全文获取类型
收费全文 | 12620篇 |
免费 | 1952篇 |
国内免费 | 1384篇 |
专业分类
化学 | 5666篇 |
晶体学 | 77篇 |
力学 | 2238篇 |
综合类 | 77篇 |
数学 | 1757篇 |
物理学 | 6141篇 |
出版年
2024年 | 38篇 |
2023年 | 177篇 |
2022年 | 578篇 |
2021年 | 583篇 |
2020年 | 572篇 |
2019年 | 533篇 |
2018年 | 403篇 |
2017年 | 448篇 |
2016年 | 645篇 |
2015年 | 518篇 |
2014年 | 686篇 |
2013年 | 1213篇 |
2012年 | 703篇 |
2011年 | 754篇 |
2010年 | 663篇 |
2009年 | 787篇 |
2008年 | 809篇 |
2007年 | 833篇 |
2006年 | 725篇 |
2005年 | 562篇 |
2004年 | 438篇 |
2003年 | 403篇 |
2002年 | 398篇 |
2001年 | 329篇 |
2000年 | 327篇 |
1999年 | 279篇 |
1998年 | 275篇 |
1997年 | 183篇 |
1996年 | 159篇 |
1995年 | 134篇 |
1994年 | 140篇 |
1993年 | 103篇 |
1992年 | 77篇 |
1991年 | 68篇 |
1990年 | 54篇 |
1989年 | 48篇 |
1988年 | 39篇 |
1987年 | 46篇 |
1986年 | 27篇 |
1985年 | 30篇 |
1984年 | 30篇 |
1983年 | 26篇 |
1982年 | 34篇 |
1981年 | 9篇 |
1980年 | 6篇 |
1979年 | 14篇 |
1978年 | 9篇 |
1976年 | 9篇 |
1971年 | 6篇 |
1957年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
121.
122.
受限水的介电特性对于石墨烯电容器的储能效率有着重大的影响.因此本文使用分子动力模方法,研究了不同石墨烯纳米孔道宽度(0.812~10 nm)下内受限水介电常数的分布及其影响因素.结果表明,在石墨烯纳米孔道内部受限水双电层结构可分为空隙层、界面层和体相层三个部分.其整体的介电常数随孔道大小的降低而线性减少.这是由内部体相层的宽度的降低而导致的.此外电极电压大小和石墨烯-水相互作用参数εCO的强弱也会显著改变电极表面的双电层(Electric Double Layers, EDLs)结构.其中电压的增大使得介电常数分布的震荡的程度也随之增加,最终导致了整体介电常数的减小.与之类似,亲水态的石墨烯表面(高εCO)下受限水分布的震荡程度也显著增加,这导致了整体介电常数的降低. 相似文献
123.
V.I. Nekorkin M.L. Voronin M.G. Velarde 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,9(3):533-543
We study the dynamics of an assembly of globally coupled bistable elements. We show that bistability of elements results in some new features of clustering in the assembly when there is global coupling. We provide conditions for the existence of stable amplitude-phase clusters and splay-phase states.
Received 12 June 1998 and Received in final form 30 November 1998 相似文献
124.
采用飞秒频率上转换技术测量了两种可溶聚乙炔衍射生物poly(phenylacetylene(PPA)和poly(1-phenyl-1-buty1)PPB)的发光动力学过程。采用非均匀展宽态密我规行走理论对上述结果进行了分析。 相似文献
125.
The processes of electron transfer and dissociative scattering are explored for collisions of hyperthermal NO+ on GaAs(110). The experiments reveal a marked angular dependence to O− emergence. A strong correlation between the O− scattering angle and the final atom-surface interaction site provides a map of the lateral dependence to reactivity. The results are modeled by sequential neutralization, dissociation, and electron attachment steps. Classical trajectory calculations, in conjunction with an empirical opacity function, accurately reproduce the experimental results. The opacity function is interpreted as the probability that an electron will attach to a departing O fragment as a function of the last surface site the atom impacts. The experiments indicate that O− emergence occurs predominantly for oxygen atoms which come in close contact with the localized dangling bond states of GaAs(110). 相似文献
126.
比较了行波与驻波两种工作方式以及前向波与返波型行波的不同特点;研究了返波型行波电子直线加速结构的工作特性;并针对返波型行波电子直线加速结构的特点,进行工作模式的选择;对工作频率为2856MHz,3π/4模的返波加速结构进行了优化设计;研究了带聚束段的返波型行波加速管的纵向与横向粒子动力学问题;为海关大型集装箱在线检测用加速器设计了一根9MeV返波型行波加速管,并与采用盘荷波导结构的加速管进行了对比.研究结果表明,返波型行波电子直线加速结构具有一定的优势,它把鼻锥型加速结构分流阻抗高及盘荷波导行波工作方式填充时间短,工作稳定性好等优点结合起来,性能明显优越. 相似文献
127.
W. Kwang-Hua Chu J. Fang 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,16(3):543-547
Continuum-mechanic derivation of the entrainment of rarefied gases induced by a surface wave along walls (or peristaltic transport)
in a confined parallel-plane microchannel is conducted by the perturbation method. Both no-slip and slip flow cases are investigated
with the former ones matched with the previous approach by Fung and Yih. Critical reflux values due to first order slip-flow
effects become trivial for the free pumping case, and decrease due to second order slip-flow effects after we compared them
with no-slip cases.
Received 27 August 1999 and Received in final form 10 January 2000 相似文献
128.
A.V. Pan P. Esquinazi 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,17(3):405-410
We have investigated the influence of a driving force on the elastic coupling (Labusch parameter) of the field-cooled state
of the flux line lattice (FLL) in 400 nm thick YBa2Cu3O7 superconducting films. We found that the FLL of a field-cooled state without driving forces is not in an equilibrium state.
Results obtained for magnetic fields applied at and 30 relative to CuO2 planes, show an enhancement of the elastic coupling of the films at driving current densities several orders of magnitude
smaller than the critical one. Our results indicate that the FLL appears to be in a relatively ordered, metastable state after
field cooling without driving forces.
Received 21 December 1999 相似文献
129.
A. Chakraborti B.K. Chakrabarti 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,17(1):167-170
We consider a simple model of a closed economic system where the total money is conserved and the number of economic agents
is fixed. Analogous to statistical systems in equilibrium, money and the average money per economic agent are equivalent to
energy and temperature, respectively. We investigate the effect of the saving propensity of the agents on the stationary or
equilibrium probability distribution of money. When the agents do not save, the equilibrium money distribution becomes the
usual Gibb's distribution, characteristic of non-interacting agents. However with saving, even for individual self-interest,
the dynamics becomes cooperative and the resulting asymmetric Gaussian-like stationary distribution acquires global ordering
properties. Intriguing singularities are observed in the stationary money distribution in the market, as functions of the
marginal saving propensity of the agents.
Received 2 May 2000 相似文献
130.
We investigate the parameter dynamics of eigenvalues of Hamiltonians (‘level dynamics’) defined on symmetric spaces relevant to condensed matter and particle physics. In particular we: (1) identify the appropriate reduced manifold on which the motion takes place, (2) identify the correct Poisson structure ensuring the Hamiltonian character of the reduced dynamics, (3) determine the canonical measure on the reduced space, (4) calculate the resulting eigenvalue density. 相似文献