Perhaps you should try some spelling variations:
"experimental analytical" » "experimental analysis", "environmental analytical", "experimental animal"
"experimental clinical" » "experimental numerical", "experimental cerebral", "experimental colitis"

You may be able to get more results by adjusting your search query.

• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"experimental clinical\") OR (\"experimental analytical\"))".
• Removing quotes may allow a broader search: (( experimental clinical ) OR ( experimental analytical )).
• Adding a wildcard symbol may retrieve word variants: (("experimental clinical") OR ("experimental analytical"))*.