Perhaps you should try some spelling variations:
associate directors » associated vectors, associated sectors, associated receptors
associated factors » associated bacteria
associated vector » associated secretory, associated infection, associated operators

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: ((((associate director) OR (((associate directors) OR (associated factors))))) OR (associated vector)).
• Adding a wildcard symbol may retrieve word variants: ((((associate director) or (((associate directors) or (associated factors))))) or (associated vector))*.