Perhaps you should try some spelling variations:
at preprocessing » data preprocessing (Expand search), and preprocessing (Expand search), by preprocessing (Expand search)
decrease akt » decrease and (Expand search), decrease after (Expand search), decrease with (Expand search)
akt decrease » and decrease (Expand search), not decrease (Expand search), any decrease (Expand search)
decrease at » decrease and (Expand search), decrease in (Expand search), decrease of (Expand search)
decrease to » decreased to (Expand search), decrease toc (Expand search), decrease the (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 akt decrease at preprocessing ) OR ( decrease _ decrease to decrease ))~".
• Adding a wildcard symbol may retrieve word variants: (( decrease akt decrease at preprocessing ) OR ( decrease _ decrease to decrease ))*.