Perhaps you should try some spelling variations:
"50 mean decrease" » "50 a decrease" (Expand Search), "50 meann decrease" (Expand Search), "50 mea_ decrease" (Expand Search), "50 meaa decrease" (Expand Search), "20 means decrease" (Expand Search)
"50 n decrease" » "50 nn decrease" (Expand Search), "50 _ decrease" (Expand Search), "50 a decrease" (Expand Search), "50 ns decrease" (Expand Search), "50 ng decrease" (Expand Search), "50 μ decrease" (Expand Search)
"50 meannn decrease" » "50 meannnn decrease" (Expand Search), "50 meann_ decrease" (Expand Search), "50 meanna decrease" (Expand Search), "20 meansnn decrease" (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: (("50 n decrease") OR ((("50 mean decrease") OR ("50 meannn decrease"))))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"50 n decrease\") OR (((\"50 mean decrease\") OR (\"50 meannn decrease\"))))*".
• Removing quotes may allow a broader search: (( 50 n decrease ) OR ((( 50 mean decrease ) OR ( 50 meannn decrease ))))*.