扩展幂律型脱钉和高温超导体及MgB2的电阻转变

近来，关于无序涡旋物质凝聚体的著名的涡旋玻璃理论受到了来自某些新实验的严重质疑．我们重新审查了高温超导体的临界标度，发现超导混合态的直流伏安特性具有扩展幂律的一般形式．由该扩展幂律型非线性方程模拟的等温线和Strachan等人得到的实验数据[Phys．Rev．Lett．87（2001），067007]符合得很好．文中还讨论了长期以来围绕纵向电阻率和霍尔电阻率的临界指数的某些争议．     

高温超导窄带广义切比雪夫函数滤波器

提出了一种用于高温超导滤波器制作的新结构窄带广义切比雪夫函数高、低通滤波器级联方式.该方式利用高温超导低插损特性,可以有效地降低极陡峭广义切比雪夫函数低通、高通滤波器的带边频滚降.依靠高、低通滤波器级联方式构建新形式的窄带极陡峭低插损高温超导滤波器,并与已有高温超导滤波器进行了比较分析.     

A Novel Heat-resisting Surfactant for the Modification of Alumina Nanoparticles

An casy preparation of controlled alumina nanoparticles by the solution precipitate method has been carried out using dendrimer as surfactant.The effects of the amount and size of surfactant on morphological control of powder have also been discussed.     

Highly Selective Diphoshinoamine/Cr(III) Catalysts for Ethylene Tetramerization

Ethylene trimerization has been attracted much attention because of their high selectivity towards 1-hexene1-6. The common belief is that ethylene tetramerization is improbable. This is because if ethylene tetramerization proceeds via the same mechanism o…     

一类二元对策问题

讨论一类二元对策问题.在对策双方能力不同的情况下,推导对策双方获胜的充要条件和获胜方获胜的具体对策方案.文后的应用实例说明,本文所讨论的问题具有一定的应用价值.     

FORMATION AND MAGNETIC PROPERTIES OF A NOVEL Gd3(Fe,Ti)29Ny NITRIDE

The novel Gd₃(Fe_0.978Ti_0.022)₂₉ compounds and their nitride have been synthesized. The X-ray diffraction patterns of the Gd₃(Fe,Ti)₂₉N_y and its parent compounds were indexed in the Nd₃(Fe,Ti)₂₉-type structure with a monoclinic symmetry and space group P2₁/c, Both the nitride and the parent compounds exhibit ferrimagnetlc coupling. Nitrogenatio led to an increase in Curie temperature and saturation magnetization. The Curie temperatures are 517K for the parent and 765K for the nitride. The saturation magnetizations σ_s at 4.2K are 101.9A·m²/kg for the parent and 128A·m²/kg for the nitride. Both the nitride and parent exhibit a planar anisotropy. Nitrogenation led to a decrease of the contribution of Fe-sublattice to planar anisotropy. The anisotropy fields at 4.2K are 9.8T for the parent and 6.5 T for the nitride.     

STUDIES ON THE DYNAMICS OF OPTICAL BISTABILITY SWITCHING IN THE INTERNAL FABRY-PEROT CAVITY WITH A CdSxSe1-x-DOPED GLASS CHANNEL WAVEGUIDE

We report the optical bistability in CdS_xSe_1-x-doped glass channel waveguide with rise and fall times of about 24 and 30ps, respectively, in bistable switching by means of fiber coupling input with a power of about 3mW. The third-order nonlinear susceptibility (x⁽³⁾) of CdS_xSe_1-x-doped glass is estimated experimentally to be 1.8×10^-9 esu. The high speed switching and the value of x⁽¹⁾ show that the optical bistability is caused by an optical nonlinearity which can be attributed to the band-filling effect.     

求最小权无三角形完美2-匹配的 O(|V|~3)算法

设 G=(V,E)是一简单图.E(G)和 V(G)分别表示 G 的边集合和顶点集合.G 的一个无三角形2-匹配是一个整数向量 x=(x_e:e∈E(G)),使得x_e≥0,(?)_e∈E(G),(1)x(δ(v))≤2,(?)_v∈V(G),(2)x(γ(s))≤2,(?)S(?)V(G),|S|=3.(3)若 x 进一步使(2)都以等式成立,则 x 称为是无三角形完美2-匹配.文献[1]证明了:(1)—(3)的可行解集合就是 G 的无三角形2-匹配的凸包多面体.[1]还同时给出了求最     

层子模型里介子的分类

在前一工作中我们应用层子模型基本上解释了所有已观察到的较肯定的稳定和不稳定的介子,指出这些介子都可看作是一对层子和反层子在赝标型简谐振子位阶中J~P=0~-和1~-的态以及这两个态的轨道角动量l=1和2的激发态。在这篇短文中,我们将较详细的给出这个结论在实验上的主要依据。     

层子模型里介子的波函数和能级

本文利用Bethe-Salpeter型的方程处理了层子模型中的介子内部波函数,指出如果层子和反层子之间的作用可以用一个赝标型位阱来代表,那么0^-和1^-介子将满足相同的近似迳向波动方程,从而导致SU₆对称性。我们以前曾经证明赝标型位阱是唯一可以导致这个对称性的单一型位阱。我们的位阱是V=V₀+V₁,V₀代表一个超强的深位阱,它的作用是降低层子的原始质量M,使它的有效值M′变得很小,使得层子在强子内部的运动是相对论的。V₁代表数量级为1/M的简谐振子位阱,另外还引入一个张量力来解释自旋和轨道角动量相同态的能级分裂。我们得出基态和角动量激发态0^-和1^-介子的解,基本上解释了所有观察到的介子。我们的理论可以同样处理重子态,只要唯象位阱V₀只有介子的值的一半。