Open Archives Service
The PubMed Central OAI service (PMC-OAI) provides access to metadata of all items in the
PubMed Central (PMC) archive, as well as to the full text of a subset of these
items.
PMC-OAI is an implementation of the Open Archives Initiative Protocol for
Metadata Harvesting (OAI-PMH), a standard for retrieving metadata from digital document
repositories. Visit the Open Archives Initiative site for more information about
the protocol and other activities of the OAI group.
PMC-OAI supports OAI-PMH version 2.0. It does not support earlier versions of the protocol.
Copyright
Most of the items in this archive are copyright protected, with copyright held by the author(s) or the depositing journal. In general, the OAI service can not be used to retrieve the full text of articles in PMC. The only exceptions to this policy are for articles that are in the public domain and those that are made available under an Open Access provision (as defined in the Open Access Subset). See the PMC Copyright Notice for more information.
Using the PMC-OAI Service
The base URL for the service is:
http://www.pubmedcentral.nih.gov/oai/oai.cgi
For more specific information, see PMC-OAI examples.
High-Volume Retrievals
If you are using a script that makes more than 100 requests of any kind, please run it outside of the PMC system's peak hours. Do not make more than one request every 3 seconds, even at off-peak times. Peak hours are Monday to Friday, 5:00 AM to 9:00 PM, U.S. Eastern time.
The PMC-OAI Service supports HTTP compression, and the Accept-Encoding HTTP header must be set to 'gzip, deflate' for the most efficient data transfer. See also HTTP compression for further information about this capability.
Access to Full Text
Some PMC journals allow harvesting of the full text of all items, others allow it for only
some items, and many do not allow it at all. See the PMC Open Access
Subset for specifics.
In addition, the parameter set=pmc-open identifies the complete collection of items
in PMC for which the full text may be harvested.
Supported Data Formats
Records may be retrieved from the PMC archive in one of the following formats:
- The NLM Journal Archiving and Interchange XML format, for metadata or full-text article
records. A DTD, W3C Schema, and complete documentation for this format are available from http://dtd.nlm.nih.gov.
- Metadata:
metadataPrefix=pmc_fm
- Full Text:
metadataPrefix=pmc
- Metadata:
- The Dublin Core format, http://dublincore.org
- Metadata:
metadataPrefix=oai_dc
- Metadata:
Automatic Segmentation of Large Result Sets
If a ListIdentifiers request results in more than 500 hits, PMC-OAI will return the first 500 with a <resumptionToken> that can be used to get the remaining items.
If a ListRecords request results is more than 25 hits for PMC full text, 50 hits for PMC metadata, or 50 hits for Dublin Core format metadata, PMC-OAI will return the first 25, or 50 records, respectively, with a <resumptionToken>.