全文获取类型
收费全文 | 160041篇 |
免费 | 11858篇 |
国内免费 | 17121篇 |
专业分类
化学 | 98231篇 |
晶体学 | 2216篇 |
力学 | 14371篇 |
综合类 | 1833篇 |
数学 | 34253篇 |
物理学 | 38116篇 |
出版年
2024年 | 192篇 |
2023年 | 1307篇 |
2022年 | 2320篇 |
2021年 | 3506篇 |
2020年 | 4079篇 |
2019年 | 3856篇 |
2018年 | 3504篇 |
2017年 | 4906篇 |
2016年 | 5576篇 |
2015年 | 4441篇 |
2014年 | 6502篇 |
2013年 | 11653篇 |
2012年 | 10389篇 |
2011年 | 9255篇 |
2010年 | 7899篇 |
2009年 | 10137篇 |
2008年 | 10223篇 |
2007年 | 10690篇 |
2006年 | 9548篇 |
2005年 | 8334篇 |
2004年 | 7729篇 |
2003年 | 6523篇 |
2002年 | 7326篇 |
2001年 | 4835篇 |
2000年 | 4512篇 |
1999年 | 4191篇 |
1998年 | 3740篇 |
1997年 | 3105篇 |
1996年 | 2656篇 |
1995年 | 2460篇 |
1994年 | 2207篇 |
1993年 | 1812篇 |
1992年 | 1735篇 |
1991年 | 1262篇 |
1990年 | 1077篇 |
1989年 | 882篇 |
1988年 | 728篇 |
1987年 | 534篇 |
1986年 | 456篇 |
1985年 | 447篇 |
1984年 | 435篇 |
1983年 | 225篇 |
1982年 | 352篇 |
1981年 | 255篇 |
1980年 | 246篇 |
1979年 | 273篇 |
1978年 | 201篇 |
1977年 | 137篇 |
1976年 | 106篇 |
1973年 | 54篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
961.
Madhu V. Nayakkankuppam 《Mathematical Programming》2007,109(2-3):477-504
We describe an approach to the parallel and distributed solution of large-scale, block structured semidefinite programs using
the spectral bundle method. Various elements of this approach (such as data distribution, an implicitly restarted Lanczos
method tailored to handle block diagonal structure, a mixed polyhedral-semidefinite subdifferential model, and other aspects
related to parallelism) are combined in an implementation called LAMBDA, which delivers faster solution times than previously
possible, and acceptable parallel scalability on sufficiently large problems.
This work was supported in part by NSF grants DMS-0215373 and DMS-0238008. 相似文献
962.
New variants of the generalized level method for minimization of convex nondifferentiable functions taking infinite values 总被引:1,自引:1,他引:0
N. A. Sokolov 《Computational Mathematics and Mathematical Physics》2007,47(12):1952-1969
New variants of the generalized level method for minimization of convex Lipschitz functions on a compact set with a nonempty interior are proposed. These variants include the well-known generalized and classical level methods. For the new variants, an estimate of the convergence rate is found, including the variants in which the auxiliary problems are solved approximately. 相似文献
963.
1引言对于非光滑方程组F(y)=0(1.1)的求解,这里F:D(?)R~n→R~n是一个非光滑映射,目前主要有两种求解方法.一种方法是由Pang提出的. 相似文献
964.
通过两个积分 (一个是不定积分 ,一个是定积分 )及一个极限 ,说明如何灵活使用积分法解决积分问题 ,方法灵活、巧妙 ,适用范围广 . 相似文献
965.
J. Haglund 《Advances in Mathematics》2003,175(2):319-334
We introduce the distribution function Fn(q,t) of a pair of statistics on Catalan words and conjecture Fn(q,t) equals Garsia and Haiman's q,t-Catalan sequence Cn(q,t), which they defined as a sum of rational functions. We show that Fn,s(q,t), defined as the sum of these statistics restricted to Catalan words ending in s ones, satisfies a recurrence relation. As a corollary we are able to verify that Fn(q,t)=Cn(q,t) when t=1/q. We also show the partial symmetry relation Fn(q,1)=Fn(1,q). By modifying a proof of Haiman of a q-Lagrange inversion formula based on results of Garsia and Gessel, we obtain a q-analogue of the general Lagrange inversion formula which involves Catalan words grouped according to the number of ones at the end of the word. 相似文献
966.
