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111.
A. D. Matveev 《Journal of Applied Mechanics and Technical Physics》2004,45(3):440-448
This paper considers composites consisting of a set of typical composite multigrid finite elements whose structures are regular and different. Mean local errors are proposed for multigrid modeling of composites. 相似文献
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通过对不同情况下参数测量误差导致的到靶激光平均功率密度变化的统计,得到了大气参数精度对激光传输计算结果的影响。风速和气溶胶吸收系数测量误差主要来自热晕效应的影响,热晕越强,对计算结果的影响就越大。强热晕时,风速±(5%~8%)的误差可导致计算结果约±10%的误差;气溶胶吸收权重±(10%~20%)的误差可导致计算结果约 10%的误差。强湍流弱热晕时,大气相干长度±(5%~7%)的误差可导致计算结果约±10%的误差。 相似文献
114.
Jheyne N. Ortiz Robson R. de Araujo Diego F. Aranha Sueli I. R. Costa Ricardo Dahab 《Entropy (Basel, Switzerland)》2021,23(9)
Several works have characterized weak instances of the Ring-LWE problem by exploring vulnerabilities arising from the use of algebraic structures. Although these weak instances are not addressed by worst-case hardness theorems, enabling other ring instantiations enlarges the scope of possible applications and favors the diversification of security assumptions. In this work, we extend the Ring-LWE problem in lattice-based cryptography to include algebraic lattices, realized through twisted embeddings. We define the class of problems Twisted Ring-LWE, which replaces the canonical embedding by an extended form. By doing so, we allow the Ring-LWE problem to be used over maximal real subfields of cyclotomic number fields. We prove that Twisted Ring-LWE is secure by providing a security reduction from Ring-LWE to Twisted Ring-LWE in both search and decision forms. It is also shown that the twist factor does not affect the asymptotic approximation factors in the worst-case to average-case reductions. Thus, Twisted Ring-LWE maintains the consolidated hardness guarantee of Ring-LWE and increases the existing scope of algebraic lattices that can be considered for cryptographic applications. Additionally, we expand on the results of Ducas and Durmus (Public-Key Cryptography, 2012) on spherical Gaussian distributions to the proposed class of lattices under certain restrictions. As a result, sampling from a spherical Gaussian distribution can be done directly in the respective number field while maintaining its format and standard deviation when seen in via twisted embeddings. 相似文献
115.
In der Arbeit wird untersucht, unter welchen analytischen Bedingungen eine quantitative Sticksoffbestimmung mit dem 15 N-Analysator NA-5A mittels Isotopenverdünnung durchzuführen ist. Es wird auf die Berechnung der N-Menge, die Abschätzung des maximalen Fehlers unter den speziellen Verhāltnissen der 15N-Analysator-Anwendung und die Auswertungsverfahren näher eingegangen. Testanalysen an unterschiedlich markierten Modell-Lösungen, bestehendaus Ammonium-, Harnstoff- und Aminosäurestickstoff, ergaben gute Übereinstimmung mit den vorgegebenen Werten. Das Verfahren wurde zur N-Bestimmung von biologish-medizinischem Material eingesetzt. Ein Arbeitsschema zur quantitativan Bestimmung von Ammonium-N, Harnstoff-N und Gesamt-N direkt in Harn wird mitgeteilt. 相似文献
116.
A factorial analysis is conducted to explore the impact of five factors — aspect ratio, radius-to-thickness ratio, material anisotropy, fiber angle and integration order on the finite element accuracy, with regard to the application of 20-node isoparametric solid elements to clamped composite cylindrical shells subjected to internal pressure. The maximum radial displacement at the central cross-section is employed as the indicator of accuracy. Results from finite element methods were compared with closed-form solutions. Aspect ratio, radius-to- thickness ratio, and integration order are significant main effects as predicted for isotropic materials. Material anisotropy shows no significant main effect, while the fiber angle does have strong impact on the finite element accuracy. In addition to four influential main effects, some multiple-factor interactions are shown to have significant influences on the finite element accuracy. The analysis is limited to the linear elastic range. 相似文献
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考虑固定设计下具有一阶非参数自回归误差的线性模型,构造了参数和非参数函数的N-W核估计,在适当的条件下,证明了参数估计的强相合性,同时给出了非参数函数估计的渐近正态性. 相似文献
119.
R. G. Thompson P. S. Dharmapala J. Diaz M. D. González-Lima R. M. Thrall 《Annals of Operations Research》1996,66(2):163-177
The setE of extreme points which are also efficient are of basic importance in defining the efficiency frontier, from which the observations for all other DMUs are evaluated in DEA. A significant question which we address is “What variations in the data can be tolerated before the membership inE is changed?” This topic is explored using (1) a simple illustrative example, and (2) production data for 30 independent oil companies during the period 1983–1985. Data were allowed to vary simultaneously for all observations and in different subsets determined by random drawings of data for points both inE and not inE. The results were found to be robust in this study, thereby lending further support to earlier studies which also found these classifications into efficient and inefficient performers to be robust in DEA. Technical developments for these new methods of sensitivity analysis are supplied. These developments feature an application of analytic center (interior point) algorithms which ensure that the Strong Complementary Slackness Condition (SCSC) is fulfilled. The solutions satisfy a mathematical condition called “centrality”. Generally, the solutions are at interior points calledanalytic centers. At these interior points, continuity of the input-output ratios ensures that DMUs inE remain inE for at least small relative variations in the data, while empirically these properties have been found to extend to much larger variations in the data sets. 相似文献
120.