NLM's PubMed Central

I've recently been reading about PubMed Central, NIH's repository for journal literature in the biomedical and life sciences. A former NLM colleague of mine works with PMC, in the NLM back issue digitization effort.

Some points that stand out:

• The full journal list is available online. What's impressive to me is the number of journals with coverage back to volume 1.
  
• The scale of the back issue digitization project is staggering. As of fall 2005, 280,000 articles and over 1.9 million pages had been digitized [source].
• Recent submissions to PMC must be in XML and validated against the NLM Journal Publishing DTD.
  
• NLM's OAI-PMH implementation, PMC's Open Archives Service, can be used to harvest PMC metadata. (Here's info on the implementation, using the OAI Identify and ListSets verbs.) There's an interesting note (given OAI-PMH 2.0's support for flow control) on this page requesting that users avoid large-scale requests during "peak hours" (M-F, 5:00 AM to 9:00 PM Eastern).
  

If you're interested in XML technologies, this is a fascinating project. There's a useful NLM XML resources site that supports work with both the Journal Publishing and the Journal Archiving and Interchange DTDs.