pmc-open-access-eutils.txt

Search PubMed for articles in the PMC Open Access Subset for which free full text (i.e. XML) is available:
http://eutils.ncbi.nlm.nih.gov/entrez/eutils/esearch.fcgi?db=pubmed&retmode=xml&term=pubmed+pmc+open+access%5Bfilter%5D+AND+free+full+text%5Bfilter%5D

Find the PMCID for an article by PMID:
http://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&db=pmc&retmode=xml&linkname=pubmed_pmc&id=24191168

Fetch full text article XML from PMC by PMCID:
http://eutils.ncbi.nlm.nih.gov/entrez/eutils/efetch.fcgi?db=pmc&id=3804407

A PMC article for which the full text XML is not available:
http://eutils.ncbi.nlm.nih.gov/entrez/eutils/efetch.fcgi?db=pmc&id=380440
A PMC article for which the full text XML is not available, but claims to be open-access:
http://eutils.ncbi.nlm.nih.gov/entrez/eutils/efetch.fcgi?db=pmc&id=4019015

Search PMC for an article by DOI:
http://eutils.ncbi.nlm.nih.gov/entrez/eutils/esearch.fcgi?db=pmc&retmax=1&term=10.1155%2F2013%2F248349%5BDOI%5D

Get XML for an article from the PMC OAI server by PMCID (namespaces <3):
http://www.pubmedcentral.nih.gov/oai/oai.cgi?verb=GetRecord&metadataPrefix=pmc&identifier=oai:pubmedcentral.nih.gov:3628370

Search PMC for articles with a certain license:
http://www.pubmedcentral.nih.gov/utils/oa/oa.fcgi?term=cc+by+nc+license%5Bfilter%5D

License vagueness:
http://www.ncbi.nlm.nih.gov/books/NBK159964/
http://oag.cottagelabs.com/

Macrodocs:
search PMC Open Access Subset, list matching articles, pick an article by DOI or PMC ID, fetch and render the XML
http://macrodocs.org/