Perhaps you should try some spelling variations:
"particle acceleration" » "particle accelerators"
"particle acceleraton" » "particles acceleration", "particle accelerations", "pareticle acceleration"
"particle accelerator" » "particle accelerators"
"practice accelerate" » "practice accelerated", "practices accelerate", "practices accelerating"

Try widening your search to All Fields.

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