Perhaps you should try some spelling variations:
"mechanical characterization" » "material characterization"
"physical characterization" » "physical characteristics", "biochemical characterization", "material characterization"
"optical characterization" » "material characterization", "biochemical characterization", "functional characterization"

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