Important sites for Clinical research and Clinical trials

first site 

http://www.sign.ac.uk/guidelines/published/index.html#CHD 

contain all disease and last trials for this disease 

second site 

http://summaries.cochrane.org/

http://www.cochrane.org/

3rd site 

http://www.lexi.com/search/?cx=002772095352357491926%3A_4b6riqnx68&cof=FORID%3A10%3BNB%3A1&ie=UTF-8&sa=Search&q=captopril

4rd 

http://www.ncbi.nlm.nih.gov/pubmed/clinical

this the most site contain newest trials 

http://www.guideline.gov/search/advanced-search.aspx