Doing searches in RDF stores is commonly done with SPARQL queries. I have been using this with the semantic web translation of WikiPathways by Andra to find common content issues, though sometimes combined with some additional Java code. For example, find PubMed identifiers that are not numbers.
Egon Willighagen (Sat,) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: