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