全文获取类型
收费全文 | 3022篇 |
免费 | 208篇 |
国内免费 | 215篇 |
专业分类
化学 | 904篇 |
晶体学 | 3篇 |
力学 | 204篇 |
综合类 | 37篇 |
数学 | 1781篇 |
物理学 | 516篇 |
出版年
2024年 | 4篇 |
2023年 | 44篇 |
2022年 | 52篇 |
2021年 | 38篇 |
2020年 | 85篇 |
2019年 | 97篇 |
2018年 | 78篇 |
2017年 | 101篇 |
2016年 | 100篇 |
2015年 | 93篇 |
2014年 | 146篇 |
2013年 | 244篇 |
2012年 | 130篇 |
2011年 | 185篇 |
2010年 | 147篇 |
2009年 | 238篇 |
2008年 | 220篇 |
2007年 | 201篇 |
2006年 | 163篇 |
2005年 | 177篇 |
2004年 | 120篇 |
2003年 | 111篇 |
2002年 | 94篇 |
2001年 | 90篇 |
2000年 | 76篇 |
1999年 | 65篇 |
1998年 | 69篇 |
1997年 | 57篇 |
1996年 | 28篇 |
1995年 | 29篇 |
1994年 | 23篇 |
1993年 | 21篇 |
1992年 | 11篇 |
1991年 | 8篇 |
1990年 | 11篇 |
1989年 | 8篇 |
1988年 | 10篇 |
1987年 | 6篇 |
1986年 | 10篇 |
1985年 | 7篇 |
1984年 | 12篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1974年 | 1篇 |
1936年 | 1篇 |
排序方式: 共有3445条查询结果,搜索用时 15 毫秒
1.
In this paper, we study the local linear convergence properties of a versatile class of Primal–Dual splitting methods for minimizing composite non-smooth convex optimization problems. Under the assumption that the non-smooth components of the problem are partly smooth relative to smooth manifolds, we present a unified local convergence analysis framework for these methods. More precisely, in our framework, we first show that (i) the sequences generated by Primal–Dual splitting methods identify a pair of primal and dual smooth manifolds in a finite number of iterations, and then (ii) enter a local linear convergence regime, which is characterized based on the structure of the underlying active smooth manifolds. We also show how our results for Primal–Dual splitting can be specialized to cover existing ones on Forward–Backward splitting and Douglas–Rachford splitting/ADMM (alternating direction methods of multipliers). Moreover, based on these obtained local convergence analysis result, several practical acceleration techniques are discussed. To exemplify the usefulness of the obtained result, we consider several concrete numerical experiments arising from fields including signal/image processing, inverse problems and machine learning. The demonstration not only verifies the local linear convergence behaviour of Primal–Dual splitting methods, but also the insights on how to accelerate them in practice. 相似文献
2.
Gauss periods give an exponentiation algorithm that is fast for many finite fields but slow for many other fields. The current paper presents a different method for construction of elements that yield a fast exponentiation algorithm for finite fields where the Gauss period method is slow or does not work. The basic idea is to use elements of low multiplicative order and search for primitive elements that are binomial or trinomial of these elements. Computational experiments indicate that such primitive elements exist, and it is shown that they can be exponentiated fast. 相似文献
3.
最速下降规则不失为一可用规则 总被引:5,自引:4,他引:1
本从统计意义上平均迭代次数的观点出发,指出求解线性规划的最速下降规则是可取的,好用的。 相似文献
4.
《Magnetic resonance in chemistry : MRC》2003,41(6):417-430
A systematic study of the one‐bond and long‐range J(C,C), J(C,H) and J(H,H) in the series of nine bicycloalkanes was performed at the SOPPA level with special emphasis on the coupling transmission mechanisms at bridgeheads. Many unknown couplings were predicted with high reliability. Further refinement of SOPPA computational scheme adjusted for better performance was carried out using bicyclo[1.1.1]pentane as a benchmark to investigate the influence of geometry, basis set and electronic correlation. The calculations performed demonstrated that classical ab initio SOPPA applied with the locally dense Dunning's sets augmented with inner core s‐functions used for coupled carbons and Sauer's sets augmented with tight s‐functions used for coupled hydrogens performs perfectly well in reproducing experimental values of different types of coupling constants (the estimated reliability is ca 1–2 Hz) in relatively large organic molecules of up to 11 carbon atoms. Additive coupling increments were derived for J(C,C), J(C,H) and J(H,H) based on the calculated values of coupling constants within SOPPA in the model bicycloalkanes, in reasonably good agreement with the known values obtained earlier on pure empirical grounds. Most of the bridgehead couplings in all but one bicycloalkane appeared to be essentially additive within ca 2–3 Hz while bicyclo[1.1.1]pentane demonstrated dramatic non‐additivity of ?14.5 Hz for J(C,C), +16.6 Hz for J(H,H) and ?5.5 Hz for J(C,H), in line with previous findings. Non‐additivity effects in the latter compound established at the SOPPA level should be attributed to the through‐space non‐bonded interactions at bridgeheads due to the essential overlapping of the bridgehead rear lobes which provides an additional and effective non‐bonding coupling path for the bridgehead carbons and their protons in the bicyclopentane framework. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
5.
Stefan Weigert 《Czechoslovak Journal of Physics》2004,54(1):147-149
The eigenstates of a diagonalizable PT-symmetric Hamiltonian satisfy unconventional completeness and orthonormality relations. These relations reflect the properties of a pair of bi-orthonormal bases associated with non-hermitean diagonalizable operators. In a similar vein, such a dual pair of bases is shown to possess, in the presence of PT symmetry, a Gram matrix of a particular structure: its inverse is obtained by simply swapping the signs of some its matrix elements. 相似文献
6.
Robust linear optimization under general norms 总被引:1,自引:0,他引:1
We explicitly characterize the robust counterpart of a linear programming problem with uncertainty set described by an arbitrary norm. Our approach encompasses several approaches from the literature and provides guarantees for constraint violation under probabilistic models that allow arbitrary dependencies in the distribution of the uncertain coefficients. 相似文献
7.
多小波子空间上的单小波表示 总被引:1,自引:0,他引:1
本文在较弱的条件下,建立了2重多小波子空间与单小波子空间的关系.即由2重多小波构造出单小波.一方面,这种单小波的平移伸缩与2重多小波的平移伸缩生成的子空间是完全相同的;另一方面,它具有插值性.因此通过构造出的单小波建立了多小波子空间上的Shannon型采样定理. 相似文献
8.
Xu Tianzhou 《东北数学》1997,(1)
ModulesoverOperatorAlgebrasandItsModuleMapsXuTianzhou(许天周)(DepartmentofMathematics,NanjingUniersity,Nanjing,210093)AbstractLe... 相似文献
9.
Banach空间上的框架与Riesz基 总被引:5,自引:0,他引:5
本文讨论Banach空间上框架、无冗框架与Riesz基之间的关系及它们的稳定性. 相似文献
10.