Perhaps you should try some spelling variations:
significantly improved » significantly increased (Expand Search)
significant level » significance level (Expand Search), significance levels (Expand Search), significant gender (Expand Search)
improved decrease » improved urease (Expand Search), marked decrease (Expand Search)
level decrease » levels decreased (Expand Search), level increased (Expand Search), teer decrease (Expand Search)

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

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