Perhaps you should try some spelling variations:
cost patient » cross patient, courts patient, class patient
patient risk » patients risk, patient task, patient cost
among sex » among smes, among eu
yang jun » yang jui, pang jun, yang jin
among di » among hiv, among idp, among _
yang up » yang jui, tying up, hang ups
wang » wing, wan, lang

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: wang yanling ((yang up) OR (yang jun)) cost patient risk ((among di) OR (among sex)) ;~.
• Adding a wildcard symbol may retrieve word variants: wang yanling ((yang up) or (yang jun)) cost patient risk ((among di) or (among sex)) ;*.