全文获取类型
收费全文 | 7136篇 |
免费 | 1134篇 |
国内免费 | 727篇 |
专业分类
化学 | 4753篇 |
晶体学 | 80篇 |
力学 | 414篇 |
综合类 | 42篇 |
数学 | 647篇 |
物理学 | 3061篇 |
出版年
2024年 | 27篇 |
2023年 | 153篇 |
2022年 | 211篇 |
2021年 | 207篇 |
2020年 | 269篇 |
2019年 | 225篇 |
2018年 | 211篇 |
2017年 | 195篇 |
2016年 | 308篇 |
2015年 | 302篇 |
2014年 | 373篇 |
2013年 | 517篇 |
2012年 | 554篇 |
2011年 | 597篇 |
2010年 | 398篇 |
2009年 | 409篇 |
2008年 | 428篇 |
2007年 | 367篇 |
2006年 | 356篇 |
2005年 | 332篇 |
2004年 | 274篇 |
2003年 | 201篇 |
2002年 | 222篇 |
2001年 | 173篇 |
2000年 | 170篇 |
1999年 | 180篇 |
1998年 | 128篇 |
1997年 | 132篇 |
1996年 | 151篇 |
1995年 | 109篇 |
1994年 | 113篇 |
1993年 | 108篇 |
1992年 | 100篇 |
1991年 | 82篇 |
1990年 | 63篇 |
1989年 | 74篇 |
1988年 | 52篇 |
1987年 | 46篇 |
1986年 | 38篇 |
1985年 | 34篇 |
1984年 | 19篇 |
1983年 | 18篇 |
1982年 | 14篇 |
1981年 | 13篇 |
1980年 | 9篇 |
1979年 | 6篇 |
1976年 | 4篇 |
1973年 | 3篇 |
1970年 | 3篇 |
1957年 | 3篇 |
排序方式: 共有8997条查询结果,搜索用时 15 毫秒
111.
Yuying Gu 《Physics letters. A》2008,372(25):4564-4568
A new type network growth rule which comprises node addition with the concept of local-world connectivity and node deleting is studied. A series of theoretical analysis and numerical simulation to the LWD network are conducted in this Letter. Firstly, the degree distribution p(k) of this network changes no longer pure scale free but truncates by an exponential tail and the truncation in p(k) increases as pa decreases. Secondly, the connectivity is tighter, as the local-world size M increases. Thirdly, the average path length L increases and the clustering coefficient 〈C〉 decreases as generally node deleting increases. Finally, 〈C〉 trends up when the local-world size M increases, so as to kmax. Hence, the expanding local-world can compensate the infection of the node deleting. 相似文献
112.
Zhang W Liu G Zhao L Liu H Meng J Dong X Lu W Wen JS Xu ZJ Gu GD Sasagawa T Wang G Zhu Y Zhang H Zhou Y Wang X Zhao Z Chen C Xu Z Zhou XJ 《Physical review letters》2008,100(10):107002
Laser-based angle-resolved photoemission measurements with superhigh resolution have been carried out on an optimally doped Bi(2)Sr(2)CaCu(2)O(8) high temperature superconductor. New high energy features at approximately 115 meV and approximately 150 meV, in addition to the prominent approximately 70 meV one, are found to develop in the nodal electron self-energy in the superconducting state. These high energy features, which cannot be attributed to electron coupling with single phonon or magnetic resonance mode, point to the existence of a new form of electron coupling in high temperature superconductors. 相似文献
113.
Block M Bachelet C Bollen G Facina M Folden CM Guénaut C Kwiatkowski AA Morrissey DJ Pang GK Prinke A Ringle R Savory J Schury P Schwarz S 《Physical review letters》2008,100(13):132501
A new long-lived isomeric state in (65)Fe has been discovered with Penning trap mass spectrometry and high-precision mass measurements of the neutron-rich isotopes (63-65)Fe and (64-66)Co have been performed with the Low-Energy Beam and Ion Trap Facility at the NSCL. For the new isomer in (65)Fe an excitation energy of 402(5) keV has been determined from the measured mass difference between the isomeric and ground states. The mass uncertainties of all isotopes have been reduced by a factor of 10-100 compared to previous results. In the case of (64)Co the previous mass value was found to deviate by about 5 standard deviations from the new measurement. 相似文献
114.
本文讨论准一维聚合物中的一维电子通过形变势与三维声学声子相互作用,对弱耦合和中间耦合情形,导出了极化子基态能量和有效质量。结果表明,在这种混合维数模型中,可形成稳定的极化子。 相似文献
115.
顾卫华 《应用数学和力学(英文版)》1985,6(12):1205-1215
The formula of BEM suited to solve the problems of wave propagation in boundlessmedium is obtained from numerical treatment of Kirchhoff integral equation.Afer quotingthe coefficients of refraction and reflection of wave at surface or interface,the expression ofBEM which is suitable for the problems of wave propagation in multi-isotropic mediums isalso given. 相似文献
116.
117.
谷安海 《应用数学和力学(英文版)》1987,8(10):991-1002
This paper is neither laudatory nor derogatory but it simply contrasts with what might be called elastostatic (or static topology),
a proposition of the famous six equations. The extension strains and the shearing strains
which were derived by A.L. Cauchy, are linearly expressed in terms of nine partial derivatives of the displacement function
(u
i
,u
j
,u
h
)=u(x
i
,x
j
,x
k
) and it is impossible for the inverse proposition to sep up a system of the above six equations in expressing the nine components
of matrix (∂(u
i
,u
j
,u
h
)/∂(x
i
,x
j
,x
k
)). This is due to the fact that our geometrical representations of deformation at a given point are as yet incomplete[1]. On the other hand, in more geometrical language this theorem is not true to any triangle, except orthogonal, for “squared
length” in space[2].
The purpose of this paper is to describe some mathematic laws of algebraic elastodynamics and the relationships between the
above-mentioned important questions. 相似文献
118.
用发酵和化学法合成的两个3-甲酰腙-利福霉素SV样品(1#,2#)具有不同的物理化学性质,本文用多种NMR技术,如1H,13C,DEPT,1H-1H COSY,反相摸式的1H-13C COSY及远程1H-13C COSY,并结合红外及紫外一可见光谱测试结果进行综合分析,确定样1#及样2#分别为酰胺式主产品及亚胺醇式导构体。根据实验结果对样1#的异构化反应进行了初步的探讨. 相似文献
119.
120.
Size dependence of a magnetopolaron in cylindrical quantum wires at arbitrary magnetic fields 总被引:8,自引:0,他引:8
With the use of variational method to solve the effective mass equation, we have studied the cyclotron resonance of a magnetopolaron in cylindrical quantum wires at arbitrary magnetic fields. The interaction of the electron with surface-optical (SO) phonons is used. Having calculated the ground state energy and the excited state energy of the magnetopolaron, we obtain the hybrid frequency of the magnetopolaron in quantum wires. 相似文献