Medline is a comprehensive biomedical information bibliographic database produced by the National Library of Medicine, and it is also a relatively recognized biomedical literature database. Sci is an American scientific citation index. These two retrieval systems are different. The former includes biomedical literature, while sci includes various journals such as natural science and engineering. Changxiao Medical Network has the function of periodical catalogue retrieval. You can enter the name of the periodical you want to query, and it will show which periodical directory the periodical belongs to.