Perhaps you should try some spelling variations:
"5 ppm decrease" » "5 _ decrease" (Expand Search)
"5 nn decrease" » "5 _ decrease" (Expand Search), "k nn decrease" (Expand Search), "_ nn decrease" (Expand Search)
"50 mg decrease" » "50 _ decrease" (Expand Search), "50 μg decrease" (Expand Search)
"50 a decrease" » "50 _ decrease" (Expand Search), "50 _ decreased" (Expand Search), "50 _ decreases" (Expand Search), "5 a decrease" (Expand Search), "50 i 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: (((((("5 ppm decrease") OR ("5 nn decrease"))) OR ("50 mg decrease"))) OR ("50 a decrease"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((((\"5 ppm decrease\") OR (\"5 nn decrease\"))) OR (\"50 mg decrease\"))) OR (\"50 a decrease\"))*".
• Removing quotes may allow a broader search: (((((( 5 ppm decrease ) OR ( 5 nn decrease ))) OR ( 50 mg decrease ))) OR ( 50 a decrease ))*.