Perhaps you should try some spelling variations:
"50 ppm decrease" » "50 _ decrease" (Expand Search), "50 pa decreased" (Expand Search), "50 we decrease" (Expand Search), "5 ppm decrease" (Expand Search)
"50 026 decrease" » "50 _ decrease" (Expand Search)
"50 nn decrease" » "50 _ decrease" (Expand Search), "50 mean decrease" (Expand Search), "50 gy decreased" (Expand Search), "50 ns decrease" (Expand Search), "50 ng decrease" (Expand Search), "50 n decrease" (Expand Search)
"5 a decrease" » "5 _ decrease" (Expand Search), "5 _ decreased" (Expand Search), "5 _ decreases" (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 (\"50 026 decrease\"))) OR (\"50 nn decrease\"))) OR (\"5 a decrease\"))~".
• Removing quotes may allow a broader search: (((((( 50 ppm decrease ) OR ( 50 026 decrease ))) OR ( 50 nn decrease ))) OR ( 5 a decrease ))~.
• Adding a wildcard symbol may retrieve word variants: (((((("50 ppm decrease") OR ("50 026 decrease"))) OR ("50 nn decrease"))) OR ("5 a decrease"))*.