全文获取类型
收费全文 | 13770篇 |
免费 | 3664篇 |
国内免费 | 1265篇 |
专业分类
化学 | 4280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 | 477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 31 毫秒
81.
D.A. Garanin E.M. Chudnovsky 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,28(1):3-7
We compute the width and shape of the EPR and tunneling resonances due to dislocations in Mn12 acetate crystals. Uncorrelated dislocations produce the Gaussian shape of resonances while dislocations bound in pairs produce
the Lorentzian shape. We stress that the uniaxial spin Hamiltonian together with crystal defects can explain the totality
of experimental data on Mn12.
Received 2 August 2001 / Received in final form 15 March 2002 Published online 17 September 2002 相似文献
82.
S. Zschocke G. Plunien G. Soff 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,19(2):147-156
The renormalization method of Bogoljubov-Parasiuk-Hepp-Zimmermann (BPHZ) is used in order to derive the renormalized energy
shift due to the gauge invariant K?llén-Sabry diagram of the two-photon vacuum polarization (VPVP) as well as the self energy
vacuum polarization S(VP)E beyond the Uehling approximation. It is outlined, that no outer renormalization is required for
the two-photon vacuum polarization and that only the inner renormalization has to be accomplished. It is shown that the so-called
nongauge invariant spurious term is absent for a wide class of vacuum polarization (VP) diagrams if one applies the widely
used spherical expansion of bound and free-electron propagator. This simplifies significantly calculations in bound state
quantum electrodynamics. As one result of our paper the use of the BPHZ-approach in bound state QED is established.
Received 28 September 2001 相似文献
83.
84.
GAO Li LIU Wen-Biao 《理论物理通讯》2006,46(10)
Hawking radiation is viewed as a process of quantum tunneling. The massive particles‘ tunneling from Garfinkle-Horowitz-Strominger black hole is investigated. Using Jingyi Zhang‘s de Broglie wave method, we get the unthermal spectrum, and the result is consistent with the underlying unitary theory. 相似文献
85.
在清华大学物理系成立60周年之际,我们对近年来清华大学物理系量子信息研究的主要进展情况作一介绍,包括量子搜索算法研究,核磁共振量子计算的实验研究,量子通讯的理论与实验研究.在量子搜索算法研究方面,我们提出了量子搜索算法的相位匹配,纠正了当时的一种错误观点,并且提出了一种成功率为100%的量子搜索算法,改进了Grover算法;在核磁共振量子计算实验方面,我们实现了2到7个量子比特的多种量子算法的实验演示;在量子通讯方面,我们提出了分布式传输的量子通讯的思想,应用于量子密钥分配、量子秘密共享、量子直接安全通讯等方面,构造了多个量子通讯的理论方案.在实验室,我们实现了2米距离的空间量子密码通讯的演示实验. 相似文献
86.
In [3] it was shown that a (real) signed measure on a cyclic coarse-grained quantum logic can be extended, as a signed measure,
over the entire power algebra. Later ([9]) this result was re-proved (and further improved on) and, moreover, the non-negative
measures were shown to allow for extensions as non-negative measures. In both cases the proof technique used was the technique
of linear algebra. In this paper we further generalize the results cited by extending group-valued measures on cyclic coarse-grained
quantum logics (or non-negative group-valued measures for lattice-ordered groups). Obviously, the proof technique is entirely
different from that of the preceding papers. In addition, we provide a new combinatorial argument for describing all atoms
of cyclic coarse-grained quantum logics. 相似文献
87.
Ahmad Afaq DU Meng-Li 《理论物理通讯》2006,46(1):119-122
The photodetachment of a negative molecular ion is studied theoretically using a two-center model. The detached electron wave function is obtained as a superposition of two coherent waves originating from each center. The photo-detached electron flux is evaluated on a screen placed at a large distance from the negative molecular ion. The electron flux on the screen displays strong interferences, the peak positions are related to the distance between the two centers in the negative molecular ion. We a/so obtained a simple analytical formula for the total photodetachment cross section. It approaches one and two times of the cross section for the one-center system in the high and lowphoton energy limits respectively. 相似文献
88.
q变形对相干态的相位概率分布特性 总被引:2,自引:0,他引:2
通过推广Pegg和Barnett的相位算符和相位态到q变形的双模情况, 应用数值计算
研究了q变形对相干态的相位概率分布特性. 结果表明, q变形对相干态的相位概率分布受到相位参数、q参数和参数│ξ│的调节, 从而反映出不同的量子相干特性. 相似文献
89.
基于傅立叶变换轮廓术的物面相位提取 总被引:1,自引:0,他引:1
采用傅立叶变换轮廓术,针对基频提取的关键技术采用逐行傅立叶变换,准确提取基频信息的方法恢复相位信息.在此基础上,以未畸变条纹为基准,得出被测物体的真实位相值.该方法只需一幅条纹图,节约了测量时间.实验证明可实现无接触面型的自动传感. 相似文献
90.
Canonical correlation analysis based on information theory 总被引:2,自引:0,他引:2
In this article, we propose a new canonical correlation method based on information theory. This method examines potential nonlinear relationships between p×1 vector Y-set and q×1 vector X-set. It finds canonical coefficient vectors a and b by maximizing a more general measure, the mutual information, between aTX and bTY. We use a permutation test to determine the pairs of the new canonical correlation variates, which requires no specific distributions for X and Y as long as one can estimate the densities of aTX and bTY nonparametrically. Examples illustrating the new method are presented. 相似文献