Perhaps you should try some spelling variations:
mark david » mare davide, parker david
study gene » study gender, study genetic, study agency
yang yang » wang yang
gene mark » gene bank, gene part, nene marc
yan yang » yao yang, dan yang, tan yang
david ng » david g, david n, david a
ng ghi » hong ghi

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

• Performing a fuzzy search may retrieve terms with similar spellings: (wing or wan) ((yan yang) or (((yang yang) or (wang yan)))) study gene mark david ng ghi ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (wing OR wan) ((yan yang) OR (((yang yang) OR (wang yan)))) study gene mark david ng ghi ;.
• Adding a wildcard symbol may retrieve word variants: (wing or wan) ((yan yang) or (((yang yang) or (wang yan)))) study gene mark david ng ghi ;*.