Perhaps you should try some spelling variations:
clone chain » closed chain, long chain
gene clone » gene one
chain lung » chin lung
wang xuan » wang xiuyan, wang xueman, wang yuhan
xuan gene » human gene
wai qian » wei qiang, wai yan, wu qian
lung san » aung san, lung can, und san

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((wai qian) OR (ji qian)) wang xuan gene clone chain lung san ;~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((wai qian) OR (ji qian)) wang xuan gene clone chain lung san ;*".