Perhaps you should try some spelling variations:
among farmers » salmon farmers
patients 1.8 » patients 10.1, patients 10.5, patients 10.6
yang yang » wang yang, wang yan
1.8 among » 1.5 among, 19 among, 1 among
yan yang » yao yang, dan yang, tan yang
fan de » aan de, jan de, can de
van de » van der, van den

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: wan ((yan yang) OR (yang yang)) ((fan de) OR (van de)) patients 1.8 among farmers ;~.
• Adding a wildcard symbol may retrieve word variants: wan ((yan yang) or (yang yang)) ((fan de) or (van de)) patients 1.8 among farmers ;*.