Perhaps you should try some spelling variations:
"classical mechanisms" » "classical mechanistic", "causal mechanisms", "chemical mechanisms", "classical mechanistics", "physical mechanisms"
"classical mechanical" » "chemical mechanical", "physical mechanical", "statistical mechanical"
"classical mechanism" » "classical mechanistic", "physical mechanism", "chemical mechanism"
"physical mechanisms" » "physiological mechanisms"

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: (((("classical mechanism") OR ("classical mechanical"))) OR ((((("classical mechanisms") OR ("classical mechanics"))) OR ("physical mechanisms")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"classical mechanism\") or (\"classical mechanical\"))) or (((((\"classical mechanisms\") OR (\"classical mechanics\"))) or (\"physical mechanisms\"))))".
• Removing quotes may allow a broader search: (((( classical mechanism ) or ( classical mechanical ))) or ((((( classical mechanisms ) OR ( classical mechanics ))) or ( physical mechanisms )))).
• Adding a wildcard symbol may retrieve word variants: (((("classical mechanism") or ("classical mechanical"))) or ((((("classical mechanisms") OR ("classical mechanics"))) or ("physical mechanisms"))))*.