Perhaps you should try some spelling variations:
"particle concentrations" » "particle concentration", "particle correlations", "particle penetration"
"particle accelerations" » "particle acceleration", "particle accelerators", "particles acceleration"
"particle accelerating" » "particle acceleration", "particle acceleraton", "particles acceleration"
"particle accelerator" » "particle accelerators", "particle acceleration"
"particle accelerate" » "particles accelerated", "particle acceleraton", "particle accelerators"

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 accelerating") OR ("particle accelerate"))) OR ((("particle accelerations") OR ("particle concentrations")))))).
• Removing quotes may allow a broader search: (( particle accelerator ) or ((((( particle accelerating ) or ( particle accelerate ))) or ((( particle accelerations ) or ( particle concentrations )))))).
• Adding a wildcard symbol may retrieve word variants: (("particle accelerator") or ((((("particle accelerating") or ("particle accelerate"))) or ((("particle accelerations") or ("particle concentrations"))))))*.