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

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