Perhaps you should try some spelling variations:
"50 ng decrease" » "50 _ decrease" (Expand Search), "10 ng decrease" (Expand Search), "50 μg decrease" (Expand Search)
"_ fe decrease" » "_ _ decrease" (Expand Search), "_ f_ decrease" (Expand Search), "_ f_ decreased" (Expand Search), "_ f_ decreases" (Expand Search), "_ e decrease" (Expand Search)
"5 e decrease" » "5 _ decrease" (Expand Search), "5 _ decreased" (Expand Search), "5 _ decreases" (Expand Search)
"_ f decrease" » "_ _ decrease" (Expand Search), "_ _ decreased" (Expand Search), "_ _ decreases" (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 ng decrease\") OR (((((\"_ fe decrease\") OR (\"5 e decrease\"))) OR (\"_ f decrease\"))))~".
• Removing quotes may allow a broader search: (( 50 ng decrease ) OR ((((( _ fe decrease ) OR ( 5 e decrease ))) OR ( _ f decrease ))))~.
• Adding a wildcard symbol may retrieve word variants: (("50 ng decrease") OR ((((("_ fe decrease") OR ("5 e decrease"))) OR ("_ f decrease"))))*.