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<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="OfBZZcCNYQZAJg1GBPePty4ZGnki3aI352l4C259yrM4DH7we8RRXGADer2uWLgn">
<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="OfBZZcCNYQZAJg1GBPePty4ZGnki3aI352l4C259yrM4DH7we8RRXGADer2uWLgn">
<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="OfBZZcCNYQZAJg1GBPePty4ZGnki3aI352l4C259yrM4DH7we8RRXGADer2uWLgn">
<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="OfBZZcCNYQZAJg1GBPePty4ZGnki3aI352l4C259yrM4DH7we8RRXGADer2uWLgn">
<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="OfBZZcCNYQZAJg1GBPePty4ZGnki3aI352l4C259yrM4DH7we8RRXGADer2uWLgn">
<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="17213501">
<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/jamia/article-lookup/doi/10.1197/jamia.M2191"
target="_blank"
rel="noopener"
ref="linksrc=fulltextorjournal_fulltext&amp;is_pmc=False&amp;PrId=7898&amp;itool=Abstract-def&amp;log$=linkouticon&amp;uid=17213501&amp;db=pubmed&amp;nlmid=9430800"
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Silverchair Information Systems
</span></a><a class="link-item
pmc
"
href="https://pmc.ncbi.nlm.nih.gov/articles/pmid/17213501/"
target="_blank"
rel="noopener"
ref="linksrc=fulltextorjournal_fulltext&amp;is_pmc=True&amp;PrId=3494&amp;itool=Abstract-def&amp;log$=linkouticon&amp;uid=17213501&amp;db=pubmed&amp;nlmid=9430800"
title="Free full text at PubMed Central"
data-ga-category="full_text"
data-ga-action="PMC"
data-ga-label="17213501"
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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="/17213501/citations/"
data-citation-style="nlm"
data-pubmed-format-link="/17213501/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="17213501" 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%2F17213501%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="OfBZZcCNYQZAJg1GBPePty4ZGnki3aI352l4C259yrM4DH7we8RRXGADer2uWLgn"><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"
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A day in the life of PubMed: analysis of a typical day&#x27;s query log
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Objective:
</strong>
To characterize PubMed usage over a typical day and compare it to previous studies of user behavior on Web search engines.
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Design:
</strong>
We performed a lexical and semantic analysis of 2,689,166 queries issued on PubMed over 24 consecutive hours on a typical day.
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Measurements:
</strong>
We measured the number of queries, number of distinct users, queries per user, terms per query, common terms, Boolean operator use, common phrases, result set size, MeSH categories, used semantic measurements to group queries into sessions, and studied the addition and removal of terms from consecutive queries to gauge search strategies.
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Results:
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The size of the result sets from a sample of queries showed a bimodal distribution, with peaks at approximately 3 and 100 results, suggesting that a large group of queries was tightly focused and another was broad. Like Web search engine sessions, most PubMed sessions consisted of a single query. However, PubMed queries contained more terms.
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PubMed's usage profile should be considered when educating users, building user interfaces, and developing future biomedical information retrieval systems.
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<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> Log file sample. The PubMed… </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> Log file sample. The PubMed log had three columns. The first column contains… </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">Log file sample. The PubMed log had three columns. The first column contains a PubMed-generated user hash, the second a timestamp (in seconds since midnight at the servers location), and the third is the actual query as submitted. These are a few consecutive lines from the raw log.</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/3fe1/2213463/ff09cb853a01/212.S1067502706002702.gr2.jpg"
itemprop="contentUrl"
aria-describedby="figure-caption-1"
role="button"
data-image-width="666"
data-image-height="711"
data-image-alt="Figure 2"
data-pmc-id="PMC2213463"
data-figure-id="fig2">
<img class="figure-thumb" itemprop="thumbnail"
id="article-image-1"
src="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/3fe1/2213463/8e2c93d2cd28/212.S1067502706002702.gr2.gif"
alt="Figure 2" />
</a>
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<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> Algorithm to classify queries as… </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> Algorithm to classify queries as informational vs. navigational. </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">Algorithm to classify queries as informational vs. navigational.</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/3fe1/2213463/ef414210afb5/212.S1067502706002702.gr3.jpg"
itemprop="contentUrl"
aria-describedby="figure-caption-2"
role="button"
data-image-width="714"
data-image-height="536"
data-image-alt="Figure 3"
data-pmc-id="PMC2213463"
data-figure-id="fig3">
<img class="figure-thumb" itemprop="thumbnail"
id="article-image-2"
src="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/3fe1/2213463/abfe000e3710/212.S1067502706002702.gr3.gif"
alt="Figure 3" />
</a>
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<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> Semantic distance determination. In this… </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> Semantic distance determination. In this example, we walk through the tree to determine… </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">Semantic distance determination. In this example, we walk through the tree to determine the semantic distance between “Myocardial infarction” and “Cerebrovascular accident,” which is six steps long (only one of the possible paths is shown).</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/3fe1/2213463/59fedd24909a/212.S1067502706002702.gr4.jpg"
