><meta property="og:description" content="This article reports on a detailed investigation of PubMed users&#x27; needs and behavior as a step toward improving biomedical information retrieval. PubMed is providing free service to researchers with access to more than 19 million citations for biomedical articles from MEDLINE and life science journa …"><meta property="og:image" content="https://cdn.ncbi.nlm.nih.gov/pubmed/persistent/pubmed-meta-image-v2.jpg"><meta property="og:image:secure_url" content="https://cdn.ncbi.nlm.nih.gov/pubmed/persistent/pubmed-meta-image-v2.jpg"><meta property="og:type" content="website"><meta property="og:site_name" content="PubMed"><meta name="twitter:domain" content="pubmed.ncbi.nlm.nih.gov"><meta name="twitter:card" content="summary_large_image"><meta name="twitter:title" content="Understanding PubMed user search behavior through log analysis - PubMed"><meta name="twitter:url" content="https://pubmed.ncbi.nlm.nih.gov/20157491/"><meta name="twitter:description" content="This article reports on a detailed investigation of PubMed users&#x27; needs and behavior as a step toward improving biomedical information retrieval. PubMed is providing free service to researchers with access to more than 19 million citations for biomedical articles from MEDLINE and life science journa …"><meta name="twitter:image" content="https://cdn.ncbi.nlm.nih.gov/pubmed/persistent/pubmed-meta-image-v2.jpg">
<!-- OpenSearch XML -->
<link rel="search" type="application/opensearchdescription+xml" href="https://cdn.ncbi.nlm.nih.gov/pubmed/persistent/opensearch.xml" title="PubMed search">
<!-- Disables severely broken elements when no JS -->
<noscript>
<link rel="stylesheet" type="text/css" href="https://cdn.ncbi.nlm.nih.gov/pubmed/277eb475-38df-4990-a0ee-0080b04e86fc/core/no-script.css">
</noscript>
<meta name="citation_title" content="Understanding PubMed user search behavior through log analysis">
<meta name="citation_authors" content="Islamaj Dogan R;Murray GC;Névéol A;Lu Z;">
<meta name="citation_date" content="2009">
<meta name="citation_publisher" content="Database (Oxford)">
<meta name="citation_journal_title" content="Database : the journal of biological databases and curation">
<meta name="citation_pmid" content="20157491">
<meta name="citation_abstract_html_url" content="https://pubmed.ncbi.nlm.nih.gov/20157491/">
<meta name="citation_volume" content="2009">
<meta name="citation_doi" content="10.1093/database/bap018">
<meta name="citation_issn" content="1758-0463">
<link rel="canonical" href="https://pubmed.ncbi.nlm.nih.gov/20157491/" />
</head>
<body >
<noscript>
<div class="no-script-banner" id="no-script-banner">
<div class="warning-message">
<div class="warning-message-text">
This site needs JavaScript to work properly. Please enable it to take advantage of the complete set of features!
</div>
</div>
</div>
</noscript>
<div class="no-session-banner" id="no-session-banner" hidden>
<div class="warning-message">
<div class="warning-message-text">
Clipboard, Search History, and several other advanced features are temporarily unavailable.
</div>
<button class="close-banner-button"
title="Close Clipboard and Search History not available warning banner"
ref="linksrc=close_no_session_banner"
aria-controls="no-session-banner"
aria-label="Close Clipboard and Search History not available warning banner"
aria-expanded="true">
</button>
</div>
</div>
<a class="usa-skipnav" href="#article-details">
Skip to main page content
</a>
<!-- ========== BEGIN HEADER ========== -->
<section class="usa-banner">
<div class="usa-accordion">
<header class="usa-banner-header">
<div class="usa-grid usa-banner-inner">
<img src="https://www.ncbi.nlm.nih.gov/coreutils/uswds/img/favicons/favicon-57.png" alt="U.S. flag" />
<p>An official website of the United States government</p>
<button
class="usa-accordion-button usa-banner-button"
aria-expanded="false"
aria-controls="gov-banner-top"
>
<span class="usa-banner-button-text">Here's how you know</span>
</button>
</div>
</header>
<div
class="usa-banner-content usa-grid usa-accordion-content"
id="gov-banner-top"
>
<div class="usa-banner-guidance-gov usa-width-one-half">
<img
class="usa-banner-icon usa-media_block-img"
src="https://www.ncbi.nlm.nih.gov/coreutils/uswds/img/icon-dot-gov.svg"
alt="Dot gov"
/>
<div class="usa-media_block-body">
<p>
<strong>The .gov means its official.</strong>
<br />
Federal government websites often end in .gov or .mil. Before
sharing sensitive information, make sure youre on a federal
government site.
</p>
</div>
</div>
<div class="usa-banner-guidance-ssl usa-width-one-half">
<img
class="usa-banner-icon usa-media_block-img"
src="https://www.ncbi.nlm.nih.gov/coreutils/uswds/img/icon-https.svg"
alt="Https"
/>
<div class="usa-media_block-body">
<p>
<strong>The site is secure.</strong>
<br />
The <strong>https://</strong> ensures that you are connecting to the
official website and that any information you provide is encrypted
and transmitted securely.
</p>
</div>
</div>
</div>
</div>
</section>
<div class="usa-overlay"></div>
<header class="ncbi-header" role="banner" data-section="Header">
<div class="usa-grid">
<div class="usa-width-one-whole">
<div class="ncbi-header__logo">
<a href="https://www.ncbi.nlm.nih.gov/" class="logo" aria-label="NCBI Logo" data-ga-action="click_image" data-ga-label="NIH NLM Logo">
<img src="https://www.ncbi.nlm.nih.gov/coreutils/nwds/img/logos/AgencyLogo.svg" alt="NIH NLM Logo" />
</a>
</div>
<div class="ncbi-header__account">
<a id="account_login" href="https://account.ncbi.nlm.nih.gov" class="usa-button header-button" style="display:none" data-ga-action="open_menu" data-ga-label="account_menu">Log in</a>
<button id="account_info" class="header-button" style="display:none"
aria-controls="account_popup">
<span class="fa fa-user" aria-hidden="true"></span>
<span class="username desktop-only" aria-hidden="true" id="uname_short"></span>
<span class="sr-only">Show account info</span>
</button>
</div>
<div class="ncbi-popup-anchor">
<div class="ncbi-popup account-popup" id="account_popup" aria-hidden="true">
<div class="ncbi-popup-head">
<button class="ncbi-close-button" data-ga-action="close_menu" data-ga-label="account_menu"><span class="fa fa-times"></span><span class="usa-sr-only">Close</span></button>
<h4>Account</h4>
</div>
<div class="account-user-info">
Logged in as:<br/>
<b><span class="username" id="uname_long">username</span></b>
</div>
<div class="account-links">
<ul class="usa-unstyled-list">
<li><a id="account_myncbi" href="/myncbi/" class="set-base-url" data-ga-action="click_menu_item" data-ga-label="account_myncbi">Dashboard</a></li>
<li><a id="account_pubs" href="/myncbi/collections/bibliography/" class="set-base-url" data-ga-action="click_menu_item" data-ga-label="account_pubs">Publications</a></li>
<li><a id="account_settings" href="/account/settings/" class="set-base-url" data-ga-action="click_menu_item" data-ga-label="account_settings">Account settings</a></li>
<li><a id="account_logout" href="/account/signout/" class="set-base-url" data-ga-action="click_menu_item" data-ga-label="account_logout">Log out</a></li>
</ul>
</div>
</div>
</div>
</div>
</div>
</header>
<div role="navigation" aria-label="access keys">
<a id="nws_header_accesskey_0" href="https://www.ncbi.nlm.nih.gov/guide/browsers/#ncbi_accesskeys" class="usa-sr-only" accesskey="0" tabindex="-1">Access keys</a>
<a id="nws_header_accesskey_1" href="https://www.ncbi.nlm.nih.gov" class="usa-sr-only" accesskey="1" tabindex="-1">NCBI Homepage</a>
<a id="nws_header_accesskey_2" href="/myncbi/" class="set-base-url usa-sr-only" accesskey="2" tabindex="-1">MyNCBI Homepage</a>
<a id="nws_header_accesskey_3" href="#maincontent" class="usa-sr-only" accesskey="3" tabindex="-1">Main Content</a>
<a id="nws_header_accesskey_4" href="#" class="usa-sr-only" accesskey="4" tabindex="-1">Main Navigation</a>
</div>
<section data-section="Alerts">
<div class="ncbi-alerts-placeholder"></div>
</section>
<!-- ========== END HEADER ========== -->
<a id="maincontent" aria-label="Main page content below" role="navigation"></a>
<input type="hidden" name="csrfmiddlewaretoken" value="FDgGdqa9AUp1mhU3YmmYkYAqbS7TDc8LWq0LQgDvavcvgI0TBFZ0O664JWP5wNG5">
<form action="/" method="get" autocomplete="off" class="usa-search usa-search-big search-form content-page-layout" id="search-form" role="search">
<div class="inner-wrap">
<a class="pubmed-logo"
aria-label="Pubmed Logo"
href="/"
data-ga-category="featured_link"
data-ga-action="pubmed_logo">
<img src="https://cdn.ncbi.nlm.nih.gov/pubmed/277eb475-38df-4990-a0ee-0080b04e86fc/core/images/pubmed-logo-blue.svg" alt="pubmed logo" />
</a>
<a href="#" class="search-input-trigger" data-alt-title="Hide search bar" title="Show search bar" aria-label="Show search bar">
</a>
<div role="search" class="search-input">
<div class="form-field ">
<label class="usa-sr-only" for="id_term">
Search:
</label>
<input
type="search"
name="term"
data-skip-ie-scroll-to-top=""
data-replace-term-with-exact=""
data-exact-query=""
placeholder=""
class="term-input"
required="required"
id="id_term"/><a href="#" class="clear-btn" aria-label="Clear search input" title="Clear search input" role="button" data-pinger-ignore></a><button type="submit" class="search-btn" aria-label="Search" disabled data-pinger-ignore><span class="usa-search-submit-text">Search</span></button>
</div>
</div>
<!-- Create alert and Create RSS are buttons that look like links -->
<!-- Better for them to look like buttons but no space -->
<div class="search-links-wrapper content-page-layout">
<div class="search-links">
<a href="/advanced/"
class="search-input-link adv-search-link"
data-ga-category="featured_link"
data-ga-action="adv_search">Advanced</a>
<a href="/clipboard/"
class="search-input-link clipboard-link hidden"
data-ga-category="featured_link"
data-ga-action="clipboard">
Clipboard <span class="amount-in-clipboard"></span>
</a>
</div>
<span class="search-input-link user-guide-link" role="navigation" aria-label="User guide">
<a href="/help/"
data-ga-category="featured_link"
data-ga-action="user_guide">
User Guide
</a>
</span>
</div>
</div>
</form>
<div id="article-page-header">
<div id="article-top-actions-bar" class="article-top-actions-bar">
<div class="inner-wrap">
<div class="actions-container">
<div class="return-to-search">
</div>
<div class="multiple-results-actions " role="region" aria-label="save, email, send to">
<button id="save-results-panel-trigger"
type="button"
class="save-results save-results-panel-trigger"
aria-expanded="false"
aria-controls="save-action-panel"
data-ga-category="save_share"
data-ga-action="save"
data-ga-label="open">
Save
</button><button id="email-results-panel-trigger"
type="button"
class="email-results email-results-panel-trigger"
aria-expanded="false"
aria-controls="email-action-panel"
data-ga-category="save_share"
data-ga-action="email"
data-ga-label="open">
Email
</button><div class="more-actions dropdown-block"><button id="more-actions-trigger"
type="button"
class="trigger more-actions-trigger"
ref="linksrc=show_moreactions_btn"
aria-label="Send to"
aria-controls="more-actions-dropdown">Send to</button><div id="more-actions-dropdown" class="dropdown dropdown-container" hidden><div class="content"><ul class="more-actions-links"><li><a class="clipboard-panel-trigger dropdown-block-link "
href="#"
role="button"
data-ga-category="save_share"
data-ga-action="clipboard"
data-ga-label="send">
Clipboard
</a></li><li><a role="button" class="dropdown-block-link bibliography-trigger-target" href="https://account.ncbi.nlm.nih.gov/?back_url=https%3A%2F%2Fpubmed.ncbi.nlm.nih.gov%2F20157491%2F%23open-bibliography-panel">My Bibliography</a></li><li><a role="button" class="dropdown-block-link collections-trigger-target" href="https://account.ncbi.nlm.nih.gov/?back_url=https%3A%2F%2Fpubmed.ncbi.nlm.nih.gov%2F20157491%2F%23open-collections-panel">Collections</a></li><li><a role="button" class="citation-manager-panel-trigger dropdown-block-link citation-manager-trigger-target" href="#">Citation manager</a></li></ul></div></div></div>
</div>
<div class="display-options" data-format-key="format"
data-default-format-value="abstract"
data-current-format-value="abstract" role="region">
<button
class="trigger usa-button"
title="Change format"
data-ga-category="display_options"
data-ga-action="display_options_dialog">
<span class="button-label">Display options</span>
</button>
<div class="dropdown" hidden>
<div class="title">
Display options
</div>
<div class="content">
<div class="format-container">
<span class="option-label">
Format
</span>
<select name="format" data-initial-value="abstract" aria-label="Display format" id="article-display-format">
<option value="abstract">Abstract</option>
<option value="pubmed">PubMed</option>
<option value="pmid">PMID</option>
</select>
</div>
</div>
</div>
</div>
<input type="hidden" name="csrfmiddlewaretoken" value="FDgGdqa9AUp1mhU3YmmYkYAqbS7TDc8LWq0LQgDvavcvgI0TBFZ0O664JWP5wNG5">
</div>
</div>
</div>
<div id="article-panels-container" class="article-panels-container">
<div id="save-action-panel" class="save-action-panel action-panel" aria-hidden="true">
<div class="inner-wrap">
<h2 class="action-panel-heading">
Save citation to file
</h2>
<form id="save-action-panel-form"
class="action-panel-content action-form"
action="/results-export-ids/"
data-by-search-action="/results-export-search-data/"
data-by-ids-action="/results-export-ids/"
method="post"
data-by-search-method="post"
data-by-ids-method="post">
<input type="hidden" name="csrfmiddlewaretoken" value="FDgGdqa9AUp1mhU3YmmYkYAqbS7TDc8LWq0LQgDvavcvgI0TBFZ0O664JWP5wNG5">
<div class="action-panel-control-wrap">
<label for="save-action-format" class="action-panel-label">
Format:
</label>
<select id="save-action-format" name="results-format" class="action-panel-selector">
<option value="summary-text">Summary (text)</option>
<option value="pubmed-text">PubMed</option>
<option value="pmid">PMID</option>
<option value="abstract">Abstract (text)</option>
<option value="csv">CSV</option>
</select>
</div>
<div class="action-panel-actions">
<button class="action-panel-submit"
type="submit"
data-loading-label="Saving..."
