This online tool helps you convert any digital object identifier (DOI) into the
corresponding PubMed Id (PMID) if any. It works for the PubMed-indexed journal articles. The journal articles indexed by
PubMed Central (PMC)
have PMIDs, too. Hence, you can use this tool for PMC-indexed articles, as well. PMC has another tool for converting the article identifiers limited to the PMC-indexed articles.
To learn DOI vs. PMCID vs. PMID, what are all these are about, click