全文获取类型
收费全文 | 13328篇 |
免费 | 1977篇 |
国内免费 | 1582篇 |
专业分类
化学 | 8989篇 |
晶体学 | 199篇 |
力学 | 811篇 |
综合类 | 151篇 |
数学 | 1907篇 |
物理学 | 4830篇 |
出版年
2024年 | 37篇 |
2023年 | 218篇 |
2022年 | 387篇 |
2021年 | 398篇 |
2020年 | 540篇 |
2019年 | 504篇 |
2018年 | 483篇 |
2017年 | 455篇 |
2016年 | 622篇 |
2015年 | 729篇 |
2014年 | 784篇 |
2013年 | 1087篇 |
2012年 | 1196篇 |
2011年 | 1202篇 |
2010年 | 898篇 |
2009年 | 869篇 |
2008年 | 932篇 |
2007年 | 809篇 |
2006年 | 694篇 |
2005年 | 591篇 |
2004年 | 432篇 |
2003年 | 349篇 |
2002年 | 361篇 |
2001年 | 244篇 |
2000年 | 249篇 |
1999年 | 178篇 |
1998年 | 111篇 |
1997年 | 107篇 |
1996年 | 98篇 |
1995年 | 91篇 |
1994年 | 76篇 |
1993年 | 74篇 |
1992年 | 54篇 |
1991年 | 52篇 |
1990年 | 53篇 |
1989年 | 40篇 |
1988年 | 60篇 |
1987年 | 28篇 |
1986年 | 40篇 |
1985年 | 38篇 |
1983年 | 32篇 |
1982年 | 34篇 |
1980年 | 39篇 |
1979年 | 35篇 |
1978年 | 52篇 |
1977年 | 41篇 |
1976年 | 44篇 |
1975年 | 35篇 |
1974年 | 34篇 |
1968年 | 28篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
141.
Acta Mathematica Sinica, English Series - We are interested in the existence and asymptotic behavior for the least energy solutions of the following fractional eigenvalue problem $$left({rm{P}}... 相似文献
142.
The Study of Full Light Speech Signal Collection System 总被引:2,自引:0,他引:2
JIA Bo JIN Yaqiu ZHANG Wei 《Chinese Journal of Lasers》2001,10(3):185-188
1 Introduction Opticfibercouplershavebeenwidelyusedintheopticalcommunicationandopticalsensors.Besidestheirpowerdistributionfunctions,thecouplers′coherentdemodulationcharacterwhichhasbeenusedinthefieldofopticinterferometer[1 ,2 ] isalsoimportant,butthatwas… 相似文献
143.
144.
M. Konôpka V. Bužek 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,10(2):285-293
We propose a method for entangling a system of two-level atoms in photonic crystals. The atoms are assumed to move in void
regions of a photonic crystal. The interaction between the atoms is mediated either via a defect mode or via a resonant dipole-dipole interaction. We show that these interactions can produce pure entangled atomic states. We analyze the problem with parameters typical
for currently existing photonic crystals and Rydberg atoms and we show that the atoms can emerge from photonic crystals in
entangled states. Depending on the linear dimensions of the crystal we estimate that a pair of atoms entangled in a photonic
crystal can be separated by tens of centimeters.
Receive 11 June 1999 and Received in final form 4 October 1999 相似文献
145.
J. Požela A. Namajūnas A. Tamaševičius J. Ulbikas 《Applied Physics A: Materials Science & Processing》1989,48(2):181-188
A method for quantitative characterization of chaotic dynamical systems is discussed. An electronic instrument for determining the number of independent variablesk
*, involved in the motion, is described. It allows one to obtain these in real time from a single observable. The suggested technique has been applied to quantification of strange attractors underlying chaotic instabilities in semi-insulating GaAsCr, and n-Ge, irradiated with high energy electrons. In n-Ge, for instance, the measured numbersk
* range from 2 to 4 depending on control parameters. These measurements reveal the highly deterministic nature of the observed chaotic oscillations. The physical mechanisms responsible for the current instabilities and chaotic behaviour are discussed. 相似文献
146.
V. A. Petržílka 《Czechoslovak Journal of Physics》1989,39(12):1372-1377
The amplification of lower hybrid (LH) driven current of various profiles has been found. The results strongly depend on the plasma temperature profile, on the LH current profile, and on the magnitude of the particle diffusion flux.This work was started during the visit of the author in the I. V. Kurchatov Institute of Atomic Energy, Moscow. The author thanks IAE for hospitality, and V. Parail, G. V. Pereverzev, A. Smoljakov and R. Klíma for many useful and critical discussions. 相似文献
147.
此文采用扭曲库仑波函数描述碰撞电子,用R─矩阵密耦波函数处理被电离电子与剩余离子构成的系统初末态,在库仑玻恩各级近似下计算了类锂离子O5+的电子碰撞电离截面及相应速率系数,这是文献中首次使用密耦方法,在考虑通道相互作用情形下得到的结果。 相似文献
148.
YAO Zhen-Zhi ZHANG Chun-Yi ZHU Hong-Wu MENG Xiang-Hua LU Xing SHAN Wen-Rui TIAN Bo 《理论物理通讯》2008,49(5):1125-1128
In this paper, we derive the bilinear form for a variable-coefficient Kadomtsev Petviashvili-typed equation. Based on the bilinear form, we obtain the Wronskian determinant solution, which is proved to be indeed an exact solution of this equation through the Wronskian technique. In addition, we testify that this equation can be reduced to a Jacobi identity by considering its solution as a Grammian determinant by means of Pfaffian derivative formulae. 相似文献
149.
In this paper, we systematically study a designed structure of a bending dual-core photonic crystal fiber (PCF). We propose the controllable wavelength-selective coupling PCF. This coupler allows highly accurate control of the filtering wavelength. The different wavelengths can be selected by controlling the bending radius of the fiber. Coupling characteristics of novel bending wavelength-selective coupling PCF are evaluated by using a vector finite element method and their application to a multiplexer demultiplexer (MUX–DEMUX) based on the novel coupler is investigated. When the fiber length is 4168 μm, the bending radius of PCF couplers for 1.48/1.55 μm, 1.3/1.55 μm, 0.98/1.55 μm, and 0.85/1.55 μm is calculated, respectively, and the beam propagation analysis is performed. Different from the traditional wavelength-selective coupling PCF, the dual-core PCF is bent and it can realize the separation of multiple wavelengths. 相似文献
150.
The properties and reactivity of Si-doped hexagonal boron nitride (h-BN) sheets were studied using density functional theory (DFT) methods. We find that Si impurity is more likely to substitute the boron site (SiB) due to the low formation energy. Si-doping severely deforms h-BN sheet, resulting in the local curvature changes of h-BN sheet. Moreover, Si-doping introduces two spin localized states within the band gap of h-BN sheet, thus rendering the two doped systems exhibit acceptor properties. The band gap of h -BN sheet is reduced from ∼4.70 eV to 1.24 (for SiB) and 0.84 eV (for SiN), respectively. In addition, Si-doped one exhibits higher activity than pristine one, endowing them wider application potential. 相似文献