全文获取类型
收费全文 | 79877篇 |
免费 | 1670篇 |
国内免费 | 2468篇 |
专业分类
化学 | 55526篇 |
晶体学 | 44篇 |
力学 | 1454篇 |
综合类 | 51篇 |
数学 | 2567篇 |
物理学 | 24373篇 |
出版年
2023年 | 175篇 |
2022年 | 194篇 |
2021年 | 157篇 |
2020年 | 149篇 |
2019年 | 127篇 |
2018年 | 190篇 |
2017年 | 86篇 |
2016年 | 192篇 |
2015年 | 218篇 |
2014年 | 374篇 |
2013年 | 325篇 |
2012年 | 7531篇 |
2011年 | 10538篇 |
2010年 | 1926篇 |
2009年 | 579篇 |
2008年 | 7305篇 |
2007年 | 7533篇 |
2006年 | 7660篇 |
2005年 | 7127篇 |
2004年 | 5612篇 |
2003年 | 3979篇 |
2002年 | 3604篇 |
2001年 | 2492篇 |
2000年 | 2748篇 |
1999年 | 1020篇 |
1998年 | 403篇 |
1997年 | 298篇 |
1996年 | 1185篇 |
1995年 | 977篇 |
1994年 | 1093篇 |
1993年 | 1362篇 |
1992年 | 1141篇 |
1991年 | 571篇 |
1990年 | 645篇 |
1989年 | 502篇 |
1988年 | 466篇 |
1987年 | 456篇 |
1986年 | 460篇 |
1985年 | 476篇 |
1984年 | 190篇 |
1983年 | 129篇 |
1982年 | 122篇 |
1981年 | 100篇 |
1975年 | 129篇 |
1959年 | 84篇 |
1958年 | 125篇 |
1957年 | 123篇 |
1956年 | 109篇 |
1955年 | 118篇 |
1954年 | 90篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
We present a Schrodinger (Liouville) type of equation for a quantum open system.It has a correlated part,and various master equations may be its special cases.It also has significant applications for constructing decoherencefree subspace for quantum computation.It is related to the original Schrodinger (Liouville)equation for the total system through a non-unitary similarity transformation.It is unnecessary for its correlated part to be self-adjoint,so there is a complex spectrum for the corresponding Hamiltonian (Liouvillian),which enables the time evolution of states to be asymmetric.This shows just the correlation to produce evolution of world. 相似文献
102.
This paper tries to introduce the reader to the method of using photochemical re-action to copy holographic optical elements(HOEs)in relief.The holographic blazing gratingso copied is groove depth adjustable phase modulability enlarged through copying and 3.3times the diffraction efficiency(DE)of the original grating.It is expected that the newmethod will lead to the mass production of the light-weight HOEs at low cost. 相似文献
103.
104.
105.
张玉虎 王华磊 柳敏良 周小红 郭文涛 G.de Angelis N.Marginean A.Gadea D.R.Napoli M.Axiotis C.Rusu T.Martinez 许甫荣 《中国物理 C》2004,28(9):907-913
利用重离子熔合蒸发反应和在束γ谱学实验方法,研究了双奇核184?Au的高自旋态能级结构.扩展了基于πh9/2ν7/2–[514]和πi13/2νi13/22准粒子组态下的转动带能级纲图,建立了两个转动带之间以及πh9/2ν7/2-[514]带与基态的谱学连接.从而确定了πi13/2νi13/2带能级的自旋和宇称,证实了此转动带在低自旋区出现旋称反转.分析了πi13/2νi13/2带和相邻核转动带的准粒子顺排特征,指出此带的第一回弯以及相邻核转动带在低频观测到的顺排异常可能与h9/2质子顺排有关. 相似文献
106.
Edward S. Fry 《量子光学学报》2006,12(B08):66-67
Since the data show that Bell inequalities are violated experimentally, we must conclude that any hidden variable theory (which correctly predicts experimental data ) will be non-local. But, to conclude that the experimental violations of Bell inequalities show quantum mechanics to be non-local is unjustified. Specifically, the key assumptions required to obtain a Bell inequality are ( 1 ) locality and (2) the assignment of meaningful ( non- negative) probabilities to seemingly physical correlations (Bell expresses these correlations via " hidden variables" ). Since the Bell inequality is violated by experiment, at least one of these assumptions is wrong. The widespread conclusion that locality must be relinquished is valid only if we retain the previously mentioned correlations ( "hidden variables" ). We will demonstrate that the latter are not physical observables - they are not elements of physical reality. 相似文献
107.
The Kurzweil-Henstock integral formalism is applied to establish the existence of solutions to the linear integral equations of Volterra-typewhere the functions are Banach-space valued. Special theorems on existence of solutions concerning the Lebesgu3 integral setting are obtained. These sharpen earlier results. 相似文献
108.
109.
Degradation of 4-chlorophenol in aqueous solution by γ-radiation and ozone oxidation 总被引:5,自引:2,他引:3
HU Jun WANG Jianlong & CHEN Rong . Laboratory of Environmental Technology Institute of Nuclear Energy Technology Tsinghua University Beijing China . State Key Joint Laboratory of Environmental Simulation Pollution Control Tsinghua University Beijing China Correspondence should be addressed to Wang Jianlong 《中国科学B辑(英文版)》2006,(2)
The application of radiation technology in the en-vironmental protection was listed as one of the mostimportant research fields by the International AtomicEnergy Agency (IAEA) for the peaceful use of nuclearenergy. It has great research value and potential appli-cation. Because of their broad-spectrum antimicrobialproperties, Cholophenols (CPs) have been used aspreservative agents for wood, paints, vegetable fibersand leather and as disinfectants. In addition, they havebeen widely employed… 相似文献
110.
A. John Peter 《中国物理快报》2006,23(4):946-949
We present a simple demonstration of the nonfeasibility of metal-insulator transition in an exactly two-dimensional (2D) system. The Hartree-Fock potential in the 3D system is suitably modified and presented for the 2D case. The many body effects are included in the screening function, and binding energies of a donor are obtained as a function of impurity concentration so as to find out the possible way leading metal-insulator transition in the 2D system. While solving for the binding energy for a shallow donor in an isolated well of a GaAs/Ga1-x Als As superlattice system within the effective mass approximation, it leads to unphysical results for higher concentrations. It shows that the phase transition, the bound electron entering into the conduction band whereby (H)min=0, is not possible beyond this concentration. The results suggest thai a phase transition is impossible in 213 systems, supporting the scaling theory of localization. The results are compared with the existing data available and discussed in the light of existing literature. 相似文献