全文获取类型
收费全文 | 13775篇 |
免费 | 3664篇 |
国内免费 | 1265篇 |
专业分类
化学 | 4285篇 |
晶体学 | 74篇 |
力学 | 129篇 |
综合类 | 212篇 |
数学 | 2149篇 |
物理学 | 11855篇 |
出版年
2024年 | 48篇 |
2023年 | 208篇 |
2022年 | 482篇 |
2021年 | 760篇 |
2020年 | 587篇 |
2019年 | 493篇 |
2018年 | 445篇 |
2017年 | 495篇 |
2016年 | 675篇 |
2015年 | 589篇 |
2014年 | 855篇 |
2013年 | 1106篇 |
2012年 | 858篇 |
2011年 | 990篇 |
2010年 | 815篇 |
2009年 | 844篇 |
2008年 | 1025篇 |
2007年 | 1009篇 |
2006年 | 954篇 |
2005年 | 806篇 |
2004年 | 702篇 |
2003年 | 631篇 |
2002年 | 583篇 |
2001年 | 432篇 |
2000年 | 457篇 |
1999年 | 305篇 |
1998年 | 325篇 |
1997年 | 227篇 |
1996年 | 140篇 |
1995年 | 135篇 |
1994年 | 104篇 |
1993年 | 78篇 |
1992年 | 75篇 |
1991年 | 57篇 |
1990年 | 61篇 |
1989年 | 68篇 |
1988年 | 39篇 |
1987年 | 25篇 |
1986年 | 34篇 |
1985年 | 37篇 |
1984年 | 26篇 |
1983年 | 14篇 |
1982年 | 13篇 |
1981年 | 13篇 |
1980年 | 8篇 |
1979年 | 8篇 |
1978年 | 15篇 |
1977年 | 7篇 |
1976年 | 9篇 |
1972年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 468 毫秒
71.
Roderich Tumulka 《Foundations of Physics》2007,37(2):186-197
In a recent paper Conway and Kochen, Found. Phys. 36, 2006, claim to have established that theories of the Ghirardi-Rimini-Weber
(RW) type, i.e., of spontaneous wave function collapse, cannot be made relativistic. On the other hand, relativistic GRW-type
theories have already been presented, in my recent paper, J. Stat. Phys. 125, 2006, and by Dowker and Henson, J. Stat. Phys.
115, 2004. Here, I elucidate why these are not excluded by the arguments of Conway and Kochen.
相似文献
72.
A. M. Chebotarev 《Mathematical Notes》2002,71(3-4):408-427
We prove that a quantum stochastic differential equation is the interaction representation of the Cauchy problem for the Schrödinger equation with Hamiltonian given by a certain operator restricted by a boundary condition. If the deficiency index of the boundary-value problem is trivial, then the corresponding quantum stochastic differential equation has a unique unitary solution. Therefore, by the deficiency index of a quantum stochastic differential equation we mean the deficiency index of the related symmetric boundary-value problem.In this paper, conditions sufficient for the essential self-adjointness of the symmetric boundary-value problem are obtained. These conditions are closely related to nonexplosion conditions for the pair of master Markov equations that we canonically assign to the quantum stochastic differential equation. 相似文献
73.
74.
The understanding of mesoscopic transport has now attained an ultimate simplicity. Indeed, orthodox quantum kinetics would seem to say little about mesoscopics that has not been revealed — nearly effortlessly — by more popular means. Such is far from the case, however. The fact that kinetic theory remains very much in charge is best appreciated through the physics of a quantum point contact. While discretization of its conductance is viewed as the exclusive result of coherent, single-electron-wave transmission, this does not begin to address the paramount feature of all metallic conduction: dissipation. A perfect quantum point contact still has finite resistance, so its ballistic carriers must dissipate the energy gained from the applied field. How do they manage that? The key is in standard many-body quantum theory, and its conservation principles. 相似文献
75.
