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

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