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2010 MAY–JUNE No. 374
May 04, 2010 [posted]

PubMed Central® Celebrates 10 Years!

An Online Archive is Born

PubMed Central (PMC) officially debuted in February 2000, with a mandate to serve as a free digital archive for life sciences and biomedical literature.

Although PMC contained only two journals at the time of its inception — Proceedings of the National Academy of Sciences of the United States of America and Molecular Biology of the Cell — a number of BioMed Central journal titles signed on a few months later, followed by Nucleic Acids Research, The Plant Cell, and Plant Physiology.

Early Growth and Development

Six months after its debut, PMC implemented a key feature — allowing users to link from PubMed citations to full-text articles in PMC. Plans for other improvements were also underway.

In the summer of 2001, a new version of PMC was released, incorporating such features as a redesigned homepage, cross-linking between related PMC articles such as commentaries and companion articles and, most important, a search function that could be accessed from any page in PMC.

By the end of 2002, PMC was growing steadily, with fifty-five life sciences journals to its name, including the Journal of the Medical Library Association. Soon after, in 2003, when PMC became accessible through the National Center for Biotechnology Information (NCBI) Entrez database, the site's search capability was greatly enhanced.

A New Article Submission Format

With the increase in the number of participating journals came the need for creating a common format in which publishers and archives could more efficiently exchange journal content. So, in 2003, NCBI unveiled the NLM Journal Archiving and Interchange Tag Suite which became widely adopted by a number of libraries and publishing houses.

A New Initiative

2003 also marked the beginning of another major PMC initiative — the back issue digitization of old journals, some dating as far back as the mid-1800s. In November 2004, the full run of the Journal of the Medical Library Association was completed, featuring volumes ranging back to 1911. The digitization project also got a major international boost, when, in that same year, the Wellcome Trust, in partnership with the United Kingdom Joint Information Systems Committee, became a collaborator — agreeing to provide both funding and early issues of significant British medical journals (see also //

More Growth and Development

In 2005, another major addition, the National Institutes of Health (NIH) Manuscript Submission System, was implemented — as a direct result of the NIH policy to encourage NIH-funded researchers to deposit their final manuscripts in the PMC archive. Concurrent with the policy, PMC began publishing reference numbers, or PMCIDs, for its articles. These PMCIDs are automatically assigned to articles upon their appearance in PMC, and are particularly useful for grantees in citing policy compliance.

Also, in 2005, PMC began developing a packaged version of its software, called Portable PMC, to serve as the platform for similar international archives. Contingent upon individual publisher agreements, PMC also began making plans to allow for the redistribution of some or most of its content to these institutions.

Two years later, in January 2007, the first of the PMC International (PMCI) centers, UKPMC, was launched, with sponsorship by the Wellcome Trust as well as several other major research funders in the United Kingdom.

In 2008, a significant PMC growth spurt occurred, after the NIH Public Access Policy became mandatory in April of that year, with the number of articles in the archive eventually increasing by almost 50%. With the advent of the mandate, various other PMC enhancements followed, such as:

  1. an updated journal list to show which journals deposit all their NIH-funded articles,
  2. a feature that allows users to find PMCIDs by associating them with their PubMed reference numbers or PMIDs,
  3. the creation of a search option to allow authors and publishers to find NIH-funded articles that are not yet publicly available, and
  4. a Public Access and PMC informational page.

More Articles, More Features

A year later, in 2009, more features were also put into place, including a new, more standardized Uniform Resource Locator format,, as well as a "preview" table of contents page for viewing immediate access articles in issues under publisher embargo.

In addition, another PMC milestone occurred in October 2009, when the most recent PMCI center, PMC Canada, became operational.

PMC Today

Currently, there are more than 600 full deposit journals as well as collections of NIH-funded articles, author manuscripts, books and other documents in the PMC archive. As PMC has grown, so has the number of users. Now, on a typical weekday, about 420,000 users are accessing 740,000 articles. What's more — a decade after its creation, PMC has become home to some two million articles!

By Marla Fogelman
National Center for Biotechnology Information

Fogelman M. PubMed Central® Celebrates 10 Years! NLM Tech Bull. 2010 May-Jun;(374):e5.