Perhaps you should try some spelling variations:
patients risk » patient risk, patients links, patients si
cost patients » cost patient, cleft patients, care patients
liang yang » liang ying, wang yang, huang yang
yang yang » wang yang, wang yan
risk hong » risk among, risk along, risk how
hong shu » cong shu, tong shui, wong shiu

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

• Performing a fuzzy search may retrieve terms with similar spellings: wang ((liang yang) or (yang yang)) a cost patients risk hong shu ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: wang ((liang yang) OR (yang yang)) a cost patients risk hong shu ;.
• Adding a wildcard symbol may retrieve word variants: wang ((liang yang) or (yang yang)) a cost patients risk hong shu ;*.