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