Data citations to the any database which is introduced

Statement: 

Data citations to the any database which is introduced $db$ (e.g., PDB) A limit of results per page $number$ (e.g. 25)

Query: 
prefix npg: <http://ns.nature.com/terms/> select ?doi ?data where { ?doi a npg:Article ; npg:hasDataCitation [ npg:hasLink [ ?_ ?data ] ; npg:type ?type ] . filter regex(?type, "??db", "i") } limit ??number