Perhaps you should try some spelling variations:
"classical mechanisms" » "classical mechanism", "classical mechanistic", "classical mechanical"
"physical mechanism" » "physical mechanisms", "physical mechanical", "chemical mechanisms"
"classical mechanics" » "classical mechanical"

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: (((("physical mechanism") OR ("classical mechanics"))) OR ("classical mechanisms")).
• Removing quotes may allow a broader search: (((( physical mechanism ) or ( classical mechanics ))) or ( classical mechanisms )).
• Adding a wildcard symbol may retrieve word variants: (((("physical mechanism") or ("classical mechanics"))) or ("classical mechanisms"))*.