全文获取类型
收费全文 | 11316篇 |
免费 | 2320篇 |
国内免费 | 860篇 |
专业分类
化学 | 2255篇 |
晶体学 | 172篇 |
力学 | 2720篇 |
综合类 | 129篇 |
数学 | 2164篇 |
物理学 | 7056篇 |
出版年
2024年 | 23篇 |
2023年 | 94篇 |
2022年 | 157篇 |
2021年 | 179篇 |
2020年 | 287篇 |
2019年 | 244篇 |
2018年 | 245篇 |
2017年 | 329篇 |
2016年 | 354篇 |
2015年 | 294篇 |
2014年 | 645篇 |
2013年 | 841篇 |
2012年 | 606篇 |
2011年 | 775篇 |
2010年 | 603篇 |
2009年 | 771篇 |
2008年 | 820篇 |
2007年 | 814篇 |
2006年 | 812篇 |
2005年 | 640篇 |
2004年 | 572篇 |
2003年 | 547篇 |
2002年 | 457篇 |
2001年 | 469篇 |
2000年 | 404篇 |
1999年 | 357篇 |
1998年 | 317篇 |
1997年 | 273篇 |
1996年 | 221篇 |
1995年 | 198篇 |
1994年 | 157篇 |
1993年 | 131篇 |
1992年 | 142篇 |
1991年 | 124篇 |
1990年 | 74篇 |
1989年 | 67篇 |
1988年 | 67篇 |
1987年 | 63篇 |
1986年 | 52篇 |
1985年 | 39篇 |
1984年 | 38篇 |
1983年 | 20篇 |
1982年 | 36篇 |
1981年 | 22篇 |
1980年 | 30篇 |
1979年 | 34篇 |
1978年 | 14篇 |
1977年 | 14篇 |
1974年 | 5篇 |
1973年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
51.
用改进的离子束增强沉积方法和恰当的退火从V2O5粉末直接制备了VO2多晶薄膜.实验测试表明,薄膜的取向单一、相变特性显著、结构致密、界面结合牢固、工艺性能良好,薄膜的电阻温度系数(TCR)最高可达4.23%/K.从成膜机理出发,较详细地讨论了离子束增强沉积 VO2多晶薄膜的TCR高于VOx薄膜的TCR的原因.分析认为,单一取向的VO2结构使薄膜晶粒具有较高的电导激活能,致密的薄膜结构减少了氧空位和晶界宽度,使离子束增强沉积 VO2多晶薄膜结构比其他方法制备的VOx薄膜更接近于单晶VO2是其具有高TCR的原
关键词:
VO2多晶薄膜
离子束增强沉积
热电阻温度系数 相似文献
52.
对于超细长弹性杆静力学的Kirchhoff方程,用动力学的概念和方法研究其常值特解 和稳定性问题.计算了Kirchhoff方程相对固定坐标系、截面主轴坐标系以及中心线Frenet 坐标系的常值特解,进行了Kirchhoff动力学比拟,用一次近似理论分别讨论了它们的Lyapu nov稳定性,导出了若干稳定性判据,并在参数平面上绘出了稳定域.
关键词:
超细长弹性杆
Kirchhoff方程
常值特解
Lyapunov稳定性 相似文献
53.
54.
55.
56.
Mari Grobbelaar‐Van Dalsen 《Mathematical Methods in the Applied Sciences》2004,27(11):1301-1315
This paper is concerned with well‐posedness results for a mathematical model for the transversal vibrations of a two‐dimensional hybrid elastic structure consisting of a rectangular Reissner–Mindlin plate with a Timoshenko beam attached to its free edge. The model incorporates linear dynamic feedback controls along the interface between the plate and the beam. Classical semigroup methods are employed to show the unique solvability of the coupled initial‐boundary‐value problem. We also show that the energy associated with the system exhibits the property of strong stability. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
57.
In this article we prove the existence of the solution to the mixed problem for Euler–Bernoulli beam equation with memory term. The existence is proved by means of the Faedo–Galerkin method and the exponential decay is obtained by making use of the multiplier technique combined with integral inequalities due to Komornik. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
58.
We investigate the effects of adding uniformity requirements to concepts in computable structure theory such as computable categoricity (of a structure) and intrinsic computability (of a relation on a computable structure). We consider and compare two different notions of uniformity, previously studied by Kudinov and by Ventsov. We discuss some of their results and establish new ones, while also exploring the connections with the relative computable structure theory of Ash, Knight, Manasse, and Slaman and Chisholm and with previous work of Ash, Knight, and Slaman on uniformity in a general computable structure-theoretical setting. 相似文献
59.
A hybrid heuristic method for combinatorial optimization problems is proposed that combines different classical techniques such as tree search procedures, bounding schemes and local search. The proposed method enhances the classic beam search approach by applying to each partial solution corresponding to a node selected by the beam, a further test that checks whether the current partial solution is dominated by another partial solution at the same level of the search tree. If this is the case, the latter solution becomes the new current partial solution. This step allows to partially recover from previous wrong decisions of the beam search procedure and can be seen as a local search step on the partial solution. We present here the application to two well known combinatorial optimization problems: the two-machine total completion time flow shop scheduling problem and the uncapacitated p-median location problem. In both cases the method strongly improves the performances with respect to the basic beam search approach and is competitive with the state of the art heuristics. 相似文献
60.
Krzysztof Pawaowski 《K-Theory》1998,13(1):41-55
The paper presents a procedure for constructing smooth actions of finite perfect groups on spheres with fixed point sets having certain prescribed properties (Theorem A); in particular, having any prescribed configuration of Chern and Pontryagin numbers (Corollary C). The main ingredients used are equivariant thickening and equivariant surgery. 相似文献