Perhaps you should try some spelling variations:
"15 fold decrease" » "15 fold increase" (Expand Search), "15 fold increased" (Expand Search), "10 fold decrease" (Expand Search), "5 fold decrease" (Expand Search)
"5 ppm decrease" » "5 _ decrease" (Expand Search), "5 a decrease" (Expand Search), "5 pa decreased" (Expand Search)
"5 nn decrease" » "5 _ decrease" (Expand Search), "5 a decrease" (Expand Search), "5 mean decrease" (Expand Search), "5 n_ decrease" (Expand Search), "5 na decrease" (Expand Search), "5 n_ decreased" (Expand Search), "5 non decrease" (Expand Search), "59 nn decrease" (Expand Search), "5 nm decrease" (Expand Search), "15 nn decrease" (Expand Search), "5 nmn decrease" (Expand Search)
"5 n decrease" » "5 _ decrease" (Expand Search), "5 a decrease" (Expand Search), "5 _ decreased" (Expand Search), "15 n decrease" (Expand Search), "5 nm 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: (("5 ppm decrease") OR ((((("5 nn decrease") OR ("5 n decrease"))) OR ("15 fold decrease"))))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"5 ppm decrease\") OR (((((\"5 nn decrease\") OR (\"5 n decrease\"))) OR (\"15 fold decrease\"))))".
• Removing quotes may allow a broader search: (( 5 ppm decrease ) OR ((((( 5 nn decrease ) OR ( 5 n decrease ))) OR ( 15 fold decrease )))).
• Adding a wildcard symbol may retrieve word variants: (("5 ppm decrease") OR ((((("5 nn decrease") OR ("5 n decrease"))) OR ("15 fold decrease"))))*.