the fundamental principle of physics that the total energy of an isolated system is constant despite internal changes

deeply understand the essence and expressions of the first law of thermodynamics ; using the expression of the first law to solve related problems occurred in practical project.

深刻理解热力学第一定律的实质，熟练掌握热力学第一定律的表达式。正确地利用热力学第一定律表达式解决工程实践中的有关问题。

the character of longitudinal-flow heat exchanger and baffle board heat exchanger is analyzed with the first law of thermodynamics and the second law of thermodynamics.

认为只有综合考虑换热器的传热特性和压降特性，才能较为準确、客观地分析换热器的性能。

molar heat capacities in the processes of quasi static state of perfect gases are discussed according to the first law of thermodynamics in this paper.

从热力学第一定律出发，详细讨论了理想气体準静态过程中的摩尔热容。

the first law of thermodynamics states that energy can neither be created nor destroyed.

热力学第一定律说明，能量既不能被创造，也不能被破坏。

we remain skeptical here, but also open to the possibility that the first law of thermodynamics has been as thoroughly violated as a white collar worker in a federal penitentiary.

在这里我们仍然持怀疑态度，但也开放给该热力学第一定律已尽可能详细的做出修改的可能性。

energy analysis mainly have tow methods, namely enthalpy analysis on the base of using the first law of thermodynamics and exergy analysis according to the second law of thermodynamics;

焓分析是基于热力学第一定律的分析方法；而（火用）分析则是基于热力学第二定律的分析方法。

the symmetry of the permittivity tensor is found to be based on the first law of thermodynamics and the non-wastage condition.

由热力学第一定律及无损条件导出了介电张量的对称性；

this paper discusses the first law of thermodynamics of the white hole, so as to provide a theoretical basis for the possibility of existence of white hole.

有待实践检验。本文从形式上给出了白洞的热力学第一定律，试图为白洞的存在提供一种理论上的可能性。

firstly, taking the cosmological constant as a thermodynamical variable, we presented the first law of thermodynamics for the (3+1)- and higher-dimensional black strings.

主要结果包括：给出了（3+1）维以及更高维黑弦的将宇宙学常数视为热力学变量的热力学第一定律；