Entrez - PubMed - MEDLINE
Entrez is the integrated, text-based search and retrieval system used at National Center for Biotechnology Information (NCBI) for the major databases, including PubMed, Nucleotide, Protein, Genome, Taxonomy, and others.
PubMed is a Web-based retrieval system developed by NCBI at the National Library of Medicine. It is part of NCBI's retrieval system, known as Entrez. PubMed is a database of bibliographic information drawn primarily from the life sciences literature. The PubMed database includes more than 20 million citations: 20556450 items as of April 27, 2011, with 3320300 citations of free full text articles. As of February 7, 2011, 5542 journals are indexed in MEDLINE.
- In-process citations which provide a record for an article before it is indexed with MeSH and added to MEDLINE or converted to out-of-scope status.
- Citations that precede the date that a journal was selected for MEDLINE indexing (when supplied electronically by the publisher).
- Some OLDMEDLINE citations that have not yet been updated with current vocabulary and converted to MEDLINE status.
- Citations to articles that are out-of-scope (e.g., covering plate tectonics or astrophysics) from certain MEDLINE journals, primarily general science and general chemistry journals, for which the life sciences articles are indexed with MeSH for MEDLINE.
- Some life science journals that submit full text to PubMedCentral and may not yet have been recommended for inclusion in MEDLINE although they have undergone a review by National Library of Medicine - National Institutes of Health (NLM), and some physics journals that were part of a prototype PubMed in the early to mid-1990's.
- Citations to author manuscripts of articles published by National Institutes of Health (NIH)-funded researchers.
MEDLINE is the NLM bibliographic database that contains references to journal articles in the life sciences with a concentration on biomedicine. A distinctive feature of MEDLINE is that the records are indexed with NLM's controlled vocabulary, the Medical Subject Headings (MeSH). The database contains citations from 1950 to the present, with some older material.
MeSH is the acronym for "Medical Subject Headings." MeSH vocabulary is used for indexing journal articles for MEDLINE. The MeSH controlled vocabulary is a distinctive feature of MEDLINE. MeSH terms are arranged in a hierarchical categorized manner called MeSH Tree Structures.