全文获取类型
收费全文 | 2740篇 |
免费 | 126篇 |
国内免费 | 187篇 |
专业分类
化学 | 301篇 |
晶体学 | 5篇 |
力学 | 114篇 |
综合类 | 20篇 |
数学 | 2221篇 |
物理学 | 392篇 |
出版年
2024年 | 5篇 |
2023年 | 48篇 |
2022年 | 37篇 |
2021年 | 46篇 |
2020年 | 58篇 |
2019年 | 56篇 |
2018年 | 69篇 |
2017年 | 56篇 |
2016年 | 62篇 |
2015年 | 40篇 |
2014年 | 95篇 |
2013年 | 202篇 |
2012年 | 148篇 |
2011年 | 134篇 |
2010年 | 118篇 |
2009年 | 186篇 |
2008年 | 257篇 |
2007年 | 183篇 |
2006年 | 146篇 |
2005年 | 132篇 |
2004年 | 79篇 |
2003年 | 105篇 |
2002年 | 84篇 |
2001年 | 86篇 |
2000年 | 69篇 |
1999年 | 86篇 |
1998年 | 64篇 |
1997年 | 81篇 |
1996年 | 42篇 |
1995年 | 38篇 |
1994年 | 34篇 |
1993年 | 23篇 |
1992年 | 24篇 |
1991年 | 17篇 |
1990年 | 9篇 |
1989年 | 10篇 |
1988年 | 11篇 |
1987年 | 8篇 |
1986年 | 5篇 |
1985年 | 16篇 |
1984年 | 12篇 |
1983年 | 13篇 |
1982年 | 13篇 |
1981年 | 6篇 |
1980年 | 14篇 |
1979年 | 5篇 |
1978年 | 11篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1973年 | 2篇 |
排序方式: 共有3053条查询结果,搜索用时 375 毫秒
51.
Harro Lentz Ernst Ulrich Franck 《Angewandte Chemie (International ed. in English)》1978,17(10):728-730
Liquid or dense supercritical ammonia has been suggested as an extraction fluid. It is indeed good solvent for very different classes of compounds, as can be seen from phase diagrams. Such diagrams for binary systems of ammonia and hydrocarbons are presented and discussed on the basis of their critical curves. Apparatus and methods for the measurement of phase equilibria and equation of state data of fluid mixtures at high pressure are described. 相似文献
52.
53.
54.
K. C. Kiwiel 《Applied Mathematics and Optimization》1995,32(3):235-254
Letf: n (–, ] be a convex polyhedral function. We show that if any standard active set method for quadratic programming (QP) findsx(t)= arg min
x
¦x¦2/2+t
f(x) for somet> 0, then its final working set defines a simple equality QP subproblem, whose Lagrange multiplier can be used both for testing ift is large enough forx(t) to coincide with the normal minimizer off, and for increasingt otherwise. The QP subproblem may easily be solved via the matrix factorizations used for findingx(t). This opens up the way for efficient implementations. We also give finite methods for computing the whole trajectory {x(t)}
t
0, minimizingf over an ellipsoid, and choosing penalty parameters inL
1QP methods for strictly convex QP.This research was supported by the State Committee for Scientific Research under Grant 8S50502206. 相似文献
55.
In this paper, we introduce a potential reduction method for harmonically convex programming. We show that, if the objective function and them constraint functions are allk-harmonically convex in the feasible set, then the number of iterations needed to find an -optimal solution is bounded by a polynomial inm, k, and log(1/). The method requires either the optimal objective value of the problem or an upper bound of the harmonic constantk as a working parameter. Moreover, we discuss the relation between the harmonic convexity condition used in this paper and some other convexity and smoothness conditions used in the literature.The authors like to thank Dr. Hans Nieuwenhuis for carefully reading this paper and the anonymous referees for the worthy suggestions. 相似文献
56.
Luis A. Caffarelli Cristian E. Gutié rrez 《Transactions of the American Mathematical Society》1996,348(3):1075-1092
In this paper we consider a family of convex sets in , , , , satisfying certain axioms of affine invariance, and a Borel measure satisfying a doubling condition with respect to the family The axioms are modelled on the properties of the solutions of the real Monge-Ampère equation. The purpose of the paper is to show a variant of the Calderón-Zygmund decomposition in terms of the members of This is achieved by showing first a Besicovitch-type covering lemma for the family and then using the doubling property of the measure The decomposition is motivated by the study of the properties of the linearized Monge-Ampère equation. We show certain applications to maximal functions, and we prove a John and Nirenberg-type inequality for functions with bounded mean oscillation with respect to
57.
O. Naselli 《Journal of Optimization Theory and Applications》1996,91(1):81-90
In this paper, we present a class of functions:f:X such that inf
xX
f(x)=
, whereX is a nonempty, finitely compact and convex set in a vector space andB
x
={xX: y aff(X){x:[x, y]X={x}. Our main tool is a recent minimax theorem by Ricceri (Ref. 1). 相似文献
58.
Onk-StrictlyConvexandk-VerySmoothBanachSpacesZhangZihou(张子厚)(HuainanTelecisionUniversity,Huainan,Anhui,232001)Abstract:Inthis... 相似文献
59.
Pravin M. Vaidya 《Mathematical Programming》1996,73(3):291-341
Let
be a convex set for which there is an oracle with the following property. Given any pointz∈ℝ
n
the oracle returns a “Yes” ifz∈S; whereas ifz∉S then the oracle returns a “No” together with a hyperplane that separatesz fromS. The feasibility problem is the problem of finding a point inS; the convex optimization problem is the problem of minimizing a convex function overS. We present a new algorithm for the feasibility problem. The notion of a volumetric center of a polytope and a related ellipsoid
of maximum volume inscribable in the polytope are central to the algorithm. Our algorithm has a significantly better global
convergence rate and time complexity than the ellipsoid algorithm. The algorithm for the feasibility problem easily adapts
to the convex optimization problem. 相似文献
60.
In this paper, we present a general scheme for bundle-type algorithms which includes a nonmonotone line search procedure and for which global convergence can be proved. Some numerical examples are reported, showing that the nonmonotonicity can be beneficial from a computational point of view.This work was partially supported by the National Research Program on Metodi di ottimizzazione per le decisioni, Ministero dell' Universitá e della Ricerca Scientifica e Tecnologica and by ASI: Agenzia Spaziale Italiana. 相似文献