Perhaps you should try some spelling variations:
"particle and nonlinear physical" » "particle and nonlinear chemical", "particle and nonlinear optical", "particle and nonlinear mechanical"
"particle and nonlinear physics" » "particle and nonlinear optics"

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