Perhaps you should try some spelling variations:
decreases sperm » decreased sperm (Expand search), decreases serum (Expand search), decreasing sperm (Expand search)
sperm decrease » term decrease (Expand search), speed decrease (Expand search), speed decreases (Expand search)
decrease any » decreases and (Expand search), decreased and (Expand search), decreased ant (Expand search)
any decrease » and decrease (Expand search), can decrease (Expand search), may decrease (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)
decrease and » decreases and (Expand search), decrease in (Expand search), decrease of (Expand search)
and objects » and object (Expand search), and subjects (Expand search), and objectives (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 any decrease NOT decrease ) OR ( decreases sperm decrease AND objects ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( decrease any decrease not decrease ) OR ( decreases sperm decrease and objects ))~".
• Adding a wildcard symbol may retrieve word variants: (( decrease any decrease not decrease ) OR ( decreases sperm decrease and objects ))*.