Perhaps you should try some spelling variations:
"particle accelerations" » "particle acceleration", "particle accelerators", "particle concentrations"
"particles acceleration" » "particle acceleration", "particle accelerators", "particles application"
"parallel acceleration" » "particle acceleration", "parallel application", "parallel operation"
"particle accelerator" » "particle accelerators", "particle acceleration"
"parallel generation" » "parallel genetic", "parallel information"

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 accelerator") OR ((("particle accelerations") OR ((("particles acceleration") OR ((("parallel acceleration") OR ("parallel generation")))))))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"particle accelerator\") or (((\"particle accelerations\") or (((\"particles acceleration\") or (((\"parallel acceleration\") OR (\"parallel generation\"))))))))".
• Removing quotes may allow a broader search: (( particle accelerator ) or ((( particle accelerations ) or ((( particles acceleration ) or ((( parallel acceleration ) OR ( parallel generation )))))))).
• Adding a wildcard symbol may retrieve word variants: (("particle accelerator") or ((("particle accelerations") or ((("particles acceleration") or ((("parallel acceleration") OR ("parallel generation"))))))))*.