全文获取类型
收费全文 | 1219篇 |
免费 | 21篇 |
国内免费 | 32篇 |
专业分类
化学 | 50篇 |
晶体学 | 1篇 |
力学 | 39篇 |
综合类 | 5篇 |
数学 | 1090篇 |
物理学 | 87篇 |
出版年
2023年 | 11篇 |
2022年 | 12篇 |
2021年 | 13篇 |
2020年 | 19篇 |
2019年 | 14篇 |
2018年 | 14篇 |
2017年 | 11篇 |
2016年 | 11篇 |
2015年 | 12篇 |
2014年 | 38篇 |
2013年 | 106篇 |
2012年 | 99篇 |
2011年 | 66篇 |
2010年 | 36篇 |
2009年 | 81篇 |
2008年 | 63篇 |
2007年 | 53篇 |
2006年 | 56篇 |
2005年 | 43篇 |
2004年 | 30篇 |
2003年 | 30篇 |
2002年 | 37篇 |
2001年 | 24篇 |
2000年 | 25篇 |
1999年 | 18篇 |
1998年 | 18篇 |
1997年 | 10篇 |
1996年 | 24篇 |
1995年 | 14篇 |
1994年 | 17篇 |
1993年 | 9篇 |
1992年 | 11篇 |
1991年 | 8篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 18篇 |
1985年 | 26篇 |
1984年 | 28篇 |
1983年 | 21篇 |
1982年 | 25篇 |
1981年 | 17篇 |
1980年 | 29篇 |
1979年 | 21篇 |
1978年 | 31篇 |
1977年 | 7篇 |
1975年 | 1篇 |
1972年 | 2篇 |
1969年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有1272条查询结果,搜索用时 343 毫秒
91.
92.
W.T. Sulaiman 《Journal of Mathematical Analysis and Applications》2006,322(2):1224-1230
Extension and improvement has been made on a recent result proved by Mazhar [S.M. Mazhar, Absolute summability factors of infinite series, Kyungpook Math. J. 39 (1999) 67-73] concerning absolute summability factors of infinite series. 相似文献
93.
P. Favati G. Lotti O. Menchi F. Romani 《Journal of Computational and Applied Mathematics》2007,210(1-2):191-199
In this paper we consider the problem of approximating the solution of infinite linear systems, finitely expressed by a sparse coefficient matrix. We analyse an algorithm based on Krylov subspace methods embedded in an adaptive enlargement scheme. The management of the algorithm is not trivial, due to the irregular convergence behaviour frequently displayed by Krylov subspace methods for nonsymmetric systems. Numerical experiments, carried out on several test problems, indicate that the more robust methods, such as GMRES and QMR, embedded in the adaptive enlargement scheme, exhibit good performances. 相似文献
94.
Jingtao He 《European Polymer Journal》2003,39(7):1297-1310
In this work, correlations for the estimation of the infinite dilution activity coefficients of non-polar solvents in polystyrene (PS), poly(vinyl acetate) (PVAc), poly(n-butyl methacrylate) (PBMA), poly(dimethyl siloxane), poly(methyl methacrylate) (PMMA), poly(ethylene oxide) (PEO), poly(vinyl chloride) (PVC), polyisobutylene and polyethylene (PE), and that of polar solvents in PS, PVAc, PBMA, PMMA, PEO, PVC and PE are proposed. A total of 205 polymer/non-polar solvent systems with 1708 data points, and 118 polymer/polar solvent systems with 695 data points were used to develop the correlations. The overall average errors were 9.6% and 11.3%, respectively, significantly lower than other predictive models. Since the new correlations require only the connectivity indices of the solvents in the calculations, and the connectivity indices can be calculated easily once the molecular structure of the substance in question is known, they are easy to apply, and are useful for process design and development. 相似文献
95.
Chao Liu Lin Huang Dexing Feng 《Journal of Mathematical Analysis and Applications》2007,331(1):655-668
In this paper, a class of pendulum-like systems in infinite-dimensional Hilbert spaces is investigated. A frequency domain criterion guaranteeing the systems with the property of Lagrange stability is established. 相似文献
96.
简要叙述了并行程序设计语言CMFortran的计算模式、并行数据结构及其主要特征.并对Fortran77和Fortran90上的扩展部分作了概要描述. 相似文献
97.
Emmanuel Fernández-Gaucherand Mrinal K. Ghosh Steven I. Marcus 《Mathematical Methods of Operations Research》1994,39(2):131-155
Stochastic control problems for controlled Markov processes models with an infinite planning horizon are considered, under some non-standard cost criteria. The classical discounted and average cost criteria can be viewed as complementary, in the sense that the former captures the short-time and the latter the long-time performance of the system. Thus, we study a cost criterion obtained as weighted combinations of these criteria, extending to a general state and control space framework several recent results by Feinberg and Shwartz, and by Krass et al. In addition, a functional characterization is given for overtaking optimal policies, for problems with countable state spaces and compact control spaces; our approach is based on qualitative properties of the optimality equation for problems with an average cost criterion.Research partially supported by the Engineering Foundation under grant RI-A-93-10, in part by the National Science Foundation under grant NSF-INT 9201430, and in part by a grant from the AT&T Foundation.Research partially supported by the Air Force Office of Scientific Research under Grant F49620-92-J-0045, and in part by the National Science Foundation under Grant CDR-8803012. 相似文献
98.
MINIMUMPERIODCONTROLPROBLEMFORINFINITEDIMENSIONALSYSTEMPAHLIPINGLIXUNJINGManuscriptreceivedDecember12,1994.RevisedApril16... 相似文献
99.
§1. Introduction Oka [40] proved that any additive Cousin problem is solvable in a domain of holomorphyin Cn. Oka [41]-Cartan [2, 3]-Serre [46] generalized this as the theorem B for analyticcoherent sheaves over Stein spaces. J. P. Serre [47] proved… 相似文献
100.
一类无穷时滞微分系统的周期解和全局渐近稳定性 总被引:2,自引:0,他引:2
利用重合度理论中的延拓定理和微分不等式讨论一类无穷时滞微分系统的周期解的存在性和全局渐近稳定性,获得了简便的判别条件. 相似文献