| − | : <math>\mathrm <math>dS = \frac{\delta Q}{T} \,\, \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \text {（封闭系统中理想状态下的可逆过程）}</math> | + | : <math>\mathrm dS = \frac{\delta Q}{T} \,\, \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \text {（封闭系统中理想状态下的可逆过程）}</math> |