data-ga-category="save_share"
data-ga-action="save"
data-ga-label="save">
Create file
</button>
<button class="action-panel-cancel"
aria-label="Close 'Save citations to file' panel"
ref="linksrc=close_save_panel"
aria-controls="save-action-panel"
aria-expanded="false"
data-ga-category="save_share"
data-ga-action="save"
data-ga-label="cancel">
Cancel
</button>
</div>
</form>
</div>
</div>
<div id="email-action-panel"
class="email-action-panel action-panel"
aria-hidden="true"
data-recaptcha-script-url="https://www.recaptcha.net/recaptcha/enterprise.js?render=explicit&onload=onloadCaptchaCallback"
data-recaptcha-enabled="true">
<div class="inner-wrap">
<h2 class="action-panel-heading">
Email citation
</h2>
<form id="email-action-panel-form"
class="action-panel-content action-form"
action="/send-email/"
data-by-search-action="/results-export-email-by-search-data/"
data-by-ids-action="/send-email/"
data-by-search-method="post"
data-by-ids-method="post"
method="post"
>
<input type="hidden" name="csrfmiddlewaretoken" value="FDgGdqa9AUp1mhU3YmmYkYAqbS7TDc8LWq0LQgDvavcvgI0TBFZ0O664JWP5wNG5">
<div class="action-panel-control-wrap">
<span class="action-panel-label">
Subject:
</span>
<span class="email-subject" id="email-subject" aria-label="Email subject">1 selected item: 20157491 - PubMed</span>
<input type="hidden" name="email-subject" value="1 selected item: 20157491"/>
<input type="hidden" name="email-subject-hash" value="f009e8c1d9565929a6b9572192dc1fc09d49318225709098f23413fcfae716b3"/>
</div>
<div class="action-panel-control-wrap">
<label for="email-to" class="action-panel-label required-field-asterisk">
To:
</label>
<input type="email" aria-label="Recipient Email Address" placeholder="email@example.com" id="email-to" class="email-to" pattern="^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$" maxlength="100" required>
</div>
<div class="action-panel-control-wrap">
<label for="email-from" class="action-panel-label">
From:
</label>
<input type="email" aria-label="Sender Email Address" placeholder="email@example.com" id="email-from" class="email-from" pattern="^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$" maxlength="256">
</div>
<div class="action-panel-control-wrap">
<label for="email-citation-format" class="action-panel-label">
Format:
</label>
<select id="email-citation-format" name="citation-format" class="action-panel-selector email-citation-format">
<option selected="selected" value="summary">Summary</option>
<option value="summary-text">Summary (text)</option>
<option value="abstract">Abstract</option>
<option value="abstract-text">Abstract (text)</option>
</select>
</div>
<div class="include-supplemental-container">
<input type="checkbox" aria-label="Include MeSH and other data" name="include-supplemental" id="email-include-supplemental" class="email-include-supplemental">
<label for="email-include-supplemental" class="email-include-supplemental-label">MeSH and other data</label>
</div>
<div class="form-field recaptcha ">
<div class="g-recaptcha" id="id-recaptcha" data-sitekey="6LfsWHMdAAAAAClKbtOpjQ2pMjgsGxvv7NdZW9uI"></div>
</div>
<div id="captcha-error-message" class="usa-input-error-message captcha-validation-message" role="alert"></div>
<div class="action-panel-actions">
<button class="action-panel-submit"
type="submit"
data-loading-label="Sending..."
data-ga-category="save_share"
data-ga-action="email"
data-ga-label="send">
Send email
</button>
<button class="action-panel-cancel"
aria-label="Close 'Email citations' panel"
ref="linksrc=close_email_panel"
aria-controls="email-action-panel"
aria-expanded="false"
data-ga-category="save_share"
data-ga-action="email"
data-ga-label="cancel">
Cancel
</button>
</div>
<input type="hidden" name="email-search-details" value="" />
<input type="hidden" name="email-search-details-hash" value="0e42663a6c3bd85498fcb88798998fed7bfdc45d457db35281e41afe13cc0524" />
</form>
</div>
</div>
<div id="collections-action-panel"
class="collections-action-panel action-panel in-progress-dots-panel"
aria-hidden="true"
data-collections-open-panel-enabled="false"
data-collections-open-panel-url-hash="#open-collections-panel">
<div class="inner-wrap">
<h3 class="action-panel-heading">
Add to Collections
</h3>
<form id="collections-action-panel-form"
class="collections-action-panel-form action-panel-content action-form action-panel-smaller-selectors"
data-existing-collections-url="/list-existing-collections/"
data-add-to-existing-collection-url="/add-to-existing-collection/"
data-create-and-add-to-new-collection-url="/create-and-add-to-new-collection/"
data-get-article-ids-by-search-url="/get-article-ids-by-search/"
data-myncbi-max-collection-name-length="100"
data-add-to-collection-max-amount="1000"
data-collections-root-url="https://www.ncbi.nlm.nih.gov/myncbi/collections/">
<input type="hidden" name="csrfmiddlewaretoken" value="FDgGdqa9AUp1mhU3YmmYkYAqbS7TDc8LWq0LQgDvavcvgI0TBFZ0O664JWP5wNG5">
<div class="choice-group" role="radiogroup">
<ul class="radio-group-items">
<li>
<input type="radio"
id="collections-action-panel-new"
class="collections-new"
name="collections"
value="new"
data-ga-category="save_share"
data-ga-action="collections"
data-ga-label="collections_radio_new">
<label for="collections-action-panel-new">Create a new collection</label>
</li>
<li>
<input type="radio"
id="collections-action-panel-existing"
class="collections-existing"
name="collections"
value="existing"
checked="true"
data-ga-category="save_share"
data-ga-action="collections"
data-ga-label="collections_radio_existing">
<label for="collections-action-panel-existing">Add to an existing collection</label>
</li>
</ul>
</div>
<div class="controls-wrapper">
<div class="action-panel-control-wrap new-collections-controls">
<label for="collections-action-panel-add-to-new" class="action-panel-label required-field-asterisk">
Name your collection:
</label>
<input
type="text"
name="add-to-new-collection"
id="collections-action-panel-add-to-new"
class="collections-action-add-to-new"
pattern="[^&quot;&amp;=&lt;&gt;\/]*" title="The following characters are not allowed in the Name field: &quot;&amp;=&lt;&gt;/"
maxlength="100"
data-ga-category="save_share"
data-ga-action="create_collection"
data-ga-label="non_favorties_collection">
<div class="collections-new-name-too-long usa-input-error-message selection-validation-message">
Name must be less than 100 characters
</div>
</div>
<div class="action-panel-control-wrap existing-collections-controls">
<label for="collections-action-panel-add-to-existing" class="action-panel-label">
Choose a collection:
</label>
<select id="collections-action-panel-add-to-existing"
class="action-panel-selector collections-action-add-to-existing"
data-ga-category="save_share"
data-ga-action="select_collection"
data-ga-label="($('#collections-action-add-to-existing').val() === 'Favorites') ? 'Favorites' : 'non_favorites_collection'">
</select>
<div class="collections-retry-load-on-error usa-input-error-message selection-validation-message">
Unable to load your collection due to an error<br>
<a href="#">Please try again</a>
</div>
</div>
</div>
<div class="action-panel-actions">
<button class="action-panel-submit"
type="submit"
data-loading-label="Adding..."
data-pinger-ignore
data-ga-category="save_share"
data-ga-action="collections"
data-ga-label="add">
Add
</button>
<button class="action-panel-cancel"
aria-label="Close 'Add to Collections' panel"
ref="linksrc=close_collections_panel"
aria-controls="collections-action-panel"
aria-expanded="false"
data-ga-category="save_share"
data-ga-action="collections"
data-ga-label="cancel">
Cancel
</button>
</div>
</form>
</div>
</div>
<div id="bibliography-action-panel"
class="bibliography-action-panel action-panel in-progress-dots-panel"
aria-hidden="true"
data-bibliography-open-panel-enabled="false"
data-bibliography-open-panel-url-hash="#open-bibliography-panel">
<div class="inner-wrap">
<h3 class="action-panel-heading">
Add to My Bibliography
</h3>
<form id="bibliography-action-panel-form"
class="bibliography-action-panel-form action-panel-content action-form action-panel-smaller-selectors"
data-add-to-bibliography-max-amount="100"
data-add-to-bibliography-batch-size="10"
data-bibliography-delegates-url="/list-bibliography-delegates/"
data-add-to-bibliography-url="/add-to-bibliography/"
data-get-article-ids-by-search-url="/get-article-ids-by-search/"
data-mybib-root-url="https://www.ncbi.nlm.nih.gov/myncbi/collections/mybibliography/">
<input type="hidden" name="csrfmiddlewaretoken" value="FDgGdqa9AUp1mhU3YmmYkYAqbS7TDc8LWq0LQgDvavcvgI0TBFZ0O664JWP5wNG5">
<div class="action-panel-control-wrap bibliographies-controls">
<div class="choice-group">
<ul class="bibliographies-action-add radio-group-items">
<li>
<input name="bibliography" id="my-bibliography" class="my-bibliography" type="radio" checked/>
<label for="my-bibliography">My Bibliography</label>
</li>
</ul>
</div>
</div>
<div class="bibliographies-retry-load-on-error usa-input-error-message selection-validation-message">
Unable to load your delegates due to an error<br>
<a href="#">Please try again</a>
</div>
<div class="action-panel-actions">
<button class="action-panel-submit"
type="submit"
data-loading-label="Adding..."
data-pinger-ignore>
Add
</button>
<button class="action-panel-cancel"
aria-label="Close 'Add to bibliography' panel"
ref="linksrc=close_bibliography_panel"
aria-controls="bibliography-action-panel"
aria-expanded="false"
data-ga-category="save_share"
data-ga-action="mybib"
data-ga-label="cancel">
Cancel
</button>
</div>
</form>
</div>
</div>
<div id="saved-search-action-panel" class="saved-search-action-panel action-panel " aria-hidden="true"
data-saved-search-open-panel-enabled="false"
data-saved-search-open-panel-url-hash="#open-saved-search-panel">
<div class="inner-wrap">
<h2 class="action-panel-heading">
Your saved search
</h2>
<form id="saved-search-action-panel-form"
class="saved-search-action-panel-form action-panel-content action-form"
data-create-saved-search-url="/create-saved-search/"
data-try-search-terms-url="/try-search-term/"
data-saved-search-root-url="https://www.ncbi.nlm.nih.gov/myncbi/searches/">
<input type="hidden" name="csrfmiddlewaretoken" value="FDgGdqa9AUp1mhU3YmmYkYAqbS7TDc8LWq0LQgDvavcvgI0TBFZ0O664JWP5wNG5">
<div class="action-panel-control-wrap">
<label for="saved-search-name" class="action-panel-label saved-search-name-label required-field-asterisk">
Name of saved search:
</label>
<input maxlength="200"
type="text"
name="saved-search-name"
id="saved-search-name"
class="saved-search-name"
value=""
required
pattern="[^&quot;&amp;=&lt;&gt;\/]*" title="The following characters are not allowed in the Name field: &quot;&amp;=&lt;&gt;/">
</div>
<div class="action-panel-control-wrap">
<label for="saved-search-term" class="action-panel-label required-field-asterisk">
Search terms:
</label>
<textarea name="saved-search-term" id="saved-search-term" class="saved-search-term" required></textarea>
</div>
<div class="test-search-term-wrap">
<a href="#" class="try-search-term">Test search terms</a>
</div>
<div class="choice-group action-panel-extra-margin-top">
<span class="action-panel-label" id="fieldset-label">
Would you like email updates of new search results?
</span>
<fieldset id="saved-search-alert" aria-describedby="fieldset-label">
<legend class="usa-sr-only">Saved Search Alert Radio Buttons</legend>
<ul class="radio-group-items">
<li>
<input type="radio" id="saved-search-alert-yes" class="saved-search-alert-yes" name="saved-search-alert" value="yes" checked>
<label for="saved-search-alert-yes" class="action-panel-label">Yes</label>
</li>
<li>
<input aria-label="No radio input" type="radio" id="saved-search-alert-no" class="saved-search-alert-no" name="saved-search-alert" value="no">
<label for="saved-search-alert-no" class="action-panel-label">No</label>
</li>
</ul>
</fieldset>
</div>
<div class="alert-schedule-wrap">
<div class="action-panel-control-wrap">
<label class="action-panel-label">
Email:
</label>
<span aria-label="Email address" id="saved-search-email" class="action-panel-label"><span class="action-panel-label-bold"></span> (<a class="myncbi-account-settings" href="https://www.ncbi.nlm.nih.gov/account/settings/">change</a>)</span>
</div>
<div class="action-panel-control-wrap action-panel-extra-margin-top">
<label for="saved-search-frequency" class="action-panel-label">
Frequency:
</label>
<select id="saved-search-frequency" class="no-border-panel-selector saved-search-frequency">
<option value="monthly">Monthly</option>
<option value="weekly">Weekly</option>
<option value="daily">Daily</option>
</select>
</div>
<div class="action-panel-control-wrap saved-search-monthly-additional">
<label for="saved-search-monthly-on-day" class="action-panel-label">
Which day?
</label>
<select id="saved-search-monthly-on-day" class="no-border-panel-selector">
<option value="Sunday">The first Sunday</option>
<option value="Monday">The first Monday</option>
<option value="Tuesday">The first Tuesday</option>
<option value="Wednesday">The first Wednesday</option>
<option value="Thursday">The first Thursday</option>
<option value="Friday">The first Friday</option>
<option value="Saturday">The first Saturday</option>
<option value="day">The first day</option>
<option value="weekday">The first weekday</option>
</select>
</div>
<div class="action-panel-control-wrap saved-search-weekly-additional">
<label for="saved-search-weekly-on-day" class="action-panel-label">
Which day?
</label>
<select id="saved-search-weekly-on-day" class="no-border-panel-selector saved-search-weekly-on-day">
<option value="Sunday">Sunday</option>
<option value="Monday">Monday</option>
<option value="Tuesday">Tuesday</option>
<option value="Wednesday">Wednesday</option>
<option value="Thursday">Thursday</option>
<option value="Friday">Friday</option>
<option value="Saturday">Saturday</option>
</select>
</div>
<div class="action-panel-control-wrap">
<label for="saved-search-report" class="action-panel-label">
Report format:
</label>
<select id="saved-search-report" class="no-border-panel-selector saved-search-report">
<option value="DocSum">Summary</option>
<option value="DocSumText">Summary (text)</option>
<option value="Abstract">Abstract</option>
<option value="AbstractText">Abstract (text)</option>
<option value="MEDLINE">PubMed</option>
</select>
</div>
<div class="action-panel-control-wrap">
<label for="saved-search-amount" class="action-panel-label">
Send at most:
</label>
<select id="saved-search-amount" class="no-border-panel-selector saved-search-amount">
<option value="1">1 item</option>
<option value="5" selected>5 items</option>
<option value="10">10 items</option>
<option value="20">20 items</option>
<option value="50">50 items</option>
<option value="100">100 items</option>
<option value="200">200 items</option>
</select>
</div>
<div>
<input type="checkbox" id="saved-search-send-if-no-result" class="saved-search-send-if-no-result" name="saved-search-send-if-no-result">
<label for="saved-search-send-if-no-result" class="action-panel-label smaller-checkbox">
Send even when there aren't any new results
</label>
</div>
<div class="action-panel-control-wrap option-text-in-email-wrap">
<label for="saved-search-email-text" class="action-panel-label">
Optional text in email:
</label>
<textarea name="saved-search-email-text"
id="saved-search-email-text"
class="saved-search-email-text"></textarea>
</div>
</div>
<div class="action-panel-actions">
<button class="action-panel-submit"
type="submit"
data-loading-label="Saving..."
data-ga-category="save_share"
data-ga-action="alert"
data-ga-label="save">
Save
</button>
<button class="action-panel-cancel"
aria-label="Close 'Your saved search' panel"
ref="linksrc=close_saved_search_panel"
aria-controls="saved-search-action-panel"
aria-expanded="false"
data-ga-category="save_share"
data-ga-action="alert"
data-ga-label="cancel">
Cancel
</button>
</div>
</form>
</div>
</div>
<div id="citation-manager-action-panel" class="citation-manager-action-panel action-panel" aria-hidden="true">
<div class="inner-wrap">
<h2 class="action-panel-heading">
Create a file for external citation management software
</h2>
<form id="citation-manager-action-panel-form"
class="action-panel-content action-form"
action="/results-export-ids/"
data-by-search-action="/results-export-search-data/"
data-by-ids-action="/results-export-ids/"
method="post"
data-by-search-method="post"
data-by-ids-method="post">
<input type="hidden" name="csrfmiddlewaretoken" value="FDgGdqa9AUp1mhU3YmmYkYAqbS7TDc8LWq0LQgDvavcvgI0TBFZ0O664JWP5wNG5">
<input name="results-format" type="hidden" value="pubmed"/>
<div class="action-panel-actions">
<button class="action-panel-submit"
type="submit"
data-loading-label="Sending..."