itemprop="contentUrl"
aria-describedby="figure-caption-3"
role="button"
data-image-width="666"
data-image-height="442"
data-image-alt="Figure 4"
data-pmc-id="PMC2213463"
data-figure-id="fig4">
<img class="figure-thumb" itemprop="thumbnail"
id="article-image-3"
src="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/3fe1/2213463/d551265c514b/212.S1067502706002702.gr4.gif"
alt="Figure 4" />
</a>
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<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> Histogram of queries issued per… </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> Histogram of queries issued per user, for all 2,689,166 queries. </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">Histogram of queries issued per user, for all 2,689,166 queries.</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/3fe1/2213463/04dc72316000/212.S1067502706002702.gr5.jpg"
itemprop="contentUrl"
aria-describedby="figure-caption-4"
role="button"
data-image-width="666"
data-image-height="477"
data-image-alt="Figure 5"
data-pmc-id="PMC2213463"
data-figure-id="fig5">
<img class="figure-thumb" itemprop="thumbnail"
id="article-image-4"
src="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/3fe1/2213463/a2755da72340/212.S1067502706002702.gr5.gif"
alt="Figure 5" />
</a>
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<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> Logarithm of the size of… </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> Logarithm of the size of the result set for a sample of 2,272… </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">Logarithm of the size of the result set for a sample of 2,272 queries.</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/3fe1/2213463/718504a83c65/212.S1067502706002702.gr6.jpg"
itemprop="contentUrl"
aria-describedby="figure-caption-5"
role="button"
data-image-width="666"
data-image-height="431"
data-image-alt="Figure 6"
data-pmc-id="PMC2213463"
data-figure-id="fig6">
<img class="figure-thumb" itemprop="thumbnail"
id="article-image-5"
src="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/3fe1/2213463/adc487fd420e/212.S1067502706002702.gr6.gif"
alt="Figure 6" />
</a>
<meta itemprop="width" itemtype="http://schema.org/ImageObject" content="666">
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<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> Relative frequency of term counts… </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> Relative frequency of term counts for 2,689,166 PubMed queries issued during a single… </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">Relative frequency of term counts for 2,689,166 PubMed queries issued during a single day (graph truncated at 20 terms).</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/3fe1/2213463/445795eaecc1/212.S1067502706002702.gr7.jpg"
itemprop="contentUrl"
aria-describedby="figure-caption-6"
role="button"
data-image-width="666"
data-image-height="437"
data-image-alt="Figure 7"
data-pmc-id="PMC2213463"
data-figure-id="fig7">
<img class="figure-thumb" itemprop="thumbnail"
id="article-image-6"
src="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/3fe1/2213463/3eccee879ae0/212.S1067502706002702.gr7.gif"
alt="Figure 7" />
</a>
<meta itemprop="width" itemtype="http://schema.org/ImageObject" content="666">
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<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> Number of sessions per user… </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> Number of sessions per user for 2,689,166 queries issued on a single day. </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">Number of sessions per user for 2,689,166 queries issued on a single day.</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">
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href="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/3fe1/2213463/1701169f5687/212.S1067502706002702.gr8.jpg"
itemprop="contentUrl"
aria-describedby="figure-caption-7"
role="button"
data-image-width="666"
data-image-height="433"
data-image-alt="Figure 8"
data-pmc-id="PMC2213463"
data-figure-id="fig8">
<img class="figure-thumb" itemprop="thumbnail"
id="article-image-7"
src="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/3fe1/2213463/798aea8a7d13/212.S1067502706002702.gr8.gif"
alt="Figure 8" />
</a>
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<strong class="figure-label">
<p> Figure 8 </p>
</strong>
<div class="figure-caption-contents"><p> Number of queries per session… </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> Number of queries per session for 2,689,166 queries issued in a single day,… </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">Number of queries per session for 2,689,166 queries issued in a single day, as a proportion of sessions with the specified number of queries. Figure truncated at 20 queries.</div>
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<span class="docsum-journal-citation full-journal-citation">J Biomed Inform. 2011 Apr;44(2):310-8. doi: 10.1016/j.jbi.2010.11.001. Epub 2010 Nov 20.</span>
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United States National Library of Medicine. Resource statistics. [Web page] c2005 Available at: <a class="external-link-urlize" href="http://www.ncbi.nih.gov/About/tools/restable_stat_pubmeddata.htm" rel="nofollow noopener" target="_blank">http://www.ncbi.nih.gov/About/tools/restable_stat_pubmeddata.htm</a>. Accessed January 17, 2006.
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Silverstein C, Henzinger M, Marais H, Moricz M. Analysis of a very large AltaVista query log. Technical Note: Digital Equipment Corporation; 1998 October 26. Report No.: SRC Technical Note 1998-014.
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Jansen BJ, Spink A, Saracevic T. Real life, real users, and real needs: a study and analysis of user queries on the web Inf Process Manage 2000;36:207-227.
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Eiron N, McCurley KS. Untangling compound documents on the webIn: Ashman H, editor. Conference on Hypertext and Hypermedia; 2003 August 2630. Nottingham, England: ACM Press; 2003. pp. 85-94.
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