http://scholar.google.com/
http://www.scirus.com/srsapp/搜索期刊(主要为sd)和专利,很不错YSyW '~!b  
http://www.ojose.com/
http://www.goole.com/  

http://citeseer.ist.psu.edu/   
http://yagoohoogle.com/  

http://www.sciseek.com/