1920s (in an earlier sense). From the name of Carl Wilhelm Ramsauer, German physicist, who described the effect in 1921 (Ann. der Physik 369 513).
英语词典包含243303条英英释义在线翻译词条,基本涵盖了全部常用单词的英英翻译及用法,是英语学习的有利工具。