There exist neither perfect insulators nor perfect conductors, for all substances offer opposition to the flow of electric current.

没有绝对的绝缘体也没有绝对的导体，因为一切物体对电流都有阻力。

youdao

According to their ability to conduct electric current, all materials may he classified into three main types: conductors, semiconductors and insulators.

根据导电性能的不同，所有的材料可分为三大类：导体、半导体和绝缘休。

youdao

It also shows that the electric strength, the material, type, structure of insulators and the water conductivity may influence the ice density.

绝缘子覆冰密度与电场强度、绝缘子材料、结构、形状、覆冰水电导率等有关。

youdao

My proposal with this fellowship will use the novel method of applying an electric field gradient instead of chemical substitution to induce charge carriers in large gap insulators, and thereby create new superconductors.

UNESCO: 2013 UK and Ireland Fellows