Perhaps you should try some spelling variations:
medical laboratories » clinical laboratories, national laboratories, hospital laboratories
federal laboratories » research laboratories, bell laboratories, general laboratory
virtual laboratories » virtual laboratory
medical laboratory » clinical 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 (medical laboratory))) OR (((((federal laboratories) OR (virtual laboratories))) OR (chemical laboratories)))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((medical laboratories) or (medical laboratory))) or (((((federal laboratories) OR (virtual laboratories))) or (chemical laboratories))))".
• Adding a wildcard symbol may retrieve word variants: ((((medical laboratories) or (medical laboratory))) or (((((federal laboratories) OR (virtual laboratories))) or (chemical laboratories))))*.