摘要
The number of the limit cycles bifurcating in small quadratic perturbations of quadratic systems with an ischronous center is studied, it turns out that the cyclicity of the period annulus around one kind of quadratic isochronous center is two.
The number of the limit cycles bifurcating in small quadratic perturbations of quadratic systems with an ischronous center is studied, it turns out that the cyclicity of the period annulus around one kind of quadratic isochronous center is two.
基金
Supported by the National Natural Science Foundation of China( No.195 310 70 ) and Natural Science Fundation ofHubei Province( No.98J12 1)
