Zobrazeno 1 - 10
of 74
pro vyhledávání: '"Zhengxin Zhou"'
Autor:
Zhengxin Zhou
Publikováno v:
Electronic Journal of Qualitative Theory of Differential Equations, Vol 2023, Iss 25, Pp 1-14 (2023)
In this paper, we give the necessary and sufficient conditions for some $\Lambda$−$\Omega$ differential systems to have an analytic commutator, use these properties to judge the origin point of the $\Lambda$−$\Omega$ differential systems to be an
Externí odkaz:
https://doaj.org/article/af691a5d5a74429385aba9bf913768cd
Autor:
Zhengxin Zhou
Publikováno v:
Electronic Journal of Qualitative Theory of Differential Equations, Vol 2022, Iss 22, Pp 1-15 (2022)
In this paper, we give the necessary and sufficient conditions for a class of higher degree polynomial systems to have a weak center. As corollaries, we prove the correctness of the two conjectures about the weak center problem for the $\Lambda$–$\
Externí odkaz:
https://doaj.org/article/ff94ba07e9b1492b81b2a3c9e07c0182
Publikováno v:
Clinical and Experimental Obstetrics & Gynecology, Vol 50, Iss 11, p 252 (2023)
Background: In this study, we sought to detect the expression of complement C3 and C4 in serum and maternal-fetal interface in patients with unexplained recurrent spontaneous abortion, and analyze their correlation, in order to explore the clinical s
Externí odkaz:
https://doaj.org/article/cd40e877281e487ebeb2087d90f56f74
Publikováno v:
Frontiers in Endocrinology, Vol 14 (2023)
BackgroundTobacco exposure is considered to be a risk factor for reduced bone mineral density (BMD), which may result in osteopenia. Cotinine, a metabolite of nicotine, is commonly utilized as a marker of tobacco exposure. Nevertheless, there are lim
Externí odkaz:
https://doaj.org/article/e5d382f6808643e4a885a96c38267db7
Autor:
Zhengxin Zhou, Yuexin Yan
Publikováno v:
Electronic Journal of Qualitative Theory of Differential Equations, Vol 2019, Iss 95, Pp 1-22 (2019)
In this paper, we prove that for a class of rigid systems the Composition Conjecture is correct. We show that the Moments Condition is the sufficient and necessary conditions for these rigid systems to have a center at origin point. By the obtained c
Externí odkaz:
https://doaj.org/article/9d6d6323ee9841e1b3c34bac34ad6492
Autor:
Zhengxin Zhou, Valery Romanovski
Publikováno v:
Electronic Journal of Qualitative Theory of Differential Equations, Vol 2018, Iss 15, Pp 1-17 (2018)
In this paper we give coefficient conditions for existence of a center in a family of planar quartic polynomial differential systems. We also show that for all considered center cases the Composition Condition is satisfied.
Externí odkaz:
https://doaj.org/article/7fd9d01e9f7a446cb52196a9b5f6d223
Autor:
Zhengxin Zhou
Publikováno v:
Abstract and Applied Analysis, Vol 2015 (2015)
We use a new method for constructing some differential equations which are equivalent to a given equation in the sense of having the same reflecting function. We completely solve the problem: when is a polynomial differential equation equivalent to a
Externí odkaz:
https://doaj.org/article/a545d83552d8441ea5e8740c8a75bb22
Autor:
Zhengxin Zhou
Publikováno v:
Abstract and Applied Analysis, Vol 2014 (2014)
We will introduce Mironenko’s method to discuss the Poincaré center-focus problem, and compare the methods of Lyapunov and Mironenko. We apply the Mironenko method to discuss the qualitative behavior of solutions of some planar polynomial differen
Externí odkaz:
https://doaj.org/article/919dc0c1a2a9445f8318d7ea6a4d0249
Publikováno v:
International Journal of Differential Equations, Vol 2014 (2014)
We have studied the periodicity of solutions of some nonlinear time-varying differential models by using the theory of reflecting functions. We have established a new relationship between the linear differential system and the Riccati equations and a
Externí odkaz:
https://doaj.org/article/90d182a7357b49168c85a59777fa49fd
Publikováno v:
Abstract and Applied Analysis, Vol 2013 (2013)
This work is devoted to investigating the stability of impulsive cellular neural networks with time-varying and distributed delays. We use the new method of fixed point theory to obtain some new and concise sufficient conditions to ensure the existen
Externí odkaz:
https://doaj.org/article/6e555b9b5c664c4e81703d257dfae96d