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

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 physical") OR ("article and nonlinear optical")).
• Removing quotes may allow a broader search: (( article and nuclear physical ) or ( article and nonlinear optical )).
• Adding a wildcard symbol may retrieve word variants: (("article and nuclear physical") or ("article and nonlinear optical"))*.