Perhaps you should try some spelling variations:
"5 ppm decrease" » "5 _ decrease" (Expand Search), "5 a decrease" (Expand Search), "5 pa decreased" (Expand Search)
"50 nn decrease" » "50 _ decrease" (Expand Search), "50 a decrease" (Expand Search), "50 mean decrease" (Expand Search), "50 ns decrease" (Expand Search), "50 n decrease" (Expand Search), "59 nn decrease" (Expand Search)
"50 ng decrease" » "50 _ decrease" (Expand Search), "50 a decrease" (Expand Search), "50 we decrease" (Expand Search), "50 mg decrease" (Expand Search), "10 ng decrease" (Expand Search), "5 ng decrease" (Expand Search)
"100 ng decrease" » "100 _ decrease" (Expand Search), "100 a decrease" (Expand Search), "100 we decrease" (Expand Search), "100 mg decrease" (Expand Search), "100 nm decrease" (Expand Search), "100 ns 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: (("5 ppm decrease") OR ((("50 nn decrease") OR ((("50 ng decrease") OR ("100 ng decrease"))))))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"5 ppm decrease\") OR (((\"50 nn decrease\") OR (((\"50 ng decrease\") OR (\"100 ng decrease\"))))))*".
• Removing quotes may allow a broader search: (( 5 ppm decrease ) OR ((( 50 nn decrease ) OR ((( 50 ng decrease ) OR ( 100 ng decrease ))))))*.