搜索文献的数据库

1、Pubmed (MEDLINE) https://www.ncbi.nlm.nih.gov/pubmed
2、Biomed CENTRAL http://www.biomedcentral.com/
3、Cochrane Collaboration https://www.cochranelibrary.com/advanced-search

数据库（Database）：
1、PubMed
2、Embase
3、Cochrane CENTRAL trials register; Cochrane Database of Systematic Reviews
4、PROSPERO
5、Clinical Trials