亚洲国产精品无码成人片久久-夜夜高潮夜夜爽夜夜爱爱-午夜精品久久久久久久无码-凹凸在线无码免费视频

摘要：This paper is concerned with small quadratic perturbations to one parameter family of generic reversible quadratic vector fields with a simple center. The first objective is to show that this system exhibits two small amplitude limit cycles emerging from a Hopf bifurcation. The second one we prove that the system has no limit cycle around the weak focus of order two. The results may be viewed as a contribution to proving the conjecture on cyclicity proposed by Iliev(1998).