Perhaps you should try some spelling variations:
"significantly smaller decrease" » "significantly higher decrease" (Expand Search), "significantly lower decrease" (Expand Search), "significantly greater decrease" (Expand Search), "significantly small decrease" (Expand Search), "significantly marked decrease" (Expand Search), "significantly smaller areas" (Expand Search)
"significantly improve decrease" » "significantly improved decrease" (Expand Search), "significantly improve disease" (Expand Search), "significantly improved urease" (Expand Search), "significantly improves disease" (Expand Search)

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("significantly smaller decrease") OR ("significantly improve decrease"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"significantly smaller decrease\") OR (\"significantly improve decrease\"))*".
• Removing quotes may allow a broader search: (( significantly smaller decrease ) OR ( significantly improve decrease ))*.