birkeland 基本例句 n.伯克兰 The effect of the distribution of ionospheric conductivity and the morphology of the convection reversal on the feature of Birkeland currents is discussed by means of simple models. 本文利用一些简单模式讨论对流转向区形态、电离层电导率的分布变化对场向电流形态的影响。 cnki