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