全文获取类型
收费全文 | 447篇 |
免费 | 64篇 |
国内免费 | 51篇 |
专业分类
化学 | 163篇 |
晶体学 | 11篇 |
力学 | 13篇 |
综合类 | 38篇 |
数学 | 203篇 |
物理学 | 134篇 |
出版年
2023年 | 3篇 |
2021年 | 11篇 |
2020年 | 9篇 |
2019年 | 12篇 |
2018年 | 13篇 |
2017年 | 17篇 |
2016年 | 12篇 |
2015年 | 26篇 |
2014年 | 57篇 |
2013年 | 56篇 |
2012年 | 81篇 |
2011年 | 59篇 |
2010年 | 64篇 |
2009年 | 44篇 |
2008年 | 16篇 |
2007年 | 21篇 |
2006年 | 16篇 |
2005年 | 9篇 |
2004年 | 3篇 |
2003年 | 2篇 |
2002年 | 2篇 |
2001年 | 7篇 |
2000年 | 3篇 |
1999年 | 7篇 |
1998年 | 3篇 |
1997年 | 5篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有562条查询结果,搜索用时 734 毫秒
11.
The composition of soluble algal products was visualized by a fingerprint analytical method. 相似文献
12.
Based on the fact that a hard aperture function can be expanded into a finite sum of complex Gaussian functions, the approximate analytical expressions for the output field distribution of an anomalous hollow beam (AHB) passing through an apertured fractional Fourier transform (FRT) system are derived. By using the approximate analytical formulae and diffraction integral formulae, the propagation properties of an AHB in circular and rectangular apertured FRT system are studied numerically. The results show that this method provides a convenient tool for studying the propagation properties of an AHB passing through apertured FRT system, and the apertured FRT system can be applied to laser beam shaping conveniently. 相似文献
13.
In this work, a projection algorithm is considered for treating strongly continuous semigroups of demicontinuous pseudocontractions. Theorems of strong convergence of fixed points are established in the framework of real Hilbert spaces. 相似文献
14.
A simple model is proposed to take into account secondary X-ray fluorescence and absorption effects near the interface. This model is based on the investigation of the shape change of the first derivative equation that can fit the sigmoidal EDS profile obtained when a high vacuum electron beam passes through the interface of two adjacent materials. The contribution of the photoelectric absorption of primary X-rays (characteristic and Bremsstrahlung) and the secondary fluorescence on the degradation of the X-ray spatial resolution can be easily quantified. The close agreement between the simulated (Monte Carlo simulation using the Casino software) and the experimental data serves to assess the reliability of this developed model. 相似文献
15.
We study smoothed quantile estimator for a class of stationary processes. We obtain the convergency rates and the Bahadur representation, as well as the asymptotic normality for this estimator by the method of m-dependent approximation. Our results can be used in the study of the estimation of value-at-risk(Va R) and applied to many time series which have important applications in econometrics. 相似文献
16.
本文首先将Clifford幺半群代数分解为交叉积的半格直和,然后将这个结果通过$H$-$G$-cleft扩张推广到所谓的$G$-交叉积上. 相似文献
17.
18.
本文研究了可加稳定过程的自相交局部时的问题.利用Borel–Canteil引理等方法,得到可加稳定过程的自相交局部时的Hlder上界,推广了文献[5]中的结果. 相似文献
19.
Yu Quan Xie 《数学学报(英文版)》2015,31(12):1963-1969
In this paper, we show that both focal submanifolds of each isoparametric hypersurface in the sphere with six distinct principal curvatures are Willmore, hence all focal submanifolds of isoparametric hypersurfaces in the sphere are Willmore. 相似文献
20.
Direct assembly of α-amino amides from N-alkyl amines and isocyanides through oxidative Ugi-type reactions in aqueous conditions, has been achieved in a Cu(I)–TBHP–surfactant catalysis system. Various N-alkyl amines and isocyanides could be tolerated in this reaction and furnish α-amino amides in moderate yields. 相似文献