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排序方式: 共有879条查询结果,搜索用时 31 毫秒
1.
Journal of Algebraic Combinatorics - By appropriately choosing a defining set, we define a class of linear codes and establish their complete weight enumerators and weight enumerators using Weil...  相似文献   
2.
Using an operator ordering method for some commutative superposition operators, we introduce two new multi-variable special polynomials and their generating functions, and present some new operator identities and integral formulas involving the two special polynomials. Instead of calculating complicated partial differential, we use the special polynomials and their generating functions to concisely address the normalization, photocount distributions and Wigner distributions of several quantum states that can be realized physically, the results of which provide real convenience for further investigating the properties and applications of these states.  相似文献   
3.
The low-cost, high specific surface area and porosity, controlled pore size, and chemical properties of metal–organic framework (MOF) materials have attracted much attention in the exploration of proton conduction. The method of chemically modifying MOF structures or introducing conductive medium into the holes can effectively improve the proton conductivities of the materials. Here, the structural tunability of ionic liquid (IL) and flexible MOF (fle-MOF) materials are matched to give full play to the conductivity of IL, the framework support, and the microporous effect of MOFs, which achieves the synergistic effect of performance and expands the temperature range of proton transfer. Three kinds of CS/IL@fle-MOF membranes were prepared by combining three fle-MOFs with 1-carboxymethyl-3-methylimidazole (CMMIM) in different proportions to obtain 15 pieces of membranes. The comparative analyses show that CS/IL@fle-MOF membranes have excellent proton conduction performance at a wider temperature range (263–353 K) and lower relative humidity (75% RH). Among them, the proton conductivities of CS/CMMIM@MIL-88A-25% and CS/CMMIM@MIL-88B-125% are up to 1.33 and 1.42 S cm−1 at 75% RH and 353 K, respectively; whereas those of CS/CMMIM@MIL-53(Fe)-75% and CS/CMMIM@MIL-88B-125% reach up to 2.1 × 10−3 and 1.28 × 10−3 S cm−1 at 75% RH and 263 K, respectively. The Ea of CS/CMMIM@fle-MOFs is in the range of 0.1–0.5 eV, suggesting that the proton transport follows predominantly the typical Grotthuss transfer mechanism. The results of this study indicate that the CS/CMMIM@fle-MOF membranes combinations offer great potential for the design of composite porous proton-conducting materials.  相似文献   
4.
The ground and excited states of a donor impurity at the center of a spherical quantum dot subject to a magnetic field are calculated within the effective-mass approximation. The barriers are infinitely high and the differential equation is solved by combining the finite-difference method with the Richardson extrapolation. The binding and transition energies are more accurate than the available variational values, and excellent agreement is found with the hydrogen atom. The transition energies for a medium-size quantum dot are given.  相似文献   
5.
Nanostructured transition metal oxides are promising alternative anodes for lithium ion batteries. Li-ion storage performance is expected to improve if high packing density energy particles are available. Herein, Mn2O3 microspheres with a ca. 18 μm diameter and a tapped density of 1.33 g/cm3 were synthesized by a facile solvothermal–thermal coversion route. Spherical MnCO3 precursors were obtained through solvothermal treatment and they decomposed and converted into Mn2O3 microspheres at an annealing temperature of 700 °C. The Mn2O3 microspheres consisted of Mn2O3 nanoparticles with an average 40 nm diameter. These porous Mn2O3 microspheres allow good electrolyte penetration and provide an ion buffer reservoir to ensure a constant electrolyte supply. The Mn2O3 microspheres have reversible capacities of 590 and 320 mAh/g at 50 and 400 mA/g, respectively. We thus report an efficient route for the fabrication of energy particles for advanced energy storage.  相似文献   
6.
《Tetrahedron letters》2019,60(46):151260
It was reported to develop a simple and convenient method for the Ni/NHC-catalyzed cross-coupling of methyl sulfinates and amines without an acid/base to afford secondary or tertiary sulfinamides in moderate to good yields. The method can provide the desired products with broad substrate scope, good chemoselectivity and good functional group compatibility. The presented approach may enrich the Ni/NHC catalyst system and promote the applications of methyl sulfinates in the organic sulfur chemistry.  相似文献   
7.
Journal of Sol-Gel Science and Technology - A novel gas sensing material, La–Y co-doped TiO2 nanoparticles, was synthesized by sol–gel method and applied to detect organic pollutants...  相似文献   
8.
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9.
The first part of this paper considers the controllability for a functional semilinear differential inclusion governed by a family of operators {A(t):t[0,b]} generating an evolution operator in a Banach space in the presence of noninstantaneous impulse effects. In the second part of this paper we study the controllability for a fractional noninstantaneous impulsive semilinear differential inclusion with delay, where the linear part is an infinitesimal generator of a C0?semigroup. Using a weakly convergent criterion in the space of piecewise continuous functions and weak topology theory (for weak sequentially closed graph operators) we establish sufficient conditions to guarantee controllability results. Examples are given to illustrate the abstract results.  相似文献   
10.
Methodology and Computing in Applied Probability - We introduce a new class of multivariate elliptically symmetric distributions including elliptically symmetric logistic distributions and Kotz...  相似文献   
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