| 释义 |
〔hafnium〕A brilliant, silvery, metallic element separated from ores of zirconium and used in nuclear reactor control rods, as a getter for oxygen and nitrogen, and in the manufacture of tungsten filaments. Atomic number 72; atomic weight 178.49; melting point 2,220°C; boiling point 5,400°C; specific gravity 13.3; valence 4. See table at element 铪：一种锆矿中分离出来的亮银色金属元素，用于核反应堆的控制棒，可形成氧气和氮气的保护膜，还用于钨丝的制造。原子序数72；原子量178.49；熔点2,220°C；沸点5,400°C；比重13.3；原子价4 参见 element〔tetrode〕A four-element electron tube containing an anode, a cathode, a control grid, and an additional electrode.四极管：包括一个阳板，一个阳极，一个控制棒和一个附加电极的四元素电子管 |