J.O. Andersen 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,28(4):389-396
We consider an interacting homogeneous Bose gas at zero temperature in two spatial dimensions. The properties of the system
can be calculated as an expansion in powers of g, where g is the coupling constant. We calculate the ground state pressure and the ground state energy density to second order in the
quantum loop expansion. The renormalization group is used to sum up leading and subleading logarithms from all orders in perturbation
theory. In the dilute limit, the renormalization group improved pressure and energy density are expansions in powers of the
T
2B and T
2Bln(T
2B), respectively, where T
2B is the two-body T-matrix.
Received 19 April 2002 Published online 13 August 2002 相似文献
76.
Electronic properties of model quantum-dot structures in zero and finite magnetic fields 总被引:1,自引:0,他引:1
H. Saarikoski E. Räsänen S. Siljamäki A. Harju M.J. Puska R.M. Nieminen 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,26(2):241-252
We have computed electronic structures and total energies of circularly confined two-dimensional quantum dots and their lateral
dimers in zero and finite uniform external magnetic fields using different theoretical schemes: the spin-density-functional
theory (SDFT), the current-and-spin-density-functional theory (CSDFT), and the variational quantum Monte Carlo (VMC) method.
The SDFT and CSDFT calculations employ a recently-developed, symmetry-unrestricted real-space algorithm allowing solutions
which break the spin symmetry. Results obtained for a six-electron dot in the weak confinement limit and in zero magnetic
field as well as in a moderate confinement and in finite magnetic fields enable us to draw conclusions about the reliability
of the more approximative SDFT and CSDFT schemes in comparison with the VMC method. The same is true for results obtained
for the two-electron quantum dot dimer as a function of inter-dot distance. The structure and role of the symmetry-breaking
solutions appearing in the SDFT and CSDFT calculations for the above systems are discussed.
Received 16 October 2001 and Received in final form 17 January 2002 相似文献
77.
CHEN Hongjia GAO Yun & SHANG Shikui Department of Mathematics University of Science Technology of China Hefei China Department of Mathematics Statistics York University Toronto Ontario Canada MJ P 《中国科学A辑(英文版)》2006,(11)
We use a fermionic extension of the bosonic module to obtain a class of B(0, A)graded Lie superalgebras with nontrivial central extensions. 相似文献
78.
Vijay Balasubramanian Donald Marolf Moshe Rozali 《General Relativity and Gravitation》2006,38(11):1529-1536
We argue that if black hole entropy arises from a finite number of underlying quantum states, then any particular such state
can be identified from infinity. The finite density of states implies a discrete energy spectrum, and, in general, such spectra
are non-degenerate except as determined by symmetries. Therefore, knowledge of the precise energy, and of other commuting
conserved charges, determines the quantum state. In a gravitating theory, all conserved charges including the energy are given
by boundary terms that can be measured at infinity. Thus, within any theory of quantum gravity, no information can be lost
in black holes with a finite number of states. However, identifying the state of a black hole from infinity requires measurements
with Planck scale precision. Hence observers with insufficient resolution will experience information loss.
First Award in the 2006 Essay Competition of the Gravity Research Foundation. 相似文献
79.
合成了两种新型噻吩基卟啉-5,15-二(2-噻吩基)-2,8,12,18-四乙基-3,7,13,17-四甲基卟啉7a(45.1%)和5,15-二(2-联噻吩基)-2,8,12,18-四乙基-3,7,13,17-四甲基卟啉7b(61.2%),并研究了它们的光谱性质,其中荧光光谱的最大发射峰蜂都在631nm处,量子产率分别为4.1%(7a)和1.4%(7b)。 相似文献
80.
The influence of the electron-LO-phonon coupling on energy spectrum of the low-lying states ofan exciton inparabolic quantum dots is investigated as a function of dot size. Calculations are made by using the method of few-bodyphysics within the effective-mass approximation. A considerable decrease of the energy in the stronger confinement rangeis found for the low-lying states of an exciton in quantum dots, which results from the confinement of electron-phononcoupling. 相似文献