Perhaps you should try some spelling variations:
decrease matter » decrease after (Expand search), decrease litter (Expand search), decrease catheter (Expand search)
matter object » alter object (Expand search), water object (Expand search), matter effect (Expand search)
in decreased » is decreased (Expand search), in deceased (Expand search), and decreased (Expand search)
decrease hiv » decrease their (Expand search), decreased high (Expand search), decrease with (Expand search)
hiv decrease » via decrease (Expand search), hiv increase (Expand search), will decrease (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 in decreased AND decrease ) OR ( decrease hiv decrease matter object ))~".
• Adding a wildcard symbol may retrieve word variants: (( decrease in decreased AND decrease ) OR ( decrease hiv decrease matter object ))*.