全文获取类型
收费全文 | 3475篇 |
免费 | 486篇 |
国内免费 | 235篇 |
专业分类
化学 | 883篇 |
晶体学 | 57篇 |
力学 | 434篇 |
综合类 | 71篇 |
数学 | 1253篇 |
物理学 | 1498篇 |
出版年
2023年 | 20篇 |
2022年 | 55篇 |
2021年 | 64篇 |
2020年 | 98篇 |
2019年 | 83篇 |
2018年 | 98篇 |
2017年 | 87篇 |
2016年 | 126篇 |
2015年 | 83篇 |
2014年 | 189篇 |
2013年 | 217篇 |
2012年 | 176篇 |
2011年 | 228篇 |
2010年 | 188篇 |
2009年 | 214篇 |
2008年 | 211篇 |
2007年 | 226篇 |
2006年 | 200篇 |
2005年 | 200篇 |
2004年 | 153篇 |
2003年 | 153篇 |
2002年 | 150篇 |
2001年 | 115篇 |
2000年 | 110篇 |
1999年 | 84篇 |
1998年 | 77篇 |
1997年 | 60篇 |
1996年 | 74篇 |
1995年 | 37篇 |
1994年 | 51篇 |
1993年 | 41篇 |
1992年 | 29篇 |
1991年 | 33篇 |
1990年 | 33篇 |
1989年 | 22篇 |
1988年 | 28篇 |
1987年 | 21篇 |
1986年 | 19篇 |
1985年 | 19篇 |
1984年 | 24篇 |
1983年 | 7篇 |
1982年 | 16篇 |
1981年 | 18篇 |
1980年 | 5篇 |
1979年 | 8篇 |
1978年 | 5篇 |
1977年 | 11篇 |
1976年 | 7篇 |
1974年 | 4篇 |
1973年 | 7篇 |
排序方式: 共有4196条查询结果,搜索用时 15 毫秒
1.
陈泽乾 《数学物理学报(B辑英文版)》2002,22(3)
A new framework of Gaussian white noise calculus is established, in line with generalized expansion in [3, 4, 7]. A suitable frame of Fock expansion is presented on Gaussian generalized expansion functionals being introduced here, which provides the integral kernel operator decomposition of the second quantization of Koopman operators for chaotic dynamical systems, in terms of annihilation operators dt and its dual, creation operators t*. 相似文献
2.
通过改变带细玻璃管的烧瓶中水的温度导致水位变化来粗略演示水的收缩情况.为较准确测定水最大密度时的温度,将2个温度计放在水下较浅处和较深处,分别测量当温度经由4℃升高时和由4℃降低时两温度计的示数,进而验证水的反常热膨胀特性. 相似文献
3.
Given a principal value convolution on the Heisenberg group Hn = Cn×R, we study the relation between its Laguerre expansion and the Fourier-Bessel expansion of its limit on Cn. We also calculate the Dirichlet kernel for the Laguerre expansion on the group Hn. 相似文献
4.
D. Yafaev 《Proceedings Mathematical Sciences》2002,112(1):245-255
We find an explicit function approximating at high energies the kernel of the scattering matrix with arbitrary accuracy. Moreover,
the same function gives all diagonal singularities of the kernel of the scattering matrix in the angular variables.
This paper is dedicated to Jean-Michel Combes on the occasion of his sixtieth birthday. 相似文献
5.
乌桕类可可脂结晶过程中表现体积变化 总被引:1,自引:0,他引:1
为了解乌桕类可可脂(CTCBE)缓冷结晶横向胀罐爆裂原因,研究CTCBE结晶过程中的膨胀特性,采用流体静力法测试了不同等温结晶条件下CTCBE结晶形成的表观密度和表观体积及其横纵向膨胀状况。结果表明,CTCBE缓冷结晶后形成外部和中部两个晶区。在5-25℃的各等温结晶范围内,当结晶温度增加时,外部结晶区域减小、表观密度变化不大;中部结晶区域增大、表观密度明显减小,CTCBE的表观体积、横向、纵向膨胀率均增大,膨胀横向大于纵向。进一步表明CTCBE在自然缓冷固化的表观体积根本上由其结晶温度决定。为有效防止横向胀罐,自然缓冷固化温度应低于10℃。 相似文献
6.
V.I. Kushch I. Sevostianov L. Mishnaevsky Jr 《International Journal of Solids and Structures》2008,45(18-19):5103-5117
The paper addresses the problem of calculation of the local stress field and effective elastic properties of a unidirectional fiber reinforced composite with anisotropic constituents. For this aim, the representative unit cell approach has been utilized. The micro geometry of the composite is modeled by a periodic structure with a unit cell containing multiple circular fibers. The number of fibers is sufficient to account for the micro structure statistics of composite. A new method based on the multipole expansion technique is developed to obtain the exact series solution for the micro stress field. The method combines the principle of superposition, technique of complex potentials and some new results in the theory of special functions. A proper choice of potentials and new results for their series expansions allow one to reduce the boundary-value problem for the multiple-connected domain to an ordinary, well-posed set of linear algebraic equations. This reduction provides high numerical efficiency of the developed method. Exact expressions for the components of the effective stiffness tensor have been obtained by analytical averaging of the strain and stress fields. 相似文献
7.
Subhashis Ghosal Tapas Samanta 《Annals of the Institute of Statistical Mathematics》1997,49(1):181-197
We study the asymptotic behaviour of the posterior distributions for a one-parameter family of discontinuous densities. It is shown that a suitably centered and normalized posterior converges almost surely to an exponential limit in the total variation norm. Further, asymptotic expansions for the density, distribution function, moments and quantiles of the posterior are also obtained. It is to be noted that, in view of the results of Ghosh et al. (1994, Statistical Decision Theory and Related Topics V, 183-199, Springer, New York) and Ghosal et al. (1995, Ann. Statist., 23, 2145-2152), the nonregular cases considered here are essentially the only ones for which the posterior distributions converge. The results obtained here are also supported by a simulation experiment. 相似文献
8.
9.
用波导本征模展开方法对用于高功率微波发射系统的方角锥高斯馈源口面场进行分析,提出结合馈源远场辐射特性和避免高功率击穿折衷选定相应的高斯模注腰半径,进而确定多个波导模幅值,从而为运用模匹配或耦合波理论设计高斯馈源提供依据。 相似文献
10.
We study the corrections to the Clausius-Mossotti formula for the dielectric constant of a disordered system of polarizable spherical particles. Previously we have derived an exact cluster expansion for the correction terms. Here we study the three-body correction in detail. We derive an explicit expression for the integrand of the three-body cluster integral for a system of polarizable point dipoles. 相似文献