Perhaps you should try some spelling variations:
national laboratories » national laboratory
clinical laboratories » clinical laboratory, virtual laboratories
federal laboratories » research laboratories, virtual laboratories, bell laboratories

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: ((((((chemical laboratories) OR (national laboratories))) OR (clinical laboratories))) OR (federal laboratories)).
• Adding a wildcard symbol may retrieve word variants: ((((((chemical laboratories) or (national laboratories))) or (clinical laboratories))) or (federal laboratories))*.