The databases listed below may be good options as a complementary search source for specialized topics. While they may have some overlap of coverage with PubMed or a larger multidisciplinary database, you will likely find unique and specialized results.
Embase is a biomedical literature database that focuses on drugs and pharmacology, medical devices, clinical medicine, and basic science relevant to clinical medicine. The database contains journal articles, conference papers, abstracts and reports in biomedicine dating back to 1947. It includes over 44 million citations and over 3,000 journals not included in PubMed.