Perhaps you should try some spelling variations:
"nato science theories a:, life sciences" » "nato science theory a:, life sciences"
"radio science theories a:, life sciences" » "radio science theory a:, life sciences"
"national science theories a:, life sciences" » "national science theory a:, life sciences", "natural science theories a:, life sciences", "spatial science theories a:, life sciences", "animal science theories a:, life sciences"
"nato science three a:, life sciences" » "nato science thin a:, life sciences", "nato science third a:, life sciences"

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: (((((("nato science theories a:, life sciences") OR ("nato science three a:, life sciences"))) OR ("radio science theories a:, life sciences"))) OR ("national science theories a:, life sciences")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((((\"nato science theories a:, life sciences\") OR (\"nato science three a:, life sciences\"))) or (\"radio science theories a:, life sciences\"))) or (\"national science theories a:, life sciences\"))".
• Removing quotes may allow a broader search: (((((( nato science theories a:, life sciences ) OR ( nato science three a:, life sciences ))) or ( radio science theories a:, life sciences ))) or ( national science theories a:, life sciences )).
• Adding a wildcard symbol may retrieve word variants: (((((("nato science theories a:, life sciences") OR ("nato science three a:, life sciences"))) or ("radio science theories a:, life sciences"))) or ("national science theories a:, life sciences"))*.