在混合扰动下从闭轨族分支的极限环

本文讨论了对确定微分方程组的向量场和分析其轨线穿过方向的参考闭曲线族同时进行扰动分支极限环的方法，并给出了一个平面二次微分系统在混合扰动下分支出三个极限环的例子

Bifurcation of Limit Cycles from Planar Isochrones Depending on a Small Parameter

In this paper planar vector fields and their periodic trajectories surrounding an isochronous center are perturbed to bifurcate limit cycles. A criterion function is given to determine the number and position of limit cycles which emerge from the periodic trajectories of unperturbed vector fields. A plane quadratic vector field is used to show the advantage of the method presented in this paper.