Perhaps you should try some spelling variations:
associated vectors » associated receptors, associated pastors, associated operators
associated factors » associated bacteria
associated factor » associate factor, associated pastors, associated fatty
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 (((((associated vectors) OR (associated factor))) OR (associated factors))))) OR (associated vector)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((associate director) or (((((associated vectors) OR (associated factor))) or (associated factors))))) or (associated vector))".
• Adding a wildcard symbol may retrieve word variants: ((((associate director) or (((((associated vectors) OR (associated factor))) or (associated factors))))) or (associated vector))*.