全文获取类型
收费全文 | 11213篇 |
免费 | 821篇 |
国内免费 | 645篇 |
专业分类
化学 | 4489篇 |
晶体学 | 172篇 |
力学 | 322篇 |
综合类 | 48篇 |
数学 | 4756篇 |
物理学 | 2892篇 |
出版年
2023年 | 52篇 |
2022年 | 146篇 |
2021年 | 160篇 |
2020年 | 146篇 |
2019年 | 245篇 |
2018年 | 268篇 |
2017年 | 241篇 |
2016年 | 224篇 |
2015年 | 211篇 |
2014年 | 345篇 |
2013年 | 772篇 |
2012年 | 511篇 |
2011年 | 742篇 |
2010年 | 582篇 |
2009年 | 885篇 |
2008年 | 838篇 |
2007年 | 679篇 |
2006年 | 673篇 |
2005年 | 509篇 |
2004年 | 504篇 |
2003年 | 435篇 |
2002年 | 435篇 |
2001年 | 312篇 |
2000年 | 276篇 |
1999年 | 310篇 |
1998年 | 251篇 |
1997年 | 209篇 |
1996年 | 222篇 |
1995年 | 172篇 |
1994年 | 201篇 |
1993年 | 153篇 |
1992年 | 129篇 |
1991年 | 78篇 |
1990年 | 77篇 |
1989年 | 62篇 |
1988年 | 53篇 |
1987年 | 50篇 |
1986年 | 29篇 |
1985年 | 42篇 |
1984年 | 51篇 |
1983年 | 33篇 |
1982年 | 48篇 |
1981年 | 74篇 |
1980年 | 58篇 |
1979年 | 75篇 |
1978年 | 44篇 |
1977年 | 11篇 |
1976年 | 10篇 |
1974年 | 11篇 |
1973年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 328 毫秒
11.
Franz H. Asthalter T. Dommach M. Ehnes A. Messel K. Sergueev I. 《Hyperfine Interactions》2002,141(1-4):131-134
The present status of the new nuclear resonance beamline PETRA 1 at HASYLAB, DESY, Hamburg is described. Besides an overview
of the experimental setup some examples of recent experiments are given. Those cover the main applications, i.e., inelastic
scattering from iron alloys and quasielastic scattering from glass-forming liquids.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
12.
Fundamental processes in long air gap discharges 总被引:2,自引:0,他引:2
I. Gallimberti G. Bacchiega Anne Bondiou-Clergerie Philippe Lalande 《Comptes Rendus Physique》2002,3(10):854
The development of atmospheric lightning is initiated and sustained by the formation in virgin air of ‘streamer corona’ and ‘leader’ discharges, very similar to those observed in laboratory long sparks. Therefore, the experimental and theoretical investigations of these laboratory discharges have become of large interest to improve the physical knowledge of the lightning process and to develop self-consistent models that could be applied to new protection concepts.In the present paper the fundamental processes of the subsequent phases of long air gap discharges are analyzed, from the first corona inception and development to the leader channel formation and propagation. For all these processes simulations models are discussed that have been essentially derived and simplified by the authors, in order to develop sequential time-dependent simulation of the laboratory breakdown, with both positive and negative voltages. The possibility of extending these models to the case of natural lightning is discussed in the companion paper, presented in this same volume. To cite this article: I. Gallimberti et al., C. R. Physique 3 (2002) 1335–1359. 相似文献
13.
14.
主要介绍了一个引理,这个引理奠定了K4-同胚图K4(α,1,1,δ,ε,η)色性研究的基础。 相似文献
15.
本文首先将文[1]中的BLD映射推广为弱(L1,L2)-BLD映射,并证明了如下正则性结果:存在两个可积指数 P1=P1(n,L1,L2)<n<q1=q1(n,L1,L2),使得对任意弱(L1,L2)-BLD映射f∈(Ω,Rn),都有f∈(Ω,Rn),即f为(L1,L2)-BLD映射. 相似文献
16.
一阶形式系统K~*及其完备性 总被引:2,自引:0,他引:2
裴道武 《数学年刊A辑(中文版)》2002,(6)
模糊命题演算的形式系统L*已经在模糊逻辑与模糊推理的结合研究中得到了成功的应用.本文考虑与系统L*相应的一阶逻辑理论,建立了一阶形式系统K*,并证明了这个系统的完备性. 相似文献
17.
Thermal behaviour and biochemical activity of potassium-silicate-phosphate glasses modified by addition of Ca, Mg, acting
as ecological fertilisers of controlled release rate of the nutrients for plants were studied. It has been found that the
biochemical activity of silicate-phosphate glasses depends on the nature and the number of components forming the glassy framework
and is related to the thermal stability of glass demonstrated by the formation of new compounds during the process of crystallisation.
It is proved that these seemingly different properties are determined by the same parameters which are the strengths bonds
of glass network-formers and modifiers as well as their chemical affinity.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
18.
U.S. NaziaA.K.M.A. Islam 《Solid State Communications》2003,125(1):37-40
The Eliashberg spectral density function is constructed for the superconducting compound BaxK1−xBiO3 with x=0.5, 0.6, 0.7. The functions, besides yielding some prominent structures, show widely spreading spectra that inhibit lattice instability by yielding not too large values of λ(<1.32). The resulting spectral functions show similar shape as other results, where available, and also successfully reproduce the observed critical temperature, isotope exponent, gap ratio and several other parameters. 相似文献
19.
Hiroto Kudo Nobuhito Ito Keiji Nakajima Masami Ochiai Tadatomi Nishikubo 《Journal of polymer science. Part A, Polymer chemistry》2007,45(19):4421-4429
The polyaddition of fluorine‐containing bis(epoxide)s and fluorine‐containing triazine di(aryl ether)s were examined to give the corresponding fluorine‐containing poly(cyanurate)s. It was observed that the synthesized fluoropolymers had good thermal stabilities and good film‐forming properties. The glass transition temperatures (Tg's) and refractive‐indices (nD's) of synthesized polymers were determined by differential scanning calorimetry and ellipsometry, respectively, and it was found that the values of Tg's and nD's were supported by their fluorine containing ratios and skeletons. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4421–4429, 2007 相似文献
20.
The existence of an attractor for a 2D-Navier-Stokes system with delay is proved. The theory of pullback attractors is successfully applied to obtain the results since the abstract functional framework considered turns out to be nonautonomous. However, on some occasions, the attractors may attract not only in the pullback sense but in the forward one as well. Also, this formulation allows to treat, in a unified way, terms containing various classes of delay features (constant, variable, distributed delays, etc.). As a consequence, some results for the autonomous model are deduced as particular cases of our general formulation. 相似文献