data-ga-category="save_share"
data-ga-action="citation_manager"
data-ga-label="save">
Create file
</button>
<button class="action-panel-cancel"
aria-label="Close 'Send citations to citation manager' panel"
ref="linksrc=close_citation_manager_panel"
aria-controls="citation-manager-action-panel"
aria-expanded="false"
data-ga-category="save_share"
data-ga-action="citation_manager"
data-ga-label="cancel">
Cancel
</button>
</div>
</form>
</div>
</div>
<div id="rss-action-panel" class="rss-action-panel action-panel " aria-hidden="true">
<div class="inner-wrap">
<h2 class="action-panel-heading">
Your RSS Feed
</h2>
<form id="rss-action-panel-form"
class="rss-action-panel-form action-panel-content action-form"
data-create-rss-feed-url="/create-rss-feed-url/"
data-search-form-term-value="">
<input type="hidden" name="csrfmiddlewaretoken" value="FDgGdqa9AUp1mhU3YmmYkYAqbS7TDc8LWq0LQgDvavcvgI0TBFZ0O664JWP5wNG5">
<div class="action-panel-control-wrap">
<label for="rss-name" class="action-panel-label required-field-asterisk">
Name of RSS Feed:
</label>
<input maxlength="200"
placeholder="Name"
type="text"
name="rss-name"
id="rss-name"
class="rss-name"
value=''
required
pattern="[^&quot;&amp;=&lt;&gt;\/]*" title="The following characters are not allowed in the Name field: &quot;&amp;=&lt;&gt;/">
</div>
<div class="rss-limit-wrap">
<div class="action-panel-control-wrap action-panel-extra-margin-top">
<label for="rss-limit" class="action-panel-label">
Number of items displayed:
</label>
<select id="rss-limit" class="no-border-panel-selector rss-limit">
<option value="5">5</option>
<option value="10">10</option>
<option value="15" selected="selected">15</option>
<option value="20">20</option>
<option value="50">50</option>
<option value="100">100</option>
</select>
</div>
</div>
<div class="action-panel-actions">
<button class="action-panel-submit"
type="submit"
data-loading-label="Creating..."
data-ga-category="save_share"
data-ga-action="alert"
data-ga-label="save">
Create RSS
</button>
<button class="action-panel-cancel"
aria-label="Close 'Your RSS' panel"
ref="linksrc=close_rss_panel"
aria-controls="rss-action-panel"
aria-expanded="false"
data-ga-category="save_share"
data-ga-action="alert"
data-ga-label="cancel">
Cancel
</button>
</div>
<div class="action-panel-control-wrap rss-link-copy-wrap">
<label for="rss-link" class="usa-sr-only">RSS Link</label>
<input placeholder="Your RSS Feed Link" type="text" name="rss-link" id="rss-link" class="rss-link" title="RSS Link">
<button
type="button"
disabled
class="rss-link-copy-button disabled"
data-ga-category="save_share"
data-ga-action="rss"
data-ga-label="copy">
Copy
</button>
</div>
</form>
</div>
</div>
</div>
</div>
<div class="article-page" id="article-page" data-article-pmid="20157491">
<aside class="page-sidebar">
<div class="inner-wrap">
<div class="full-text-links">
<div class="full-view">
<h3 class="title">
Full text links
</h3>
<div class="full-text-links-list">
<a class="link-item
dialog-focus"
href="https://academic.oup.com/database/article-lookup/doi/10.1093/database/bap018"
target="_blank"
rel="noopener"
ref="linksrc=fulltextorjournal_fulltext&amp;is_pmc=False&amp;PrId=7898&amp;itool=Abstract-def&amp;log$=linkouticon&amp;uid=20157491&amp;db=pubmed&amp;nlmid=101517697"
title="See full text options at Silverchair Information Systems"
data-ga-category="full_text"
data-ga-action="Silverchair Information Systems"
data-ga-label="20157491"
><img src="https://cdn.ncbi.nlm.nih.gov/corehtml/query/egifs/https:--academic.oup.com-images-oup_pubmed.png" alt="Silverchair Information Systems full text link"><span class="text">
Silverchair Information Systems
</span></a><a class="link-item
pmc
"
href="https://pmc.ncbi.nlm.nih.gov/articles/pmid/20157491/"
target="_blank"
rel="noopener"
ref="linksrc=fulltextorjournal_fulltext&amp;is_pmc=True&amp;PrId=3494&amp;itool=Abstract-def&amp;log$=linkouticon&amp;uid=20157491&amp;db=pubmed&amp;nlmid=101517697"
title="Free full text at PubMed Central"
data-ga-category="full_text"
data-ga-action="PMC"
data-ga-label="20157491"
><span class="text">
Free PMC article
</span></a>
</div>
</div>
<div class="short-view">
<a href="#" class="full-text-links-button full-text-links-dialog-trigger">
Full text links
</a>
</div>
</div>
<div class="actions-buttons sidebar"><h3 class="title">Actions</h3><div class="inner-wrap"><button class="citation-button citation-dialog-trigger"
aria-label="Open dialog with citation text in different styles"
data-ga-category="save_share"
data-ga-action="cite"
data-ga-label="open"
data-all-citations-url="/20157491/citations/"
data-citation-style="nlm"
data-pubmed-format-link="/20157491/export/"><span class="button-label">Cite</span></button><link type="text/css" href="ncbi-overlay-block/src/overlay-block.css"><div class="collections-button-container" data-article-id="20157491" data-article-db="pubmed"><button class="collections-button collections-dialog-trigger"
aria-label="Save article in MyNCBI collections."
data-ga-category="collections_button"
data-ga-action="click"
data-ga-label="collections_button"
data-collections-open-dialog-enabled="false"
data-collections-open-dialog-url="https://account.ncbi.nlm.nih.gov/?back_url=https%3A%2F%2Fpubmed.ncbi.nlm.nih.gov%2F20157491%2F%23open-collections-dialog"
data-in-collections="false"><span class="button-label">Collections</span></button><div class="overlay" role="dialog"><div id="collections-action-dialog"
class="dialog collections-dialog"
aria-hidden="true"><div class="title">Add to Collections</div><div class="collections-action-panel action-panel"><form id="collections-action-dialog-form"
class="collections-action-panel-form action-panel-content action-form action-panel-smaller-selectors"
data-existing-collections-url="/list-existing-collections/"
data-add-to-existing-collection-url="/add-to-existing-collection/"
data-create-and-add-to-new-collection-url="/create-and-add-to-new-collection/"
data-myncbi-max-collection-name-length="100"
data-collections-root-url="https://www.ncbi.nlm.nih.gov/myncbi/collections/"><input type="hidden" name="csrfmiddlewaretoken" value="FDgGdqa9AUp1mhU3YmmYkYAqbS7TDc8LWq0LQgDvavcvgI0TBFZ0O664JWP5wNG5"><div class="choice-group" role="radiogroup"><ul class="radio-group-items"><li><input type="radio"
id="collections-action-dialog-new"
class="collections-new"
name="collections"
value="new"
data-ga-category="collections_button"
data-ga-action="click"
data-ga-label="collections_radio_new"><label for="collections-action-dialog-new">Create a new collection</label></li><li><input type="radio"
id="collections-action-dialog-existing"
class="collections-existing"
name="collections"
value="existing"
checked="true"
data-ga-category="collections_button"
data-ga-action="click"
data-ga-label="collections_radio_existing"><label for="collections-action-dialog-existing">Add to an existing collection</label></li></ul></div><div class="controls-wrapper"><div class="action-panel-control-wrap new-collections-controls"><label for="collections-action-dialog-add-to-new" class="action-panel-label required-field-asterisk">
Name your collection:
</label><input
type="text"
name="add-to-new-collection"
id="collections-action-dialog-add-to-new"
class="collections-action-add-to-new"
pattern="[^&quot;&amp;=&lt;&gt;\/]*" title="The following characters are not allowed in the Name field: &quot;&amp;=&lt;&gt;/"
maxlength="100"
data-ga-category="collections_button"
data-ga-action="create_collection"
data-ga-label="non_favorties_collection"><div class="collections-new-name-too-long usa-input-error-message selection-validation-message">
Name must be less than 100 characters
</div></div><div class="action-panel-control-wrap existing-collections-controls"><label for="collections-action-dialog-add-to-existing" class="action-panel-label">
Choose a collection:
</label><select id="collections-action-dialog-add-to-existing"
class="action-panel-selector collections-action-add-to-existing"
data-ga-category="collections_button"
data-ga-action="select_collection"
data-ga-label="($('.collections-action-add-to-existing').val() === 'Favorites') ? 'Favorites' : 'non_favorites_collection'"></select><div class="collections-retry-load-on-error usa-input-error-message selection-validation-message">
Unable to load your collection due to an error<br><a href="#">Please try again</a></div></div></div><div class="action-panel-actions"><button class="action-panel-submit"
type="submit"
data-loading-label="Adding..."
data-pinger-ignore
data-ga-category="collections_button"
data-ga-action="click"
data-ga-label="add">
Add
</button><button class="action-panel-cancel"
aria-label="Close 'Add to Collections' panel"
ref="linksrc=close_collections_panel"
aria-controls="collections-action-panel"
aria-expanded="false"
data-ga-category="collections_button"
data-ga-action="click"
data-ga-label="cancel">
Cancel
</button></div></form></div></div></div></div><button class="more-actions-button more-actions-dialog-trigger"
title="Open dialog with more actions to take"
ref="linksrc=more_actions_btn"></button><div class="display-options" data-format-key="format"
data-default-format-value="abstract"
data-current-format-value="abstract" role="region"><button
class="trigger usa-button"
title="Change format"
data-ga-category="display_options"
data-ga-action="display_options_dialog"><span class="button-label">Display options</span></button><div class="dropdown" hidden><div class="title">
Display options
</div><div class="content"><div class="format-container"><span class="option-label">
Format
</span><select name="format" data-initial-value="abstract" aria-label="Display format" id="sidebar-actions-display-format"><option value="abstract">Abstract</option><option value="pubmed">PubMed</option><option value="pmid">PMID</option></select></div></div></div></div></div></div>
<div class="social-sharing">
<h3 class="title">
Share
</h3>
<ul class="social-sharing-links usa-unstyled-list">
<li>
<a href="http://twitter.com/intent/tweet?text=Understanding%20PubMed%20user%20search%20behavior%20through%20log%20analysis%20https%3A//pubmed.ncbi.nlm.nih.gov/20157491/"
class="share-link share-link-twitter"
rel="noreferrer noopener"
target="Pubmed-Social-Media-Share-Popup"
title="Share article on Twitter"
data-ga-category="save_share"
data-ga-action="social"
data-ga-label="twitter"></a>
</li>
<li>
<a href="http://www.facebook.com/sharer/sharer.php?u=https%3A//pubmed.ncbi.nlm.nih.gov/20157491/"
class="share-link share-link-facebook"
rel="noreferrer noopener"
target="Pubmed-Social-Media-Share-Popup"
title="Share article on Facebook"
data-ga-category="save_share"
data-ga-action="social"
data-ga-label="fb"></a>
</li>
<li>
<div class="share-permalink">
<button class="trigger"
title="Show article permalink"
ref="linksrc=show_permalink_btn">
</button>
<div class="dropdown" hidden>
<div class="title">
Permalink
</div>
<div class="content">
<input type="text"
class="permalink-text"
value="https://pubmed.ncbi.nlm.nih.gov/20157491/"
aria-label="Article permalink"/><button class="permalink-copy-button usa-button-primary"
title="Copy article permalink"
data-ga-category="save_share"
data-ga-action="link"
data-ga-label="copy_link"><span class="button-title">Copy</span></button>
</div>
</div>
</div>
</li>
</ul>
</div>
<nav class="page-navigator" role="navigation" aria-label="Page navigation">
<div class="full-view">
<h3 class="title">
Page navigation
</h3>
<ul class="items-list">
<li class="heading ">
<a href="#heading"
aria-label="navigate to Title &amp; authors section"
data-ga-category="page_nav"
data-ga-action="heading">
Title &amp; authors
</a>
</li>
<li class="abstract ">
<a href="#abstract"
aria-label="navigate to Abstract section"
data-ga-category="page_nav"
data-ga-action="abstract">
Abstract
</a>
</li>
<li class="figures ">
<a href="#figures"
aria-label="navigate to Figures section"
data-ga-category="page_nav"
data-ga-action="figures">
Figures
</a>
</li>
<li class="similar ">
<a href="#similar"
aria-label="navigate to Similar articles section"
data-ga-category="page_nav"
data-ga-action="similar">
Similar articles
</a>
</li>
<li class="citedby ">
<a href="#citedby"
aria-label="navigate to Cited by section"
data-ga-category="page_nav"
data-ga-action="citedby">
Cited by
</a>
</li>
<li class="references ">
<a href="#references"
aria-label="navigate to References section"
data-ga-category="page_nav"
data-ga-action="references">
References
</a>
</li>
<li class="linkout ">
<a href="#linkout"
aria-label="navigate to LinkOut - more resources section"
data-ga-category="page_nav"
data-ga-action="linkout">
LinkOut - more resources
</a>
</li>
</ul>
</div>
<select class="short-view" autocomplete="off" title="navigate to selected section" aria-label="Navigate to page section">
<option value="heading">Title &amp; authors</option>
<option value="abstract">Abstract</option>
<option value="figures">Figures</option>
<option value="similar">Similar articles</option>
<option value="citedby">Cited by</option>
<option value="references">References</option>
<option value="linkout">LinkOut - more resources</option>
</select>
</nav>
</div>
</aside>
<main class="article-details" id="article-details">
<!-- "Filters applied" shows only when page is redirected from search -->
<!-- because search found one result -->
<header class="heading" id="heading">
<div class="full-view" id="full-view-heading">
<div class="article-citation">
<div class="article-source">
<div class="journal-actions dropdown-block"><button id="full-view-journal-trigger"
class="journal-actions-trigger trigger"
ref="linksrc=journal_actions_btn"
title="Database : the journal of biological databases and curation"
tabindex="0"
aria-controls="full-view-journal"
aria-expanded="false"
aria-label="Toggle dropdown menu for journal Database : the journal of biological databases and curation"
data-pinger-ignore>
Database (Oxford)
</button><div id="full-view-journal"
class="journal-actions-dropdown dropdown dropdown-container"
hidden
aria-label="Dropdown menu for journal Database : the journal of biological databases and curation"><div class="title">Actions</div><div class="content"><ul class="journal-actions-links"><li><a class="search-in-pubmed-link dropdown-block-link"
href="/?term=%22Database+%28Oxford%29%22%5Bjour%5D&amp;sort=date&amp;sort_order=desc"
data-href="/?term=%22Database+%28Oxford%29%22%5Bjour%5D&amp;sort=date&amp;sort_order=desc"
ref="linksrc=search_in_pubmed_journal_name_link&amp;journal_abbrev=Database (Oxford)"
data-ga-category="search"
data-ga-action="journal_link"
data-ga-label="Database (Oxford)">
Search in PubMed
</a></li><li><a class="search-in-nlm-catalog-link dropdown-block-link"
ref ="linksrc=search_in_nlm_catalog_link"
href="https://www.ncbi.nlm.nih.gov/nlmcatalog?term=%22Database+%28Oxford%29%22%5BTitle+Abbreviation%5D"
data-ga-category="search_catalog"
data-ga-action="journal_link"
data-ga-label="Database (Oxford)">
Search in NLM Catalog
</a></li><li><a class="add-to-search-link dropdown-block-link"
ref ="linksrc=add_to_search_link"
role="button"
data-search-term='"Database (Oxford)"[jour]'
data-ga-category="search"
data-ga-action="add_to_search"
data-ga-label='"Database (Oxford)"[jour]'
href="#">
Add to Search
</a></li></ul></div></div></div><span class="period">. </span><span class="cit">2009:2009:bap018.</span>
</div>
<span class="citation-doi">
doi: 10.1093/database/bap018.
