This should be particularly bothersome to you because, as you've already experienced in 5.60, There are a lot of partial derivatives.

对你们来说这可能很让人头疼，就像你们在5。60里体验过的那样，这有很多偏微分和变量。

麻省理工公开课 - 热力学与动力学课程节选

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