Perhaps you should try some spelling variations:
"particle concentrations" » "particle concentration", "particle correlations", "particle penetration"
"particle accelerations" » "particles acceleration", "particle accelerator", "particelle acceleratori"
"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 acceleration") OR ((("particle accelerators") OR ((("particle accelerations") OR ("particle concentrations")))))).
• Removing quotes may allow a broader search: (( particle acceleration ) or ((( particle accelerators ) or ((( particle accelerations ) or ( particle concentrations )))))).
• Adding a wildcard symbol may retrieve word variants: (("particle acceleration") or ((("particle accelerators") or ((("particle accelerations") or ("particle concentrations"))))))*.