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81.
82.
In this article, we prove the existence and multiplicity of non-trivial solutions for an indefinite fractional elliptic equation with magnetic field and concave–convex nonlinearities. Our multiplicity results are based on studying the decomposition of the Nehari manifold. 相似文献
83.
Necessary conditions for the existence of a super‐simple, decomposable, near‐resolvable ‐balanced incomplete block design (BIBD) whose 2‐component subdesigns are both near‐resolvable ‐BIBDs are (mod ) and . In this paper, we show that these necessary conditions are sufficient. Using these designs, we also establish that the necessary conditions for the existence of a super‐simple near‐resolvable ‐RBIBD, namely (mod ) and , are sufficient. A few new pairwise balanced designs are also given. 相似文献
84.
This paper is concerned with the Langford ODE and PDE systems. For the Langford ODE system, the existence of steady-state solutions is firstly obtained by Lyapunov–Schmidt method, and the stability and bifurcation direction of periodic solutions are established. Then for the Langford PDE system, the steady-state bifurcations from simple and double eigenvalues are intensively studied. The techniques of space decomposition and implicit function theorem are adopted to deal with the case of double eigenvalue. Finally, by the center manifold theory and the normal form method, the direction of Hopf bifurcation and the stability of spatially homogeneous and inhomogeneous periodic solutions for the PDE system are investigated. 相似文献
85.
本文给出了利用基本的物理原理结合高等数学公式的方法推导单摆做简谐运动的周期公式,可以简明扼要地理解单摆简谐运动的过程. 相似文献
86.
XU ShangJin WU ZhengFei & DENG YunPing College of Mathematics Information Science Guangxi University Nanning 《中国科学A辑(英文版)》2009,(2)
A graph is said to be s-arc-regular if its full automorphism group acts regularly on the set of its s-arcs. In this paper, we investigate connected cubic s-arc-regular Cayley graphs of finite nonabelian simple groups. Two suffcient and necessary conditions for such graphs to be 1- or 2-arc-regular are given and based on the conditions, several infinite families of 1-or 2-arc-regular cubic Cayley graphs of alternating groups are constructed. 相似文献
87.
ZHANG YongBing 《中国科学A辑(英文版)》2009,(8)
We use the contact Yamabe flow to find solutions of the contact Yamabe problem on K-contact manifolds. 相似文献
88.
Bi-f-harmonic maps are the critical points of bi-f-energy functional. This class of maps tends to integrate bi-harmonic maps and f-harmonic maps. In this paper, we show that bi-f-harmonic maps are not only an extension of f-harmonic maps but also an extension of bi-harmonic maps, and that there should exist many examples of proper bi-f-harmonic maps.In order to find some concrete examples of proper bi-f-harmonic maps, we study the basic properties of bi-f-harmonic maps from two directions which are conformal maps between the same dimensional manifolds and some special maps from or into a warped product manifold. 相似文献
89.
以(NH4)6Mo7O24·4H2O和Bi(NO3)3·5H2O为原料,采用普通水热法制备Bi2MoO6光催化剂,研究pH值对制备该光催化剂的影响.对所制备的系列样品,采用X-射线衍射仪(XRD)、扫描电子显微镜(SEM)、比表面积分析仪、X射线光电子能谱仪(XPS)和紫外-可见漫反射(UV-Vis DRS)进行表征.结果表明:pH值对Bi2MoO6晶体的物相组成、形貌和光催化性能均有显著影响.pH值为1~7时,所制备的样品为纯相Bi2MoO6,pH值为9或11时,出现第二相Bi3.64Mo0.36O6.55;随着pH值的升高,形貌依次为纳米棒、纳米片和无规则纳米颗粒.在可见光(λ≥420 nm)照射下,通过光催化降解罗丹明B(Rhodamine B,RhB),探讨了制备Bi2MoO6的pH值对其可见光催化活性的影响.当pH=7时,制备的样品光催化效果最好,光照50 min后对初始浓度为5 mg·L-1的罗丹明B溶液的降解率为85%. 相似文献
90.
While removing the TBDMS group from OH protection, a novel epoxidation reaction occurred across acrylate ester attached to a forskolin fragment. Besides spectroscopic data, the epoxide formation was confirmed by ring opening with a secondary amine. This unique epoxidation reaction, to our knowledge, is not known in the literature. This reaction led us to discover a simple deblocking protocol. The epoxide and the desired Michael substrates were used to introduce imidazole into forskolin. 相似文献