Perhaps you should try some spelling variations:
"particle concentrations" » "particle concentration", "particle correlations", "particle penetration"
"particles acceleration" » "particle acceleration", "particle accelerators", "particles application"
"parallel acceleration" » "particle acceleration", "parallel generation", "parallel application"
"particle accelerator" » "particle accelerators", "particle acceleration"

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