Perhaps you should try some spelling variations:
"50 ppm decrease" » "50 _ decrease" (Expand Search), "50 a decrease" (Expand Search), "50 nn decrease" (Expand Search), "5 ppm decrease" (Expand Search)
"50 ns decrease" » "50 nn decrease" (Expand Search), "50 _ decrease" (Expand Search), "50 a decrease" (Expand Search), "50 ms decrease" (Expand Search)
"_ we decrease" » "_ _ decrease" (Expand Search), "_ a decrease" (Expand Search), "_ nn decrease" (Expand Search), "_ web decrease" (Expand Search), "_ wet decrease" (Expand Search), "_ e decrease" (Expand Search)
"5 w decrease" » "5 _ decrease" (Expand Search), "5 a decrease" (Expand Search), "5 _ decreased" (Expand Search), "5 wt decrease" (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 ns decrease\") OR (((\"5 w decrease\") OR (\"_ we decrease\"))))))~".
• Removing quotes may allow a broader search: (( 50 ppm decrease ) OR ((( 50 ns decrease ) OR ((( 5 w decrease ) OR ( _ we decrease ))))))~.
• Adding a wildcard symbol may retrieve word variants: (("50 ppm decrease") OR ((("50 ns decrease") OR ((("5 w decrease") OR ("_ we decrease"))))))*.