PubMed Central is an archive of about 8 million full text articles from 3000 biomedical and life science journals ranging from the late 1700s to the present.  It is another database that the National Library of Medicine (NLM) maintains.  NLM has a statutory mission to collect, index, preserve, and make available biomedical and health-related literature of the present-day and from the past. As such, PMC is designated to provide permanent access to all of its content, even as technology evolves.