| 1. | Creation and disappearance of limit cycles in quadratic system
0类二次系统极限环的产生与消失 |
| 2. | Limit cycle problem of quadratic system n
0的极限环问题 |
| 3. | The planar quadratic system with an invariant cubic curve has at most one limit cycle
类方程的极限环存在性的注记 |
| 4. | Sufficient and necessary conditions of existence of limit cycle for one kind quadratic system
一类二次系统极限环存在的充要条件 |
| 5. | On the reflective function and the periodic solution of the second order differential quadratic systems
二次微分系统的反射函数及其周期解 |
| 6. | The first 3 focus quantities and the first 3 saddle quantities are derived simply and quickly with the formulas for real planar quadratic systems
利用这一公式我们极其简捷地推导出二次系统的前三个焦点量和鞍点量公式。 |
| 7. | At the end of this paper we talk about the question of the maximal number of limit cycles in quadratic system and some applied uses in ecological circumstances
在本文的最后略为涉及hilbert第十六问题中的极限环的个数问题及其在生态环境上的应用。 |
| 8. | The results prove that df could simplify the solve process and its shortcoming of restriction in approximately denotation , frequency unitary 1 and inapplicability in more commonly quadratic system are also shown at the same time
结果证明：使用描述函数法能够简化该问题的求解，但也暴露出其存在着近似表示，频率归1以及更一般二阶系统不适用等方面的局限和不足。 |
| 9. | By using the known results of type quadratic system , we analyse thecreation and disappearance of limit cycles for type system as a = 0 , and obtainsome new topological structures of phase - portraits , which do not appear for type system
利用关于类二次系统的已知结果,在此文中我们系统分析了类二次系统当= 0时其极限环的产生与消失的整个过程,并给出了一些新的拓扑结构变化,它们在类系统中是不会出现的 |
| 10. | In this paper we will prove that quadratic system has at most finitely limit cycles . bamon claimed that he had finished the demonstration of the finiteness of limit cycles , but he used il ' yashenko theorem , which involves some knowledge of complex domain , so it is the main idea to give il ' yashenko theorem an elementary proof in this paper
本文将用纯初等方法研究二次系统极限环的有限性，虽然bamon宣布已经完成了二次系统极限环的有限性证明，但其证明过程中用到了涉及复域的il ' yashenko定理，从而给il ' yashenko定理一个初等的证明是本文的主要思想。 |
