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