Perhaps you should try some spelling variations:
mechanical harvesting » mechanized harvesting (Expand search), mechanical testing (Expand search)
decrease mechanical » disease mechanical (Expand search), database mechanical (Expand search)
decrease toc » decrease of (Expand search), decreased to (Expand search), decrease or (Expand search)
toc decrease » to decrease (Expand search), not decrease (Expand search), of decrease (Expand search)
decrease the » decreases the (Expand search), decrease in (Expand search), decrease of (Expand search)
the decrease » to decrease (Expand search), and 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 toc decrease mechanical harvesting ) OR ( decrease _ decrease the decrease ))~".
• Adding a wildcard symbol may retrieve word variants: (( decrease toc decrease mechanical harvesting ) OR ( decrease _ decrease the decrease ))*.