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