Perhaps you should try some spelling variations:
"2 mechanical material" » "2 mechanics materials", "2 mechanical metamaterials", "2 mechanical scattering", "2 mechanisms material", "2 mechanik material"
"iii clinical material" » "iii clinical trial", "iii clinical potential", "iii clinical trials", "ii clinical material"

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: (("2 mechanical material") OR ("iii clinical material")).
• Removing quotes may allow a broader search: (( 2 mechanical material ) or ( iii clinical material )).
• Adding a wildcard symbol may retrieve word variants: (("2 mechanical material") or ("iii clinical material"))*.