Perhaps you should try some spelling variations:
"improving food performance contract." » "improving food performance contracts.", "improving good performance contract.", "improving fund performance contract.", "improving bond performance contract."
"improving thermal performance series." » "improving thermal performance studies.", "improving thermal performance size.", "improving external performance series.", "improving animal performance series.", "improving erm performance series."

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

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