Perhaps you should try some spelling variations:
"parallel acceleration" » "particle acceleration", "parallel generation", "parallel application"
"particle accelerator" » "particle acceleration"
"particle accelerators" » "particle accelerations", "particle accelerated", "particle accelerating"
"particle accelerate" » "particles accelerated", "particle acceleraton", "particle acceleration"

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

• If you are trying to use Boolean operators, they must be ALL CAPS: (((("particle accelerate") OR ("parallel acceleration"))) OR ((("particle accelerator") OR ("particle accelerators")))).
• Removing quotes may allow a broader search: (((( particle accelerate ) or ( parallel acceleration ))) or ((( particle accelerator ) or ( particle accelerators )))).
• Adding a wildcard symbol may retrieve word variants: (((("particle accelerate") or ("parallel acceleration"))) or ((("particle accelerator") or ("particle accelerators"))))*.