二阶常微分方程的周期解

Periodic Solutions of Second Order Differential Equatons

研究二阶常微分方程“ｘ＋ｆ（ｘ，ｘ）ｘ＋ｇ（ｘ）＝０”的非平凡周期解的存在。所获结果推广了一些经典的结果，并且适用于阻尼项没有下界及Ｇ（ｘ）＜＋∞的情形。

This paper studies the existence of non-trivial periodic solutions of the equation x··+f(x,)+g(x)=0. The obtaind result qeneralizes a few classic results and can be applied to the system with the damping item while having no lower bounfdary and G(x)<+∞