全文获取类型
收费全文 | 152966篇 |
免费 | 6009篇 |
国内免费 | 3355篇 |
专业分类
化学 | 64262篇 |
晶体学 | 2238篇 |
力学 | 10144篇 |
综合类 | 139篇 |
数学 | 29967篇 |
物理学 | 55580篇 |
出版年
2024年 | 138篇 |
2023年 | 746篇 |
2022年 | 1359篇 |
2021年 | 1462篇 |
2020年 | 1467篇 |
2019年 | 1471篇 |
2018年 | 10970篇 |
2017年 | 11806篇 |
2016年 | 6268篇 |
2015年 | 2662篇 |
2014年 | 2379篇 |
2013年 | 3167篇 |
2012年 | 8318篇 |
2011年 | 17453篇 |
2010年 | 10420篇 |
2009年 | 10462篇 |
2008年 | 14395篇 |
2007年 | 18027篇 |
2006年 | 2714篇 |
2005年 | 9513篇 |
2004年 | 5418篇 |
2003年 | 5019篇 |
2002年 | 2772篇 |
2001年 | 1628篇 |
2000年 | 1401篇 |
1999年 | 1117篇 |
1998年 | 873篇 |
1997年 | 839篇 |
1996年 | 934篇 |
1995年 | 743篇 |
1994年 | 642篇 |
1993年 | 521篇 |
1992年 | 522篇 |
1991年 | 458篇 |
1990年 | 420篇 |
1989年 | 352篇 |
1988年 | 283篇 |
1987年 | 259篇 |
1986年 | 259篇 |
1985年 | 248篇 |
1984年 | 208篇 |
1983年 | 182篇 |
1982年 | 153篇 |
1981年 | 148篇 |
1980年 | 121篇 |
1979年 | 136篇 |
1978年 | 141篇 |
1976年 | 98篇 |
1973年 | 116篇 |
1968年 | 112篇 |
排序方式: 共有10000条查询结果,搜索用时 2 毫秒
781.
Stadia are popular models of chaotic billiards introduced by Bunimovich in 1974. They are analogous to dispersing billiards
due to Sinai, but their fundamental technical characteristics are quite different. Recently many new results were obtained
for various chaotic billiards, including sharp bounds on correlations and probabilistic limit theorems, and these results
require new, more powerful technical apparatus. We present that apparatus here, in the context of stadia, and prove “regularity”
properties.
相似文献
782.
We give a new independent self-dual 3-basis for the trivial variety with two binary operations.
Received October 24, 2006; accepted in final form January 25, 2007. 相似文献
783.
A mistake concerning the ultra LI-ideal of a lattice implication algebra is pointed out, and some new sufficient and necessary conditions for an LI-ideal to be an ultra LI-ideal are given. Moreover, the notion of an LI-ideal is extended to MTL-algebras, the notions of a (prime, ultra, obstinate, Boolean) LI-ideal and an ILI-ideal of an MTL-algebra are introduced, some important examples are given, and the following notions are proved to be equivalent in MTL-algebra: (1) prime proper LI-ideal and Boolean LI-ideal, (2) prime proper LI-ideal and ILI-ideal, (3) proper obstinate LI-ideal, (4) ultra LI-ideal.
This work was supported by the Zhejiang Provincial Natural Science Foundation of China (Grant No. Y605389) and K. C. Wong
Magna Fund in Ningbo University. 相似文献
784.
We use the Schaefer fixed-point theorem, combined with the Bressan-Colombo selection theorem for lower-semicontinuous multivalued
operators with nonempty closed and decomposable values, for the investigation of the existence of solutions for first-and
second-order impulsive functional differential inclusions with variable times.
Published in Neliniini Kolyvannya, Vol. 10, No. 4, pp. 443–463, October–December, 2007. 相似文献
785.
Based on the matrix-analytic approach to fluid flows initiated by Ramaswami, we develop an efficient time dependent analysis
for a general Markov modulated fluid flow model with a finite buffer and an arbitrary initial fluid level at time 0. We also
apply this to an insurance risk model with a dividend barrier and a general Markovian arrival process of claims with possible
dependencies in successive inter-claim intervals and in claim sizes. We demonstrate the implementability and accuracy of our
algorithms through a set of numerical examples that could also serve as test cases for comparing other solution approaches.
相似文献
786.
We discuss determination of jumps for functions with generalized bounded variation. The questions are motivated by A. Gelb
and E. Tadmor [1], F. Móricz [5] and [6] and Q. L. Shi and X. L. Shi [7]. Corollary 1 improves the results proved in B. I.
Golubov [2] and G. Kvernadze [3].
Supported by NSFC 10671062. 相似文献
787.
S.G. Li G. Fu I. Reading S.B. Tor N.H. Loh P. Chaturvedi S.F. Yoon K. Youcef-Toumi 《Applied Physics A: Materials Science & Processing》2007,89(3):721-728
Micro powder injection molding (μPIM) is one of the potential processes for the mass production of metallic microstructures
and micro components. Here, μPIM is the miniaturization of conventional PIM, which involves four processing steps: mixing,
injection molding, debinding and sintering. This paper looks into the feasibility and effectiveness of μPIM as a key mass
production process for the fabrication of metallic micro components. For it to be an effective re-production process, it is
imperative to examine how well parts can be duplicated/fabricated from a master mold. In this work, the dimensional variation
of high-aspect-ratio micro-pillars arrays, in particular the dimensional shrinkage, global warpage, and surface roughness
at each stage of the μPIM process for a range of molding pressures, are quantified and compared in detail. The sensitivity
of the dimensional variation of the microstructures to the packing pressure is reported. The mechanism behind the dimensional
variation is analyzed.
PACS 81.20.Ev; 81.20.Hy; 81.70.Fy; 07.60.Ly; 81.05.-t 相似文献
788.
I. V. Kuchin N. B. Ur’ev 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2007,81(3):349-353
The main rules governing the redistribution of microparticles in disperse systems were revealed by computer simulation. These rules predetermine the character and properties of the structure being formed, which opens up the possibility to control the properties of disperse materials, including sorbents and catalysts based on high-dispersity solid phases. 相似文献
789.
A fully coupled formulation combining reactive transport and an existing thermo-hydro-mechanical (THM) code is presented.
Special attention has been given to phenomena likely to be encountered in clay barriers used as part of containment systems
of nuclear waste. The types of processes considered include hydrolysis, complex formation, oxidation/reduction reactions,
acid/base reactions, precipitation/dissolution of minerals and cation exchange. Both kinetically-controlled and equilibrium-controlled
reactions have been incorporated. The total analytical concentrations (including precipitated minerals) are adopted as basic
transport variables and chemical equilibrium is achieved by minimizing Gibbs Free Energy. The formulation has been incorporated
in a general purpose computer code capable of performing numerical analysis of engineering problems. A validation exercise
concerning a laboratory experiment involving the heating and hydration of an expansive compacted clay is described. 相似文献
790.
M. Köhl A. Öttl S. Ritter T. Donner T. Bourdel T. Esslinger 《Applied physics. B, Lasers and optics》2007,86(3):391-393
We report an experimental investigation of two-particle correlations between neutral atoms in a Hanbury Brown and Twiss experiment.
Both an atom laser beam and a pseudo-thermal atomic beam are extracted from a Bose–Einstein condensate and the atom flux is
measured with a single atom counter. We determine the conditional and the unconditional detection probabilities for the atoms
in the beam and find good agreement with the theoretical predictions.
PACS 03.75.Pp; 05.30.Jp; 07.77.Gx; 42.50.Pq 相似文献