Perhaps you should try some spelling variations:
"particle concentrations" » "particle concentration", "particle correlations", "trace concentrations"
"particle accelerations" » "particle acceleration", "particle accelerators", "particelle acceleratori"
"particles acceleration" » "particle acceleration", "particle accelerators", "parallel acceleration"
"particle accelerator" » "particle accelerators", "particle acceleration"
"particle penetration" » "particle generation", "particle concentration", "particle separation"

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