Perhaps you should try some spelling variations:
"5 ppm decrease" » "5 _ decrease" (Expand Search), "5 a decrease" (Expand Search), "5 nn decrease" (Expand Search)
"5 ng decrease" » "5 nn decrease" (Expand Search), "5 _ decrease" (Expand Search), "5 a decrease" (Expand Search), "5 n_ decrease" (Expand Search), "5 na decrease" (Expand Search), "5 ngy decreased" (Expand Search), "5 mg decrease" (Expand Search), "5 nm decrease" (Expand Search), "5 kg decrease" (Expand Search)
"50 c decrease" » "50 c decreased" (Expand Search), "50 _ decrease" (Expand Search), "50 a decrease" (Expand Search), "5 c decrease" (Expand Search), "50 μ decrease" (Expand Search)
"5 g decrease" » "5 _ decrease" (Expand Search), "5 a decrease" (Expand Search), "5 gy decreased" (Expand Search), "5 mg 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 c decrease") OR ((("5 ng decrease") OR ("5 g decrease"))))))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"5 ppm decrease\") OR (((\"50 c decrease\") OR (((\"5 ng decrease\") OR (\"5 g decrease\"))))))*".
• Removing quotes may allow a broader search: (( 5 ppm decrease ) OR ((( 50 c decrease ) OR ((( 5 ng decrease ) OR ( 5 g decrease ))))))*.