Perhaps you should try some spelling variations:
"5 ppm decrease" » "5 _ decrease" (Expand Search)
"50 ng decrease" » "50 _ decrease" (Expand Search), "10 ng decrease" (Expand Search), "50 μg decrease" (Expand Search)
"100 ng decrease" » "100 _ decrease" (Expand Search), "100 nm decrease" (Expand Search), "10 ng decrease" (Expand Search), "100 mg 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)

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 ng decrease") OR ("100 ng decrease"))))))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"5 ppm decrease\") OR (((\"50 a decrease\") OR (((\"50 ng decrease\") OR (\"100 ng decrease\"))))))*".
• Removing quotes may allow a broader search: (( 5 ppm decrease ) OR ((( 50 a decrease ) OR ((( 50 ng decrease ) OR ( 100 ng decrease ))))))*.