知识贝壳
知识贝壳
所属栏目：英汉双解无机化学
A soft,silvery-white,highly ra-dioactive metallic element of group 3 (for-merly ⅢB) of the periodic table. It is usual-ly considered to be the first member of theACTINOID series. It occurs in minute quan-tities in uranium ores as a result of the natu-ral ......（本文共 842 字 ） [阅读本文] >>