Perhaps you should try some spelling variations:
clone chain » closed chain, long chain
gene clone » gene one
chain lung » chin lung
qian wang » yiqian wang, qian rong, yan wang
xuan gene » human gene
qian yan » qian jun, qian yi
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 wang) OR (qian yan)) xuan gene clone chain lung san ;~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "wai ((qian wang) OR (qian yan)) xuan gene clone chain lung san ;*".