Perhaps you should try some spelling variations:
ppm decrease » _ decrease (Expand Search), a decrease (Expand Search), pa decreased (Expand Search)
nn decrease » _ decrease (Expand Search), a decrease (Expand Search), mean decrease (Expand Search)
ms decrease » _ decrease (Expand Search), a decrease (Expand Search), mean decrease (Expand Search)
n decrease » _ decrease (Expand Search), a decrease (Expand Search), _ decreased (Expand Search)
50 ms » 50 mg (Expand Search), 50 mm (Expand Search)
50 n » 50 ns (Expand Search), 50 ng (Expand Search), 50 μ (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 (nn decrease)) ) OR ((( 50 n decrease ) OR ( 50 ms decrease ))))~".
• Adding a wildcard symbol may retrieve word variants: (( 50 ((ppm decrease) OR (nn decrease)) ) OR ((( 50 n decrease ) OR ( 50 ms decrease ))))*.