Perhaps you should try some spelling variations:
"50 ppm decrease" » "50 _ decrease" (Expand Search), "50 a decrease" (Expand Search), "50 pa decreased" (Expand Search)
"5 ppm decrease" » "5 _ decrease" (Expand Search), "5 a decrease" (Expand Search), "5 pa decreased" (Expand Search)
"5 nn decrease" » "5 _ decrease" (Expand Search), "5 a decrease" (Expand Search), "5 mean decrease" (Expand Search), "5 non decrease" (Expand Search), "59 nn decrease" (Expand Search), "5 nm decrease" (Expand Search)
"50 we decrease" » "50 _ decrease" (Expand Search), "50 a decrease" (Expand Search), "50 mean 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 ppm decrease") OR ("5 nn decrease"))))) OR ("50 we decrease"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"50 ppm decrease\") OR (((\"5 ppm decrease\") OR (\"5 nn decrease\"))))) OR (\"50 we decrease\"))".
• Removing quotes may allow a broader search: (((( 50 ppm decrease ) OR ((( 5 ppm decrease ) OR ( 5 nn decrease ))))) OR ( 50 we decrease )).
• Adding a wildcard symbol may retrieve word variants: (((("50 ppm decrease") OR ((("5 ppm decrease") OR ("5 nn decrease"))))) OR ("50 we decrease"))*.