| 释义 |
radon Chem.|ˈreɪdɒn|
[a. G. radon (C. Schmidt 1918, in Zeitschr. f. Anorg. Chem. CIII. 114): see radium and -on2.]
1. A short-lived radioactive element which belongs to the group of noble gases and occurs naturally in trace amounts as a result of the decay of radium and other radioactive elements; orig. spec. the longest-lived isotope, radon 222, having a half-life of 3·82 days. Atomic number 86, symbol Rn (orig. Ro). Cf. radium emanation s.v. radium 3 b.
1918Jrnl. Chem. Soc. CXIV. ii. 306 Radium emanation is given the name Radon, Ro, which at once indicates its origin and its relationship to the argon group. 1927Observer 3 Apr. 20/2 The Radium Institute sends radium, or rather radon, its active principle, to hospitals all over the country. 1938R. W. Lawson tr. Hevesy & Paneth's Man. Radioactivity (ed. 2) xxiii. 227 The first five disintegration products of the gas radon are isotopes of the metals polonium, lead, bismuth, or thallium. 1942S. Tolansky Introd. Atomic Physics xiii. 218 A body exposed for a short time to radon coats with an active deposit which emits α-, β-, and γ- radiation and exhibits a regular decay. 1974Environmental Conservation I. 24/1 Uranium miners are known to suffer from an increased risk of lung cancer from inhaled radon. 1977Time 22 Aug. 8/2 The radon in these waters is supposed to be good for everything from paralysis to curvature of the spine.
2. Special comb.: radon seed, a short tube containing radon that is used in radiotherapy as a source of alpha radiation.
1925A. E. H. Pinch Clin. Index Radium Therapy 61 Treatment by the burying..of numerous unscreened radon ‘seeds’..will often prove effective. 1930Sunday Times 12 Oct. 24/2 Medical evidence showed that the child was placed under an anæsthetic and radon seeds..were placed in the growths. 1966Henschke & Hilaris in G. H. Fletcher Textbk. Radiotherapy i. 43/1 Ninety radon seeds each 0·75 cm. were permanently implanted through 17 needles and the uterus was sutured over the implant. |