</span>
<span class="secondary-date">
Epub 2009 Nov 27.
</span>
</div>
<h1 class="heading-title">
Understanding PubMed user search behavior through log analysis
</h1>
<div class="inline-authors">
<div class="authors">
<div class="authors-list">
<span class="authors-list-item "><a class="full-name"
href="/?term=Islamaj+Dogan+R&amp;cauthor_id=20157491"
ref="linksrc=author_name_link"
data-ga-category="search"
data-ga-action="author_link"
data-ga-label="Rezarta Islamaj Dogan">Rezarta Islamaj Dogan</a><sup class="affiliation-links"><span class="author-sup-separator">&nbsp;</span><a class="affiliation-link" title="National Center for Biotechnology Information, US National Library of Medicine, Bethesda, MD 20894, USA." href="#full-view-affiliation-1" ref="linksrc=author_aff">
1
</a></sup><span class="comma">,&nbsp;</span></span><span class="authors-list-item "><a class="full-name"
href="/?term=Murray+GC&amp;cauthor_id=20157491"
ref="linksrc=author_name_link"
data-ga-category="search"
data-ga-action="author_link"
data-ga-label="G Craig Murray">G Craig Murray</a><span class="comma">,&nbsp;</span></span><span class="authors-list-item "><a class="full-name"
href="/?term=N%C3%A9v%C3%A9ol+A&amp;cauthor_id=20157491"
ref="linksrc=author_name_link"
data-ga-category="search"
data-ga-action="author_link"
data-ga-label="Aurélie Névéol">Aurélie Névéol</a><span class="comma">,&nbsp;</span></span><span class="authors-list-item "><a class="full-name"
href="/?term=Lu+Z&amp;cauthor_id=20157491"
ref="linksrc=author_name_link"
data-ga-category="search"
data-ga-action="author_link"
data-ga-label="Zhiyong Lu">Zhiyong Lu</a></span>
</div>
</div>
</div>
<div class="short-article-details">
Affiliations
<button
class="more-details"
id="toggle-authors"
data-alt-text="Collapse"
aria-controls="expanded-authors"
aria-expanded="false"
data-pinger-ignore
data-fetch-url="/20157491/long-authors/"
data-id-prefix="">
<span class="title">
Expand
</span>
</button>
</div>
<div class="extended-article-details" id="expanded-authors" aria-hidden="true">
<div class="expanded-authors" id="full-view-expanded-authors">
<div class="affiliations">
<h3 class="title">
Affiliation
</h3>
<ul class="item-list">
<li data-affiliation-id="full-view-affiliation-1"
id="full-view-affiliation-1"
><sup class="key">1</sup> National Center for Biotechnology Information, US National Library of Medicine, Bethesda, MD 20894, USA.</li>
</ul>
</div>
</div>
</div>
<ul class="identifiers" id="full-view-identifiers">
<li>
<span class="identifier pubmed">
<span class="id-label">
PMID:
</span>
<strong class="current-id" title="PubMed ID">20157491</strong>
</span>
</li>
<li>
<span class="identifier pmc">
<span class="id-label">
PMCID:
</span>
<a class="id-link"
target="_blank"
rel="noopener"
ref="linksrc=article_id_link&amp;article_id=PMC2797455&amp;id_type=PMC"
href="https://pmc.ncbi.nlm.nih.gov/articles/PMC2797455/"
data-ga-category="full_text"
data-ga-action="PMCID"
>
PMC2797455
</a>
</span>
</li>
<li>
<span class="identifier doi">
<span class="id-label">
DOI:
</span>
<a class="id-link"
target="_blank"
rel="noopener"
ref="linksrc=article_id_link&amp;article_id=10.1093/database/bap018&amp;id_type=DOI"
href="https://doi.org/10.1093/database/bap018"
data-ga-category="full_text"
data-ga-action="DOI"
>
10.1093/database/bap018
</a>
</span>
</li>
</ul>
<div class="in-clipboard-label " hidden>
Item in Clipboard
</div>
</div>
<div class="short-view" id="short-view-heading">
<h1 class="heading-title">
Understanding PubMed user search behavior through log analysis
</h1>
<div class="short-citation">
<span class="authors-list">
<span class="authors-list-item "><span class="full-name">Rezarta Islamaj Dogan</span><span class="citation-separator">&nbsp;et al.</span></span>
</span>
<span class="citation-journal">
Database (Oxford)<span class="citation-separator">.</span>
</span>
<span class="date">
<span class="citation-year">2009</span><span class="citation-separator">.</span>
</span>
</div>
<div class="more-article-details-section with-display-settings">
<button class="more-article-details"
id="toggle-article-details"
data-alt-text="Hide details"
ref="linksrc=toggle_article_details"
aria-controls="full-article-details"
aria-expanded="false"
data-fetch-url="/20157491/long-authors/"
data-id-prefix="">
<span class="title">Show details</span>
</button>
<div class="display-options" data-format-key="format"
data-default-format-value="abstract"
data-current-format-value="abstract" role="region">
<button
class="trigger usa-button"
title="Change format"
data-ga-category="display_options"
data-ga-action="display_options_dialog">
<span class="button-label">Display options</span>
</button>
<div class="dropdown" hidden>
<div class="title">
Display options
</div>
<div class="content">
<div class="format-container">
<span class="option-label">
Format
</span>
<select name="format" data-initial-value="abstract" aria-label="Display format" id="mobile-display-format">
<option value="abstract">Abstract</option>
<option value="pubmed">PubMed</option>
<option value="pmid">PMID</option>
</select>
</div>
</div>
</div>
</div>
</div>
<div class="extended-article-details" id="full-article-details" aria-hidden="true">
<div class="article-citation">
<div class="article-source">
<div class="journal-actions dropdown-block"><button id="short-view-journal-trigger"
class="journal-actions-trigger trigger"
ref="linksrc=journal_actions_btn"
title="Database : the journal of biological databases and curation"
tabindex="0"
aria-controls="short-view-journal"
aria-expanded="false"
aria-label="Toggle dropdown menu for journal Database : the journal of biological databases and curation"
data-pinger-ignore>
Database (Oxford)
</button><div id="short-view-journal"
class="journal-actions-dropdown dropdown dropdown-container"
hidden
aria-label="Dropdown menu for journal Database : the journal of biological databases and curation"><div class="title">Actions</div><div class="content"><ul class="journal-actions-links"><li><a class="search-in-pubmed-link dropdown-block-link"
href="/?term=%22Database+%28Oxford%29%22%5Bjour%5D&amp;sort=date&amp;sort_order=desc"
data-href="/?term=%22Database+%28Oxford%29%22%5Bjour%5D&amp;sort=date&amp;sort_order=desc"
ref="linksrc=search_in_pubmed_journal_name_link&amp;journal_abbrev=Database (Oxford)"
data-ga-category="search"
data-ga-action="journal_link"
data-ga-label="Database (Oxford)">
Search in PubMed
</a></li><li><a class="search-in-nlm-catalog-link dropdown-block-link"
ref ="linksrc=search_in_nlm_catalog_link"
href="https://www.ncbi.nlm.nih.gov/nlmcatalog?term=%22Database+%28Oxford%29%22%5BTitle+Abbreviation%5D"
data-ga-category="search_catalog"
data-ga-action="journal_link"
data-ga-label="Database (Oxford)">
Search in NLM Catalog
</a></li><li><a class="add-to-search-link dropdown-block-link"
ref ="linksrc=add_to_search_link"
role="button"
data-search-term='"Database (Oxford)"[jour]'
data-ga-category="search"
data-ga-action="add_to_search"
data-ga-label='"Database (Oxford)"[jour]'
href="#">
Add to Search
</a></li></ul></div></div></div><span class="period">. </span><span class="cit">2009:2009:bap018.</span>
</div>
<span class="citation-doi">
doi: 10.1093/database/bap018.
</span>
<span class="secondary-date">
Epub 2009 Nov 27.
</span>
</div>
<div class="expanded-authors" id="short-view-expanded-authors">
<div class="authors">
<h3 class="title">
Authors
</h3>
<div class="authors-list">
<span class="authors-list-item "><a class="full-name"
href="/?term=Islamaj+Dogan+R&amp;cauthor_id=20157491"
ref="linksrc=author_name_link"
data-ga-category="search"
data-ga-action="author_link"
data-ga-label="Rezarta Islamaj Dogan">Rezarta Islamaj Dogan</a><sup class="affiliation-links"><span class="author-sup-separator">&nbsp;</span><a class="affiliation-link" title="National Center for Biotechnology Information, US National Library of Medicine, Bethesda, MD 20894, USA." href="#short-view-affiliation-1" ref="linksrc=author_aff">
1
</a></sup><span class="comma">,&nbsp;</span></span><span class="authors-list-item "><a class="full-name"
href="/?term=Murray+GC&amp;cauthor_id=20157491"
ref="linksrc=author_name_link"
data-ga-category="search"
data-ga-action="author_link"
data-ga-label="G Craig Murray">G Craig Murray</a><span class="comma">,&nbsp;</span></span><span class="authors-list-item "><a class="full-name"
href="/?term=N%C3%A9v%C3%A9ol+A&amp;cauthor_id=20157491"
ref="linksrc=author_name_link"
data-ga-category="search"
data-ga-action="author_link"
data-ga-label="Aurélie Névéol">Aurélie Névéol</a><span class="comma">,&nbsp;</span></span><span class="authors-list-item "><a class="full-name"
href="/?term=Lu+Z&amp;cauthor_id=20157491"
ref="linksrc=author_name_link"
data-ga-category="search"
data-ga-action="author_link"
data-ga-label="Zhiyong Lu">Zhiyong Lu</a></span>
</div>
</div>
<div class="affiliations">
<h3 class="title">
Affiliation
</h3>
<ul class="item-list">
<li data-affiliation-id="short-view-affiliation-1"
id="short-view-affiliation-1"
><sup class="key">1</sup> National Center for Biotechnology Information, US National Library of Medicine, Bethesda, MD 20894, USA.</li>
</ul>
</div>
</div>
<ul class="identifiers" id="short-view-identifiers">
<li>
<span class="identifier pubmed">
<span class="id-label">
PMID:
</span>
<strong class="current-id" title="PubMed ID">20157491</strong>
</span>
</li>
<li>
<span class="identifier pmc">
<span class="id-label">
PMCID:
</span>
<a class="id-link"
target="_blank"
rel="noopener"
ref="linksrc=article_id_link&amp;article_id=PMC2797455&amp;id_type=PMC"
href="https://pmc.ncbi.nlm.nih.gov/articles/PMC2797455/"
data-ga-category="full_text"
data-ga-action="PMCID"
>
PMC2797455
</a>
</span>
</li>
<li>
<span class="identifier doi">
<span class="id-label">
DOI:
</span>
<a class="id-link"
target="_blank"
rel="noopener"
ref="linksrc=article_id_link&amp;article_id=10.1093/database/bap018&amp;id_type=DOI"
href="https://doi.org/10.1093/database/bap018"
data-ga-category="full_text"
data-ga-action="DOI"
>
10.1093/database/bap018
</a>
</span>
</li>
</ul>
<div class="in-clipboard-label " hidden>
Item in Clipboard
</div>
</div>
</div>
</header>
<div class="actions-buttons inline"><div class="inner-wrap"><button class="full-text-links-button full-text-links-dialog-trigger"
title="Open dialog with full text links"
ref="linksrc=full_text_links">
Full text links
</button><button class="citation-button citation-dialog-trigger"
aria-label="Open dialog with citation text in different styles"
data-ga-category="save_share"
data-ga-action="cite"
data-ga-label="open"
data-all-citations-url="/20157491/citations/"
data-citation-style="nlm"
data-pubmed-format-link="/20157491/export/"><span class="button-label">Cite</span></button><button class="more-actions-button more-actions-dialog-trigger"
title="Open dialog with more actions to take"
ref="linksrc=more_actions_btn"></button><div class="display-options" data-format-key="format"
data-default-format-value="abstract"
data-current-format-value="abstract" role="region"><button
class="trigger usa-button"
title="Change format"
data-ga-category="display_options"
data-ga-action="display_options_dialog"><span class="button-label">Display options</span></button><div class="dropdown" hidden><div class="title">
Display options
</div><div class="content"><div class="format-container"><span class="option-label">
Format
</span><select name="format" data-initial-value="abstract" aria-label="Display format" id="inline-actions-display-format"><option value="abstract">Abstract</option><option value="pubmed">PubMed</option><option value="pmid">PMID</option></select></div></div></div></div></div></div>
<div class="abstract" id="abstract">
<h2 class="title">
Abstract
</h2>
<div class="abstract-content selected"
id="eng-abstract">
<p>
This article reports on a detailed investigation of PubMed users' needs and behavior as a step toward improving biomedical information retrieval. PubMed is providing free service to researchers with access to more than 19 million citations for biomedical articles from MEDLINE and life science journals. It is accessed by millions of users each day. Efficient search tools are crucial for biomedical researchers to keep abreast of the biomedical literature relating to their own research. This study provides insight into PubMed users' needs and their behavior. This investigation was conducted through the analysis of one month of log data, consisting of more than 23 million user sessions and more than 58 million user queries. Multiple aspects of users' interactions with PubMed are characterized in detail with evidence from these logs. Despite having many features in common with general Web searches, biomedical information searches have unique characteristics that are made evident in this study. PubMed users are more persistent in seeking information and they reformulate queries often. The three most frequent types of search are search by author name, search by gene/protein, and search by disease. Use of abbreviation in queries is very frequent. Factors such as result set size influence users' decisions. Analysis of characteristics such as these plays a critical role in identifying users' information needs and their search habits. In turn, such an analysis also provides useful insight for improving biomedical information retrieval.Database URL:http://www.ncbi.nlm.nih.gov/PubMed.
</p>
</div>
</div>
<p class="disclaimer" id="disclaimer">
<a href="/disclaimer/" target="_blank" data-ga-category="literature_resources"
data-ga-action="disclaimer_link" data-ga-label="under_abstract">PubMed Disclaimer</a>
</p>
<div class="figures" id="figures">
<h2 class="title">
Figures
</h2>
<div class="figures-list" id="slides-container"
itemscope itemtype="http://schema.org/ImageGallery">
<figure class="figure-item "
itemscope itemtype="http://schema.org/ImageObject"
itemprop="associatedMedia"
data-slide-index="0"
data-label-slug="figure-1">
<a class="figure-link"
href="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/1add/2797455/7ba9c46094ef/bap018f1.jpg"
itemprop="contentUrl"
aria-describedby="figure-caption-0"
role="button"
data-image-width="640"
data-image-height="427"
data-image-alt="Figure 1."
data-pmc-id="PMC2797455"
data-figure-id="F1">
<img class="figure-thumb" itemprop="thumbnail"
id="article-image-0"
src="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/1add/2797455/1d4a51af38cd/bap018f1.gif"
alt="Figure 1." />
</a>
<meta itemprop="width" itemtype="http://schema.org/ImageObject" content="640">
<meta itemprop="height" itemtype="http://schema.org/ImageObject" content="427">
<div class="figure-caption figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="caption" aria-hidden="true">
<div class="caption-wrap">
<strong class="figure-label">
<p> Figure 1. </p>
</strong>
<div class="figure-caption-contents"><p> An overview of user interactions… </p></div>
</div>
</div>
<div class="figure-caption-medium figure-caption-text" aria-hidden="true">
<strong class="figure-label">
<p> Figure 1. </p>
</strong>
<div class="figure-caption-contents"><p> An overview of user interactions with PubMed. A user queries PubMed or uses… </p></div>
</div>
<figcaption id="figure-caption-0" class="figure-caption-full figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="description">
<strong class="figure-label">
Figure 1.
