全文获取类型
收费全文 | 9437篇 |
免费 | 600篇 |
国内免费 | 435篇 |
专业分类
化学 | 1537篇 |
晶体学 | 20篇 |
力学 | 456篇 |
综合类 | 42篇 |
数学 | 4004篇 |
物理学 | 1855篇 |
综合类 | 2558篇 |
出版年
2024年 | 14篇 |
2023年 | 54篇 |
2022年 | 152篇 |
2021年 | 134篇 |
2020年 | 135篇 |
2019年 | 280篇 |
2018年 | 300篇 |
2017年 | 161篇 |
2016年 | 170篇 |
2015年 | 259篇 |
2014年 | 458篇 |
2013年 | 585篇 |
2012年 | 481篇 |
2011年 | 727篇 |
2010年 | 596篇 |
2009年 | 633篇 |
2008年 | 656篇 |
2007年 | 748篇 |
2006年 | 587篇 |
2005年 | 424篇 |
2004年 | 378篇 |
2003年 | 328篇 |
2002年 | 281篇 |
2001年 | 202篇 |
2000年 | 218篇 |
1999年 | 192篇 |
1998年 | 163篇 |
1997年 | 143篇 |
1996年 | 132篇 |
1995年 | 117篇 |
1994年 | 104篇 |
1993年 | 125篇 |
1992年 | 88篇 |
1991年 | 76篇 |
1990年 | 49篇 |
1989年 | 59篇 |
1988年 | 53篇 |
1987年 | 39篇 |
1986年 | 29篇 |
1985年 | 32篇 |
1984年 | 22篇 |
1983年 | 12篇 |
1982年 | 14篇 |
1981年 | 6篇 |
1980年 | 14篇 |
1979年 | 11篇 |
1978年 | 4篇 |
1977年 | 11篇 |
1976年 | 4篇 |
1974年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
用600keV的Kr~ 离子轰击Al/Cr双层薄膜样品进行界面原子反应及相互混合的研究。实验样品是在单晶硅上蒸镀约500nm厚的铝膜,相继再蒸上所需厚度的铬膜而制成的。轰击剂量为2.0×10~(15)-2.5×10~(16)Kr~ /cm~2。用2.0MeVa粒子对轰击前后的样品进行了卢瑟福背散射(RBS)分析,发现界面处有明显的原子混合存在;当轰击剂量≥1.0×10~(16)Kr~ /cm~2时,RBS谱出现有明显的坪台,经拟合计算和x射线衍射(XRD)测量证实确有化合物Al_(13)Cr_2存在;还分别得到了原子混合量及混合效率与轰击剂量的关系;最后对界面处的原子混合机制进行了讨论。 相似文献
92.
V. E. Neuvazhaev I.É. Parshukov N. V. Pervinenko A. V. Ponomarev 《Journal of Applied Mechanics and Technical Physics》2004,45(5):656-664
Based on numerical calculations, the experiments on mixing at the interface of gases are analyzed. Single-mode and random disturbances of the interface and superposition of random disturbances onto long-wave perturbations are considered. Possible reasons for the higher value of the mixing constant obtained in the experiments are discussed. 相似文献
93.
The Castelnuovo-Mumford regularity of a module gives a rough measure of its complexity. We bound the regularity of a module given a system of approximating modules whose regularities are known. Such approximations can arise naturally for modules constructed by inductive combinatorial means. We apply these methods to bound the regularity of ideals constructed as combinations of linear ideals and the module of derivations of a hyperplane arrangement as well as to give degree bounds for invariants of finite groups. 相似文献
94.
In this paper, we study the Hilbert–Samuel function of a generic standard graded K-algebrawhen refined by an (ℓ)-adic filtration, ℓ being a linear form. From this we obtain a structure theorem which describes the stairs of a generic complete intersection for the degree-reverse-lexicographic order. We show what this means for generic standard (or Gröbner) bases for this order; in particular, we consider an “orderly filling up” conjecture, and we propose a strategy for the standard basis algorithm which could be useful in generic-like cases. 相似文献
K[X1,…,Xn]/(g1,…,gm)
95.
Jean Dolbeault Maria J Esteban Michael Loss Luis Vega 《Journal of Functional Analysis》2004,216(1):1-21
We prove some sharp Hardy-type inequalities related to the Dirac operator by elementary, direct methods. Some of these inequalities have been obtained previously using spectral information about the Dirac-Coulomb operator. Our results are stated under optimal conditions on the asymptotics of the potentials near zero and near infinity. 相似文献
96.
设A是希尔伯特空间H上的自伴算子代数,α是A上的*-自同态.如果存在单位向量e∈H,使得对任意α∈A和单位向量h∈H,有lim_(n→∞)〈α~n(a)h,h〉=〈αe,e〉成立,那么称α是A上的σ-弱混合的*-自同态.本文研究了这一有趣性质,并得到了一个*-自同态是σ-弱混合的充分条件. 相似文献
97.
A recent conjecture of Myerson and Sander concerns divisibility properties of certain multinomial coefficients. We obtain results in this direction by further pursuing a line of attack developed earlier by the first author. 相似文献
98.
Lenny Fukshansky 《Journal of Number Theory》2004,108(1):29-43
Given a quadratic form and M linear forms in N+1 variables with coefficients in a number field K, suppose that there exists a point in KN+1 at which the quadratic form vanishes and all the linear forms do not. Then we show that there exists a point like this of relatively small height. This generalizes a result of D.W. Masser. 相似文献
99.
J. Browkin 《Journal of Number Theory》2004,109(2):379-389
The aim of the paper is to determine all free separable quadratic algebras over the rings of integers of quadratic fields in terms of the properties of the fundamental unit in the real case. The paper corrects some earlier published results on the subject. 相似文献
100.
We provide a proof of Connes’ formula for a representative of the Hochschild class of the Chern character for (p,∞)-summable spectral triples. Our proof is valid for all semifinite von Neumann algebras, and all integral p?1. We employ the minimum possible hypotheses on the spectral triples. 相似文献