全文获取类型
收费全文 | 5088篇 |
免费 | 785篇 |
国内免费 | 451篇 |
专业分类
化学 | 1668篇 |
晶体学 | 26篇 |
力学 | 57篇 |
综合类 | 18篇 |
数学 | 355篇 |
物理学 | 4200篇 |
出版年
2024年 | 14篇 |
2023年 | 55篇 |
2022年 | 103篇 |
2021年 | 128篇 |
2020年 | 180篇 |
2019年 | 135篇 |
2018年 | 132篇 |
2017年 | 125篇 |
2016年 | 198篇 |
2015年 | 162篇 |
2014年 | 184篇 |
2013年 | 323篇 |
2012年 | 233篇 |
2011年 | 309篇 |
2010年 | 242篇 |
2009年 | 333篇 |
2008年 | 360篇 |
2007年 | 398篇 |
2006年 | 333篇 |
2005年 | 259篇 |
2004年 | 228篇 |
2003年 | 273篇 |
2002年 | 242篇 |
2001年 | 189篇 |
2000年 | 207篇 |
1999年 | 147篇 |
1998年 | 143篇 |
1997年 | 87篇 |
1996年 | 47篇 |
1995年 | 66篇 |
1994年 | 47篇 |
1993年 | 47篇 |
1992年 | 46篇 |
1991年 | 27篇 |
1990年 | 35篇 |
1989年 | 29篇 |
1988年 | 22篇 |
1987年 | 23篇 |
1986年 | 29篇 |
1985年 | 25篇 |
1984年 | 24篇 |
1983年 | 7篇 |
1982年 | 10篇 |
1981年 | 23篇 |
1980年 | 18篇 |
1979年 | 12篇 |
1978年 | 13篇 |
1977年 | 14篇 |
1976年 | 12篇 |
1974年 | 8篇 |
排序方式: 共有6324条查询结果,搜索用时 15 毫秒
11.
CuPc molecules adsorbed on Au(1 1 0)-(1 × 2): growth morphology and evolution of valence band states
Fabrizio Evangelista A. RuoccoValdis Corradini M.P. DonzelloCarlo Mariani Maria Grazia Betti 《Surface science》2003,531(2):123-130
We present the growth morphology, the long-range ordering, and the evolution of the valence band electronic states of ultrathin films of copper phthalocyanine (CuPc) deposited on the Au(1 1 0)-(1 × 2) reconstructed surface, as a function of the organic molecule coverage. The low energy electron diffraction patterns present a (5 × 3) reconstruction from the early adsorption stages. High-resolution UV photoelectron spectroscopy data show the disappearance of the Au surface states related to the (1 × 2) reconstruction, and the presence of new electronic features related to the molecule-substrate interaction and to the CuPc molecular states. The CuPc highest occupied molecular orbital gradually emerges in the valence band, while the interface electronic states are quenched, upon increasing the coverage. 相似文献
12.
Some aspects of electrical conduction through resonant states in metallic electrochemical nanowires are briefly discussed in a semi-quantitative way by means of concepts associated with electron gas, conductance quantization, and Fermi energy level. Aspects related to some experimental data are also discussed. 相似文献
13.
Employing positive-definiteness arguments we analyse Boson field states, which combine classical and quantum mechanical features (signal and noise), in a constructive manner. Mathematically, they constitute Bauer simplexes within the convex, weak-*-compact state space of the C*-Weyl algebra, defined by a presymplectic test function space (smooth one-Boson wave functions) and are affinely homeomorphic to a state space of a classical field. The regular elements are expressed in terms of weak distributions (probability premeasures) on the dual test function space. The Bauer simplex arising from the bare vacuum is shown to generalize the quantum optical photon field states with positive P-functions. 相似文献
14.
A pseudopotential depending on an effective core radius is proposed to study the binding energy, equation of state, ion-ion
interaction, phonon dispersion curves (q-space and r-space analysis), mode Grüneisen parameters and dynamical elastic constants
of some fcc f-shell metals La, Yb, Ce and Th. The contribution of the s-like electrons is calculated in the second-order perturbation
theory for the potential while d and f-like electron is taken into account by introducing repulsive short-range Born-Mayer
term. The parameter of the potential is evaluated by zero pressure condition. An excellent agreement between theoretical investigations
and experimental findings is achieved which confirms the present formalism 相似文献
15.
考虑到量子相干效应和界面散射效应 ,利用 L ambert理论模型 ,计算正常金属 /绝缘层 /超导 /绝缘层 /正常金属双垒隧道结中的准粒子输运系数和隧道谱。研究表明 :( 1)所有的准粒子输运系数和电导谱在超导能隙之上都随能量作周期性振荡 ,其振荡周期依赖于超导层的厚度 ;( 2 )在超导能隙之上 Andreev反射系数随能量呈现周期性消失现象 ;( 3)在绝缘层势垒强度取很大的隧道极限下 ,超导层中会形成一系列的准粒子束缚态 ,其位置由量子化条件决定 ;( 4)界面散射效应不仅能压低各子能隙电导峰 ,还能使子能隙电导峰劈裂为两个峰。 相似文献
16.
The theoretical investigation of the image states in front of an ultrathin iron film grown on copper has been performed by means of the embedding method and a recently developed procedure for the inclusion of the image potential tail in a first principle calculation. From the electronic response to an applied electric field, the image plane position has been evaluated. This also allows one to obtain useful information about the spin dependent screening properties of the system. Exchange splitting, effective mass, and lifetime of such surface states result in good agreement with recently performed two-photon photoemission experiments [see A.B. Schmidt, M. Pickel, M. Wiemhöfer, M. Donath, M. Weinelt, Phys. Rev. Lett. 95 (2005) 107402]. 相似文献
17.
18.
《Journal of Differential Equations》2003,190(2):663-685
The existence of global smooth solutions to the multi-dimensional hydrodynamic model for plasmas of electrons and positively charged ions is shown under the assumption that the initial densities are close to a constant. The model consists of the conservation laws for the particle densities and the current densities, coupled to the Poisson equation for the electrostatic potential. Furthermore, it is proved that the particle densities converge exponentially fast to the (constant) steady state. The proof uses a higher-order energy method inspired from extended thermodynamics. 相似文献
19.
T. Van Cauteren J. Ryckebusch B. Metsch H. -R. Petry 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):613-615
We present some of our results for the electromagnetic properties of excited Σ hyperons, computed within the framework of the Bonn constituent-quark model, which is based on the Bethe-Salpeter approach.
The seven parameters entering the model are fitted against the best-known baryon masses. Accordingly, the results for the
form factors and helicity amplitudes are genuine predictions. We compare with the scarce experimental data available and discuss
the processes in which Σ
*'s may play an important role. 相似文献
20.