全文获取类型
收费全文 | 15220篇 |
免费 | 3882篇 |
国内免费 | 1349篇 |
专业分类
化学 | 6306篇 |
晶体学 | 78篇 |
力学 | 460篇 |
综合类 | 100篇 |
数学 | 1307篇 |
物理学 | 12200篇 |
出版年
2024年 | 66篇 |
2023年 | 257篇 |
2022年 | 576篇 |
2021年 | 629篇 |
2020年 | 618篇 |
2019年 | 565篇 |
2018年 | 526篇 |
2017年 | 574篇 |
2016年 | 718篇 |
2015年 | 694篇 |
2014年 | 876篇 |
2013年 | 1213篇 |
2012年 | 1039篇 |
2011年 | 1156篇 |
2010年 | 865篇 |
2009年 | 894篇 |
2008年 | 1111篇 |
2007年 | 1086篇 |
2006年 | 1012篇 |
2005年 | 908篇 |
2004年 | 784篇 |
2003年 | 691篇 |
2002年 | 638篇 |
2001年 | 449篇 |
2000年 | 523篇 |
1999年 | 350篇 |
1998年 | 347篇 |
1997年 | 240篇 |
1996年 | 167篇 |
1995年 | 144篇 |
1994年 | 102篇 |
1993年 | 91篇 |
1992年 | 102篇 |
1991年 | 84篇 |
1990年 | 69篇 |
1989年 | 64篇 |
1988年 | 37篇 |
1987年 | 32篇 |
1986年 | 32篇 |
1985年 | 24篇 |
1984年 | 24篇 |
1983年 | 11篇 |
1982年 | 12篇 |
1981年 | 10篇 |
1979年 | 5篇 |
1978年 | 7篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1972年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
G. Lanyi 《Foundations of Physics》2003,33(3):511-528
In 1916, Einstein rederived the blackbody radiation law of Planck that originated the idea of quantized energy one hundred years ago. For this purpose, Einstein introduced the concept of transition probability, which had a profound influence on the development of quantum theory. In this article, we adopt Einstein's assumptions with two exceptions and seek the statistical condition for the thermal equilibrium of matter without referring to the inner details of either statistical thermodynamics or quantum theory. It is shown that the conditions of thermodynamic equilibrium of electromagnetic radiation and the energy balance of thermal radiation by the matter, between any of its two energy-states, not only result in Planck's radiation law and the Bohr frequency condition, but they remarkably yield the law of the statistical thermal equilibrium of matter: the Maxwell–Boltzmann distribution. Since the transition probabilities of the modern quantum theory of radiation coincide with their definition in Einstein's theory of blackbody radiation, the presented deduction of the Maxwell–Boltzmann distribution is equally valid within the bounds of modern quantum theory. Consequently, within the framework of the fundamental assumptions, the Maxwell–Boltzmann distribution of energy-states is not only a sufficient, but a necessary condition for thermal equilibrium between the matter and radiation. 相似文献
102.
R. Brunner R. Meisels F. Kuchar M. ElHassan J. Bird K. Ishibashi 《Physica E: Low-dimensional Systems and Nanostructures》2004,21(2-4):491
The properties of open quantum dots are examined in magneto-transport. The quantum dots are prepared from a two-dimensional electron system (2DES) in AlGaAs/GaAs by lateral gate structures. These quantum dots are open, i.e. they are still connected to the surrounding 2DES regions. The low magnetic field magnetoresistance shows peak structures. These structures can be related to semi-classical ballistic trajectories in the confining potential of a dot. The calculations of different confining potentials (abrupt “hard-wall” and parabolic “soft-wall”) are compared with the experimental results. The experiments are better described by a soft-wall potential. 相似文献
103.
