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

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: ((((((medical laboratories) OR (chemical laboratories))) OR (clinical laboratories))) OR (((federal laboratories) OR (virtual laboratories)))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((((medical laboratories) OR (chemical laboratories))) or (clinical laboratories))) or (((federal laboratories) or (virtual laboratories))))".
• Adding a wildcard symbol may retrieve word variants: ((((((medical laboratories) OR (chemical laboratories))) or (clinical laboratories))) or (((federal laboratories) or (virtual laboratories))))*.