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