Perhaps you should try some spelling variations:
using drag » using drg, using dea, using dna
hua gene » human gene, a gene, hua ren
gene yan » gene bank, ren yan, see yan
yan than » van thanh, yan zhang, yan clan
hong ghi » zhong zhi, hong g, hong hai
wong yue » wang yue, hong yu
using a » using _

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: done ((using drag) OR (using a)) hua gene yan than ((hong ghi) OR (wong yue)) ;~.
• Adding a wildcard symbol may retrieve word variants: done ((using drag) or (using a)) hua gene yan than ((hong ghi) or (wong yue)) ;*.