When you say that, it implies that the differential is given by this pair of partial derivatives.

这就意味着，内能的微分,等于偏u偏T，保持体积不变。

麻省理工公开课 - 热力学与动力学课程节选

We have discovered that this partial derivative that appears in the definition, the abstract definition of the differential for internal energy, is just equal to the constant volume heat capacity.

我们还发现,这个偏微分出现在了，内能的偏微分,定义式中，它也就是热容。

麻省理工公开课 - 热力学与动力学课程节选