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About the Cover


Eighteen of 1989's top scientific achievements are discussed in a year-end wrap-up, and from this group the “Molecule of the Year” was chosen. The winner—an enzyme that drives a cyclic amplification reaction that produces millions of copies of interesting genes and gene segments. See page 1541 and 1543. [Image by Lewis E. Calver, courtesy of Cetus Corporation, Emeryville, CA 94608]


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Science. ISSN 0036-8075 (print), 1095-9203 (online)