Perhaps you should try some spelling variations:
"particle concentrations" » "particle concentration", "particle correlations", "trace concentrations"
"particles acceleration" » "particle acceleration", "parallel acceleration", "particles application"
"particle accelerator" » "particle acceleration"
"particle accelerators" » "particle accelerations", "particle accelerated", "particle accelerate", "particle accelerating"
"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 accelerators") OR ((("particles acceleration") OR ((("particle concentrations") OR ("particle penetration")))))))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"particle accelerator\") or (((\"particle accelerators\") or (((\"particles acceleration\") or (((\"particle concentrations\") OR (\"particle penetration\"))))))))".
• Removing quotes may allow a broader search: (( particle accelerator ) or ((( particle accelerators ) or ((( particles acceleration ) or ((( particle concentrations ) OR ( particle penetration )))))))).
• Adding a wildcard symbol may retrieve word variants: (("particle accelerator") or ((("particle accelerators") or ((("particles acceleration") or ((("particle concentrations") OR ("particle penetration"))))))))*.