Perhaps you should try some spelling variations:
decrease during » increase during (Expand search), increases during (Expand search), increased during (Expand search)
during decrease » during increased (Expand search), during depressed (Expand search), during disease (Expand search)
pcr protocols » pcr protocol (Expand search), care protocols (Expand search), and protocols (Expand search)
decrease hiv » decrease in (Expand search), decrease their (Expand search), decreased high (Expand search)
hiv decrease » via decrease (Expand search), hiv increase (Expand search), will decrease (Expand search)
decrease not » decrease of (Expand search), decrease akt (Expand search), decrease at (Expand search)
not increase » and increase (Expand search), an increase (Expand search)
increase pcr » increase cu (Expand search), increase pv (Expand search), increase ppard (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 during decrease hiv decrease ) OR ( decrease NOT increase pcr protocols ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( decrease during decrease hiv decrease ) OR ( decrease not increase pcr protocols ))~".
• Adding a wildcard symbol may retrieve word variants: (( decrease during decrease hiv decrease ) OR ( decrease not increase pcr protocols ))*.