Perhaps you should try some spelling variations:
decreased sperm » decreased sleep (Expand search)
sperm decrease » term decrease (Expand search), speed decrease (Expand search), speed decreases (Expand search)
decrease their » decrease the (Expand search), increase their (Expand search), decreases the (Expand search)
their projects » the projects (Expand search), their products (Expand search), thematic projects (Expand search)
not decreased » not decrease (Expand search), to decreased (Expand search), not increased (Expand search)
decrease not » decrease of (Expand search), decrease akt (Expand search), decrease at (Expand search)
decrease on » decrease in (Expand search), decrease of (Expand search), decrease or (Expand search)
on decrease » on decreased (Expand search), of decrease (Expand search), or decrease (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 decreased sperm decrease ) OR ( decrease on decrease their projects ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( decrease not decreased sperm decrease ) OR ( decrease on decrease their projects ))~".
• Adding a wildcard symbol may retrieve word variants: (( decrease not decreased sperm decrease ) OR ( decrease on decrease their projects ))*.