Perhaps you should try some spelling variations:
associated pastors » associated pairs, associated operators, associated gastric
associated factors » associated bacteria
associated vector » associate director, associated secretory, associated infection

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