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