Perhaps you should try some spelling variations:
"particle and nuclear medical" » "particle and nuclear medicine", "particle and nuclear material"
"particle and nuclear optical" » "particle and nuclear option", "particle and nonlinear optical"

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 medical") OR ("particle and nuclear optical"))*.
• Removing quotes may allow a broader search: (( particle and nuclear medical ) or ( particle and nuclear optical ))*.