全文获取类型
收费全文 | 4365篇 |
免费 | 831篇 |
国内免费 | 265篇 |
专业分类
化学 | 1037篇 |
晶体学 | 6篇 |
力学 | 368篇 |
综合类 | 81篇 |
数学 | 1097篇 |
物理学 | 2872篇 |
出版年
2024年 | 4篇 |
2023年 | 51篇 |
2022年 | 86篇 |
2021年 | 120篇 |
2020年 | 103篇 |
2019年 | 95篇 |
2018年 | 112篇 |
2017年 | 160篇 |
2016年 | 210篇 |
2015年 | 195篇 |
2014年 | 353篇 |
2013年 | 337篇 |
2012年 | 287篇 |
2011年 | 353篇 |
2010年 | 256篇 |
2009年 | 295篇 |
2008年 | 324篇 |
2007年 | 272篇 |
2006年 | 241篇 |
2005年 | 235篇 |
2004年 | 190篇 |
2003年 | 187篇 |
2002年 | 130篇 |
2001年 | 124篇 |
2000年 | 97篇 |
1999年 | 92篇 |
1998年 | 94篇 |
1997年 | 66篇 |
1996年 | 72篇 |
1995年 | 51篇 |
1994年 | 46篇 |
1993年 | 33篇 |
1992年 | 31篇 |
1991年 | 23篇 |
1990年 | 15篇 |
1989年 | 26篇 |
1988年 | 23篇 |
1987年 | 13篇 |
1986年 | 8篇 |
1985年 | 11篇 |
1984年 | 12篇 |
1983年 | 4篇 |
1982年 | 11篇 |
1979年 | 3篇 |
1977年 | 4篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有5461条查询结果,搜索用时 15 毫秒
51.
Our object of study is the asymptotic behavior of the sequence of polynomials orthogonal with respect to the discrete Sobolev
inner product <formula> \langle f, g \rangle = ∈t_{E} f(ξ) \overline{g(ξ)} ρ(ξ) |d ξ|+ f(Z) A g(Z)^H, </formula> where E is a rectifiable Jordan curve or arc in the complex plane
f(Z) = (f(z_1), \ldots, f^{(l_1)}(z_1) , \ldots , f(z_m) , \ldots ,f^{(l_m)}(z_m)),
A is an M \times M Hermitian matrix, M l
1
+ ⋅s + l
m
+ m , |d ξ| denotes the arc length measure, ρ is a nonnegative function on E , and z
i
∈Ω,
i=1,2,\ldots,m , where Ω is the exterior region to E .
July 23, 1999. Dates revised: September 11, 2000 and February 16, 2001. Date accepted: February 26, 2001. 相似文献
52.
We consider a two-dimensional Coulomb gas of positive and negative pointlike unit charges interacting via a logarithmic potential. The density (rather than the charge) correlation functions are studied. In the bulk, the form-factor theory of an equivalent sine-Gordon model is used to determine the density correlation length. At the surface of a rectilinear plain wall, the universality of the asymptotic behavior of the density correlations is suggested. A scaling analysis implies a local form of the compressibility sum rule near a hard wall. A symmetry of the Coulomb system with respect to the Möbius conformal transformation, which induces a gravitational source acting on the particle density, is established. Among the consequences, a universal term of the finite-size expansion of the grand potential is derived exactly for a disk geometry of the confining domain. 相似文献
53.
54.
新药交沙霉素能否制成片剂,取决于能否找到最佳的片剂处方.本文运用正交试验法成功地解决了这一问题. 相似文献
55.
A probe-corrected theory based on complex point sources is presented for computing the acoustic field of an arbitrary finite source from measurements of the near field on a cylindrical scanning surface. The complex point sources are used both as basis functions for the expansion of the field outside the scan cylinder and for the representation of the probe. The resulting probe-corrected formulas are considerably simpler than the standard probe-corrected formulas based on cylindrical waves. The new formulation makes simulations of near-field scanning systems much less computationally intensive than simulations based on standard theory. The complex point-source theory is validated through numerical examples involving a baffled circular piston transducer probe. 相似文献
56.
57.
提出了基于小波包分析及支持向量机的超音速目标识别方法 .通过 5 .5 6mm ,7.6 2mm和 12 .7mm三种枪弹试验获取信号 ,用小波包分解激波信号 ,统计每个频带的能量特征 ,用支持向量机方法训练测试样本 ,获得了很好的分类效果 .仿真结果表明基于超音速飞行体产生的激波信号来识别目标是可行的 . 相似文献
58.
AO Sheng-Mei YAN Jia-Ren 《理论物理通讯》2007,47(1):15-18
Three types of expression in the dark-soliton perturbation theory based on squared Jost solutions are invesgigaged in ghis paper. It is shown that there are three formally different results about the effects of perturbagion on a dark soliton, and it is proved by means of a transformation between two integral variables that they are essentially equivalent. 相似文献
59.
Tomohiro Shirai 《Optical Review》2004,11(5):312-319
Spatial coherence of the field modified by low-order adaptive optics is analyzed to establish a theoretical basis for the recent idea of using adaptive optics as a spatial coherence modifier. In this context low-order adaptive optics has the ability to correct some of the low-order aberrations specified by Zernike polynomials. The initial field to be modified is assumed to be a spatially partially coherent one resulting from phase disturbance. It is demonstrated, as in the previous study, that low-order adaptive optics serves to enhance the spatial coherence of the resultant field and that the effect of the enhancement becomes stronger as the spatial coherence of the initially partially coherent field increases. Potential applications of low-order adaptive optics as a spatial coherence modifier are briefly discussed. 相似文献
60.
平面物体在曲面状态下扫描仪图像的校正理论 总被引:6,自引:5,他引:1
平面物体在曲面状态下经扫描仪扫描后,其图像将发生复杂的畸变。提出将其分类为灰度畸变、投影畸变和成像畸变。通过理论分析,提出了在二元曲面模型下对投影畸变和成像畸变进行数字校正的方法,给出了对灰度畸变进行数字校正的实用方法。 相似文献