Perhaps you should try some spelling variations:
yang guang » yang yang, yan guan, yang liang
wai yang » wai yan, wei yang, wang yang
hua gene » human gene, hua ren, hy5 gene
tang kia » tang li, kang kim, pang kin
yu chen » yu cheng, yi chen, yulu chen
hong yu » wong yue
a gene » a genre, a gender, a gentle

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: wai yang guang ((((hua gene) OR (a gene))) OR (yu chen)) tang kia hong yu ;~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "wai yang guang ((((hua gene) OR (a gene))) or (yu chen)) tang kia hong yu ;~".
• Adding a wildcard symbol may retrieve word variants: wai yang guang ((((hua gene) OR (a gene))) or (yu chen)) tang kia hong yu ;*.