PubMed Tutorial from The Levy Library: 1. MEDLINE/PubMed Basics
Intro to PubMed and MEDLINE
PubMed is a database of over 25 million biomedical article citations created and maintained by the National Library of Medicine. MEDLINE is the subset of PubMed records which have been indexed by the National Library of Medicine and have had Medical Subject Headings (MeSH) terms applied. Currently approximately 80% of PubMed records are indexed for MEDLINE.
Subject Coverage: Biomedicine and the health care sciences. MEDLINE also covers medically relevant fields of the biosciences such as microbiology, immunology, virology and neuroscience.
Publication Date Coverage: Approximately 1950 to present. The earliest citations in PubMed date back to the late 1940s, but consistent coverage and indexing began in earnest in the early 1950s.
Record Content: PubMed records are comprised of fields, or "data elements", such as Author, Title, Publication Date, Abstract, MeSH Terms, etc. A PubMed record can have as many as 60 different fields. It is important to note that PubMed is a citation database, not a full text database so when searching PubMed, you are searching the citation information contained in these fields only, not the entire text of the article.
Sample PubMed Citation
Record Nuts & Bolts
Publishers usually upload citation records to the PubMed database at which time each record is assigned a PubMed Unique Identifier (PMID).
When a citation is indexed for MEDLINE, professional indexers working for the National Library of Medicine read the full article (not just the citation) and apply appropriate MeSH Terms according to a set of indexing rules.
How quickly a citation is indexed for MEDLINE once it has been added to PubMed varies significantly from journal to journal. Citations for articles published in journals such as NEJM, JAMA, and Annals of Internal Medicine (i.e. heavily read, highly cited, “high impact” journals) tend to be indexed within 2-3 weeks. Citations for articles published in less well known journals can take 6+ months to be indexed.