全文获取类型
收费全文 | 27541篇 |
免费 | 878篇 |
国内免费 | 504篇 |
专业分类
化学 | 3441篇 |
晶体学 | 123篇 |
力学 | 654篇 |
综合类 | 68篇 |
数学 | 19284篇 |
物理学 | 5353篇 |
出版年
2024年 | 29篇 |
2023年 | 174篇 |
2022年 | 267篇 |
2021年 | 266篇 |
2020年 | 424篇 |
2019年 | 625篇 |
2018年 | 642篇 |
2017年 | 462篇 |
2016年 | 440篇 |
2015年 | 478篇 |
2014年 | 924篇 |
2013年 | 1574篇 |
2012年 | 784篇 |
2011年 | 2059篇 |
2010年 | 1512篇 |
2009年 | 1765篇 |
2008年 | 2087篇 |
2007年 | 2004篇 |
2006年 | 1457篇 |
2005年 | 1189篇 |
2004年 | 986篇 |
2003年 | 770篇 |
2002年 | 729篇 |
2001年 | 495篇 |
2000年 | 487篇 |
1999年 | 604篇 |
1998年 | 498篇 |
1997年 | 456篇 |
1996年 | 496篇 |
1995年 | 469篇 |
1994年 | 473篇 |
1993年 | 417篇 |
1992年 | 370篇 |
1991年 | 249篇 |
1990年 | 216篇 |
1989年 | 228篇 |
1988年 | 145篇 |
1987年 | 154篇 |
1986年 | 147篇 |
1985年 | 218篇 |
1984年 | 193篇 |
1983年 | 113篇 |
1982年 | 190篇 |
1981年 | 162篇 |
1980年 | 116篇 |
1979年 | 74篇 |
1978年 | 110篇 |
1977年 | 78篇 |
1976年 | 59篇 |
1974年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
Rajiv Manohar G. Tripathi A.K. Srivastava A.K. Prajapati 《Journal of Physics and Chemistry of Solids》2006,67(11):2300-2304
Dielectric properties of polymer-liquid crystal mixture, having constituent polymer, poly-butyl methacrylate (PBMA) and liquid crystal, cholesteryl nonanoate, are reported as a function of frequency and temperature. The measurement has been done in a temperature range of 300-375 K and frequency range of 100 Hz-10 MHz. The dielectric permittivity and dielectric loss shows significant changes with the addition of polymer molecules in liquid crystal. The significant feature of composite formation is that the pure liquid crystal and polymer do not show dielectric relaxation in the frequency range covered, while the composite shows relaxation peak at a particular frequency. The optical transmittance of pure liquid crystal and composite has also been measured and compared. 相似文献
5.
M. Brokate D. Rachinskii 《NoDEA : Nonlinear Differential Equations and Applications》2006,13(4):385-411
The paper is concerned with the study of plasticity models described by differential equations with stop and play operators.
We suggest sufficient conditions for the global stability of a unique periodic solution for the scalar models and for the
vector models with biaxial inputs of a particular form, namely the sum of a uniaxial function and a constant term. For another
class of simple biaxial inputs, we present an example of the existence of unstable periodic solutions.
The paper was written during the research stay of D. Rachinskii at the Technical University Munich supported by the research
fellowship from the Alexander von Humboldt Foundation. His work was partially supported by the Russian Science Support Foundation, Russian Foundation for Basic Research (Grant No. 01-01-00146, 03-01-00258), and the Grants of the President of Russia (Grant No. MD-87.2003.01, NS-1532.2003.1). The support is gratefully acknowledged. 相似文献
6.
A. M. Vinogradov 《Acta Appl Math》1989,15(1-2):3-21
The main notions and results which are necessary for finding higher symmetries and conservation laws for general systems of partial differential equations are given. These constitute the starting point for the subsequent papers of this volume. Some problems are also discussed. 相似文献
7.
Camillo Costantini 《Topology and its Applications》2006,153(7):1056-1078
For X a metrizable space and (Y,ρ) a metric space, with Y pathwise connected, we compute the density of (C(X,(Y,ρ)),σ)—the space of all continuous functions from X to (Y,ρ), endowed with the supremum metric σ. Also, for (X,d) a metric space and (Y,‖⋅‖) a normed space, we compute the density of (UC((X,d),(Y,ρ)),σ) (the space of all uniformly continuous functions from (X,d) to (Y,ρ), where ρ is the metric induced on Y by ‖⋅‖). We also prove that the latter result extends only partially to the case where (Y,ρ) is an arbitrary pathwise connected metric space.To carry such an investigation out, the notions of generalized compact and generalized totally bounded metric space, introduced by the author and A. Barbati in a former paper, turn out to play a crucial rôle. Moreover, we show that the first-mentioned concept provides a precise characterization of those metrizable spaces which attain their extent. 相似文献
8.
A Volterra type integral equation in a Hilbert space with an additional linear operator L and a spectral parameter depending
on time is considered. If the parameter does not belong to the spectrum of L unconditional solvability of the considered problem
is proved. In the case where the initial value of the parameter coincides with some isolated point of the spectrum of the
operator L sufficient conditions for solvability are established. The obtained results are applied to the partial integral
equations associated with a contact problem of the theory of elasticity. 相似文献
9.
Saida Sultanic 《Integral Equations and Operator Theory》2006,55(4):573-595
The central question of this paper is the one of finding the right analogue of the Commutant Lifting Theorem for the Bergman
space La2. We also analyze the analogous problem for weighted Bergman spaces La,α2, − 1 < α < ∞. 相似文献
10.
GAO Jing ZHOU Xiaohua CHEN Xun Chongqing University Chemical Engineering Department Chongqing China 《Chinese Journal of Reactive Polymers》2006,(2)
1. INTRODUCTION In the process of coking plant, about 30%~35% sulfur is transformed to H2S and some other sulfide, which form impurity in coal gas together with NH3 and HCN. Only 0.1% H2S containing in air can lead to die, so it is very important to carry on desulphurization and decyanation with coal gas [1~3]. Currently desulphurization and decyanation craft technique have Dry Oxidation Technology, Wet Oxidation Technology and Liquid Absorption Technology [2] three main kinds. The… 相似文献