全文获取类型
收费全文 | 1355篇 |
免费 | 94篇 |
国内免费 | 86篇 |
专业分类
化学 | 174篇 |
力学 | 156篇 |
综合类 | 30篇 |
数学 | 791篇 |
物理学 | 384篇 |
出版年
2023年 | 22篇 |
2022年 | 17篇 |
2021年 | 21篇 |
2020年 | 27篇 |
2019年 | 30篇 |
2018年 | 23篇 |
2017年 | 34篇 |
2016年 | 32篇 |
2015年 | 32篇 |
2014年 | 60篇 |
2013年 | 76篇 |
2012年 | 74篇 |
2011年 | 89篇 |
2010年 | 49篇 |
2009年 | 94篇 |
2008年 | 82篇 |
2007年 | 87篇 |
2006年 | 87篇 |
2005年 | 61篇 |
2004年 | 63篇 |
2003年 | 47篇 |
2002年 | 44篇 |
2001年 | 48篇 |
2000年 | 42篇 |
1999年 | 41篇 |
1998年 | 29篇 |
1997年 | 37篇 |
1996年 | 29篇 |
1995年 | 21篇 |
1994年 | 15篇 |
1993年 | 6篇 |
1992年 | 8篇 |
1991年 | 7篇 |
1990年 | 10篇 |
1989年 | 7篇 |
1988年 | 11篇 |
1987年 | 8篇 |
1986年 | 8篇 |
1985年 | 5篇 |
1984年 | 8篇 |
1983年 | 3篇 |
1982年 | 7篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1973年 | 2篇 |
1969年 | 3篇 |
排序方式: 共有1535条查询结果,搜索用时 828 毫秒
91.
Ekaterina Alekseeva Yuri Kochetov Alexander Plyasunov 《European Journal of Operational Research》2008
We study the complexity of finding local minima for the p-median problem. The relationship between Swap local optima, 0–1 local saddle points, and classical Karush–Kuhn–Tucker conditions is presented. It is shown that the local search problems with some neighborhoods are tight PLS-complete. Moreover, the standard local descent algorithm takes exponential number of iterations in the worst case regardless of the tie-breaking and pivoting rules used. To illustrate this property, we present a family of instances where some local minima may be hard to find. Computational results with different pivoting rules for random and Euclidean test instances are discussed. These empirical results show that the standard local descent algorithm is polynomial in average for some pivoting rules. 相似文献
92.
Chandra Sekhar Pedamallu Linet Özdamar Tibor Csendes Tamás Vinkó 《Journal of Global Optimization》2008,42(3):369-384
A new efficient interval partitioning approach to solve constrained global optimization problems is proposed. This involves
a new parallel subdivision direction selection method as well as an adaptive tree search. The latter explores nodes (intervals
in variable domains) using a restricted hybrid depth-first and best-first branching strategy. This hybrid approach is also
used for activating local search to identify feasible stationary points. The new tree search management technique results
in improved performance across standard solution and computational indicators when compared to previously proposed techniques.
On the other hand, the new parallel subdivision direction selection rule detects infeasible and suboptimal boxes earlier than
existing rules, and this contributes to performance by enabling earlier reliable deletion of such subintervals from the search
space. 相似文献
93.
BiNing HuangDaren 《高校应用数学学报(英文版)》2001,16(4):397-401
In this note, a criterion for orthonormality of refinable functions via characteristicpolynomial of a matrix is given. 相似文献
94.
We introduce a general method in order to construct the nonchiral fusion rules which determine the operator content of the operator product algebra for rational conformal field theories. We are particularly interested in the models of the complementary D-like solutions of the modular invariant partition functions with cyclic center Z
N
. We find that the nonchiral fusion rules have a Z
N
-grading structure. 相似文献
95.
Simple ingredients leading to very efficient heuristics for the maximum clique problem 总被引:2,自引:0,他引:2
Starting from an algorithm recently proposed by Pullan and Hoos, we formulate and analyze iterated local search algorithms
for the maximum clique problem. The basic components of such algorithms are a fast neighbourhood search (not based on node
evaluation but on completely random selection) and simple, yet very effective, diversification techniques and restart rules.
A detailed computational study is performed in order to identify strengths and weaknesses of the proposed algorithms and the
role of the different components on several classes of instances. The tested algorithms are very fast and reliable: most of
the DIMACS benchmark instances are solved within very short CPU times. For one of the hardest tests, a new putative optimum
was discovered by one of our algorithms. Very good performances were also shown on recently proposed and more difficult instances.
It is important to remark that the heuristics tested in this paper are basically parameter free (the appropriate value for
the unique parameter is easily identified and was, in fact, the same value for all problem instances used in this paper). 相似文献
96.
Numerical treatment of retarded boundary integral equations by sparse panel clustering 总被引:1,自引:0,他引:1
97.
General field theories are considered, within the functional differential formalism of quantum field theory, with interaction Lagrangian densities L
I
(x;λ), with λ a generic coupling constant, such that the following expression ∂
L
I
(x;λ)/∂
λ may be expressed as quadratic functions in dependent fields but may, in general, be arbitrary functions of independent fields. These necessarily include, as special cases, present renormalizable gauge theories. It is shown, in a unified manner,
that the vacuum-to-vacuum transition amplitude (the generating functional) may be explicitly derived in functional differential
form which, in general, leads to modifications to computational rules by including such factors as Faddeev–Popov ones and
modifications thereof which are explicitly obtained. The derivation is given in the presence of external sources and does not rely on any symmetry and invariance arguments as is often done in gauge theories and no
appeal is made to path integrals. 相似文献
98.
S. S. Dragomir 《Journal of Computational Analysis and Applications》2001,3(4):343-360
A generalization of Ostrowski integral inequality for mappings whose derivatives belong to L_1 [a,b], and applications for general quadrature formulae are given. 相似文献
99.
100.