Perhaps you should try some spelling variations:
their preprocessing » the preprocessing (Expand search), their processing (Expand search), the reprocessing (Expand search)
decrease their » decrease the (Expand search), increase their (Expand search), decreases the (Expand search)
decrease not » decrease of (Expand search), decrease akt (Expand search), decrease at (Expand search)
not decrease » to decrease (Expand search), not increase (Expand search), and decrease (Expand search)
in decreased » is decreased (Expand search), in deceased (Expand search), and decreased (Expand search)

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

• If you are trying to use Boolean operators, they must be ALL CAPS: (( decrease NOT decrease their preprocessing ) OR ( decrease _ decrease in decreased ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( decrease not decrease their preprocessing ) OR ( decrease _ decrease in decreased ))~".
• Adding a wildcard symbol may retrieve word variants: (( decrease not decrease their preprocessing ) OR ( decrease _ decrease in decreased ))*.