Perhaps you should try some spelling variations:
"a greatest decrease" » "a greater decrease" (Expand Search), "a treatment decreased" (Expand Search), "a greater increase" (Expand Search)
"c large decrease" » "c marked decrease" (Expand Search), "c large increases" (Expand Search), "c large degree" (Expand Search), "_ large decrease" (Expand Search), "a large decrease" (Expand Search), "i large decrease" (Expand Search)
"c2 levels increased" » "2 levels increased" (Expand Search), "c levels increased" (Expand Search), "42 levels increased" (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: "((((\"a greatest decrease\") OR (\"c large decrease\"))) OR (\"c2 levels increased\"))~".
• Removing quotes may allow a broader search: (((( a greatest decrease ) OR ( c large decrease ))) OR ( c2 levels increased ))~.
• Adding a wildcard symbol may retrieve word variants: (((("a greatest decrease") OR ("c large decrease"))) OR ("c2 levels increased"))*.