全文获取类型
收费全文 | 3451篇 |
免费 | 338篇 |
国内免费 | 414篇 |
专业分类
化学 | 386篇 |
晶体学 | 14篇 |
力学 | 420篇 |
综合类 | 72篇 |
数学 | 2782篇 |
物理学 | 529篇 |
出版年
2024年 | 9篇 |
2023年 | 51篇 |
2022年 | 32篇 |
2021年 | 57篇 |
2020年 | 85篇 |
2019年 | 84篇 |
2018年 | 77篇 |
2017年 | 98篇 |
2016年 | 113篇 |
2015年 | 107篇 |
2014年 | 159篇 |
2013年 | 271篇 |
2012年 | 139篇 |
2011年 | 169篇 |
2010年 | 140篇 |
2009年 | 204篇 |
2008年 | 208篇 |
2007年 | 223篇 |
2006年 | 250篇 |
2005年 | 234篇 |
2004年 | 174篇 |
2003年 | 175篇 |
2002年 | 160篇 |
2001年 | 153篇 |
2000年 | 172篇 |
1999年 | 143篇 |
1998年 | 94篇 |
1997年 | 104篇 |
1996年 | 76篇 |
1995年 | 41篇 |
1994年 | 33篇 |
1993年 | 27篇 |
1992年 | 14篇 |
1991年 | 8篇 |
1990年 | 14篇 |
1989年 | 12篇 |
1988年 | 11篇 |
1987年 | 9篇 |
1986年 | 7篇 |
1985年 | 11篇 |
1984年 | 13篇 |
1983年 | 8篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1936年 | 1篇 |
排序方式: 共有4203条查询结果,搜索用时 156 毫秒
61.
A. N. Koryukin 《Algebra and Logic》2003,42(6):387-397
We generalize a well-known two-parameter quantization for the group GL
2(k) (over an arbitrary field k). Specifically, a certain class of Hopf algebras is constructed containing that quantization. The algebras are constructed given an arbitrary coalgebra and an arbitrary pair of its commuting anti-isomorphisms, and are defined by quadratic relations. They are densely linked to the compact quantum groups introduced by Woronowicz. We give examples of Hopf algebras that can be rowed up to the two-parameter quantization for GL
2(k). 相似文献
62.
《Surface and interface analysis : SIA》2004,36(1):61-70
In spectroscopy, the recorded spectra can often be modelled as the noisy convolution product of an instrumental function with the ‘true’ signal to be estimated. Such models have often been used for high‐resolution electron energy‐loss spectroscopy (HREELS). In this article, a new method is suggested to estimate the ‘true’ HREELS signal, i.e. the original electronic diffusion function with ‘true’ peak intensities. Our method relies upon the use of wavelets that, because they exhibit simultaneous time and frequency localization, are well‐suited for signal analysis. Firstly, a wavelet shrinkage algorithm is used to filter the noise. This is achieved by decomposing the noisy signal into an appropriate wavelet basis and then thresholding the wavelet coefficients that contain noise. This algorithm has a particular threshold related to frequency and time. Secondly, the broadening due to the instrumental response is eliminated through a deconvolution process. This step mainly rests on the existing relation between the Lipschitz regularity of the signal and the decay with scale of its wavelet coefficients and on least squares. The efficiency of this technique is highlighted by comparing the results obtained with those provided by other published methods. This work is the second in a series of three papers in this issue. The first one presents background knowledge on the wavelets required to understand the estimation methods. The third paper explores the application of wavelet filtering and deconvolution techniques to x‐ray photoelectron spectroscopy. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
63.
设φ是单位园盘D到自身的解析映射,X是D上解析函数的Banach空间,对f∈X,定义复合算子C_φ∶C_φ)(f)=fφ.我们利用从B~0到E(p,q)和E_0(p,q)空间的复合算子研究了空间E(p,q)和E_0(p,q),给出了一个新的特征. 相似文献
64.