</strong>
<div class="figure-caption-contents">An overview of user interactions with PubMed. A user queries PubMed or uses other systems for a particular biomedical information need. Offered a set of retrieved documents, the user can browse the result set and subsequently click to view abstracts or full-text articles, issue a new query or abandon the current search. Solid lines show the basic user action leading to a set of results. Dashed lines show the possible follow-on actions.</div>
</figcaption>
</figure>
<figure class="figure-item "
itemscope itemtype="http://schema.org/ImageObject"
itemprop="associatedMedia"
data-slide-index="1"
data-label-slug="figure-2">
<a class="figure-link"
href="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/1add/2797455/55eb5a43f013/bap018f2.jpg"
itemprop="contentUrl"
aria-describedby="figure-caption-1"
role="button"
data-image-width="640"
data-image-height="450"
data-image-alt="Figure 2."
data-pmc-id="PMC2797455"
data-figure-id="F2">
<img class="figure-thumb" itemprop="thumbnail"
id="article-image-1"
src="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/1add/2797455/0a3755cb54c7/bap018f2.gif"
alt="Figure 2." />
</a>
<meta itemprop="width" itemtype="http://schema.org/ImageObject" content="640">
<meta itemprop="height" itemtype="http://schema.org/ImageObject" content="450">
<div class="figure-caption figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="caption" aria-hidden="true">
<div class="caption-wrap">
<strong class="figure-label">
<p> Figure 2. </p>
</strong>
<div class="figure-caption-contents"><p> Histogram view of the distribution… </p></div>
</div>
</div>
<div class="figure-caption-medium figure-caption-text" aria-hidden="true">
<strong class="figure-label">
<p> Figure 2. </p>
</strong>
<div class="figure-caption-contents"><p> Histogram view of the distribution of users, detailed by number of queries they… </p></div>
</div>
<figcaption id="figure-caption-1" class="figure-caption-full figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="description">
<strong class="figure-label">
Figure 2.
</strong>
<div class="figure-caption-contents">Histogram view of the distribution of users, detailed by number of queries they issue.</div>
</figcaption>
</figure>
<figure class="figure-item "
itemscope itemtype="http://schema.org/ImageObject"
itemprop="associatedMedia"
data-slide-index="2"
data-label-slug="figure-3">
<a class="figure-link"
href="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/1add/2797455/afcf7dcdb437/bap018f3.jpg"
itemprop="contentUrl"
aria-describedby="figure-caption-2"
role="button"
data-image-width="640"
data-image-height="479"
data-image-alt="Figure 3."
data-pmc-id="PMC2797455"
data-figure-id="F3">
<img class="figure-thumb" itemprop="thumbnail"
id="article-image-2"
src="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/1add/2797455/f2e7c9aa53c0/bap018f3.gif"
alt="Figure 3." />
</a>
<meta itemprop="width" itemtype="http://schema.org/ImageObject" content="640">
<meta itemprop="height" itemtype="http://schema.org/ImageObject" content="479">
<div class="figure-caption figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="caption" aria-hidden="true">
<div class="caption-wrap">
<strong class="figure-label">
<p> Figure 3. </p>
</strong>
<div class="figure-caption-contents"><p> Distribution of number of queries… </p></div>
</div>
</div>
<div class="figure-caption-medium figure-caption-text" aria-hidden="true">
<strong class="figure-label">
<p> Figure 3. </p>
</strong>
<div class="figure-caption-contents"><p> Distribution of number of queries relative to the number of tokens. </p></div>
</div>
<figcaption id="figure-caption-2" class="figure-caption-full figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="description">
<strong class="figure-label">
Figure 3.
</strong>
<div class="figure-caption-contents">Distribution of number of queries relative to the number of tokens.</div>
</figcaption>
</figure>
<figure class="figure-item "
itemscope itemtype="http://schema.org/ImageObject"
itemprop="associatedMedia"
data-slide-index="3"
data-label-slug="figure-4">
<a class="figure-link"
href="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/1add/2797455/4935179ae3d4/bap018f4.jpg"
itemprop="contentUrl"
aria-describedby="figure-caption-3"
role="button"
data-image-width="640"
data-image-height="471"
data-image-alt="Figure 4."
data-pmc-id="PMC2797455"
data-figure-id="F4">
<img class="figure-thumb" itemprop="thumbnail"
id="article-image-3"
src="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/1add/2797455/3a3fee47cb4a/bap018f4.gif"
alt="Figure 4." />
</a>
<meta itemprop="width" itemtype="http://schema.org/ImageObject" content="640">
<meta itemprop="height" itemtype="http://schema.org/ImageObject" content="471">
<div class="figure-caption figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="caption" aria-hidden="true">
<div class="caption-wrap">
<strong class="figure-label">
<p> Figure 4. </p>
</strong>
<div class="figure-caption-contents"><p> Annotated queries by category. Queries… </p></div>
</div>
</div>
<div class="figure-caption-medium figure-caption-text" aria-hidden="true">
<strong class="figure-label">
<p> Figure 4. </p>
</strong>
<div class="figure-caption-contents"><p> Annotated queries by category. Queries annotated with bibliographic categories (Author Name, Citation, Journal… </p></div>
</div>
<figcaption id="figure-caption-3" class="figure-caption-full figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="description">
<strong class="figure-label">
Figure 4.
</strong>
<div class="figure-caption-contents">Annotated queries by category. Queries annotated with bibliographic categories (Author Name, Citation, Journal Name and MEDLINE Title) are shown in purple, queries annotated with non-bibliographic categories (Gene/Protein, Disorder, Chemical/Drug, Biological Process, Medical Procedure, Living Being, Research Procedure, Cell Component, Body Part, Device or Tissue) are shown in blue, the percentage of queries containing an abbreviation is shown in yellow, and the queries that could not be fitted in the proposed set of categories are shown in red.</div>
</figcaption>
</figure>
<figure class="figure-item "
itemscope itemtype="http://schema.org/ImageObject"
itemprop="associatedMedia"
data-slide-index="4"
data-label-slug="figure-5">
<a class="figure-link"
href="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/1add/2797455/e7a394494451/bap018f5.jpg"
itemprop="contentUrl"
aria-describedby="figure-caption-4"
role="button"
data-image-width="640"
data-image-height="466"
data-image-alt="Figure 5."
data-pmc-id="PMC2797455"
data-figure-id="F5">
<img class="figure-thumb" itemprop="thumbnail"
id="article-image-4"
src="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/1add/2797455/3d7ff4337696/bap018f5.gif"
alt="Figure 5." />
</a>
<meta itemprop="width" itemtype="http://schema.org/ImageObject" content="640">
<meta itemprop="height" itemtype="http://schema.org/ImageObject" content="466">
<div class="figure-caption figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="caption" aria-hidden="true">
<div class="caption-wrap">
<strong class="figure-label">
<p> Figure 5. </p>
</strong>
<div class="figure-caption-contents"><p> Distribution of queries according to… </p></div>
</div>
</div>
<div class="figure-caption-medium figure-caption-text" aria-hidden="true">
<strong class="figure-label">
<p> Figure 5. </p>
</strong>
<div class="figure-caption-contents"><p> Distribution of queries according to their returned result set size. One third of… </p></div>
</div>
<figcaption id="figure-caption-4" class="figure-caption-full figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="description">
<strong class="figure-label">
Figure 5.
</strong>
<div class="figure-caption-contents">Distribution of queries according to their returned result set size. One third of queries returned from 1 to 20 citations, which are displayed in a single page.</div>
</figcaption>
</figure>
<figure class="figure-item "
itemscope itemtype="http://schema.org/ImageObject"
itemprop="associatedMedia"
data-slide-index="5"
data-label-slug="figure-6">
<a class="figure-link"
href="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/1add/2797455/b99e663ff9c9/bap018f6.jpg"
itemprop="contentUrl"
aria-describedby="figure-caption-5"
role="button"
data-image-width="640"
data-image-height="468"
data-image-alt="Figure 6."
data-pmc-id="PMC2797455"
data-figure-id="F6">
<img class="figure-thumb" itemprop="thumbnail"
id="article-image-5"
src="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/1add/2797455/bd8d8e5aa0c8/bap018f6.gif"
alt="Figure 6." />
</a>
<meta itemprop="width" itemtype="http://schema.org/ImageObject" content="640">
<meta itemprop="height" itemtype="http://schema.org/ImageObject" content="468">
<div class="figure-caption figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="caption" aria-hidden="true">
<div class="caption-wrap">
<strong class="figure-label">
<p> Figure 6. </p>
</strong>
<div class="figure-caption-contents"><p> Distribution of bibliographic queries (author… </p></div>
</div>
</div>
<div class="figure-caption-medium figure-caption-text" aria-hidden="true">
<strong class="figure-label">
<p> Figure 6. </p>
</strong>
<div class="figure-caption-contents"><p> Distribution of bibliographic queries (author name, journal name, title and other citation information)… </p></div>
</div>
<figcaption id="figure-caption-5" class="figure-caption-full figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="description">
<strong class="figure-label">
Figure 6.
</strong>
<div class="figure-caption-contents">Distribution of bibliographic queries (author name, journal name, title and other citation information) and non-bibliographic queries (disorder, gene/protein, research or medical procedure, device, body part, cell, tissue or living being) according to their result set size.</div>
</figcaption>
</figure>
<figure class="figure-item tail"
itemscope itemtype="http://schema.org/ImageObject"
itemprop="associatedMedia"
data-slide-index="6"
data-label-slug="figure-7">
<a class="figure-link"
href="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/1add/2797455/75556d494482/bap018f7.jpg"
itemprop="contentUrl"
aria-describedby="figure-caption-6"
role="button"
data-image-width="640"
data-image-height="461"
data-image-alt="Figure 7."
data-pmc-id="PMC2797455"
data-figure-id="F7">
<img class="figure-thumb" itemprop="thumbnail"
id="article-image-6"
src="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/1add/2797455/15b4a4e6d4c3/bap018f7.gif"
alt="Figure 7." />
</a>
<meta itemprop="width" itemtype="http://schema.org/ImageObject" content="640">
<meta itemprop="height" itemtype="http://schema.org/ImageObject" content="461">
<div class="figure-caption figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="caption" aria-hidden="true">
<div class="caption-wrap">
<strong class="figure-label">
<p> Figure 7. </p>
</strong>
<div class="figure-caption-contents"><p> Distribution of abstract view requests… </p></div>
</div>
</div>
<div class="figure-caption-medium figure-caption-text" aria-hidden="true">
<strong class="figure-label">
<p> Figure 7. </p>
</strong>
<div class="figure-caption-contents"><p> Distribution of abstract view requests for ordinal positions of the first page of… </p></div>
</div>
<figcaption id="figure-caption-6" class="figure-caption-full figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="description">
<strong class="figure-label">
Figure 7.
</strong>
<div class="figure-caption-contents">Distribution of abstract view requests for ordinal positions of the first page of results (data follows a Power law shown with the red line).</div>
</figcaption>
</figure>
<figure class="figure-item tail"
itemscope itemtype="http://schema.org/ImageObject"
itemprop="associatedMedia"
data-slide-index="7"
data-label-slug="figure-8">
<a class="figure-link"
href="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/1add/2797455/5c55ea9d9251/bap018f8.jpg"
itemprop="contentUrl"
aria-describedby="figure-caption-7"
role="button"
data-image-width="640"
data-image-height="444"
data-image-alt="Figure 8."
data-pmc-id="PMC2797455"
data-figure-id="F8">
<img class="figure-thumb" itemprop="thumbnail"
id="article-image-7"
src="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/1add/2797455/9992ca8b43d2/bap018f8.gif"
alt="Figure 8." />
</a>
<meta itemprop="width" itemtype="http://schema.org/ImageObject" content="640">
<meta itemprop="height" itemtype="http://schema.org/ImageObject" content="444">
<div class="figure-caption figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="caption" aria-hidden="true">
<div class="caption-wrap">
<strong class="figure-label">
<p> Figure 8. </p>
</strong>
<div class="figure-caption-contents"><p> Distribution of abstract retrievals per… </p></div>
</div>
</div>
<div class="figure-caption-medium figure-caption-text" aria-hidden="true">
<strong class="figure-label">
<p> Figure 8. </p>
</strong>
<div class="figure-caption-contents"><p> Distribution of abstract retrievals per ordinal position. </p></div>
</div>
<figcaption id="figure-caption-7" class="figure-caption-full figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="description">
<strong class="figure-label">
Figure 8.
</strong>
<div class="figure-caption-contents">Distribution of abstract retrievals per ordinal position.</div>
</figcaption>
</figure>
<figure class="figure-item tail"
itemscope itemtype="http://schema.org/ImageObject"
itemprop="associatedMedia"
data-slide-index="8"
data-label-slug="figure-9">
<a class="figure-link"
href="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/1add/2797455/74b24a6b341d/bap018f9.jpg"
itemprop="contentUrl"
aria-describedby="figure-caption-8"
role="button"
data-image-width="640"
data-image-height="422"
data-image-alt="Figure 9."
data-pmc-id="PMC2797455"
data-figure-id="F9">
<img class="figure-thumb" itemprop="thumbnail"
id="article-image-8"
src="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/1add/2797455/c3299c14ee65/bap018f9.gif"
alt="Figure 9." />
</a>
<meta itemprop="width" itemtype="http://schema.org/ImageObject" content="640">
<meta itemprop="height" itemtype="http://schema.org/ImageObject" content="422">
<div class="figure-caption figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="caption" aria-hidden="true">
<div class="caption-wrap">
<strong class="figure-label">
<p> Figure 9. </p>
</strong>
<div class="figure-caption-contents"><p> Distribution of abstract retrievals per… </p></div>
</div>
</div>
<div class="figure-caption-medium figure-caption-text" aria-hidden="true">
<strong class="figure-label">
<p> Figure 9. </p>
</strong>
<div class="figure-caption-contents"><p> Distribution of abstract retrievals per ordinal position (ratio is computed per page). </p></div>
</div>
<figcaption id="figure-caption-8" class="figure-caption-full figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="description">
<strong class="figure-label">
Figure 9.
</strong>
<div class="figure-caption-contents">Distribution of abstract retrievals per ordinal position (ratio is computed per page).</div>
</figcaption>
</figure>
<figure class="figure-item tail"
itemscope itemtype="http://schema.org/ImageObject"
itemprop="associatedMedia"
data-slide-index="9"
data-label-slug="figure-10">
<a class="figure-link"
href="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/1add/2797455/d9afba754739/bap018f10.jpg"
itemprop="contentUrl"
aria-describedby="figure-caption-9"
role="button"
data-image-width="640"
data-image-height="456"
data-image-alt="Figure 10."
data-pmc-id="PMC2797455"
data-figure-id="F10">
<img class="figure-thumb" itemprop="thumbnail"
id="article-image-9"
src="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/1add/2797455/2784c33f82f1/bap018f10.gif"
alt="Figure 10." />
</a>
<meta itemprop="width" itemtype="http://schema.org/ImageObject" content="640">
<meta itemprop="height" itemtype="http://schema.org/ImageObject" content="456">
<div class="figure-caption figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="caption" aria-hidden="true">
<div class="caption-wrap">
<strong class="figure-label">
<p> Figure 10. </p>
</strong>
<div class="figure-caption-contents"><p> Distribution of abstract and full-text… </p></div>
</div>
</div>
<div class="figure-caption-medium figure-caption-text" aria-hidden="true">
<strong class="figure-label">
<p> Figure 10. </p>
</strong>
<div class="figure-caption-contents"><p> Distribution of abstract and full-text requests given the number of citations returned per… </p></div>
</div>
<figcaption id="figure-caption-9" class="figure-caption-full figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="description">
<strong class="figure-label">
Figure 10.
