全文获取类型
收费全文 | 1355篇 |
免费 | 54篇 |
国内免费 | 4篇 |
专业分类
化学 | 942篇 |
晶体学 | 10篇 |
力学 | 45篇 |
数学 | 147篇 |
物理学 | 269篇 |
出版年
2023年 | 6篇 |
2022年 | 11篇 |
2021年 | 14篇 |
2020年 | 17篇 |
2019年 | 21篇 |
2018年 | 13篇 |
2017年 | 10篇 |
2016年 | 27篇 |
2015年 | 32篇 |
2014年 | 61篇 |
2013年 | 71篇 |
2012年 | 73篇 |
2011年 | 101篇 |
2010年 | 42篇 |
2009年 | 47篇 |
2008年 | 94篇 |
2007年 | 84篇 |
2006年 | 77篇 |
2005年 | 65篇 |
2004年 | 56篇 |
2003年 | 35篇 |
2002年 | 40篇 |
2001年 | 15篇 |
2000年 | 26篇 |
1999年 | 18篇 |
1998年 | 13篇 |
1997年 | 9篇 |
1996年 | 16篇 |
1995年 | 11篇 |
1994年 | 11篇 |
1993年 | 15篇 |
1992年 | 7篇 |
1991年 | 10篇 |
1990年 | 14篇 |
1989年 | 14篇 |
1988年 | 12篇 |
1987年 | 10篇 |
1985年 | 13篇 |
1984年 | 12篇 |
1983年 | 8篇 |
1982年 | 12篇 |
1981年 | 14篇 |
1980年 | 17篇 |
1979年 | 16篇 |
1978年 | 11篇 |
1977年 | 15篇 |
1976年 | 7篇 |
1975年 | 7篇 |
1974年 | 19篇 |
1973年 | 12篇 |
排序方式: 共有1413条查询结果,搜索用时 296 毫秒
131.
132.
Ghizzo A. Bertrand P. Begue M.L. Johnston T.W. Shoucri M. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1996,24(2):370-378
High-frequency beatwave simulations relevant to the University of California at Los Angeles (UCLA) experiment with relativistic eulerian hybrid Vlasov code are presented. These Hilbert-Masov simulations revealed a rich variety of phenomena associated with the fast particle dynamics induced by beatwave experiment for a high ratio of driver frequency to plasma frequency ωpump/ωplasma ≈33. The present model allows us to extend detailed modeling to frequency ratios greater than the current practical maximum of 10 or so, for Vlasov or particle-in-cell (PIC) codes, by replacing the Maxwell equations by mode equations for the electromagnetic Vlasov code. Numerical results, including beat frequency chirping (i.e., pump frequency linearly decreasing with time), show that the amplitude limit due to relativistic detuning can be enhanced with accelerated particles up to the ultrarelativistic energies with a high-acceleration gradient of more than 25 GeV/m 相似文献
133.
The purpose of this work is to prove the existence of an algebraic moduli classifying objects in a given triangulated category.To any dg-category T (over some base ring k), we define a D−-stack MT in the sense of [Toën B., Vezzosi G., Homotopical algebraic geometry II: Geometric stacks and applications, Mem. Amer. Math. Soc., in press], classifying certain Top-dg-modules. When T is saturated, MT classifies compact objects in the triangulated category [T] associated to T. The main result of this work states that under certain finiteness conditions on T (e.g. if it is saturated) the D−-stack MT is locally geometric (i.e. union of open and geometric sub-stacks). As a consequence we prove the algebraicity of the group of auto-equivalences of saturated dg-categories. We also obtain the existence of reasonable moduli for perfect complexes on a smooth and proper scheme, as well as complexes of representations of a finite quiver. 相似文献
134.
We give a new and direct proof of the nonexistence of limit cycle in a bimolecular system and the characterization of the unique bimolecular oscillator. The proof is an application of classification theorems on vector fields with homogeneous second degree polynomial perturbations. 相似文献
135.
136.
La0.7Ce0.3MnO3 epitaxial films were successfully fabricated via a pulsed laser deposition method by controlling the experimental conditions. A series of experiments with varying the oxygen pressure and the substrate temperature demonstrated that the use of appropriate conditions is crucial for fabricating the epitaxial thin films. The existence of such suitable conditions was thermodynamically interpreted in terms of the stability of Mn2+ ion. Both XRD and EPMA measurements indicated that La0.7Ce0.3MnO3 thin films fabricated herein form single phases, although it was difficult to present the direct experimental evidence to prove that Ce ion can really exist within the perovskite structure. The resultant films with oxygen annealing showed a metal-insulator transition and ferromagnetic property with Curie temperature of 275 K. 相似文献
137.
Dominique Delbourg Gérard Penillault Tran Khan Tuong Martial Decourt Nicole Borome Henri Harroch Bertrand Lessellier Bernard Waast Jean Pierre Mouffron 《Pramana》2002,59(6):1025-1033
A new control system was designed for the tandem MP-9 at Orsay. Because of the existing devices located on high voltage platforms
and the lack of space inside the accelerator, in-house electronic cards based on micro-controllers and an optical fieldbus
were developed to collect data. VME processors under VxWorks, a real time operating system, manage the fieldbus, concentrate
the accelerator information and transmit it to the supervisory software through the ethernet network. This software consists
of a collection of Java virtual machines (JVM) running on several Unix work-stations and PCs under Windows. Some of the Java
virtual machines manage apparatus, instruments, local display and connections to an object database and VME concentrators.
Other manage general synoptics. JVMs communicate between themselves with RMI protocol and JRPC with VME concentrators. So
the supervisory software can be spread over several control stations throughout the network. 相似文献
138.
Shyong Jian Shyu Peng-Yeng Yin Bertrand M.T. Lin 《Annals of Operations Research》2004,131(1-4):283-304
Given an undirected graph and a weighting function defined on the vertex set, the minimum weight vertex cover problem is to find a vertex subset whose total weight is minimum subject to the premise that the selected vertices cover all edges in the graph. In this paper, we introduce a meta-heuristic based upon the Ant Colony Optimization (ACO) approach, to find approximate solutions to the minimum weight vertex cover problem. In the literature, the ACO approach has been successfully applied to several well-known combinatorial optimization problems whose solutions might be in the form of paths on the associated graphs. A solution to the minimum weight vertex cover problem however needs not to constitute a path. The ACO algorithm proposed in this paper incorporates several new features so as to select vertices out of the vertex set whereas the total weight can be minimized as much as possible. Computational experiments are designed and conducted to study the performance of our proposed approach. Numerical results evince that the ACO algorithm demonstrates significant effectiveness and robustness in solving the minimum weight vertex cover problem. 相似文献
139.
140.
We investigate the behavior of fluid–particle mixtures subject to shear stress, by mean of direct simulation. This approach is meant to give some hints to explain the influence of interacting red cells on the global behavior of the blood. We concentrate on the apparent viscosity, which we define as a macroscopic quantity which characterizes the resistance of a mixture against externally imposed shear motion. Our main purpose is to explain the non-monotonous variations of this apparent viscosity when a mixture of fluid and interacting particles is submitted to shear stress during a certain time interval. Our analysis of these variations is based on preliminary theoretical remarks, and some computations for some well-chosen static configurations. To cite this article: A. Lefebvre, B. Maury, C. R. Mecanique 333 (2005). 相似文献