全文获取类型
收费全文 | 1503篇 |
免费 | 52篇 |
国内免费 | 145篇 |
专业分类
化学 | 101篇 |
晶体学 | 1篇 |
力学 | 54篇 |
综合类 | 10篇 |
数学 | 1265篇 |
物理学 | 269篇 |
出版年
2024年 | 2篇 |
2023年 | 13篇 |
2022年 | 17篇 |
2021年 | 22篇 |
2020年 | 23篇 |
2019年 | 41篇 |
2018年 | 41篇 |
2017年 | 33篇 |
2016年 | 29篇 |
2015年 | 26篇 |
2014年 | 63篇 |
2013年 | 167篇 |
2012年 | 50篇 |
2011年 | 60篇 |
2010年 | 55篇 |
2009年 | 99篇 |
2008年 | 112篇 |
2007年 | 91篇 |
2006年 | 86篇 |
2005年 | 68篇 |
2004年 | 66篇 |
2003年 | 64篇 |
2002年 | 46篇 |
2001年 | 60篇 |
2000年 | 61篇 |
1999年 | 51篇 |
1998年 | 44篇 |
1997年 | 37篇 |
1996年 | 36篇 |
1995年 | 13篇 |
1994年 | 17篇 |
1993年 | 17篇 |
1992年 | 17篇 |
1991年 | 14篇 |
1990年 | 11篇 |
1989年 | 4篇 |
1988年 | 11篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 2篇 |
排序方式: 共有1700条查询结果,搜索用时 422 毫秒
961.
A family of probability measures on the unit ball in generates a family of generalized Steiner (GS-)points for every convex compact set in . Such a “rich” family of probability measures determines a representation of a convex compact set by GS-points. In this way,
a representation of a set-valued map with convex compact images is constructed by GS-selections (which are defined by the
GS-points of its images). The properties of the GS-points allow to represent Minkowski sum, Demyanov difference and Demyanov
distance between sets in terms of their GS-points, as well as the Aumann integral of a set-valued map is represented by the
integrals of its GS-selections. Regularity properties of set-valued maps (measurability, Lipschitz continuity, bounded variation)
are reduced to the corresponding uniform properties of its GS-selections. This theory is applied to formulate regularity conditions
for the first-order of convergence of iterated set-valued quadrature formulae approximating the Aumann integral.
相似文献
962.
963.
964.
We give a simple proof of the well-known Hamilton's result [1] on the heat flows and harmonic maps from manifolds with boundary using the approach of Ding-Lin [2]. 相似文献
965.
Q. H. Ansari T. C. Lai J. C. Yao 《Journal of Optimization Theory and Applications》1999,102(2):277-288
In this paper, we derive some equivalences of generalized nonlinear programs, generalized least-element problems, and extended generalized complementarity problems under certain regularity and growth conditions. We also generalize the notion of a Z-map for point-to-set maps. Our results extend recent results by Schaible and Yao (Ref. 1). 相似文献
966.
Yi-fa Tang 《计算数学(英文版)》1999,17(6):561-568
1.IntroductionFirstofall,let'srecallthedefinitionsofsymplecticschemes,revertibleschemes,andFeng'swayofconstructionofsymplecticmethodsviageneratingfunctions.Aswell-known,thephaseflow{g',tER}ofanyHamiltoniansystem(whereJ~I--i:n1,H:RZn-- RIisasmoothfunc... 相似文献
967.
所有以单位圆周上的ω为一固定特征的辛矩阵构成实辛群SP(2n)中之一超曲面.本文研究此超曲面与它在Sp(2n)中之补集的拓扑结构. 相似文献
968.
Hamilton体系下环扇形域的Stokes流动问题 总被引:1,自引:0,他引:1
基于极坐标下Stokes流的基本方程,将径向坐标模拟为时间坐标,推导了Hamilton体系下Stokes流动问题的对偶方程,采用本征向量展开法对环扇形域Stokes流动问题进行了分析,并给出了相应的实际算例,其结果说明了本文方法的有效性。 相似文献
969.
Hydroxyl and acid number prediction in polyester resins by near infrared spectroscopy and artificial neural networks 总被引:2,自引:0,他引:2
Back-propagation artificial neural networks (BP-ANN) are applied for modeling hydroxyl number and acid value of a set of 62 samples of polyester resins from their near infrared (NIR) spectra. The results are compared to the classical calibration approaches, i.e. principal component regression (PCR) and partial least squares (PLS). The set of available samples is split into: (i) a training set, for models calculation; (ii) a test set, for setting the correct number of latent variables in PCR and PLS and for selecting the end point of the training phase of BP-ANN; (iii) a “production set” of samples, which are predicted to evaluate the models predictive ability. This approach guarantees that the predictive ability of the models is evaluated by genuine predictions. BP-ANN resulted always better than the classical PCR and PLS, from the point of view of the predictive ability. The study of the breakdown number of experiments to include in the training set showed instead that this factor does influence PCR and PLS at a lesser degree than what happens for BP-ANN. The latter approach requires a larger number of experiments for obtaining good results. The choice of optimal training sets is efficiently performed by Kohonen self-organizing maps (SOMs). It can be concluded that FT-NIR spectroscopy and BP-ANN models can be properly employed for monitoring the polyesterification of dicarboxylic acids with diols by predicting the acid and hydroxyl numbers directly along the process line. 相似文献
970.
Another Construction of Cartesian Authentication Codes from Geometry of Classical Groups 总被引:3,自引:0,他引:3
Feng Rongquan 《东北数学》1999,(1)
§1.IntroductionLetS,EandMbethreenon-emptysetsandletf:S×E→Mbeamap.Thefourtuple(S,E,M;f)iscaledanauthenticationcode(see[1]),if(... 相似文献