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

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 accelerators") OR ((("particle accelerations") OR ("parallel acceleration")))).
• Removing quotes may allow a broader search: (( particle accelerators ) or ((( particle accelerations ) or ( parallel acceleration )))).
• Adding a wildcard symbol may retrieve word variants: (("particle accelerators") or ((("particle accelerations") or ("parallel acceleration"))))*.