</strong>
<div class="figure-caption-contents">Distribution of abstract and full-text requests given the number of citations returned per query. (Number of returned citations is shown in log scale).</div>
</figcaption>
</figure>
<figure class="figure-item tail"
itemscope itemtype="http://schema.org/ImageObject"
itemprop="associatedMedia"
data-slide-index="10"
data-label-slug="figure-11">
<a class="figure-link"
href="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/1add/2797455/a53bb8d60aca/bap018f11.jpg"
itemprop="contentUrl"
aria-describedby="figure-caption-10"
role="button"
data-image-width="640"
data-image-height="450"
data-image-alt="Figure 11."
data-pmc-id="PMC2797455"
data-figure-id="F11">
<img class="figure-thumb" itemprop="thumbnail"
id="article-image-10"
src="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/1add/2797455/c2ddd2494637/bap018f11.gif"
alt="Figure 11." />
</a>
<meta itemprop="width" itemtype="http://schema.org/ImageObject" content="640">
<meta itemprop="height" itemtype="http://schema.org/ImageObject" content="450">
<div class="figure-caption figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="caption" aria-hidden="true">
<div class="caption-wrap">
<strong class="figure-label">
<p> Figure 11. </p>
</strong>
<div class="figure-caption-contents"><p> Distribution of subsequent queries according… </p></div>
</div>
</div>
<div class="figure-caption-medium figure-caption-text" aria-hidden="true">
<strong class="figure-label">
<p> Figure 11. </p>
</strong>
<div class="figure-caption-contents"><p> Distribution of subsequent queries according to their time difference. </p></div>
</div>
<figcaption id="figure-caption-10" class="figure-caption-full figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="description">
<strong class="figure-label">
Figure 11.
</strong>
<div class="figure-caption-contents">Distribution of subsequent queries according to their time difference.</div>
</figcaption>
</figure>
<figure class="figure-item tail"
itemscope itemtype="http://schema.org/ImageObject"
itemprop="associatedMedia"
data-slide-index="11"
data-label-slug="figure-12">
<a class="figure-link"
href="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/1add/2797455/9102f94e0848/bap018f12.jpg"
itemprop="contentUrl"
aria-describedby="figure-caption-11"
role="button"
data-image-width="640"
data-image-height="442"
data-image-alt="Figure 12."
data-pmc-id="PMC2797455"
data-figure-id="F12">
<img class="figure-thumb" itemprop="thumbnail"
id="article-image-11"
src="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/1add/2797455/db7a1560bc91/bap018f12.gif"
alt="Figure 12." />
</a>
<meta itemprop="width" itemtype="http://schema.org/ImageObject" content="640">
<meta itemprop="height" itemtype="http://schema.org/ImageObject" content="442">
<div class="figure-caption figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="caption" aria-hidden="true">
<div class="caption-wrap">
<strong class="figure-label">
<p> Figure 12. </p>
</strong>
<div class="figure-caption-contents"><p> Distribution of queries subsequent to… </p></div>
</div>
</div>
<div class="figure-caption-medium figure-caption-text" aria-hidden="true">
<strong class="figure-label">
<p> Figure 12. </p>
</strong>
<div class="figure-caption-contents"><p> Distribution of queries subsequent to zero-result queries, detailed by the number of returned… </p></div>
</div>
<figcaption id="figure-caption-11" class="figure-caption-full figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="description">
<strong class="figure-label">
Figure 12.
</strong>
<div class="figure-caption-contents">Distribution of queries subsequent to zero-result queries, detailed by the number of returned citations.</div>
</figcaption>
</figure>
<figure class="figure-item tail"
itemscope itemtype="http://schema.org/ImageObject"
itemprop="associatedMedia"
data-slide-index="12"
data-label-slug="figure-13">
<a class="figure-link"
href="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/1add/2797455/01ed2b92320c/bap018f13.jpg"
itemprop="contentUrl"
aria-describedby="figure-caption-12"
role="button"
data-image-width="640"
data-image-height="452"
data-image-alt="Figure 13."
data-pmc-id="PMC2797455"
data-figure-id="F13">
<img class="figure-thumb" itemprop="thumbnail"
id="article-image-12"
src="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/1add/2797455/90213faddee1/bap018f13.gif"
alt="Figure 13." />
</a>
<meta itemprop="width" itemtype="http://schema.org/ImageObject" content="640">
<meta itemprop="height" itemtype="http://schema.org/ImageObject" content="452">
<div class="figure-caption figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="caption" aria-hidden="true">
<div class="caption-wrap">
<strong class="figure-label">
<p> Figure 13. </p>
</strong>
<div class="figure-caption-contents"><p> Distribution of the abandoned queries… </p></div>
</div>
</div>
<div class="figure-caption-medium figure-caption-text" aria-hidden="true">
<strong class="figure-label">
<p> Figure 13. </p>
</strong>
<div class="figure-caption-contents"><p> Distribution of the abandoned queries and subsequent queries according to their returned number… </p></div>
</div>
<figcaption id="figure-caption-12" class="figure-caption-full figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="description">
<strong class="figure-label">
Figure 13.
</strong>
<div class="figure-caption-contents">Distribution of the abandoned queries and subsequent queries according to their returned number of citations.</div>
</figcaption>
</figure>
<figure class="figure-item tail"
itemscope itemtype="http://schema.org/ImageObject"
itemprop="associatedMedia"
data-slide-index="13"
data-label-slug="figure-14">
<a class="figure-link"
href="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/1add/2797455/b9de33a7e693/bap018f14.jpg"
itemprop="contentUrl"
aria-describedby="figure-caption-13"
role="button"
data-image-width="640"
data-image-height="448"
data-image-alt="Figure 14."
data-pmc-id="PMC2797455"
data-figure-id="F14">
<img class="figure-thumb" itemprop="thumbnail"
id="article-image-13"
src="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/1add/2797455/8aadf6797667/bap018f14.gif"
alt="Figure 14." />
</a>
<meta itemprop="width" itemtype="http://schema.org/ImageObject" content="640">
<meta itemprop="height" itemtype="http://schema.org/ImageObject" content="448">
<div class="figure-caption figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="caption" aria-hidden="true">
<div class="caption-wrap">
<strong class="figure-label">
<p> Figure 14. </p>
</strong>
<div class="figure-caption-contents"><p> Distribution of time to first… </p></div>
</div>
</div>
<div class="figure-caption-medium figure-caption-text" aria-hidden="true">
<strong class="figure-label">
<p> Figure 14. </p>
</strong>
<div class="figure-caption-contents"><p> Distribution of time to first and last click in minutes. </p></div>
</div>
<figcaption id="figure-caption-13" class="figure-caption-full figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="description">
<strong class="figure-label">
Figure 14.
</strong>
<div class="figure-caption-contents">Distribution of time to first and last click in minutes.</div>
</figcaption>
</figure>
</div>
<div class="see-all actions-bar">
<button
class="show-more"
aria-controls="slides-container"
data-ga-category="figure"
data-ga-action="show_all">
All figures (14)
</button>
</div>
<!-- Root element of PhotoSwipe. Must have class pswp. -->
<div class="pswp figures-dialog" id="figures-dialog" tabindex="-1" role="dialog" aria-hidden="true"
data-image-gallery-uid="article-figures" aria-label="Figures Dialog">
<!-- Background of PhotoSwipe.
It's a separate element as animating opacity is faster than rgba(). -->
<div class="pswp__bg"></div>
<!-- Slides wrapper with overflow:hidden. -->
<div class="pswp__scroll-wrap">
<!-- Container that holds slides.
PhotoSwipe keeps only 3 of them in the DOM to save memory.
Don't modify these 3 pswp__item elements, data is added later on. -->
<div class="pswp__container">
<div class="pswp__item"></div>
<div class="pswp__item"></div>
<div class="pswp__item"></div>
</div>
<!-- Default (PhotoSwipeUI_Default) interface on top of sliding area. Can be changed. -->
<div class="pswp__ui pswp__ui--hidden">
<div class="pswp__top-bar">
<!-- Controls are self-explanatory. Order can be changed. -->
<div class="pswp__counter"></div>
<button class="pswp__button pswp__button--close" title="Close (Esc)"></button>
<button class="pswp__button pswp__button--share" title="Share"></button>
<button class="pswp__button pswp__button--fs" title="Toggle fullscreen"></button>
<button class="pswp__button pswp__button--zoom" title="Zoom in/out"></button>
<!-- Preloader demo http://codepen.io/dimsemenov/pen/yyBWoR -->
<!-- element will get class pswp__preloader--active when preloader is running -->
<div class="pswp__preloader">
<div class="pswp__preloader__icn">
<div class="pswp__preloader__cut">
<div class="pswp__preloader__donut"></div>
</div>
</div>
</div>
</div>
<div class="pswp__share-modal pswp__share-modal--hidden pswp__single-tap">
<div class="pswp__share-tooltip"></div>
</div>
<button class="pswp__button pswp__button--arrow--left" title="Previous (arrow left)">
</button>
<button class="pswp__button pswp__button--arrow--right" title="Next (arrow right)">
</button>
<div class="pswp__caption">
<div class="pswp__caption__center"></div>
</div>
</div>
</div>
</div>
<div class="figure-dialog-caption">
<div class="figure-caption-link-container">
<a class="figure-caption-link" href="#">See this image and copyright information in PMC</a>
</div>
<div class="figure-caption-center"
data-expand-title="click to show full caption"
data-collapse-title="click to hide full caption">
</div>
<button class="figure-caption-toggle-btn"
aria-label="show full caption"
data-expand-text="show full caption"
data-collapse-text="hide full caption">
<!-- Dynamic text -->
</button>
</div>
</div>
<div class="similar-articles" id="similar">
<h2 class="title">
Similar articles
</h2>
<ul class="articles-list" id="similar-articles-list">
<li class="full-docsum">
<div class="docsum-content" style="display:inline;">
<a class="docsum-title"
href="/25474588/"
ref="article_id=25474588&amp;linksrc=similar_articles_link&amp;ordinalpos=1"
data-ga-category="similar_article"
data-ga-action="25474588"
data-ga-label="">
G-Bean: an ontology-graph based web tool for biomedical literature retrieval.
</a>
<div class="docsum-citation full-citation">
<span class="docsum-authors full-authors">Wang JZ, Zhang Y, Dong L, Li L, Srimani PK, Yu PS.</span>
<span class="docsum-authors short-authors">Wang JZ, et al.</span>
<span class="docsum-journal-citation full-journal-citation">BMC Bioinformatics. 2014;15 Suppl 12(Suppl 12):S1. doi: 10.1186/1471-2105-15-S12-S1. Epub 2014 Nov 6.</span>
<span class="docsum-journal-citation short-journal-citation">BMC Bioinformatics. 2014.</span>
<span class="citation-part">PMID: <span class="docsum-pmid">25474588</span></span>
<span class="free-resources spaced-citation-item citation-part">Free PMC article.</span>
</div>
</div>
</li>
<li class="full-docsum">
<div class="docsum-content" style="display:inline;">
<a class="docsum-title"
href="/26139516/"
ref="article_id=26139516&amp;linksrc=similar_articles_link&amp;ordinalpos=2"
data-ga-category="similar_article"
data-ga-action="26139516"
data-ga-label="">
Analysis of PubMed User Sessions Using a Full-Day PubMed Query Log: A Comparison of Experienced and Nonexperienced PubMed Users.
</a>
<div class="docsum-citation full-citation">
<span class="docsum-authors full-authors">Yoo I, Mosa AS.</span>
<span class="docsum-authors short-authors">Yoo I, et al.</span>
<span class="docsum-journal-citation full-journal-citation">JMIR Med Inform. 2015 Jul 2;3(3):e25. doi: 10.2196/medinform.3740.</span>
<span class="docsum-journal-citation short-journal-citation">JMIR Med Inform. 2015.</span>
<span class="citation-part">PMID: <span class="docsum-pmid">26139516</span></span>
<span class="free-resources spaced-citation-item citation-part">Free PMC article.</span>
</div>
</div>
</li>
<li class="full-docsum">
<div class="docsum-content" style="display:inline;">
<a class="docsum-title"
href="/19162232/"
ref="article_id=19162232&amp;linksrc=similar_articles_link&amp;ordinalpos=3"
data-ga-category="similar_article"
data-ga-action="19162232"
data-ga-label="">
Improving accuracy for identifying related PubMed queries by an integrated approach.
</a>
<div class="docsum-citation full-citation">
<span class="docsum-authors full-authors">Lu Z, Wilbur WJ.</span>
<span class="docsum-authors short-authors">Lu Z, et al.</span>
<span class="docsum-journal-citation full-journal-citation">J Biomed Inform. 2009 Oct;42(5):831-8. doi: 10.1016/j.jbi.2008.12.006. Epub 2008 Dec 30.</span>
<span class="docsum-journal-citation short-journal-citation">J Biomed Inform. 2009.</span>
<span class="citation-part">PMID: <span class="docsum-pmid">19162232</span></span>
<span class="free-resources spaced-citation-item citation-part">Free PMC article.</span>
</div>
</div>
</li>
<li class="full-docsum">
<div class="docsum-content" style="display:inline;">
<a class="docsum-title"
href="/16186693/"
ref="article_id=16186693&amp;linksrc=similar_articles_link&amp;ordinalpos=4"
data-ga-category="similar_article"
data-ga-action="16186693"
data-ga-label="">
Searching the MEDLINE literature database through PubMed: a short guide.
</a>
<div class="docsum-citation full-citation">
<span class="docsum-authors full-authors">Motschall E, Falck-Ytter Y.</span>
<span class="docsum-authors short-authors">Motschall E, et al.</span>
<span class="docsum-journal-citation full-journal-citation">Onkologie. 2005 Oct;28(10):517-22. doi: 10.1159/000087186. Epub 2005 Aug 19.</span>
<span class="docsum-journal-citation short-journal-citation">Onkologie. 2005.</span>
<span class="citation-part">PMID: <span class="docsum-pmid">16186693</span></span>
<span class="publication-type spaced-citation-item citation-part">Review.</span>
</div>
</div>
</li>
<li class="full-docsum">
<div class="docsum-content" style="display:inline;">
<a class="docsum-title"
href="/21245076/"
ref="article_id=21245076&amp;linksrc=similar_articles_link&amp;ordinalpos=5"
data-ga-category="similar_article"
data-ga-action="21245076"
data-ga-label="">
PubMed and beyond: a survey of web tools for searching biomedical literature.
</a>
<div class="docsum-citation full-citation">
<span class="docsum-authors full-authors">Lu Z.</span>
<span class="docsum-authors short-authors">Lu Z.</span>
<span class="docsum-journal-citation full-journal-citation">Database (Oxford). 2011 Jan 18;2011:baq036. doi: 10.1093/database/baq036. Print 2011.</span>
<span class="docsum-journal-citation short-journal-citation">Database (Oxford). 2011.</span>
<span class="citation-part">PMID: <span class="docsum-pmid">21245076</span></span>
<span class="free-resources spaced-citation-item citation-part">Free PMC article.</span>
<span class="publication-type spaced-citation-item citation-part">Review.</span>
</div>
</div>
</li>
</ul>
<div class="actions-bar">
<a
class="show-all-linked-articles"
data-href="/?linkname=pubmed_pubmed&from_uid=20157491"
data-ga-category="similar_article"
data-ga-action="show_all"
>
See all similar articles
</a>
</div>
</div>
<div class="citedby-articles" id="citedby">
<h2 class="title">
Cited by
</h2>
<ul class="articles-list" id="citedby-articles-list">
<li class="full-docsum">
<div class="docsum-content" style="display:inline;">
<a class="docsum-title"
href="/23714302/"
ref="article_id=23714302&amp;linksrc=citedby_articles_link&amp;ordinalpos=1"
data-ga-category="cited_by"
data-ga-action="23714302"
data-ga-label="">
Are systematic reviews up-to-date at the time of publication?
</a>
<div class="docsum-citation full-citation">
<span class="docsum-authors full-authors">Beller EM, Chen JK, Wang UL, Glasziou PP.</span>
<span class="docsum-authors short-authors">Beller EM, et al.</span>
<span class="docsum-journal-citation full-journal-citation">Syst Rev. 2013 May 28;2:36. doi: 10.1186/2046-4053-2-36.</span>
<span class="docsum-journal-citation short-journal-citation">Syst Rev. 2013.</span>
<span class="citation-part">PMID: <span class="docsum-pmid">23714302</span></span>
<span class="free-resources spaced-citation-item citation-part">Free PMC article.</span>
</div>
</div>
</li>
<li class="full-docsum">
<div class="docsum-content" style="display:inline;">
<a class="docsum-title"
href="/22693219/"
ref="article_id=22693219&amp;linksrc=citedby_articles_link&amp;ordinalpos=2"
data-ga-category="cited_by"
data-ga-action="22693219"
data-ga-label="">
GeneView: a comprehensive semantic search engine for PubMed.
