Perhaps you should try some spelling variations:
optimal preprocessing » optical processing (Expand search), spectral preprocessing (Expand search), data preprocessing (Expand search)
decreased optimal » decreased total (Expand search), decreased natural (Expand search), decreased glial (Expand search)
decrease break » decreases breast (Expand search), decreases areas (Expand search), decrease treg (Expand search)
break decrease » urea decrease (Expand search)
in decreased » is decreased (Expand search), in deceased (Expand search), and decreased (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 optimal preprocessing ) OR ( decrease _ decrease break decrease ))~".
• Adding a wildcard symbol may retrieve word variants: (( decrease in decreased optimal preprocessing ) OR ( decrease _ decrease break decrease ))*.