NIH-funded articles should be submitted to PMC immediately after being accepted by a journal; the manuscripts are made publicly available within 12 months of publication.The submission process is quite easy and fast: For methods A and B: Many journals have agreements to deposit articles in PMC, some of them with full participation, others offering selective deposit, and others with an NIH portfolio agreement, which means that they only deposit NIH-funded articles.MEDLINE and Pub Med policies for the selection of journals for database inclusion are slightly different.
The secondary identifier field is to store accession numbers to various databases of molecular sequence data, gene expression or chemical compounds and clinical trial IDs.
For clinical trials, Pub Med extracts trial IDs for the two largest trial registries: Clinical (NCT identifier) and the International Standard Randomized Controlled Trial Number Register (IRCTN identifier).
To help authors find out which method is supported by a particular journal, the NIH has published several lists on their homepage as well as additional information on how to submit a manuscript to PMC.
Pub Med is a free search engine accessing primarily the MEDLINE database of references and abstracts on life sciences and biomedical topics.
A reference which is judged particularly relevant can be marked and "related articles" can be identified.
If relevant, several studies can be selected and related articles to all of them can be generated (on Pub Med or any of the other NCBI Entrez databases) using the 'Find related data' option.
Pub Med, first released in January 1996, ushered in the era of private, free, home- and office-based MEDLINE searching.
Pub Med has been reported to include some articles published in predatory journals.
Simple searches on Pub Med can be carried out by entering key aspects of a subject into Pub Med's search window.
Pub Med translates this initial search formulation and automatically adds field names, relevant Me SH (Medical Subject Headings) terms, synonyms, Boolean operators, and 'nests' the resulting terms appropriately, enhancing the search formulation significantly, in particular by routinely combining (using the OR operator) textwords and Me SH terms.