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