Subhashis Nag 《Proceedings Mathematical Sciences》1989,99(2):103-111
We study some explicit relations between the canonical line bundle and the Hodge bundle over moduli spaces for low genus.
This leads to a natural measure on the moduli space of every genus which is related to the Siegel symplectic metric on Siegel
upper half-space as well as to the Hodge metric on the Hodge bundle. 相似文献
65.
We investigate which types of asymptotic distributions can be generated by the knots of convergent sequences of interpolatory integration rules. It will turn out that the class of all possible distributions can be described exactly, and it will be shown that the zeros of polynomials that are orthogonal with respect to varying weight functions are good candidates for knots of integration rules with a prescribed asymptotic distribution.Research supported by the Deutsche Forschungsgemeinschaft (AZ: Sta 299/4-2). 相似文献
66.
Ali Ghaffari 《Proceedings Mathematical Sciences》2007,117(2):177-183
In this paper, among other things, we state and prove the mean ergodic theorem for amenable semigroup algebras. 相似文献
67.
Monika Remy 《manuscripta mathematica》1988,62(3):277-296
For every finite measure space (X,A,P) we find a unique representation P=Q1+Q2+Q3 such that Q1 is compact, Q2 is perfect and purely noncompact and Q3 is purely nonperfect. We show that every Pachl-O-disintegrable probability space is Ramachandran-O-disintegrable and therefore perfect and under a certain condition we prove the equivalence between compactness and Ramachandran-O-disintegrability. 相似文献
68.
P. J. Forrester 《Journal of statistical physics》1989,56(5-6):767-782
The vicious random walker problem on a line is studied in the limit of a large number of walkers. The multidimensional integral representing the probability that thep walkers will survive a timet (denotedP
t
(p)
) is shown to be analogous to the partition function of a particular one-component Coulomb gas. By assuming the existence of the thermodynamic limit for the Coulomb gas, one can deduce asymptotic formulas forP
t
(p)
in the large-p, large-t limit. A straightforward analysis gives rigorous asymptotic formulas for the probability that after a timet the walkers are in their initial configuration (this event is termed a reunion). Consequently, asymptotic formulas for the conditional probability of a reunion, given that all walkers survive, are derived. Also, an asymptotic formula for the conditional probability density that any walker will arrive at a particular point in timet, given that allp walkers survive, is calculated in the limittp. 相似文献
69.
燮理阴阳胶囊的制备与质量标准研究 总被引:1,自引:0,他引:1
为研制燮理阴阳胶囊生产工艺,并建立相应的质量标准,采用正交实验法进行了工艺研究,采用薄层色谱法进行了鉴定,确立了水煎提取的工艺条件,建立了知母、熟地黄、淫羊藿的鉴别方法。该制剂的制备工艺简单易行,质量检定方法可行,质量稳定。 相似文献
70.
超细Sr2CeO4 粉体微乳液-高温法制备条件的正交试验及其发光性能研究 总被引:2,自引:0,他引:2
本文首先利用正交试验确定了微乳液-高温法合成蓝色发光Sr2CeO4超细粉体的最佳制备条件。接着研究了最佳条件下制备的Sr2CeO4超细粉体的性能。场发射扫描电镜(FE-SEM)显示,在850 ℃、900 ℃、1 000 ℃或者更高温度下退火4 h制备的粉体的形状分别呈球状、梭状和球状,平均粒径分别在100 nm左右和1 μm以内。X射线粉末衍射数据分析表明,该超细粉体属于正交晶系。室温下的光致发光光谱显示,该粉体的激发光谱有3个激发峰,主峰分别位于262 nm、281 nm和341 nm,而其发射光谱只呈现出1个发射峰,主峰位于约470 nm。与高温固相制备方法相比,微乳液-高温法可以在较低温度下制备出超细的粉体,而且它不但在262 nm处出现了一个新的激发峰,主激发峰和发射峰的位置也分别蓝移了大约30 nm和12 nm。 相似文献