Perhaps you should try some spelling variations:
greater decrease » greatest decrease (Expand Search), greater increase (Expand Search), greater disease (Expand Search)
significant main » significant gap (Expand Search), significant amount (Expand Search), significant cause (Expand Search)
main decrease » gain decreased (Expand Search), mean decrease (Expand Search), point decrease (Expand Search)
nn decrease » _ decrease (Expand Search), a decrease (Expand Search), mean 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: "(( significantly ((nn decrease) OR (greater decrease)) ) OR ( significant main decrease ))~".
• Adding a wildcard symbol may retrieve word variants: (( significantly ((nn decrease) OR (greater decrease)) ) OR ( significant main decrease ))*.