单词 | fr |
释义 | Frn. Chemistry. The element francium. ΚΠ 1946 Jrnl. & Proc. Royal Inst. Chem. Dec. 277 For element 87, discovered as a branch product of the Ac series in 1939 by Mlle. Perey in Paris, the name Francium (Fr) has been suggested. 1988 D. B. J. Easton et al. tr. C. Keller Radiochem. vii. 123 Francium and astatine..have only short-lived isotopes, e.g. 223Fr,t½ = 22 min, and 219At,t½ = 0·9 min. 2004 Nucl. Physics A. 746 460c/1 Fr is transported as an ion beam through a small hole in the shielding wall. This is a new entry (OED Third Edition, December 2013; most recently modified version published online March 2022). < |
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