Perhaps you should try some spelling variations:
"50 ppm decrease" » "50 a decrease" (Expand Search), "50 nn decrease" (Expand Search), "50 pa decreased" (Expand Search), "5 ppm decrease" (Expand Search)
"50 n_ decrease" » "50 nn decrease" (Expand Search), "50 _ decreased" (Expand Search), "50 _ decreases" (Expand Search), "50 ns decrease" (Expand Search), "50 ng decrease" (Expand Search), "50 ns_ decrease" (Expand Search), "50 ng_ decrease" (Expand Search), "50 μ_ decrease" (Expand Search)
"50 n decrease" » "50 nn decrease" (Expand Search), "50 a decrease" (Expand Search), "50 _ decreased" (Expand Search), "50 ns decrease" (Expand Search), "50 ng decrease" (Expand Search), "50 μ decrease" (Expand Search)

Try widening your search to All Fields.

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

• Performing a fuzzy search may retrieve terms with similar spellings: (((("50 _ decrease") OR ("50 ppm decrease"))) OR ((("50 n_ decrease") OR ("50 n decrease"))))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"50 _ decrease\") OR (\"50 ppm decrease\"))) OR (((\"50 n_ decrease\") OR (\"50 n decrease\"))))".
• Removing quotes may allow a broader search: (((( 50 _ decrease ) OR ( 50 ppm decrease ))) OR ((( 50 n_ decrease ) OR ( 50 n decrease )))).
• Adding a wildcard symbol may retrieve word variants: (((("50 _ decrease") OR ("50 ppm decrease"))) OR ((("50 n_ decrease") OR ("50 n decrease"))))*.