Perhaps you should try some spelling variations:
"improving chain performance series." » "improving chain performance studies.", "improving chain performance size.", "improving loan performance series.", "improving managing performance series.", "improving brain performance series.", "improving caring performance series.", "improving air performance series."
"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 chain performance series.") or ("improving thermal performance series."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving chain performance series.") OR ("improving thermal performance series.")).
• Removing quotes may allow a broader search: (( improving chain performance series. ) or ( improving thermal performance series. )).
• Adding a wildcard symbol may retrieve word variants: (("improving chain performance series.") or ("improving thermal performance series."))*.