全文获取类型
收费全文 | 5155篇 |
免费 | 722篇 |
国内免费 | 319篇 |
专业分类
化学 | 921篇 |
晶体学 | 17篇 |
力学 | 520篇 |
综合类 | 82篇 |
数学 | 3394篇 |
物理学 | 1262篇 |
出版年
2024年 | 10篇 |
2023年 | 48篇 |
2022年 | 46篇 |
2021年 | 85篇 |
2020年 | 135篇 |
2019年 | 131篇 |
2018年 | 157篇 |
2017年 | 204篇 |
2016年 | 213篇 |
2015年 | 164篇 |
2014年 | 212篇 |
2013年 | 409篇 |
2012年 | 224篇 |
2011年 | 297篇 |
2010年 | 227篇 |
2009年 | 263篇 |
2008年 | 310篇 |
2007年 | 355篇 |
2006年 | 329篇 |
2005年 | 296篇 |
2004年 | 219篇 |
2003年 | 242篇 |
2002年 | 225篇 |
2001年 | 202篇 |
2000年 | 162篇 |
1999年 | 157篇 |
1998年 | 137篇 |
1997年 | 124篇 |
1996年 | 82篇 |
1995年 | 85篇 |
1994年 | 66篇 |
1993年 | 56篇 |
1992年 | 50篇 |
1991年 | 38篇 |
1990年 | 27篇 |
1989年 | 24篇 |
1988年 | 25篇 |
1987年 | 15篇 |
1986年 | 17篇 |
1985年 | 16篇 |
1984年 | 13篇 |
1983年 | 8篇 |
1982年 | 18篇 |
1981年 | 13篇 |
1980年 | 22篇 |
1979年 | 10篇 |
1978年 | 5篇 |
1977年 | 11篇 |
1969年 | 2篇 |
1957年 | 3篇 |
排序方式: 共有6196条查询结果,搜索用时 31 毫秒
61.
A. I. Vanin 《Journal of Applied Spectroscopy》1997,64(2):242-245
Light scattering by groups of spherical particles is considered. It is shown that the structure of the groups and their orientational
distribution can be judged from the spectrum and polarization of the scattered light.
Syktyvkar State University, 55, Oktyabr'skii Ave., Syktyvkar, 167001, Russia. Translated from Zhurnal Prikladnoi Spektroskopii,
Vol. 64, No. 2, pp. 228–231, March–April, 1997. 相似文献
62.
In this paper, we propose and analyze an SQP-type method for solving linearly constrained convex minimization problems where the objective functions are too complex to be evaluated exactly. Some basic results for global convergence and local superlinear convergence are obtained according to the properties of the approximation sequence. We illustrate the applicability of our approach by proposing a new method for solving two-stage stochastic programs with fixed recourse. 相似文献
63.
研究一类食饵具常数存放且功能反应函数为次线性函数的食饵-捕食者模型,获得了一些平衡点全局渐近稳定,极限环存在惟一的充分条件.利用数值仿真检验了我们的结论. 相似文献
64.
§ 1 IntroductionConsiderthefollowingnonlinearoptimizationproblem :minimizef(x)subjecttoC(x) =0 , a≤x≤b ,( 1 .1 )wheref(x) :Rn→R ,C(x) =(c1(x) ,c2 (x) ,...,cm(x) ) T:Rn→Rm aretwicecontinuouslydifferentiable,m≤n ,a ,b∈Rn.Trustregionalgorithmsareveryeffectiveforsolvingnonlinearoptimi… 相似文献
65.
本文提出一个新的非线性最小二乘的信赖域方法,在该方法中每个信赖域子问题只需要一次求解,而且每次迭代的一维搜索步长因子是给定的,避开一维搜索的环节,大大地提高了算法效率.文中证明了在一定的条件下算法的全局收敛性. 相似文献
66.
Wei Mingjun Zhu Wanzhen 《Annals of Differential Equations》2007,23(4):511-518
In this paper we consider the system of classical particles coupled with a Klein-Gordon field in two dimensions.We establish a-priori-bounds on the solutions of this system with initial data satisfying a size restriction derived from conservation of energy.This result,together with the smoothing of"velocity averaging",yields the existence of global weak solutions to the corresponding restricted initial value problem.The size restriction is necessary since energy of the system is indefinite.Finally,we show that the weak solutions preserve the total mass. 相似文献
67.
Li Lin 《Annals of Differential Equations》2007,23(4):433-439
In this paper,we study some permanence and global stability to a nonau- tonomous nonlinear discrete single species system,and obtain some sufficient condition of global stability to the system. 相似文献
68.
文章讨论无界区域上GBBM方程的Cauchy问题,对方程的解进行了先验估计,并证明了在H1弱拓扑中整体吸引子的存在性. 相似文献
69.
Effect of the subdivision strategy on convergence and efficiency of some global optimization algorithms 总被引:2,自引:0,他引:2
Hoang Tuy 《Journal of Global Optimization》1991,1(1):23-36
We investigate subdivision strategies that can improve the convergence and efficiency of some branch and bound algorithms of global optimization. In particular, a general class of so called weakly exhaustive simplicial subdivision processes is introduced that subsumes all previously known radial exhaustive processes. This result provides the basis for constructing flexible subdivision strategies that can be adapted to take advantage of various problem conditions. 相似文献
70.
Parking Capacity and Pricing in Park'n Ride Trips: A Continuous Equilibrium Network Design Problem 总被引:2,自引:0,他引:2
In this paper we consider the problem of designing parking facilities for park'n ride trips. We present a new continuous equilibrium network design problem to decide the capacity and fare of these parking lots at a tactical level. We assume that the parking facilities have already been located and other topological decisions have already been taken.The modeling approach proposed is mathematical programming with equilibrium constraints. In the outer optimization problem, a central Authority evaluates the performance of the transport network for each network design decision. In the inner problem a multimodal traffic assignment with combined modes, formulated as a variational inequality problem, generates the share demand for modes of transportation, and for parking facilities as a function of the design variables of the parking lots. The objective is to make optimal parking investment and pricing decisions in order to minimize the total travel cost in a subnetwork of the multimodal transportation system.We present a new development in model formulation based on the use of generalized parking link cost as a design variable.The bilevel model is solved by a simulated annealing algorithm applied to the continuous and non-negative design decision variables. Numerical tests are reported in order to illustrate the use of the model, and the ability of the approach to solve applications of moderate size. 相似文献