has interface Entrez The Entrez Global Query Cross-Database Search System is a powerful federated search engine, or web portal that allows users to search many discrete health sciences databases at the National Center for Biotechnology Information (NCBI) website. Ncbi Resource, C. (2012). "Database resources of the National Center for Biotechnology Information". Nucleic Acids Research 41 (Database issue): D8–D20. doi:10.1093/nar/gks1189. PMC 3531099. Entrez Global Query Cross-Database Search System search engine web user interface