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One search portal for all content
Unlike other PubMed/PubMedCentral sites, Europe PMC allows users to search for biomedical content, returning both full text and abstract results in the same portal.
Enter your search term at the top of the page, as shown in Figure 2 below, for example 'zebra fish'.
Figure 2 Search results page for 'zebra fish'.
The results obtained from searching 28 million abstracts are presented as default ('All citations') - this is highlighted in the red box [a] in Figure 2 above. When there is a full text version of the abstract available in Europe PMC, the words 'Free full text article' and an associated icon are displayed on the record retrieved (as shown in the first search result in Figure 2 [c]). Clicking on the 'Full text articles' tab (next to 'All citations', highlighted in the red box [b]) displays the full text search results.
Note that the advanced search form (accessed via the 'cog' button next to the search icon) provides many useful features designed to help you find what you are looking for.
Europe PMC results can be sorted as follows (see [a] for options in Figure 3 below):
1) All citations: by relevance, date and times cited.
2) Full text articles: by relevance and date.
Figure 3 Search results for 'FOG-1', sorted by 'Times Cited'. The most highly cited articles are diplayed in descending order.
The citations network
If you select an abstract, you can view the citation information by clicking the 'Citations' tab, as shown in Figure 4 below, [a].
Figure 4 The 'Citations tab' for a search on 'FOG-1'.
The Citations tab shows all the papers that have cited the selected article [b], and also those papers which the selected article cites [c].
A note of caution about citation counts: recently published papers may not yet have citations and many papers have no citations at all. The counts per paper in Europe PMC might be somewhat lower than the counts achieved in Scopus or Web of Science because we do not have access to the same content as these resources. However, highly cited articles in Europe PMC correlate with highly cited papers on other platforms, and the information on which papers are doing the citing is freely available.
For more information about how Europe PMC derives its citation counts, see our FAQs.
When database records are submitted or curated, references to the literature are frequently added (Bioentities tab on Figure 5 [a] below). These article citations from the databases are exploited in Europe PMC - you can click the links to move from the article back to the original database record. For example, in Figure 5 [b] you can see that there are 65 different UniProt records that cite this one article. Other databases that provide cross-links in this way include ENA, InterPro, PDB, IntAct, ChEMBL, ChEBI and ArrayExpress.
Figure 5 The BioEntities tab. The links presented are hyperlinked to take the user to the source database if required.
In the abstract view you can highlight biological terms, as shown in Figure 6 [a] (below).
Figure 6 The 'Abstract' tab, showing the biological terms (highlighted).
These terms are also listed in the 'BioEntities' tab in Figure 7 [b] - the number in brackets [c] indicates how many times a particular term occurs in the full text.
Figure 7 The 'BioEntities' tab, showing occurrences of the biological terms.
As well as database cross-references, we also apply text mining to the full text articles and abstracts. Several types of term are text-mined, including gene symbols, diseases, chemicals, organisms, Gene Ontology terms, and accession numbers. Accession numbers are a special case as they represent specific data citations, in a similar vein to article citations within an article. In the above example (Figure 7 [c]), there are 16 gene symbols mined out of the full text (which are linked back to UniProt).
Text-mined terms can be browsed under the BioEntities tab for full text articles. For abstracts, terms of interest can be highlighted (as shown in Figure 6, [a]). In both cases, highlighted terms link back to related data resources.