Perhaps you should try some spelling variations:
"50 mean decrease" » "50 a decrease" (Expand Search), "20 means decrease" (Expand Search)
"5 ppm decrease" » "5 _ decrease" (Expand Search), "5 a decrease" (Expand Search), "5 nn decrease" (Expand Search)
"50 ng decrease" » "50 nn decrease" (Expand Search), "50 _ decrease" (Expand Search), "50 a decrease" (Expand Search), "50 n_ decrease" (Expand Search), "50 na decrease" (Expand Search), "50 ngy decreased" (Expand Search), "50 mg decrease" (Expand Search), "10 ng decrease" (Expand Search), "5 ng 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 mean decrease") OR ((("50 ng decrease") OR ("5 g decrease"))))))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"5 ppm decrease\") OR (((\"50 mean decrease\") OR (((\"50 ng decrease\") OR (\"5 g decrease\"))))))*".
• Removing quotes may allow a broader search: (( 5 ppm decrease ) OR ((( 50 mean decrease ) OR ((( 50 ng decrease ) OR ( 5 g decrease ))))))*.