P. Schlagheck A. Buchleitner 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(3):401-415
We provide a detailed quantum treatment of the spectral characteristics and of the dynamics of nondispersive two-electron
wave packets along the periodically driven, collinear frozen planet configuration of helium. These highly correlated, long-lived
wave packets arise as a quantum manifestation of regular islands in a mixed classical phase space, which are induced by nonlinear
resonances between the external driving and the unperturbed dynamics of the frozen-planet configuration. Particular emphasis
is given to the dependence of the ionization rates of the wave packet states on the driving field parameters and on the quantum
mechanical phase space resolution, preceded by a comparison of 1D and 3D life times of the unperturbed frozen planet. Furthermore,
we study the effect of a superimposed static electric field component, which, on the grounds of classical considerations,
is expected to stabilize the real 3D dynamics against large (and possibly ionizing) deviations from collinearity.
Received 7 November 2002 / Received in final form 2 December 2002 Published online 28 January 2003 相似文献
104.
A. Vukics H. Ritsch 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(3):585-599
We present a framework for efficiently performing Monte Carlo
wave-function simulations in cavity QED with moving particles. It
relies heavily on the object-oriented programming paradigm as realised
in C++, and is extensible and applicable for simulating open
interacting qua
ntum dynamics in general. The user is provided with a
number of “elements”, e.g. pumped moving particles, pumped lossy
cavity modes, and various interactions to compose complex interacting
systems, which contain several particles moving in electromagnetic
fields of various configurations, and perform wave-function
simulations on such systems. A number of tools are provided to
facilitate the implementation of new elements. 相似文献
105.
106.
C. Fabre U. Andersen H. Bachor B. Buchler S. Gigan P. K. Lam A. Maître N. Treps 《Superlattices and Microstructures》2002,32(4-6)
Optical images can be used to transport, store and process information in a parallel way. We discuss different results obtained in the domain of ‘quantum imaging’, aiming at exploiting at the same time the quantum properties of optical images and their intrinsic parallelism. We define the notion of standard quantum limit (SQL) in optical resolution, set by the quantum noise of usual coherent light, and show that it can be much lower than the diffraction limit. We also prove that this limit can be circumvented by especially designed nonclassical and multimode light. We present an experiment showing that OPOs oscillating inside an exactly confocal cavity actually produce such transverse multimode nonclassical light. We finally describe another experiment which has surpassed the SQL in the case of beam positioning, both in the 1D and 2D cases. 相似文献
107.
We show that the complex projection of a completely positive quaternionic map of quaternionic density matrices is a positive
map in the space of complex density matrices, and we briefly outline some of its properties. To illustrate this result, we
study the complex projection of a one-parameter quaternionic unitary dynamics of a spin-1/2 quantum system.
__________
Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 151, No. 3, pp. 360–370, June, 2007. 相似文献
108.
The methods for the few-body system are introduced to investigate the states of the barrier Li quantumdots (QDs) in an arbitrary strength of magnetic field. The configuration, which consists of a positive ion located on thez-axis at a distance d from the two-dimensional QD plane (the x-y plane) and three electrons in the dot plane boundby the positive ion, is called a barrier Li center. The system, which consists of three electrons in the dot plane bound bythe ion, is called a barrier Li QD. The dependence of energy of the state of the barrier Li QD on an external magneticfield B and the distance d is obtained. The angular momentum L of the ground states is found to jump not only withthe variation of B but also with d. 相似文献
109.
本文讨论了流动注射-ICP光谱分析中的基体效应和酸效应。当基体(Na、Ca、Fe、Zn)的浓度大于5mg/ml时,待测元素的谱线强度表现出不同程度的降低;上述基体的引入对激发温度和电子密度的影响不明显;基体产生的抑制效应可能与改变了待测元素粒子的激发几率的因素有关;于载流体中加入一定量的基体元素,是消除或降低基体效应的有效方法。酸(HCl、HNO_3、H_2SO_4)对待测元素表现出不同程度的抑制效应,其主要原因是物理干扰所致。 相似文献
110.
Diming Lu 《中国科学A辑(英文版)》1998,41(2):139-146
Let (H,R) be a triangular Hopf algebra. The monoidal functors on the category of representations ofH is studied, and a universal quantum commutative algebraSeR(M) and a dual H°-comoduleM° for any H-moduleM with an integrale are constructed. Both constructions given here have tensor isomorphism properties.
Project supported by the National Natural Science Foundation of China. 相似文献