The oxidation of aminoethanethiol (1) was investigated in acid solutions on a glass carbon anode. It was shown that at relatively low anode potentials thiyl radicals RS· are released into the solution, but this does not lead to binding of the oxygen in the solution. Raising the anode potential leads to binding of oxygen, which is probably due to the formation of the intermediate RS+. The oxidation of 1 was studied in Ce(SO4)2+H2SO4 solution. It was shown that under certain conditions the intermediate is RS+, which subsequently converts to a product that could not be identified as any previously described product of the oxidation of thiols. Proposals are made regarding its structure and conversion pathways.B. P. Konstantinov Institute of Nuclear Physics, Russian Academy of Sciences, 188350 Leningrad. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 2, pp. 278–288, February, 1992. 相似文献
967.
T. Roubíček 《Journal of Optimization Theory and Applications》2007,132(1):41-50
Existence of a Nash equilibrium in a noncooperative game governed by the one-dimensional Burgers equation, proposed in the
case of pointwise controls in Ref. 1, is proved under data qualifications that guarantee the diffusion term in the Burgers’
equation to be dominant enough with respect to the uniform convexity of the payoffs.
This work was partly supported by Grants 201/03/0934 (GA čR) and MSM 0021620839 (MšMT čR). Inspiring discussions with Angel
M. Ramos are acknowledged. 相似文献
968.
Qin Jiang 《Journal of Mathematical Analysis and Applications》2007,328(1):380-389
Some solvability conditions of periodic and subharmonic solutions are obtained for a class of subquadratic nonautonomous second-order Hamiltonian systems by the minimax methods in critical point theory. 相似文献
969.
L. Bartosch P. Kopietz 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,28(1):29-36
We consider the effect of Coulomb interactions on the average density of states (DOS) of disordered low-dimensional metals
for temperatures T and frequencies ω smaller than the inverse elastic life-time 1/τ. Using the fact that long-range Coulomb interactions in two dimensions (2d) generate ln2-singularities in the DOS ν(ω) but only ln-singularities in the conductivity σ(ω), we can re-sum the most singular contributions
to the average DOS via a simple gauge-transformation. If σ(ω) > 0, then a metallic Coulomb gapν(ω) ∝ |ω|/e
4 appears in the DOS at T = 0 for frequencies below a certain crossover frequency Ω
2 which depends on the value of the DC conductivity σ(0). Here, - e is the charge of the electron. Naively adopting the same procedure to calculate the DOS in quasi 1d metals, we find ν(ω) ∝ (|ω|/Ω
1)1/2exp(- Ω
1/|ω|) at T = 0, where Ω
1 is some interaction-dependent frequency scale. However, we argue that in quasi 1d the above gauge-transformation method is on less firm grounds than in 2d. We also discuss the behavior of the DOS at finite temperatures and give numerical results for the expected tunneling conductance
that can be compared with experiments.
Received 28 August 2001 / Received in final form 28 January 2002 Published online 9 July 2002 相似文献
970.
V. B. Sokolov A. N. Chekhlov T. A. Epishina I. V. Martynov 《Russian Chemical Bulletin》1992,41(2):236-240
The O-(arylcarbamoyl)butyrhydroximoyl chlorides were synthesized, and the x-ray structural analysis (XSA) of one of them — O-(o-tolylcarbamoyl)butyrhydroximoyl chloride — was performed. It was established from the data of the XSA and the PMR spectra that all synthesized compounds are the Z isomers.Institute of Physiologically Active Substances, Russian Academy of Sciences, 142432 Chernogolovka. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 2, pp. 315–319, February, 1992. 相似文献