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