初积分 meaning in Chinese

first integral

We analyze every kind of terms of extremum , and proceed the early integral calculus and analyze the boundary terms
分析了模型取极值的各种条件，对模型进行初积分处理并分析了边界条件。
The analytical expressions of constraint force , internal force on cross section , and flexibility of the rod are obtained via the first integrals
利用方程的初积分导出约束力、截面内力及挠性线的解析表达式。