PMC Overview

PubMed Central® (PMC) is a free full-text archive of biomedical and life sciences journal literature at the U.S. National Institutes of Health's National Library of Medicine (NIH/NLM). In keeping with NLM’s legislative mandate to collect and preserve the biomedical literature, PMC serves as a digital counterpart to NLM’s extensive print journal collection.

PMC was developed and is managed by NLM’s National Center for Biotechnology Information (NCBI).

About the Content

Since its inception in 2000, PMC has grown from comprising only two journals, PNAS: Proceedings of the National Academy of Sciences and Molecular Biology of the Cell, to an archive of articles from thousands of journals.

Today, PMC contains more than 5 million full-text records, spanning several centuries of biomedical and life science research (late 1700s to present). Content is added to the archive through

Journal and Publisher Program Deposit

NLM has agreements with publishers, scholarly societies, and other content owners to deposit journal articles directly to PMC.

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Author Manuscript Deposit

NLM partners with a number of scientific research funders to accept the deposit of author manuscripts in compliance with funder policies.

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Digitization Projects

NLM collaborates with publishers and other organizations to preserve the historical literature through scanning of journal content.

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The resulting collaborations with publishers, societies, research funders, and international organizations form the foundation of PMC. PMC is not a publisher and does not publish journal articles itself.

As of June 2020, PMC also includes preprints that report NIH-funded research results. To learn more, see NIH Preprint Pilot.

For more information on content in PMC, see Policies and the PMC Disclaimer.

Total PMC records and breakdown by digitized content, author manuscripts and PMC journals and publisher programs

About the Archive

NLM’s fundamental responsibility is to permanently preserve periodicals, among other materials, pertinent to medicine. (See the NLM Preservation Policy for more information.) As such, PMC is designed to provide permanent access to all of its content, even as technology evolves. To do so,

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PMC makes all content free to read (in some cases, following an embargo period), as NLM believes that the best way to ensure the accessibility and viability of digital material over time is through consistent and active use of the archive. However, free access does not mean that there is no copyright protection (see the PMC Copyright Notice).

RSS Feed

PMC stores content in eXtensible Markup Language (XML), which represents the structure and meaning of a document in a relatively simple and human-readable form. All PMC content is converted to and stored in the NISO Z39.96-2015 JATS XML format. This standard format is the most effective and widely used archival format for journal articles.

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NLM operates the PMC International network, which provides a framework to maintain copies of the PMC corpus in other reliable international archives that share the goals of PMC and operate on the same principles.

Because PMC has the capacity to store and cross reference data from diverse sources in a common format within a central repository, a PMC user can quickly search the entire collection of full-text articles and locate all relevant material. The structure of the PMC archive also supports the integration of the literature with other resources.

Bulk retrieval of files for text mining and other purposes is permitted within certain collections or subsets of the PMC archive. An overview of these subsets of the archive is available at Text Mining Collections.

About PMC Archive Use

In addition to ensuring the long-term preservation of the scientific literature, PMC provides access to the archive in human- and machine-readable formats. Use of PMC has increased as the archive has grown. Numbers reported below reflect access to the PMC website in the last month of each fiscal year (i.e., September).

Fiscal Year Articles Available Avg. Unique Sessions /
Weekday
FY19 5,725,819 2.6 million
FY18 5,107,590 2.4 million
FY17 4,553,343 2.1 million
FY16 4,054,283 1.3 million
FY15 3,623,566 1.2 million
FY14 3,227,379 886,000
FY13 2,859,268 834,000

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Last updated: Mon., 8 Jun 2020