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991.
Norbert Kalus 《Journal of statistical physics》1981,25(4):635-643
We describe a new class of single spin measures on then-dimensional sphereS
r
n
of radiusr (n 4) for which Lebowitz-type [J. Lebowitz,J. Stat. Phys.
16:463 (1977)] inequalities hold. This is achieved by an appropriate parametrization ofS
r
n
. The above class includes the uniform measures onxs Rn ¦x¦ r for any 0 p r. The second topic of this paper is an abstract formulation of the first Griffiths inequality [R. B. Griffiths,J. Math. Phys.
8:478 (1967)] and the underlying symmetry property. 相似文献
992.
Barry Simon 《Journal of statistical physics》1981,26(2):307-311
For a one-dimensional array ofS
N–1 spins (N 2) with isotropic pair interactions (and more general systems) with J(j–i) obeying supn[n–1
1
n
j
2|J(j)|]<, we prove that every equilibrium state is invariant under the natural action ofSO(N). In particular, there is no long-range order of the conventional type. Included is the caseJ(n)=n
–2.Research partially supported by U.S.N.S.F. Grant No. MCS-78-01885.S. Fairchild Scholar at Caltech. On leave from Departments of Mathematics and Physics, Princeton University, Princeton, New Jersey 08544. 相似文献
993.
C. Cammarota 《Journal of statistical physics》1981,25(1):143-152
A field theory model onR
2 in which the basic fields are Ising spins instead of Gaussian spins is examined. Using statistical mechanics techniques we discuss the ultraviolet and the infrared problems. In particular we discuss a technique yielding the asymptotic expansion in of the ground state energy, as 0, without using the cluster expansion.Supported in part by Consiglio Nazionale delle Ricerche. 相似文献
994.
构建微生物细胞工厂是化学品、生物能源以及药物分子可持续生产的可行性策略。然而,微生物的代谢复杂、调控严谨,制约着目标产物高效合成。蛋白质组学和代谢组学可以从系统生物学角度分析酶和代谢物组分,从而理解复杂的生物系统,为微生物代谢工程改造提供重要线索。该文介绍了蛋白质组学和代谢组学在微生物代谢工程中的应用,包括基因组尺度代谢模型构建、菌株生物合成优化、指导菌株耐受性改造、限速步骤预测、植物次级代谢途径挖掘,从而为微生物合成天然产物提供新的基因或途径。在此基础上,该文还展望了生物大数据未来的发展方向。 相似文献
995.
本文对一类非线性时间序列模型xt=φ(xt-1,…,xt-p)+εth(xt-1,…,xt-p)给出了高阶矩的存在条件。 相似文献
996.
一般增长曲线模型参数阵的BLU估计 总被引:4,自引:0,他引:4
考虑一般增长曲线模型:Y=X1BX2+εE(Vec(ε))=0V(Vec(ε))=σ2VIn(V0)本文对任一可估函数KBL给出了它的BLU估计(最佳线性无偏估计),并得到了方差σ2的一个无偏估计. 相似文献
997.
This paper describes the structural and optical properties of Cu–Se thin films. The surface morphology of thin films was investigated by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Formation of Cu–Se thin films is concluded to proceed unevenly, in the form of islands which later grew into agglomerates. The structural characterization of Cu–Se thin film was investigated using X-ray diffraction pattern (XRD). The presence of two-phase system is observed. One is the solid solution of Cu in Se and the other is low-pressure modification of CuSe2. The Raman spectroscopy was used to identify and quantify the individual phases present in the Cu–Se films. Red shift and asymmetry of Raman mode characteristic for CuSe2 enable us to estimate nanocrystal dimension. In the analysis of the far-infrared reflection spectra, numerical model for calculating the reflectivity coefficient of layered system, which includes film with nanocrystalite inclusions (modeled by Maxwell-Garnett approximation) and substrate, has been applied. 相似文献
998.
One‐pot synthesis of 1‐ and 5‐substituted 1H‐tetrazoles using 1,4‐dihydroxyanthraquinone–copper(II) supported on superparamagnetic Fe3O4@SiO2 magnetic porous nanospheres as a recyclable catalyst
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An effective one‐pot, convenient process for the synthesis of 1‐ and 5‐substituted 1H‐tetrazoles from nitriles and amines is described using1,4‐dihydroxyanthraquinone–copper(II) supported on Fe3O4@SiO2 magnetic porous nanospheres as a novel recyclable catalyst. The application of this catalyst allows the synthesis of a variety of tetrazoles in good to excellent yields. The preparation of the magnetic nanocatalyst with core–shell structure is presented by using nano‐Fe3O4 as the core, tetraethoxysilane as the silica source and poly(vinyl alcohol) as the surfactant, and then Fe3O4@SiO2 was coated with 1,4‐dihydroxyanthraquinone–copper(II) nanoparticles. The new catalyst was characterized using Fourier transform infrared spectroscopy, X‐ray diffraction, transmission electron microscopy, field emission scanning electron microscopy, dynamic light scattering, thermogravimetric analysis, vibration sample magnetometry, X‐ray photoelectron spectroscopy, nitrogen adsorption–desorption isotherm analysis and inductively coupled plasma analysis. This new procedure offers several advantages such as short reaction times, excellent yields, operational simplicity, practicability and applicability to various substrates and absence of any tedious workup or purification. In addition, the excellent catalytic performance, thermal stability and separation of the catalyst make it a good heterogeneous system and a useful alternative to other heterogeneous catalysts. Also, the catalyst could be magnetically separated and reused six times without significant loss of catalytic activity. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
999.
Marvin Ross 《高压研究》2013,33(5-6):649-657
Abstract Superfluid Helium (11) and liquid nitrogen are the only liquids which have been shown experimentally, to exhibit shock cooling. In the present paper we use the Landau model to demonstrate theoretically that the roton gap, which decreases with increasing density, plays the same role leading to shock cooling in liquid helium as the dissociation energy does in liquid nitrogen. 相似文献
1000.
针对交可约粒度空间中覆盖、基和粒结构的关系,结合偏序关系的哈斯图,给出一种约简粒度空间的方法.另外,通过限定上、下近似算子的取值范围,重新定义了交可约粒度空间上的粗糙集模型,并讨论了其相关性质. 相似文献