Perhaps you should try some spelling variations:
"nato science services a:, life sciences" » "nato science service a:, life sciences", "nato voice services a:, life sciences", "national science services a:, life sciences"
"radio science services a:, life sciences" » "radio science service a:, life sciences", "radio voice services a:, life sciences"
"nato science overview a:, life sciences" » "nato science review a:, life sciences", "nato service overview a:, life sciences", "nato change overview a:, life sciences", "national science overview 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 services a:, life sciences") OR ("radio science services a:, life sciences"))) OR ("nato science overview a:, life sciences")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"nato science services a:, life sciences\") OR (\"radio science services a:, life sciences\"))) or (\"nato science overview a:, life sciences\"))".
• Removing quotes may allow a broader search: (((( nato science services a:, life sciences ) OR ( radio science services a:, life sciences ))) or ( nato science overview a:, life sciences )).
• Adding a wildcard symbol may retrieve word variants: (((("nato science services a:, life sciences") OR ("radio science services a:, life sciences"))) or ("nato science overview a:, life sciences"))*.