Perhaps you should try some spelling variations:
dong yang » dong hoang, wang yang, yang yang
patient a » patient _, patient 1, patient care
dong cao » dong xiao, dan cao, dong nan
patent a » patents a, patent _, patent 7
long du » long d, long run, long did
long do » long d, longer do, long ago
ya a » a a, y a, ye a

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: ((dong cao) OR (dong yang)) ya a ((patent a) OR (patient a)) eu ((long du) OR (long do)) ;~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((dong cao) or (dong yang)) ya a ((patent a) or (patient a)) eu ((long du) OR (long do)) ;~".
• Adding a wildcard symbol may retrieve word variants: ((dong cao) or (dong yang)) ya a ((patent a) or (patient a)) eu ((long du) OR (long do)) ;*.