麦克斯韦方程中有某些特性是恒定不变的——磁场强度、电位移场以及描述电磁场电通量的坡印廷矢量。

Maxwell's equations conserve certain properties-the magnetic field intensity, the electric displacement field and the Poynting vector that describes the electric flux of an electromagnetic field.

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对于空气氧化膜，电化学反应速度逐步变慢，直至达到相应于稳定钝态的恒定值，同时电位向正移动，表明膜中的微裂纹不断得到修补。

With air-formed films the faradaic processes decreased progressively to a constant rate consistent with the increase in potential, indicating the healing of surface flaws.

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研究发现杆塔电位包括可变的抵消分量和雷电单极电荷引起的恒定分量两部分。

It is found that the potential of the tower system is composed of two components, that are, the variable offset potential and the constant potential caused by unipolar charges of the lightning.

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