Perhaps you should try some spelling variations:
disease desertification » disease identification (Expand search), areas desertification (Expand search), diversity desertification (Expand search)
desertification process » identification process (Expand search), identification processes (Expand search)
decrease their » decrease the (Expand search), increase their (Expand search), decreases the (Expand search)
their disease » the disease (Expand search), hair diseases (Expand search)
decrease toc » decrease of (Expand search), decrease the (Expand search), decreased to (Expand search)
toc decrease » the decrease (Expand search), not decrease (Expand search), of decrease (Expand search)
decrease to » decreased to (Expand search), decrease the (Expand search), decrease pro (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: "(( decrease their disease desertification process ) OR ( decrease to decrease toc decrease ))~".
• Adding a wildcard symbol may retrieve word variants: (( decrease their disease desertification process ) OR ( decrease to decrease toc decrease ))*.