全文获取类型
收费全文 | 11335篇 |
免费 | 2499篇 |
国内免费 | 1431篇 |
专业分类
化学 | 6496篇 |
晶体学 | 160篇 |
力学 | 578篇 |
综合类 | 72篇 |
数学 | 382篇 |
物理学 | 7577篇 |
出版年
2024年 | 38篇 |
2023年 | 131篇 |
2022年 | 357篇 |
2021年 | 346篇 |
2020年 | 433篇 |
2019年 | 408篇 |
2018年 | 348篇 |
2017年 | 397篇 |
2016年 | 534篇 |
2015年 | 477篇 |
2014年 | 630篇 |
2013年 | 1195篇 |
2012年 | 801篇 |
2011年 | 880篇 |
2010年 | 625篇 |
2009年 | 806篇 |
2008年 | 789篇 |
2007年 | 822篇 |
2006年 | 710篇 |
2005年 | 565篇 |
2004年 | 509篇 |
2003年 | 450篇 |
2002年 | 443篇 |
2001年 | 369篇 |
2000年 | 338篇 |
1999年 | 261篇 |
1998年 | 236篇 |
1997年 | 180篇 |
1996年 | 147篇 |
1995年 | 144篇 |
1994年 | 126篇 |
1993年 | 134篇 |
1992年 | 99篇 |
1991年 | 75篇 |
1990年 | 68篇 |
1989年 | 50篇 |
1988年 | 41篇 |
1987年 | 41篇 |
1986年 | 33篇 |
1985年 | 42篇 |
1984年 | 47篇 |
1983年 | 17篇 |
1982年 | 24篇 |
1981年 | 15篇 |
1980年 | 15篇 |
1979年 | 12篇 |
1978年 | 11篇 |
1977年 | 11篇 |
1976年 | 11篇 |
1973年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
A theoretical study of the electron dynamics in image potential states on Cu(1 0 0) surfaces with different types of adsorbates is presented. Scattering of the image state electron by an adsorbate induces inter-band and intra-band transitions leading respectively to the population decay and to the dephasing of the image state. We compare results obtained with low coverage (typically 1 adsorbate atom per 1000 surface atoms) Cs, Ar, and a model electronegative adsorbates. As follows from our results, Cs adsorbates lead to both appreciable dephasing and decay, while electronegative adsorbates mostly affect the dephasing rate. The effect of low coverage Ar adsorbates is small, consistent with their neutrality. 相似文献
62.
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
63.
64.
We study theoretically a nonlinear response of the planar metal/dielectric nanostructures constituted from periodical array
of ultra thin silver layers and the layers of Kerr-like nonlinear dielectric. We predict hysteresis-type dependences of the
components of the tensor of effective dielectric permittivity on the field intensity allowing the change in material transmission
properties from transparent to opaque and back at extremely low intensities of the light. It makes possible to control the
light by light in all-optical nanoscale devices and circuits. 相似文献
65.
66.
Mihai V. Putz 《International journal of quantum chemistry》2006,106(2):361-389
A unified Mulliken valence with Parr ground‐state electronegativity picture is presented. It provides a useful analytical tool on which the absolute hardness as well ionization potential and electron affinity functionals are based. For all these chemical reactivity indices, systematic approximate density functionals are formulated within density functional softness theory and are applied to atomic systems. For the absolute hardness, a special relationship with the new electronegativity ansatz and a particular atomic trend paralleling the absolute electron affinity are established that should complement and augment the earlier finite‐difference energetic approach. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 相似文献
67.
In this short communication, we have evaluated the effect of thermal velocity of the plasma particles on the energy of resonantly
interacting energetic electrons with the propagating whistler mode waves as a function of wave frequency and L-value for the
normal and disturbed magnetospheric conditions. During the disturbed conditions when the magnetosphere is depleted in electron
density, the resonance energy of the electron enhances by an order of magnitude at higher latitudes, whereas the effect is
small at low latitudes. An attempt is made to explain the enhanced wave activity observed during magnetic storm periods. 相似文献
68.
采用模匹配方法,研究了非均匀磁场下开放的四端量子波导中的电子输运性质. 结果表明,从一端入射的电子可以透射到两个与之垂直的输出端和一个与之平行的输出端. 在没有外加磁场的情况下,两个垂直输出端的输运概率是相同的,但垂直端与水平端的输运概率不同;在外加磁场下,由于磁边缘态效应,两个垂直输出端的输运概率也有着相当大的差别. 通过施加不同的磁场,我们能获得丰富的电子输运结构,如台阶,宽谷,尖峰等;通过调节磁场的大小和比例以及结构参数可控制该量子结构在各输出端的输运概率.
关键词:
电子输运
介观体系
磁效应 相似文献
69.
70.
Arabinda Mallick 《Journal of luminescence》2006,118(2):165-172
Solvatochromic effects on the fluorescence behavior of 7-hydroxy-4-methyl-8-(4′-methyl-piperazine-1′ yl)methylcoumarin (HMMC) was studied in different solvents. The fluorescence of HMMC was found to be highly sensitive to both the polarity and the protic character of the solvent. Exploiting the polarity-sensitive fluorescence property of HMMC, its excited-state dipole moment has been determined. Fluorescence (Förster) resonance energy transfer (FRET) process from HMMC to a potent bioactive molecule 3-acetyl-4-oxo-6,7-dihydro-12 H indolo-[2,3-a] quinolizine (AODIQ) was studied. From the determined KSV and R0 values, it is argued that a long-range dipole-dipole interaction is operating for the energy transfer mechanism. The energy transfer efficiency (E) and the distance between the acceptor and the donor (r0) have been determined. 相似文献