Perhaps you should try some spelling variations:
significantly improves » significantly improved (Expand Search), significantly improve (Expand Search), significant improvements (Expand Search)
significantly mediate » significantly mediated (Expand Search), significantly moderate (Expand Search), significantly predicted (Expand Search)
improves decrease » improves disease (Expand Search), improve disease (Expand Search), improved urease (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 improves decrease ))*.