全文获取类型
收费全文 | 1274篇 |
免费 | 48篇 |
国内免费 | 114篇 |
专业分类
化学 | 342篇 |
晶体学 | 2篇 |
力学 | 105篇 |
综合类 | 2篇 |
数学 | 568篇 |
物理学 | 417篇 |
出版年
2024年 | 3篇 |
2023年 | 24篇 |
2022年 | 20篇 |
2021年 | 15篇 |
2020年 | 23篇 |
2019年 | 23篇 |
2018年 | 22篇 |
2017年 | 19篇 |
2016年 | 28篇 |
2015年 | 20篇 |
2014年 | 68篇 |
2013年 | 103篇 |
2012年 | 57篇 |
2011年 | 79篇 |
2010年 | 80篇 |
2009年 | 89篇 |
2008年 | 87篇 |
2007年 | 101篇 |
2006年 | 66篇 |
2005年 | 45篇 |
2004年 | 52篇 |
2003年 | 52篇 |
2002年 | 33篇 |
2001年 | 38篇 |
2000年 | 28篇 |
1999年 | 41篇 |
1998年 | 27篇 |
1997年 | 31篇 |
1996年 | 26篇 |
1995年 | 17篇 |
1994年 | 19篇 |
1993年 | 10篇 |
1992年 | 11篇 |
1991年 | 12篇 |
1990年 | 8篇 |
1989年 | 10篇 |
1988年 | 6篇 |
1987年 | 5篇 |
1986年 | 1篇 |
1985年 | 5篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 7篇 |
1981年 | 8篇 |
1980年 | 6篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1974年 | 1篇 |
排序方式: 共有1436条查询结果,搜索用时 33 毫秒
1.
2.
Santwana Mukhopadhyay 《Mechanics Research Communications》2004,31(1):81-89
The present work is concerned with the thermally induced vibration in a homogeneous and isotropic unbounded body with a spherical cavity. The Green and Nagdhi model of thermoelasticity without energy dissipation is employed. The closed form solutions for distributions of displacement, temperature and stresses are obtained. The solutions valid in the case of small frequency are deduced and the results are compared with the corresponding results obtained in other generalized thermoelasticity theories. Numerical results applicable to a copper-like material are also presented graphically and the nature of variations of the physical quantities with radial coordinate and with frequency of vibration is analyzed. 相似文献
3.
时滞种群模型的正周期解对所有正解的吸引性 总被引:5,自引:0,他引:5
李永昆 《高校应用数学学报(A辑)》1997,(3)
建立了对数种群模型N′(t)=N(t){r(t)-a1(t)ln[N(t)]-a2(t)ln[N(t-τ(t))]}的周期正解的存在性,并得到了正周期解对所有正解的吸引性. 相似文献
4.
In ECRH system of HL-2A tokamak, we chose a new type of gyrotron imported from Russia. We finished the installation and testing last year with the help of Russian experts. We got a lot of useful data and satisfying results after our experiments with the operating of gyrotron. 相似文献
5.
Most operational models in atmospheric physics, meteorology and climatology nowadays adopt spherical geodesic grids and require “ad hoc” developed interpolation procedures. The author does a comparison between chosen representatives of linear, distance-based and cubic interpolation schemes outlining their advantages and drawbacks in this specific application field. Numerical experiments on a standard test problem, while confirming a good performance of linear and distance-based schemes in a single interpolation step, also show their minor accuracy with respect to the cubic scheme in the more realistic simulation of advection of a meteorological field. 相似文献
6.
Henrik Stetkær 《Journal of Functional Analysis》2007,252(1):1-33
We extend results on square integrable representations of a locally compact group to subrepresentations of a representations induced from a character of a closed subgroup. We do so working in the framework of quotient representations of ∗-algebras. 相似文献
7.
S.K. Mahapatra B.K. Dandapat 《Journal of Quantitative Spectroscopy & Radiative Transfer》2006,102(2):277-292
The current study addresses the mathematical modeling aspects of coupled conductive and radiative heat transfer in the presence of absorbing, emitting and isotropic scattering gray medium within two-dimensional square enclosure. A blended method where the concepts of modified differential approximation employed by combining discrete ordinate method and spherical harmonics method, has been developed for modeling the radiative transport equation. The gray participating medium is bounded by isothermal walls of two-dimensional enclosure which are considered to be opaque, diffuse and gray. The effect of various influencing parameters i.e., radiation-conduction parameter, surface emissivity, single scattering albedo and optical thickness has been illustrated. The adaptability of the present method has also been addressed. 相似文献
8.
高抗冲聚丙烯序列结构的综合表征 总被引:3,自引:0,他引:3
用高分辨^13C NMR、FTIR等手段获得了高抗冲聚丙烯的组成和序列分布等链结构方面的信息。用DSC、WAXD等方法研究了它们的结晶行为、熔融转变及晶体结构,多种方法相结合有效地表征了高抗冲聚丙烯的序列结构。 相似文献
9.
Testing goodness of fit for the distribution of errors in multivariate linear models 总被引:2,自引:0,他引:2
M.D. Jimnez Gamero J. Muoz García R. Pino Mejías 《Journal of multivariate analysis》2005,95(2):301-322
In this paper, to test goodness of fit to any fixed distribution of errors in multivariate linear models, we consider a weighted integral of the squared modulus of the difference between the empirical characteristic function of the residuals and the characteristic function under the null hypothesis. We study the limiting behaviour of this test statistic under the null hypothesis and under alternatives. In the asymptotics, the rank of the design matrix is allowed to grow with the sample size. 相似文献
10.
Eero Immonen 《Journal of Mathematical Analysis and Applications》2004,300(1):79-101
In this article, we study the effect of the chosen representation of a point value (and point evaluation) on the class of periodic signals realizable using a certain type of infinite-dimensional linear system. By suitably representing the point evaluation at the origin in a Hilbert space, we are able to give a complete characterization of its extensions. These extensions involve a new concept called δ-sequence, the use of which as an observation operator of an infinite-dimensional linear system is studied in this article. In particular, we consider their use in the realization of periodic signals. We also investigate how the use of δ-sequences affects the convergence properties of such realizations; we consider the rate and character of convergence and the removal of the Gibbs phenomenon. As still a further demonstration of the significance of the chosen concept of a point value, we discuss the use of distributional point values in the realization of periodic distributions. The possible applications of this work lie in regulator problems of infinite-dimensional control theory, as is indicated by the well-known internal model principle. 相似文献