Perhaps you should try some spelling variations:
patients risk » patient risk, patients links, patients si
cost patients » cost patient, cleft patients, care patients
cheng zhang » cheng han, zhen zhang, chen zheng
using run » during run, using r, using ann
ming run » being run, ming hung, long run
hong shu » tong shui, wong shiu, hong seo

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: cheng zhang ((ming run) OR (using run)) cost patients risk ((hong shu) OR (cong shu)) ;~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "cheng zhang ((ming run) OR (using run)) cost patients risk ((hong shu) or (cong shu)) ;~".
• Adding a wildcard symbol may retrieve word variants: cheng zhang ((ming run) OR (using run)) cost patients risk ((hong shu) or (cong shu)) ;*.