Perhaps you should try some spelling variations:
"article and nonlinear physical" » "article and nonlinear physics", "article and nonlinear chemical", "article and nonlinear optical"
"article and nuclear optical" » "article and nuclear option", "article and nuclear medical", "article and nonlinear 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: (("article and nuclear optical") OR ("article and nonlinear physical")).
• Removing quotes may allow a broader search: (( article and nuclear optical ) or ( article and nonlinear physical )).
• Adding a wildcard symbol may retrieve word variants: (("article and nuclear optical") or ("article and nonlinear physical"))*.