Perhaps you should try some spelling variations:
associated receptors » associated factors, associated secretory, activated receptors
associated vector » associated factors, associate director, associated secretory
associate factor » associated factors, associate director, associate editors

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: ((((associated vector) OR (associated receptors))) OR (associate factor)).
• Adding a wildcard symbol may retrieve word variants: ((((associated vector) or (associated receptors))) or (associate factor))*.