Columbia Encyclopedia

Search results

500 results found

perfluoroalkyl and polyfluoroalkyl substances

(Encyclopedia)perfluoroalkyl and polyfluoroalkyl substances (PFAS), a group of several thousand synthetic organic chemical compounds made up of a chain of carbon atoms bonded to fluorine atoms. PFAS, which resist w...

placenta

(Encyclopedia)placenta pləsĕnˈtə [key] or afterbirth, organ that develops in the uterus during pregnancy. It is a unique characteristic of the higher (or placental) mammals. In humans it is a thick mass, about ...

reserpine

(Encyclopedia)reserpine rĕsûrˈpēn [key], alkaloid isolated from the root of the snakeroot plant (Rauwolfia serpentina), a small evergreen climbing shrub of the dogbane family native to the Indian subcontinent. ...

rattan

(Encyclopedia)rattan rătănˈ [key], name for a number of plants of the genera Calamus, Daemonorops, and Korthalsia climbing palms of tropical Asia, belonging to the family Palmae (palm family). Rattan leaves, unl...

prostaglandin

(Encyclopedia)prostaglandin prŏsˌtəglănˈdən [key], any of a group of about a dozen compounds synthesized from fatty acids in mammals as well as in lower animals. Prostaglandins are highly potent substances th...

nosebleed

(Encyclopedia)nosebleed, nasal hemorrhage occurring as the result of local injury or disturbance. Most nosebleeds are not serious and occur when one of the small veins of the septum (the partition between the nostr...

Vane, Sir John Robert

(Encyclopedia)Vane, Sir John Robert, 1927–2004, British pharmacologist, Ph.D. Oxford, 1953. With B. I. Samuelsson and Sune K. Bergström, Vane was awarded the 1982 Nobel Prize in Physiology or Medicine. The trio ...

tamoxifen

(Encyclopedia)tamoxifen təmŏkˈsĭfĕnˌ [key], synthetic hormone used in the treatment of breast cancer. Introduced in 1978, tamoxifen is used to prevent recurrences of cancer in women who have already undergone...

Tertullian

(Encyclopedia)Tertullian (Quintus Septimus Florens Tertullianus) tûrtŭlˈyən [key], c.160–c.230, Roman theologian and Christian apologist, b. Carthage. He was the son of a centurion and was well educated, espe...

aerobics

(Encyclopedia)aerobics ârōˈbiks [key], [Gr.,=with oxygen], system of endurance exercises that promote cardiovascular fitness by producing and sustaining an elevated heart rate for a prolonged period of time, the...