Category Archives: About Resources

Citation Number Limits in PubMed

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When handling search results in PubMed a user may encounter a situation when some operations are limited to a certain number of citations. While some users may think that, in practice, they will never need to deal with a very large number of citations, such situations do occur.

Below are instances when PubMed users will encounter a limit to the number of citations (and Pubmed messages alerting to that):

  • When browsing a lengthy list of search results or jumping to a page towards the end of a search results list (This site can display up to 10,000 results. Please see the User Guide for more information on navigating your search results.)
  • When saving citations to file (Only the first 10,000 citations will be saved in your file.)
  • When e-mailing your citations (Only the first 1,000 citations will be sent in your email. You will receive citations in multiple emails.)
  • When adding citations to a Collection in My NCBI account: (Only the first 1,000 citations will be added to collection.)
  • When sending citations to Clipboard (Only the first 500 items will be sent to clipboard.)

These problems can be addressed with the following options:

Other databases, such as Embase, CINAHL, Scopus, Web of Science, have similar, but not exactly the same maximums of the number of citations allowed for certain operations.

Tools for Ranking Journals by Impact

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Many considerations should factor into a well-made decision about which journal(s) an author should target for manuscript submission. (For more info, see the MSK Library’s Support for Authors LibGuide.) 

As they explore their options, it’s often useful for authors to get a sense of how reputable a particular journal title is based on how this journal ranks – in terms of impact – versus other journals within the same discipline. In general, journal impact metrics are generated using a mathematical algorithm that is largely based on article citation counts over a pre-specified time period. Citation count data can provide some indication of a journal’s influence and reach, particularly when considered relative to other journals.

Below are three tools (two subscription databases available via the MSK Library and one free online search engine) that can be used to generate journal impact ranking information that can aid with the journal selection process.

Journal Impact FactorsTM – and the Journal Citation Reports (JCR) rankings that they lead to – are generated using two years-worth of article citation data compiled in Clarivate’s Web of Science database. This metric has been around for over 50 years, and was developed by the originator of the citation analysis concept, Eugene Garfield, who is often considered the grandfather of information science and scientometrics. 

See more details on how the Journal Impact FactorTM is calculated.

Elsevier generates it own impact metric, called the CiteScoreTM, by using the citations to articles, reviews, conference papers, book chapters and data papers published over a four-year publication window. Similar to Clarivate, Elsevier can generate these metrics because the data needed for the calculations is available from its flagship Scopus database.

See more details on how the CiteScoreTM is calculated.

Google Scholar, although not a structured database populated with records that have standard fields (as is the case in JCR and Elsevier’s Scopus Sources) still collects citation data that it compiles via the Google Scholar search crawler. It then uses citation data to generate an h-index type metric for the entire journal, as opposed to the usual use of the h-index to evaluate the productivity of an individual researcher. Google Scholar h5 metrics are calculations based on the citation count to published items from the last five complete calendar years.

See more details on how Google Scholar h-based metrics are calculated.

Be sure to check out the MSK Library’s Measuring Research Impact class and the Evaluating Journal Quality class if you have questions, or Ask Us! 

New MeSH Terms for 2022

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The Medical Subject Headings (MeSH) thesaurus is a controlled and hierarchically-organized vocabulary produced by the National Library of Medicine (NLM). It is used for indexing, cataloging, and searching of biomedical and health-related information. MeSH includes the subject headings appearing in MEDLINE/PubMed, the NLM Catalog, and other NLM databases.

The NLM has released its annual list of MeSH changes, including highly anticipated NEW MeSH (Medical Subject Heading) terms for 2022!

The list covers a variety of changes and updates made to MeSH, including:

  • Updated terms — these are MeSH terms that have been deleted, changed, or replaced to reflect more updated terminology
    • 24 terms were updated for 2022
  • New terms — these are brand new MeSH terms added
    • 277 new MeSH Descriptors were added for 2022
    • 218 new Supplementary Concepts were added for 2022

New Covid-19-related MeSH Headings:

New Cancer-related MeSH Headings:

Note: The MeSH Browser can be used to conduct in-depth searches of the vocabulary within MeSH, whereas the MeSH Database is a mapping tool within PubMed to quickly locate terms and add them to search strategies.