Perhaps you should try some spelling variations:
risk decrease » risk decreases (Expand search), risk increase (Expand search), break decrease (Expand search)
decrease risk » decreased risk (Expand search), increase risk (Expand search), decrease hiv (Expand search)
decrease yiel » decreases yield (Expand search), decrease il (Expand search), increase yield (Expand search)
yiel pattern » yield pattern (Expand search), diel pattern (Expand search), diel patterns (Expand search)
in decrease » in decreased (Expand search), on decrease (Expand search), pain decrease (Expand search)
of decrease » or decrease (Expand search), not decrease (Expand search), to decrease (Expand search)

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "(( decrease in decrease of decrease ) OR ( decrease risk decrease yiel pattern ))~".
• Adding a wildcard symbol may retrieve word variants: (( decrease in decrease of decrease ) OR ( decrease risk decrease yiel pattern ))*.