Perhaps you should try some spelling variations:
"chemical mechanisms" » "biochemical mechanisms", "physical mechanisms", "central mechanisms"
"physical mechanical" » "physico mechanical", "physical mechanisms", "chemical mechanical"
"thermal mechanical" » "thermo mechanical"

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