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51.
52.
使用密度泛函理论B3LYP方法,对西红花酸二甲酯的结构、电子吸收光谱、热力学性质进行理论计算研究,并基于Tomasi的极化统一场模型(PCM)讨论溶剂效应.结果显示,溶剂对西红花酸二甲酯的前线分子轨道特征几乎无影响,溶剂作用使该分子的最大吸收波长红移约42 nm,红移程度与溶剂极性无关.西红花酸二甲酯分子的气态热力学性质与温度的关系式分别为:Cm p=189.782+0.925T,S m=457.503+1.366T,H m=1164.899+0.195T+4.671×10-4T2,Gm=1164.899-0.263T-8.989×10-4T2.298 K时,西红花酸二甲酯分子的气态标准摩尔生成焓和标准摩尔生成自由能分别为-1180.67和-733.23 kJ·mol-1. 相似文献
53.
The title compound, 1-(naphthalene-2-yl)-2-(1H-pyrazol-1-yl)ethanone O-butyl oxime, I, was synthesized. The crystal and molecular structures of I were determined by IR, 1H-NMR, mass spectrum, elemental analysis and X-ray single crystal diffraction. Molecular geometry from X-ray experiment of I in the ground state was compared using the Density Functional Theory (DFT) with B3LYP/6-311G(d,p) basis set. In addition, DFT calculation, molecular electrostatic potentials (MEP) and frontier molecular orbitals of I were performed at the B3LYP/6-311G(d,p) level of the theory. 相似文献
54.
选用密度泛函理论(DET)中的B3LYP方法,在6-311++G(d,p)下对菲分子结构进行优化,计算了其振动频率、极化率及热力学参数,对比了菲分子实测光谱图,首次对其振动频率进行了完全归属。此外,分析并讨论了其前线分子轨道、分子静电势和密立根布局,获得了HOMO-LUMO能隙、分子静电势分布、原子电荷分布等与分子性质密切相关的重要数据,为后续其他多环芳烃分子的光谱检测技术及其光谱和电子结构的分析提供了理论基础。 相似文献
55.
Noel D. Uri 《商业与工业应用随机模型》2001,17(3):231-244
Incentive regulation has become an important regulatory tool in the telecommunications industry in the United States. The issue explored here is whether incentive regulation has resulted in an increase in productive efficiency. After providing an overview of the nature of incentive regulation, a methodology for measuring technical inefficiency and its change is introduced. This is a stochastic frontier production function approach reflecting technical inefficiency effects. The results of implementing this methodology suggest that in the production of interLATA billed access minutes for interstate calls, there was no change in technical efficiency, something that incentive regulation was specifically designed to enhance. Finally, an assessment of technical efficiency across individual LECs in the United States indicates considerable variability. Published in 2001 by John Wiley & Sons, Ltd. 相似文献
56.
Marcos Pereira Estellita Lins Luiz Fernando de Lyra Novaes Luiz Fernando Loureiro Legey 《Annals of Operations Research》2005,138(1):79-96
This paper proposes a new methodology for the assessment of the value range for real estate units. The theoretical basis of
the methodology is built on the Data Envelopment Analysis—DEA approach, which has its original concept adapted to the case
where the units under assessment consist of transactions among sellers and buyers. The proposed approach—christened Double
Perspective-Data Envelopment Analysis (DP-DEA)—is applied to a database comprising the prices and features of the units under
assessment. It is shown that the DP-DEA presents some specific advantages when compared to the usual regression analysis method
employed in real estate value assessment. 相似文献
57.
参数和非参数前沿方法是测度生产率效率的两种重要方法,本文构建了一个将二者结合起来的研究框架。在此基础上,以我国30个省份的第一产业为例,对各省份的农业生产率效率进行了测度和比较。虽然两种方法各有优缺点,但结合使用不仅能提高各自的准确度,也能优化各决策单元的投入与产出比例,同时也是进一步经济计量分析的一个重要参照系。 相似文献
58.
本文选取1999-2004年间中国城市公共交通行业的面板数据,在Cobb-Douglas函数的基础上运用随机边界法对我国城市公共交通行业的技术效率进行了考察,并从时间、地域、交通工具类型和客运规模方面,分析了该行业的效率差异及其产生原因,旨在为该行业的未来发展和管制改革提供决策依据。研究结果表明,我国城市公共交通行业技术效率情况为:近几年虽有小幅上升,但基数总体不高;东部地区技术效率偏高;客运量大和拥有轨道交通的省市的技术效率较高。 相似文献
59.
Wang Yi Chen Zhiping Zhang Kecun Department of Scientific Computing Applied Softwares Faculty of Science Xi''''an Jiaotong University Xi''''an China. 《高校应用数学学报(英文版)》2006,(4)
In order to study the effect of different risk measures on the efficient portfolios (frontier) while properly describing the characteristic of return distributions in the stock market, it is assumed in this paper that the joint return distribution of risky assets obeys the multivari-ate t-distribution. Under the mean-risk analysis framework, the interrelationship of efficient portfolios (frontier) based on risk measures such as variance, value at risk (VaR), and expected shortfall (ES) is analyzed and compared. It is proved that, when there is no riskless asset in the market, the efficient frontier under VaR or ES is a subset of the mean-variance (MV) efficient frontier, and the efficient portfolios under VaR or ES are also MV efficient; when there exists a riskless asset in the market, a portfolio is MV efficient if and only if it is a VaR or ES efficient portfolio. The obtained results generalize relevant conclusions about investment theory, and can better guide investors to make their investment decision. 相似文献
60.
D. Li 《Journal of Optimization Theory and Applications》1996,88(1):177-196
The convexity of a noninferior frontier can be achieved in an appropriate equivalent objective space for general nonconvex multi-objective optimization problems. Specifically, this paper proves that applying thep-power to the objective functions can act as a convexification scheme for a noninferior frontier.The author appreciates the discussions with Jian-Bo Yang and the comments from Yacov Y. Haimes. 相似文献