Perhaps you should try some spelling variations:
significantly improved » significantly increased (Expand Search)
significantly mediate » significantly mediated (Expand Search), significantly moderate (Expand Search), significantly predicted (Expand Search)
improved decrease » improved urease (Expand Search), marked decrease (Expand Search)
mediate decrease » mediated defense (Expand Search), mean decrease (Expand Search)

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

• Removing quotes may allow a broader search: (( significantly mediate decrease ) OR ( significantly improved decrease ))*.