全文获取类型
收费全文 | 96711篇 |
免费 | 956篇 |
国内免费 | 487篇 |
专业分类
化学 | 37795篇 |
晶体学 | 969篇 |
力学 | 7067篇 |
综合类 | 1篇 |
数学 | 34655篇 |
物理学 | 17667篇 |
出版年
2022年 | 163篇 |
2021年 | 198篇 |
2020年 | 294篇 |
2019年 | 292篇 |
2018年 | 10568篇 |
2017年 | 10384篇 |
2016年 | 6417篇 |
2015年 | 1183篇 |
2014年 | 730篇 |
2013年 | 1221篇 |
2012年 | 4709篇 |
2011年 | 11643篇 |
2010年 | 6198篇 |
2009年 | 6517篇 |
2008年 | 7523篇 |
2007年 | 9730篇 |
2006年 | 1267篇 |
2005年 | 2309篇 |
2004年 | 2383篇 |
2003年 | 2689篇 |
2002年 | 1726篇 |
2001年 | 490篇 |
2000年 | 534篇 |
1999年 | 378篇 |
1998年 | 413篇 |
1997年 | 402篇 |
1996年 | 477篇 |
1995年 | 337篇 |
1994年 | 285篇 |
1993年 | 334篇 |
1992年 | 252篇 |
1991年 | 243篇 |
1990年 | 213篇 |
1989年 | 196篇 |
1988年 | 198篇 |
1987年 | 212篇 |
1986年 | 191篇 |
1985年 | 246篇 |
1984年 | 290篇 |
1983年 | 213篇 |
1982年 | 259篇 |
1981年 | 278篇 |
1980年 | 226篇 |
1979年 | 223篇 |
1978年 | 248篇 |
1977年 | 178篇 |
1976年 | 172篇 |
1975年 | 164篇 |
1974年 | 176篇 |
1973年 | 164篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
We present some results on the impact of demand variability on stocking policies and incentives to forecast, in the context of single period inventory-based contracts in a manufacturer-retailer channel. 相似文献
152.
153.
In this note we show how 1-factors in the middle two layers of the discrete cube can be used to construct 2-factors in the
Odd graph (the Kneser graph of (k − 1)-sets from a (2k − 1)-set). In particular, we use the lexical matchings of Kierstead and Trotter, and the modular matchings of Duffus, Kierstead
and Snevily, to give explicit constructions of two different 2-factorisations of the Odd graph.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献
154.
Siaw-Lynn Ng 《Order》2004,21(1):1-5
We present a characterisation of posets of size n with linear discrepancy n − 2. These are the posets that are “furthest” from a linear order without being an antichain.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献
155.
Curtis T. Mcmullen 《Acta Mathematica》2003,191(2):191-223
156.
We will prove a result concerning the inclusion of non-trivial invariant ideals inside non-trivial ideals of a twisted crossed
product. We will also give results concerning the primeness and simplicity of crossed products of twisted actions of locally
compact groups on -algebras.
Received: 25 January 2002; in final form: 22 May 2002/Published online: 2 December 2002
This work is partially supported by Hong Kong RGC Direct Grant. 相似文献
157.
Paul Binding 《Mathematical Methods in the Applied Sciences》2003,26(4):349-357
Sturm–Liouville equations will be considered where the boundary conditions depend rationally on the eigenvalue parameter. Such problems apply to a variety of engineering situations, for example to the stability of rotating axles. Classesof these problems will be isolated with a rather rich spectral structure, for example oscillation, comparison and completeness properties analogous to thoseof the ‘usual’ Sturm–Liouville problem which has constant boundary conditions.In fact it will be shown how these classes can be converted into each other, andinto the ‘usual’ Sturm–Liouville problem, by means of transformations preserving all but finitely many eigenvalues. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
158.
The influence of the sample orientation on the effective value of the hydrostatic piezoelectric coefficients d
h
(i)
of Sn2P2S6 crystals has been studied. The hydrostatic piezoelectric coefficients d
h
(1)
and d′
h
(3)
, were measured, d
h
(1)
=(244±3) pC/N and d′
h
(3)
=(92±1) pC/N. The hydrostatic piezoelectric coefficient d
h
(3)
for orthogonal axis system was calculated to be d
h
(3)
=(87±2) pC/N. The, optimal orientation of the sample has been found as (Xy l)−20°-cut. Maximal value of the effective hydrostatic piezoelectric coefficient d
h
(1)
equals 260 pC/N. Double rotated samples were also studied. The orientation of the samples insensitive to the pressure has
been found. The theoretical mean value of hydrostatic piezoelectric coefficient (d
h
)
mean
corresponding to randomly oriented Sn2P2S6 grains in a poled composite has been calculated to be (d
h
)
mean
=136 pC/N. 相似文献
159.
Lev Buhovsky 《Israel Journal of Mathematics》2004,143(1):181-187
In this paper we find homological restrictions on Lagrangians in cotangent bundles of spheres and Lens spaces.
This research was supported by the Israel Science Foundation (grand No. 205/02). 相似文献
160.
Harish C. Bahl Stanley Zionts 《The Journal of the Operational Research Society》1987,38(12):1141-1148
Scheduling the production of several items requires the determination of production quantities in different periods in the presence of resource constraints. Several approximate and heuristic algorithms have been proposed to solve this problem. However, no method for finding an optimal solution has as yet been developed. It is shown that the problem may be solved advantageously using Benders' decomposition. The subproblem in Benders' decomposition is shown to be a transportation problem, and some strategies for solving the master problem are indicated. The paper concludes with a sample problem demonstrating the application of the method. 相似文献