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polymerase chain reaction

(Encyclopedia)polymerase chain reaction pŏlˈĭmərāsˌ [key] (PCR), laboratory process in which a particular DNA segment from a mixture of DNA chains is rapidly replicated, producing a large, readily analyzed sa...

ozone

(Encyclopedia)ozone ōˈzōn [key], an allotropic form of the chemical element oxygen (see allotropy). Pure ozone is an unstable, faintly bluish gas with a characteristic fresh, penetrating odor. The gas has a dens...

Holmes, Oliver Wendell, American jurist

(Encyclopedia)Holmes, Oliver Wendell, 1841–1935, American jurist, associate justice of the U.S. Supreme Court (1902–32), b. Boston; son of the writer Oliver Wendell Holmes. He served (1861–64) with distinctio...

Grand Army of the Republic

(Encyclopedia)Grand Army of the Republic (GAR), organization established by Civil War veterans of the Union army and navy. Principal figures in the founding of the GAR were John A. Logan and Richard J. Oglesby. The...

Treasury, United States Department of the

(Encyclopedia)Treasury, United States Department of the, federal executive department established in 1789. It is charged with advising the president on fiscal policy and acting as fiscal agent for the federal gover...

Port Authority of New York and New Jersey

(Encyclopedia)Port Authority of New York and New Jersey, self-sustaining public corporation established in 1921 by the states of New York and New Jersey to administer the activities of the New York–New Jersey por...

zebra

(Encyclopedia)zebra, herbivorous hoofed African mammal of the genus Equus, which also includes the horse and the ass. It is distinguished by its striking pattern of black or dark brown stripes alternating with whit...

Saratoga campaign

(Encyclopedia)Saratoga campaign, June–Oct., 1777, of the American Revolution. Lord George Germain and John Burgoyne were the chief authors of a plan to end the American Revolution by splitting the colonies along ...

Williams, Roger

(Encyclopedia)Williams, Roger, c.1603–1683, clergyman, advocate of religious freedom, founder of Rhode Island, b. London. A protégé of Sir Edward Coke, he graduated from Pembroke College, Cambridge, in 1627 and...

activation energy

(Encyclopedia)CE5 Energy profile of an exothermic reaction: Although the total energy of the products is less than that of the reactants, the activation energy must be added to weaken or break existing bonds bef...