四极核中心跃迁
Central transition of quadrupolar nucleus
四极管场效晶体管
tetrode field effect transistor
四单极质谱计
quadruple monopole mass spectrometer
四层二极管调制器
four-layer diode modulator
水相极浓体系
extremely dense aqueous system
水平谐变电偶极源
Horizontal harmonic electric dipole