Perhaps you should try some spelling variations:
mean decrease » a decrease (Expand Search)
ppm decrease » _ decrease (Expand Search), a decrease (Expand Search), pa decreased (Expand Search)
nn decrease » _ decrease (Expand Search), a decrease (Expand Search), gy decreased (Expand Search)
nm decrease » _ decrease (Expand Search), a decrease (Expand Search), we decrease (Expand Search)
50 ppm » 5 ppm (Expand Search)
50 nn » 50 ns (Expand Search), 50 ng (Expand Search), 50 n (Expand Search)

You may be able to get more results by adjusting your search query.

• The words AND, OR and NOT may confuse the search; try adding quotes: "(( 50 ppm decrease ) OR ((( 50 nn decrease ) OR ( 5 ((nm decrease) OR (mean decrease)) ))))~".
• Adding a wildcard symbol may retrieve word variants: (( 50 ppm decrease ) OR ((( 50 nn decrease ) OR ( 5 ((nm decrease) OR (mean decrease)) ))))*.