</a>
<div class="docsum-citation full-citation">
<span class="docsum-authors full-authors">Thomas P, Starlinger J, Vowinkel A, Arzt S, Leser U.</span>
<span class="docsum-authors short-authors">Thomas P, et al.</span>
<span class="docsum-journal-citation full-journal-citation">Nucleic Acids Res. 2012 Jul;40(Web Server issue):W585-91. doi: 10.1093/nar/gks563. Epub 2012 Jun 12.</span>
<span class="docsum-journal-citation short-journal-citation">Nucleic Acids Res. 2012.</span>
<span class="citation-part">PMID: <span class="docsum-pmid">22693219</span></span>
<span class="free-resources spaced-citation-item citation-part">Free PMC article.</span>
</div>
</div>
</li>
<li class="full-docsum">
<div class="docsum-content" style="display:inline;">
<a class="docsum-title"
href="/21917645/"
ref="article_id=21917645&amp;linksrc=citedby_articles_link&amp;ordinalpos=3"
data-ga-category="cited_by"
data-ga-action="21917645"
data-ga-label="">
Predicting biomedical document access as a function of past use.
</a>
<div class="docsum-citation full-citation">
<span class="docsum-authors full-authors">Goodwin JC, Johnson TR, Cohen T, Herskovic JR, Bernstam EV.</span>
<span class="docsum-authors short-authors">Goodwin JC, et al.</span>
<span class="docsum-journal-citation full-journal-citation">J Am Med Inform Assoc. 2012 May-Jun;19(3):473-8. doi: 10.1136/amiajnl-2011-000325. Epub 2011 Sep 13.</span>
<span class="docsum-journal-citation short-journal-citation">J Am Med Inform Assoc. 2012.</span>
<span class="citation-part">PMID: <span class="docsum-pmid">21917645</span></span>
<span class="free-resources spaced-citation-item citation-part">Free PMC article.</span>
</div>
</div>
</li>
<li class="full-docsum">
<div class="docsum-content" style="display:inline;">
<a class="docsum-title"
href="/24980129/"
ref="article_id=24980129&amp;linksrc=citedby_articles_link&amp;ordinalpos=4"
data-ga-category="cited_by"
data-ga-action="24980129"
data-ga-label="">
BioC interoperability track overview.
</a>
<div class="docsum-citation full-citation">
<span class="docsum-authors full-authors">Comeau DC, Batista-Navarro RT, Dai HJ, Doğan RI, Yepes AJ, Khare R, Lu Z, Marques H, Mattingly CJ, Neves M, Peng Y, Rak R, Rinaldi F, Tsai RT, Verspoor K, Wiegers TC, Wu CH, Wilbur WJ.</span>
<span class="docsum-authors short-authors">Comeau DC, et al.</span>
<span class="docsum-journal-citation full-journal-citation">Database (Oxford). 2014 Jun 30;2014:bau053. doi: 10.1093/database/bau053. Print 2014.</span>
<span class="docsum-journal-citation short-journal-citation">Database (Oxford). 2014.</span>
<span class="citation-part">PMID: <span class="docsum-pmid">24980129</span></span>
<span class="free-resources spaced-citation-item citation-part">Free PMC article.</span>
<span class="publication-type spaced-citation-item citation-part">Review.</span>
</div>
</div>
</li>
<li class="full-docsum">
<div class="docsum-content" style="display:inline;">
<a class="docsum-title"
href="/28815123/"
ref="article_id=28815123&amp;linksrc=citedby_articles_link&amp;ordinalpos=5"
data-ga-category="cited_by"
data-ga-action="28815123"
data-ga-label="">
Rapid and Reusable Text Visualization and Exploration Development with DELVE.
</a>
<div class="docsum-citation full-citation">
<span class="docsum-authors full-authors">Harris DR, Kavuluru R, Jaromczyk JW, Johnson TR.</span>
<span class="docsum-authors short-authors">Harris DR, et al.</span>
<span class="docsum-journal-citation full-journal-citation">AMIA Jt Summits Transl Sci Proc. 2017 Jul 26;2017:139-148. eCollection 2017.</span>
<span class="docsum-journal-citation short-journal-citation">AMIA Jt Summits Transl Sci Proc. 2017.</span>
<span class="citation-part">PMID: <span class="docsum-pmid">28815123</span></span>
<span class="free-resources spaced-citation-item citation-part">Free PMC article.</span>
</div>
</div>
</li>
</ul>
<div class="actions-bar">
<a
class="show-all-linked-articles"
data-href="/?linkname=pubmed_pubmed_citedin&from_uid=20157491"
data-ga-category="cited_by"
data-ga-action="show_all"
>
See all "Cited by" articles
</a>
</div>
</div>
<div class="references" id="references">
<h2 class="title">
References
</h2>
<div id='top-references-list' class="references-lists-container">
<div class="refs-list">
<ol id="top-references-list-1" class="references-list">
<li>
<ol class="references-and-notes-list">
<li
class="skip-numbering"
value="1">
Hunter L, Cohen KB. Biomedical language processing: what's; beyond PubMed? Mol. Cell. 2006;21:589594.
-
<a
class="reference-link"
href="https://pmc.ncbi.nlm.nih.gov/articles/PMC1702322/"
ref="linksrc=references_link&amp;ordinalpos=1"
data-ga-category="reference"
data-ga-action="PMC1702322"
>
PMC
</a>
-
<a
class="reference-link"
href="/16507357/"
ref="linksrc=references_link&amp;ordinalpos=2"
data-ga-category="reference"
data-ga-action="16507357"
>
PubMed
</a>
</li>
</ol>
</li>
<li>
<ol class="references-and-notes-list">
<li
class="skip-numbering"
value="1">
Tenopir C. Online databases: are e-journals good for science? Library J. 2008;133:24.
</li>
</ol>
</li>
<li>
<ol class="references-and-notes-list">
<li
class="skip-numbering"
value="1">
Taylor R. Question negotiation and information seeking in libraries. College Res. Libraries. 1968;29:178194.
</li>
</ol>
</li>
<li>
<ol class="references-and-notes-list">
<li
class="skip-numbering"
value="1">
Murray GC, Teevan J. Query log analysis: social and technological challenges (WWW 2007 Workshop Report) ACM SIGIR Forum. 2007;41:112120.
</li>
</ol>
</li>
<li>
<ol class="references-and-notes-list">
<li
class="skip-numbering"
value="1">
Spink A, Jansen BJ, editors. Web Search: Public Searching of the Web. Kluwer, Dordrecht: 2004.
</li>
</ol>
</li>
</ol>
<div class="actions-bar">
<button
class="show-all"
ref="linksrc=show_all_references_link"
aria-controls="top-references-list-1"
data-next-page-url="/20157491/references/"
data-ga-category="reference"
data-ga-action="show_more"
>
Show all 80 references
</button>
</div>
</div>
</div>
</div>
<div id="linkout" class="linkout">
<h2 class="title">
LinkOut - more resources
</h2>
<ul class="linkout-list"><li><h3 class="linkout-category">Full Text Sources</h3><ul class="linkout-category-links"><li><a
href="https://air.unimi.it/handle/2434/235313"
target="_blank"
rel="noopener"
ref="linksrc=linkout_link&PrId=9730&uid=20157491&db=pubmed&itool=Abstract&log$=linkoutlink&nlmid=101517697"
data-ga-category="link_out"
data-ga-action="Full Text Sources"
data-ga-label="Archivio Istituzionale della Ricerca Unimi - Access Free Full Text"
>
Archivio Istituzionale della Ricerca Unimi - Access Free Full Text
</a></li><li><a
href="https://europepmc.org/abstract/MED/20157491"
target="_blank"
rel="noopener"
ref="linksrc=linkout_link&PrId=6082&uid=20157491&db=pubmed&itool=Abstract&log$=linkoutlink&nlmid=101517697"
data-ga-category="link_out"
data-ga-action="Full Text Sources"
data-ga-label="Europe PubMed Central"
>
Europe PubMed Central
</a></li><li><a
href="https://pmc.ncbi.nlm.nih.gov/articles/pmid/20157491/"
target="_blank"
rel="noopener"
ref="linksrc=linkout_link&PrId=3494&uid=20157491&db=pubmed&itool=Abstract&log$=linkoutlink&nlmid=101517697"
data-ga-category="link_out"
data-ga-action="Full Text Sources"
data-ga-label="PubMed Central"
>
PubMed Central
</a></li><li><a
href="https://academic.oup.com/database/article-lookup/doi/10.1093/database/bap018"
target="_blank"
rel="noopener"
ref="linksrc=linkout_link&PrId=7898&uid=20157491&db=pubmed&itool=Abstract&log$=linkoutlink&nlmid=101517697"
data-ga-category="link_out"
data-ga-action="Full Text Sources"
data-ga-label="Silverchair Information Systems"
>
Silverchair Information Systems
</a></li></ul></li><li><h3 class="linkout-category">Other Literature Sources</h3><ul class="linkout-category-links"><li><a
href="https://www.lens.org/lens/search/patent/list?q=reference_cited.npl.ids.pmid:20157491"
target="_blank"
rel="noopener"
ref="linksrc=linkout_link&PrId=8681&uid=20157491&db=pubmed&itool=Abstract&log$=linkoutlink&nlmid=101517697"
data-ga-category="link_out"
data-ga-action="Other Literature Sources"
data-ga-label="The Lens - Patent Citations Database"
>
The Lens - Patent Citations Database
</a></li></ul></li></ul>
</div>
</main>
<div class="overlay" role="dialog" aria-label="Full Text Links Dialog">
<div id="full-text-links-dialog" class="dialog full-text-links-dialog">
<strong class="title">Full text links</strong>
<button class="close-overlay" tabindex="3">[x]</button>
<div class="full-text-links-list">
<a class="link-item
dialog-focus"
href="https://academic.oup.com/database/article-lookup/doi/10.1093/database/bap018"
target="_blank"
rel="noopener"
ref="linksrc=fulltextorjournal_fulltext&amp;is_pmc=False&amp;PrId=7898&amp;itool=Abstract-def&amp;log$=linkouticon&amp;uid=20157491&amp;db=pubmed&amp;nlmid=101517697"
title="See full text options at Silverchair Information Systems"
tabindex="1"
data-ga-category="full_text"
data-ga-action="Silverchair Information Systems"
data-ga-label="20157491"
><img src="https://cdn.ncbi.nlm.nih.gov/corehtml/query/egifs/https:--academic.oup.com-images-oup_pubmed.png" alt="Silverchair Information Systems full text link"><span class="text">
Silverchair Information Systems
</span></a><a class="link-item
pmc
"
href="https://pmc.ncbi.nlm.nih.gov/articles/pmid/20157491/"
target="_blank"
rel="noopener"
ref="linksrc=fulltextorjournal_fulltext&amp;is_pmc=True&amp;PrId=3494&amp;itool=Abstract-def&amp;log$=linkouticon&amp;uid=20157491&amp;db=pubmed&amp;nlmid=101517697"
title="Free full text at PubMed Central"
tabindex="2"
data-ga-category="full_text"
data-ga-action="PMC"
data-ga-label="20157491"
><span class="text">
Free PMC article
</span></a>
</div>
</div>
</div>
<div class="overlay" role="dialog" aria-label="Citation Dialog">
<div class="dialog citation-dialog">
<button class="close-overlay" tabindex="1">[x]</button>
<div class="title">Cite</div>
<div class="citation-text-block">
<div class="citation-text"></div>
<div class="citation-actions">
<button
class="copy-button dialog-focus"
data-ga-category="save_share"
data-ga-action="cite"
data-ga-label="copy"
tabindex="2">
Copy
</button>
<form method="post">
<input type="hidden" name="csrfmiddlewaretoken" value="FDgGdqa9AUp1mhU3YmmYkYAqbS7TDc8LWq0LQgDvavcvgI0TBFZ0O664JWP5wNG5">
<button type="submit"
class="export-button"
data-ga-category="save_share"
data-ga-action="cite"
data-ga-label="download"
title="Download a file for external citation management software"
tabindex="3">
<span class="download-title">Download .nbib</span>
<span class="download-title-mobile">.nbib</span>
</button>
</form>
<div class="citation-style-selector-wrapper">
<label class="selector-label">Format:</label>
<select aria-label="Format" class="citation-style-selector" tabindex="4">
<option data-style-url-name="ama"
value="AMA"
>
AMA
</option>
<option data-style-url-name="apa"
value="APA"
>
APA
</option>
<option data-style-url-name="mla"
value="MLA"
>
MLA
</option>
<option data-style-url-name="nlm"
value="NLM"
selected="selected">
NLM
</option>
</select>
</div>
</div>
</div>
</div>
</div>
<div class="overlay" role="dialog" aria-label="More Actions Dialog">
<div id="more-actions-dialog" class="dialog more-actions-dialog">
<strong class="title">Send To</strong>
<ul class="more-actions-links">
<li><a id="clipboard-trigger" role="button" class="submit-button clipboard-trigger clipboard-trigger-target dialog-focus link-item " href="#">Clipboard</a></li>
<li><a class="email-trigger link-item" role="button" href="#">Email</a></li>
<li><a class="save-trigger link-item" role="button" href="#">Save</a></li>
<li><a class="link-item" role="button" href="https://account.ncbi.nlm.nih.gov/?back_url=https%3A%2F%2Fpubmed.ncbi.nlm.nih.gov%2F20157491%2F%23open-bibliography-panel">My Bibliography</a></li>
<li><a class="link-item" role="button" href="https://account.ncbi.nlm.nih.gov/?back_url=https%3A%2F%2Fpubmed.ncbi.nlm.nih.gov%2F20157491%2F%23open-collections-panel">Collections</a></li>
<li><a class="citation-manager-trigger link-item" role="button" href="#">Citation Manager</a></li>
</ul>
<button class="close-overlay">[x]</button>
</div>
</div>
</div>
<div id="ncbi-footer">
<div class="literature-footer" role="complementary" title="Links to NCBI Literature Resources">
<div class="usa-grid">
<p class="literature-footer-text">NCBI Literature Resources</p>
<p class="literature-footer-text">
<a class="literature-footer-link" data-ga-category="literature_resources" data-ga-action="mesh_link" href="https://www.ncbi.nlm.nih.gov/mesh/">MeSH</a>
