全文获取类型
收费全文 | 1330篇 |
免费 | 45篇 |
国内免费 | 47篇 |
专业分类
化学 | 583篇 |
晶体学 | 20篇 |
力学 | 48篇 |
综合类 | 5篇 |
数学 | 342篇 |
物理学 | 424篇 |
出版年
2024年 | 5篇 |
2023年 | 43篇 |
2022年 | 7篇 |
2021年 | 19篇 |
2020年 | 26篇 |
2019年 | 39篇 |
2018年 | 30篇 |
2017年 | 22篇 |
2016年 | 33篇 |
2015年 | 31篇 |
2014年 | 43篇 |
2013年 | 144篇 |
2012年 | 70篇 |
2011年 | 63篇 |
2010年 | 56篇 |
2009年 | 74篇 |
2008年 | 68篇 |
2007年 | 68篇 |
2006年 | 63篇 |
2005年 | 42篇 |
2004年 | 40篇 |
2003年 | 42篇 |
2002年 | 40篇 |
2001年 | 36篇 |
2000年 | 30篇 |
1999年 | 33篇 |
1998年 | 22篇 |
1997年 | 20篇 |
1996年 | 23篇 |
1995年 | 27篇 |
1994年 | 21篇 |
1993年 | 15篇 |
1992年 | 9篇 |
1991年 | 9篇 |
1990年 | 6篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 11篇 |
1984年 | 4篇 |
1983年 | 7篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1980年 | 9篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1974年 | 4篇 |
1973年 | 10篇 |
排序方式: 共有1422条查询结果,搜索用时 312 毫秒
1.
3.
M. Brando N. Büttgen V. Fritsch J. Hemberger H. Kaps H.-A. Krug von Nidda M. Nicklas K. Pucher W. Trinkl A. Loidl E.W. Scheidt M. Klemm S. Horn 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,25(3):289-298
We present susceptibility, microwave resistivity, NMR and heat-capacity results for Li1-xZnx(V1-yTiy)2O4 with 0 ?
x
? 0.3 and 0 ?
y
? 0.3. For all doping levels the susceptibility curves can be fitted with a Curie-Weiss law. The paramagnetic Curie-Weiss temperatures
remain negative with an average value close to that of the pure compound Θ≈ - 36 K. Spin-glass anomalies are observed in the susceptibility, heat-capacity and NMR measurements for both type of dopants.
From the temperature dependence of the spin-lattice relaxation rate we found critical-dynamic behavior in the Zn doped compounds
at the freezing temperatures. For the Ti-doped samples two successive freezing transitions into disordered low-temperature
states can be detected. The temperature dependence of the heat capacity for Zn-doped compounds does not resemble that of canonical
spin glasses and only a small fraction of the total vanadium entropy is frozen at the spin-glass transitions. For pure LiV2O4 the spin-glass transition is completely suppressed. The temperature dependence of the heat capacity for LiV2O4 can be described using a nuclear Schottky contribution and the non-Fermi liquid model, appropriate for a system close to
a spin-glass quantum critical point. Finally an (
x
/
y
,
T
)-phase diagram for the low-doping regime is presented.
Received 16 March 2001 and Received in final form 30 October 2001 相似文献
4.
On the average complexity of 3D-Voronoi diagrams of random points on convex polytopes 总被引:1,自引:0,他引:1
It is well known that the complexity, i.e. the number of vertices, edges and faces, of the 3-dimensional Voronoi diagram of n points can be as bad as Θ(n2). It is also known that if the points are chosen Independently Identically Distributed uniformly from a 3-dimensional region such as a cube or sphere, then the expected complexity falls to O(n). In this paper we introduce the problem of analyzing what occurs if the points are chosen from a 2-dimensional region in 3-dimensional space. As an example, we examine the situation when the points are drawn from a Poisson distribution with rate n on the surface of a convex polytope. We prove that, in this case, the expected complexity of the resulting Voronoi diagram is O(n). 相似文献
5.
Electron beam induced quantitative X-ray mapping has become a very useful characterisation tool for determining the elemental
distribution in materials, whether using energy dispersive spectroscopy or wavelength dispersive spectroscopy. The X-ray intensity
distributions of the elements from an X-ray map allow us to generate two dimensional and ternary scatter diagrams thus converting
spatial information into concentration dimensions, which is an important tool for displaying the spatial relationships of
elements or correlated elements (phases) in materials. To best understand how to use this tool, we need to understand the
production and features of the scatter diagram. The type of clustering observed in the scatter diagram, whether oval, linear
or spherical, can give the major and trace element distributions within phases as well as qualitative and quantitative phase
information. This paper demonstrates the generation of scatter diagrams, properties of scatter diagrams, interpretation of
scatter diagrams and the advantages of scatter diagrams through the use of examples. 相似文献
6.
Geng Sheng WANG 《数学学报(英文版)》2005,21(5):1005-1014
This work is concerned with Pontryagin's maximum principle of optimal control problems governed by some non-well-posed semilinear heat equations. A type of approach to the non-well-posed optimal control problem is given. 相似文献
7.
基于MATLAB的异步电动机线性化控制系统的仿真 总被引:1,自引:0,他引:1
从异步电动机在同步旋转坐标系下的状态方程出发,在一定的条件下,对其系数矩阵简化.推出异步电动机的线性化控制模型.并基于该模型得出异步电动机的线性化控制系统.以给定电机为例,对该模型的有效性、响应用MATLAB进行仿真分析.验证的结果说明上述模型具有实用价值. 相似文献
8.
Multinomial permutations on a circle are considered in the framework of combinatorics. Different cases are presented and shown to agree with previously derived formula for the number of cyclic necklaces. Two applied examples are discussed with a view to illustrate the implications of derived formulas. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
9.
In this paper, the possibility of using the gradients of the temperature and of the internal parameters as additional state variables in Continuum Thermodynamics is considered. The expressions of the two principles are discussed and Clausius–Duhem inequality is derived under an appropriate statement of the internal entropy production. Several formulations are proposed and compared to existing results in the literature. To cite this article: P. Ireman, Q.S. Nguyen, C. R. Mecanique 332 (2004). 相似文献
10.