Perhaps you should try some spelling variations:
"50 ppm decrease" » "50 _ decrease" (Expand Search), "50 pa decreased" (Expand Search), "50 026 decrease" (Expand Search), "5 ppm decrease" (Expand Search)
"5 nn decrease" » "5 _ decrease" (Expand Search), "5 mean decrease" (Expand Search), "5 gy decreased" (Expand Search), "5 non decrease" (Expand Search), "59 nn decrease" (Expand Search), "5 nm decrease" (Expand Search)
"_ we decrease" » "_ _ decrease" (Expand Search), "_ mean decrease" (Expand Search), "_ teer decrease" (Expand Search), "_ web decrease" (Expand Search), "_ wet decrease" (Expand Search), "_ e decrease" (Expand Search)
"50 a decrease" » "50 _ decrease" (Expand Search), "50 _ decreased" (Expand Search), "50 _ decreases" (Expand Search), "50 μ decrease" (Expand Search), "50 c decrease" (Expand Search)

Try widening your search to All Fields.

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 ("_ we 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 (\"_ we decrease\"))) OR (\"50 a decrease\"))))".
• Removing quotes may allow a broader search: (( 50 ppm decrease ) OR ((((( 5 nn decrease ) OR ( _ we decrease ))) OR ( 50 a decrease )))).
• Adding a wildcard symbol may retrieve word variants: (("50 ppm decrease") OR ((((("5 nn decrease") OR ("_ we decrease"))) OR ("50 a decrease"))))*.