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