Perhaps you should try some spelling variations:
"improving chain performance contract." » "improving chain performance contracts.", "improving loan performance contract.", "improving managing performance contract.", "improving brain performance contract.", "improving caring performance contract.", "improving air performance contract."
"improving mental performance evidence." » "improving general performance evidence.", "improving senegal performance evidence.", "improving annual performance evidence.", "improving maternal performance evidence.", "improving fiscal performance evidence.", "improving gender performance evidence."

Try widening your search to All Fields.

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("improving mental performance evidence.") or ("improving chain performance contract."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving mental performance evidence.") OR ("improving chain performance contract.")).
• Removing quotes may allow a broader search: (( improving mental performance evidence. ) or ( improving chain performance contract. )).
• Adding a wildcard symbol may retrieve word variants: (("improving mental performance evidence.") or ("improving chain performance contract."))*.