<a class="literature-footer-link" data-ga-category="literature_resources" data-ga-action="pmc_link" href="https://www.ncbi.nlm.nih.gov/pmc/">PMC</a>
<a class="literature-footer-link" data-ga-category="literature_resources" data-ga-action="bookshelf_link" href="https://www.ncbi.nlm.nih.gov/books">Bookshelf</a>
<a class="literature-footer-link" data-ga-category="literature_resources" data-ga-action="disclaimer_link" href="/disclaimer/">Disclaimer</a>
</p>
<p class="literature-footer-text attribution-statement">The PubMed wordmark and PubMed logo are registered trademarks of the U.S. Department of Health and Human Services (HHS). Unauthorized use of these marks is strictly prohibited.</p>
</div>
</div>
<!-- ========== BEGIN FOOTER ========== -->
<footer>
<section class="icon-section">
<div id="icon-section-header" class="icon-section_header">Follow NCBI</div>
<div class="grid-container container">
<div class="icon-section_container">
<a class="footer-icon" id="footer_twitter" href="https://twitter.com/ncbi" aria-label="Twitter">
<svg width="40" height="40" viewBox="0 0 40 37" fill="none" xmlns="http://www.w3.org/2000/svg">
<title>Twitter</title>
<g id="twitterx1008">
<path id="path1008"
d="M6.06736 7L16.8778 20.8991L6.00001 32.2H10.2L18.6 23.1L25.668 32.2H34L22.8 17.5L31.9 7H28.4L20.7 15.4L14.401 7H6.06898H6.06736ZM9.66753 8.73423H12.9327L29.7327 30.4658H26.5697L9.66753 8.73423Z"
fill="#5B616B"/>
</g>
</svg>
</a>
<a class="footer-icon" id="footer_facebook" href="https://www.facebook.com/ncbi.nlm" aria-label="Facebook"><svg
data-name="Layer 1" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 300 300">
<title>Facebook</title>
<path class="cls-11"
d="M210.5,115.12H171.74V97.82c0-8.14,5.39-10,9.19-10h27.14V52l-39.32-.12c-35.66,0-42.42,26.68-42.42,43.77v19.48H99.09v36.32h27.24v109h45.41v-109h35Z">
</path>
</svg></a>
<a class="footer-icon" id="footer_linkedin"
href="https://www.linkedin.com/company/ncbinlm"
aria-label="LinkedIn"><svg data-name="Layer 1" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 300 300">
<title>LinkedIn</title>
<path class="cls-11"
d="M101.64,243.37H57.79v-114h43.85Zm-22-131.54h-.26c-13.25,0-21.82-10.36-21.82-21.76,0-11.65,8.84-21.15,22.33-21.15S101.7,78.72,102,90.38C102,101.77,93.4,111.83,79.63,111.83Zm100.93,52.61A17.54,17.54,0,0,0,163,182v61.39H119.18s.51-105.23,0-114H163v13a54.33,54.33,0,0,1,34.54-12.66c26,0,44.39,18.8,44.39,55.29v58.35H198.1V182A17.54,17.54,0,0,0,180.56,164.44Z">
</path>
</svg></a>
<a class="footer-icon" id="footer_github" href="https://github.com/ncbi" aria-label="GitHub"><svg
data-name="Layer 1" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 300 300">
<defs>
<style>
.cls-11,
.cls-12 {
fill: #737373;
}
.cls-11 {
fill-rule: evenodd;
}
</style>
</defs>
<title>GitHub</title>
<path class="cls-11"
d="M151.36,47.28a105.76,105.76,0,0,0-33.43,206.1c5.28,1,7.22-2.3,7.22-5.09,0-2.52-.09-10.85-.14-19.69-29.42,6.4-35.63-12.48-35.63-12.48-4.81-12.22-11.74-15.47-11.74-15.47-9.59-6.56.73-6.43.73-6.43,10.61.75,16.21,10.9,16.21,10.9,9.43,16.17,24.73,11.49,30.77,8.79,1-6.83,3.69-11.5,6.71-14.14C108.57,197.1,83.88,188,83.88,147.51a40.92,40.92,0,0,1,10.9-28.39c-1.1-2.66-4.72-13.42,1-28,0,0,8.88-2.84,29.09,10.84a100.26,100.26,0,0,1,53,0C198,88.3,206.9,91.14,206.9,91.14c5.76,14.56,2.14,25.32,1,28a40.87,40.87,0,0,1,10.89,28.39c0,40.62-24.74,49.56-48.29,52.18,3.79,3.28,7.17,9.71,7.17,19.58,0,14.15-.12,25.54-.12,29,0,2.82,1.9,6.11,7.26,5.07A105.76,105.76,0,0,0,151.36,47.28Z">
</path>
<path class="cls-12"
d="M85.66,199.12c-.23.52-1.06.68-1.81.32s-1.2-1.06-.95-1.59,1.06-.69,1.82-.33,1.21,1.07.94,1.6Zm-1.3-1">
</path>
<path class="cls-12"
d="M90,203.89c-.51.47-1.49.25-2.16-.49a1.61,1.61,0,0,1-.31-2.19c.52-.47,1.47-.25,2.17.49s.82,1.72.3,2.19Zm-1-1.08">
</path>
<path class="cls-12"
d="M94.12,210c-.65.46-1.71,0-2.37-.91s-.64-2.07,0-2.52,1.7,0,2.36.89.65,2.08,0,2.54Zm0,0"></path>
<path class="cls-12"
d="M99.83,215.87c-.58.64-1.82.47-2.72-.41s-1.18-2.06-.6-2.7,1.83-.46,2.74.41,1.2,2.07.58,2.7Zm0,0">
</path>
<path class="cls-12"
d="M107.71,219.29c-.26.82-1.45,1.2-2.64.85s-2-1.34-1.74-2.17,1.44-1.23,2.65-.85,2,1.32,1.73,2.17Zm0,0">
</path>
<path class="cls-12"
d="M116.36,219.92c0,.87-1,1.59-2.24,1.61s-2.29-.68-2.3-1.54,1-1.59,2.26-1.61,2.28.67,2.28,1.54Zm0,0">
</path>
<path class="cls-12"
d="M124.42,218.55c.15.85-.73,1.72-2,1.95s-2.37-.3-2.52-1.14.73-1.75,2-2,2.37.29,2.53,1.16Zm0,0"></path>
</svg></a>
<a class="footer-icon" id="footer_blog" href="https://ncbiinsights.ncbi.nlm.nih.gov/" aria-label="Blog">
<svg id="Layer_1" data-name="Layer 1" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 40 40"><defs><style>.cls-1{fill:#737373;}</style></defs><path class="cls-1" d="M14,30a4,4,0,1,1-4-4,4,4,0,0,1,4,4Zm11,3A19,19,0,0,0,7.05,15a1,1,0,0,0-1,1v3a1,1,0,0,0,.93,1A14,14,0,0,1,20,33.07,1,1,0,0,0,21,34h3a1,1,0,0,0,1-1Zm9,0A28,28,0,0,0,7,6,1,1,0,0,0,6,7v3a1,1,0,0,0,1,1A23,23,0,0,1,29,33a1,1,0,0,0,1,1h3A1,1,0,0,0,34,33Z"/></svg>
</a>
</div>
</div>
</section>
<section class="container-fluid bg-primary">
<div class="container pt-5">
<div class="row mt-3">
<div class="col-lg-3 col-12">
<p><a class="text-white" href="https://www.nlm.nih.gov/socialmedia/index.html">Connect with NLM</a></p>
<ul class="list-inline social_media">
<li class="list-inline-item"><a href="https://twitter.com/NLM_NIH" aria-label="Twitter"
target="_blank" rel="noopener noreferrer">
<svg width="35" height="35" viewBox="0 0 38 35" fill="none" xmlns="http://www.w3.org/2000/svg">
<title>Twitter</title>
<g id="twitterx1009" clip-path="url(#clip0_65276_3946)">
<path id="Vector" d="M17.5006 34.6565C26.9761 34.6565 34.6575 26.9751 34.6575 17.4996C34.6575 8.02416 26.9761 0.342773 17.5006 0.342773C8.02514 0.342773 0.34375 8.02416 0.34375 17.4996C0.34375 26.9751 8.02514 34.6565 17.5006 34.6565Z" fill="#205493" stroke="white" stroke-width="1.2" stroke-miterlimit="10"></path>
<path id="path1009" d="M8.54811 8.5L16.2698 18.4279L8.50001 26.5H11.5L17.5 20L22.5486 26.5H28.5L20.5 16L27 8.5H24.5L19 14.5L14.5007 8.5H8.54927H8.54811ZM11.1197 9.73873H13.4519L25.4519 25.2613H23.1926L11.1197 9.73873Z" fill="white"></path>
</g>
<defs>
<clipPath id="clip0_65276_3946">
<rect width="38" height="38" fill="white"></rect>
</clipPath>
</defs>
</svg></a>
</li>
<li class="list-inline-item"><a href="https://www.facebook.com/nationallibraryofmedicine"
aria-label="Facebook" rel="noopener noreferrer" target="_blank">
<svg version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px"
y="0px" viewBox="0 0 249 249" style="enable-background:new 0 0 249 249;" xml:space="preserve">
<style type="text/css">
.st10 {
fill: #FFFFFF;
}
.st110 {
fill: none;
stroke: #FFFFFF;
stroke-width: 8;
stroke-miterlimit: 10;
}
</style>
<title>SM-Facebook</title>
<g>
<g>
<path class="st10" d="M159,99.1h-24V88.4c0-5,3.3-6.2,5.7-6.2h16.8V60l-24.4-0.1c-22.1,0-26.2,16.5-26.2,27.1v12.1H90v22.5h16.9
v67.5H135v-67.5h21.7L159,99.1z"></path>
</g>
</g>
<circle class="st110" cx="123.6" cy="123.2" r="108.2"></circle>
</svg>
</a></li>
<li class="list-inline-item"><a href="https://www.youtube.com/user/NLMNIH" aria-label="Youtube"
target="_blank" rel="noopener noreferrer"><svg version="1.1" xmlns="http://www.w3.org/2000/svg"
xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px" viewBox="0 0 249 249"
style="enable-background:new 0 0 249 249;" xml:space="preserve">
<title>SM-Youtube</title>
<style type="text/css">
.st4 {
fill: none;
stroke: #FFFFFF;
stroke-width: 8;
stroke-miterlimit: 10;
}
.st5 {
fill: #FFFFFF;
}
</style>
<circle class="st4" cx="124.2" cy="123.4" r="108.2"></circle>
<g transform="translate(0,-952.36218)">
<path class="st5"
d="M88.4,1037.4c-10.4,0-18.7,8.3-18.7,18.7v40.1c0,10.4,8.3,18.7,18.7,18.7h72.1c10.4,0,18.7-8.3,18.7-18.7
v-40.1c0-10.4-8.3-18.7-18.7-18.7H88.4z M115.2,1058.8l29.4,17.4l-29.4,17.4V1058.8z"></path>
</g>
</svg></a></li>
</ul>
</div>
<div class="col-lg-3 col-12">
<p class="address_footer text-white">National Library of Medicine<br>
<a href="https://www.google.com/maps/place/8600+Rockville+Pike,+Bethesda,+MD+20894/@38.9959508,-77.101021,17z/data=!3m1!4b1!4m5!3m4!1s0x89b7c95e25765ddb:0x19156f88b27635b8!8m2!3d38.9959508!4d-77.0988323"
class="text-white" target="_blank" rel="noopener noreferrer">8600 Rockville Pike<br>
Bethesda, MD 20894</a></p>
</div>
<div class="col-lg-3 col-12 centered-lg">
<p><a href="https://www.nlm.nih.gov/web_policies.html" class="text-white">Web Policies</a><br>
<a href="https://www.nih.gov/institutes-nih/nih-office-director/office-communications-public-liaison/freedom-information-act-office"
class="text-white">FOIA</a><br>
<a href="https://www.hhs.gov/vulnerability-disclosure-policy/index.html" class="text-white" id="vdp">HHS Vulnerability Disclosure</a></p>
</div>
<div class="col-lg-3 col-12 centered-lg">
<p><a class="supportLink text-white" href="https://support.nlm.nih.gov/">Help</a><br>
<a href="https://www.nlm.nih.gov/accessibility.html" class="text-white">Accessibility</a><br>
<a href="https://www.nlm.nih.gov/careers/careers.html" class="text-white">Careers</a></p>
</div>
</div>
<div class="row">
<div class="col-lg-12 centered-lg">
<nav class="bottom-links">
<ul class="mt-3">
<li>
<a class="text-white" href="//www.nlm.nih.gov/">NLM</a>
</li>
<li>
<a class="text-white"
href="https://www.nih.gov/">NIH</a>
</li>
<li>
<a class="text-white" href="https://www.hhs.gov/">HHS</a>
</li>
<li>
<a
class="text-white" href="https://www.usa.gov/">USA.gov</a>
</li>
</ul>
</nav>
</div>
</div>
</div>
</section>
</footer>
<!-- ========== END FOOTER ========== -->
<!-- javascript to inject NWDS meta tags. Note: value of nwds_version is updated by "npm version" command -->
<script type="text/javascript">
var nwds_version = "1.2.3";
var meta_nwds_ver = document.createElement('meta');
meta_nwds_ver.name = 'ncbi_nwds_ver';
meta_nwds_ver.content = nwds_version;
document.getElementsByTagName('head')[0].appendChild(meta_nwds_ver);
var meta_nwds = document.createElement('meta');
meta_nwds.name = 'ncbi_nwds';
meta_nwds.content = 'yes';
document.getElementsByTagName('head')[0].appendChild(meta_nwds);
var alertsUrl = "/core/alerts/alerts.js";
if (typeof ncbiBaseUrl !== 'undefined') {
alertsUrl = ncbiBaseUrl + alertsUrl;
}
</script>
</div>
<!-- jQuery with plugins -->
<script src="https://cdn.ncbi.nlm.nih.gov/pubmed/277eb475-38df-4990-a0ee-0080b04e86fc/CACHE/js/output.293fbf76aa18.js"></script>
<!-- Project base scripts -->
<script src="https://cdn.ncbi.nlm.nih.gov/pubmed/277eb475-38df-4990-a0ee-0080b04e86fc/CACHE/js/output.550e9c8906a2.js"></script>
<script>
ncbi.awesome.basePage.init({
userInfo: {
isLoggedIn: false,
username: "",
loginUrl: "https://account.ncbi.nlm.nih.gov/?back_url=https%3A%2F%2Fpubmed.ncbi.nlm.nih.gov%2F20157491%2F",
logoutUrl: "https://www.ncbi.nlm.nih.gov/account/signout/?back_url=https%3A//pubmed.ncbi.nlm.nih.gov/20157491/"
},
baseUrl: 'https://www.ncbi.nlm.nih.gov',
noSessionCookieName: "pm-ns",
searchIdCookieName: "pm-sid",
adjNavSearchIdCookieName: "pm-adjnav-sid",
searchFormSubmittedCookieName: "pm-sfs",
isOnSearchPageCookieName: "pm-iosp",
backToSearchCookieName: "pm-btsl",
clinicalSeeAllCookieName: "pm-csa",
jsCookieDomain: "pubmed.ncbi.nlm.nih.gov",
userShareRequestFailed: "",
noSharedSettings: "myncbi_no_shared_settings",
noSharedAccount: "myncbi_no_shared_account"
});
</script>
<script type="module">
import dismissableNCBIAlert from "https://cdn.ncbi.nlm.nih.gov/pubmed/277eb475-38df-4990-a0ee-0080b04e86fc/core/dismissable-ncbi-alert.js";
jQuery.getScript("https://www.ncbi.nlm.nih.gov/core/alerts/alerts.js", function () {
galert(['body > *:last-child']);
dismissableNCBIAlert();
}).fail(function() {
});
</script>
<script defer type="text/javascript" src="https://cdn.ncbi.nlm.nih.gov/core/pinger/pinger.js"> </script>
<script src="https://cdn.ncbi.nlm.nih.gov/pubmed/277eb475-38df-4990-a0ee-0080b04e86fc/CACHE/js/output.e3950ac8c6da.js"></script>
<script>
ncbi.awesome.articlePage.init({
baseSuggestionsUrl: "/suggestions/",
mathJaxUrl: "https://cdn.ncbi.nlm.nih.gov/pubmed/277eb475-38df-4990-a0ee-0080b04e86fc/mathjax/unpacked/MathJax.js?config=MML_CHTML",
clipboardAPIRoot: "/ajax/clipboard/",
clipboardNextPageUrl: "/clipboard-next-page/",
searchIdCookieName: "pm-sid",
searchFormSubmittedCookieName: "pm-sfs",
backToSearchCookieName: "pm-btsl",
jsCookieDomain: "pubmed.ncbi.nlm.nih.gov",
longTermPrefix: "longquery",
adjNavURLPath: "/20157491/adj-nav/",
adjNavSearchIdCookieName: "pm-adjnav-sid",
articlePageUrl: "/20157491/",
markJSUrl: "https://cdn.ncbi.nlm.nih.gov/pubmed/277eb475-38df-4990-a0ee-0080b04e86fc/mark.js/dist/jquery.mark.js",
termHighlightColor: "",
highlightedTokens: "",
citeFormatPreferenceCookieName: "pm-cf"
});
</script>
</body>
</html>