Perhaps you should try some spelling variations:
database quality » data quality (Expand search), database query (Expand search)
quality problems » quality programs (Expand search), quality program (Expand search), quality protein (Expand search)
decrease ratio » decreased ratio (Expand search), decrease at (Expand search), decreased rate (Expand search)
ratio database » rating database (Expand search), rate database (Expand search), relation database (Expand search)
decrease akt » decrease at (Expand search), decrease and (Expand search), decrease after (Expand search)
akt decrease » and decrease (Expand search), not decrease (Expand search), any decrease (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 ratio database quality problems ) OR ( decrease to decrease akt decrease ))~".
• Adding a wildcard symbol may retrieve word variants: (( decrease ratio database quality problems ) OR ( decrease to decrease akt decrease ))*.