Perhaps you should try some spelling variations:
"50 na decrease" » "50 nn decrease" (Expand Search), "50 pa decreased" (Expand Search), "50 la decreased" (Expand Search), "50 n_ decreased" (Expand Search), "50 n_ decreases" (Expand Search), "50 ns decrease" (Expand Search), "50 ng decrease" (Expand Search), "50 n decrease" (Expand Search)
"5 ng decrease" » "5 nn decrease" (Expand Search), "5 we decrease" (Expand Search), "5 gy decreased" (Expand Search), "5 mg decrease" (Expand Search), "5 g decrease" (Expand Search), "5 nm decrease" (Expand Search)
"50 a decrease" » "50 _ decreased" (Expand Search), "50 _ decreases" (Expand Search), "50 μ decrease" (Expand Search), "50 c decrease" (Expand Search), "5 a decrease" (Expand Search)

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"50 _ decrease\") OR (\"50 na decrease\"))) OR (((\"50 a decrease\") OR (\"5 ng decrease\"))))~".
• Removing quotes may allow a broader search: (((( 50 _ decrease ) OR ( 50 na decrease ))) OR ((( 50 a decrease ) OR ( 5 ng decrease ))))~.
• Adding a wildcard symbol may retrieve word variants: (((("50 _ decrease") OR ("50 na decrease"))) OR ((("50 a decrease") OR ("5 ng decrease"))))*.