全文获取类型
收费全文 | 471篇 |
免费 | 17篇 |
国内免费 | 24篇 |
专业分类
化学 | 23篇 |
晶体学 | 6篇 |
力学 | 103篇 |
综合类 | 4篇 |
数学 | 316篇 |
物理学 | 60篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 3篇 |
2021年 | 6篇 |
2020年 | 3篇 |
2019年 | 5篇 |
2018年 | 8篇 |
2017年 | 8篇 |
2016年 | 19篇 |
2015年 | 7篇 |
2014年 | 9篇 |
2013年 | 56篇 |
2012年 | 14篇 |
2011年 | 16篇 |
2010年 | 20篇 |
2009年 | 39篇 |
2008年 | 28篇 |
2007年 | 39篇 |
2006年 | 21篇 |
2005年 | 25篇 |
2004年 | 24篇 |
2003年 | 26篇 |
2002年 | 23篇 |
2001年 | 12篇 |
2000年 | 8篇 |
1999年 | 19篇 |
1998年 | 11篇 |
1997年 | 15篇 |
1996年 | 6篇 |
1995年 | 6篇 |
1994年 | 7篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1981年 | 2篇 |
排序方式: 共有512条查询结果,搜索用时 36 毫秒
451.
纵向剪切三相共焦点椭圆模型的精确解及其应用 总被引:3,自引:1,他引:2
推广夹杂问题的三相同心圆模型,提出了三相共焦点椭圆模型,从而计及了夹杂形状变化的重要因素。利用保角变换结合罗朗级数展开技术获得了纵向剪切载荷下的封闭形式解。本模型和解答对夹杂、界面层附近的细观应力场分析、对复合材料和含缺陷材料的有效弹性模量预测有重要实用价值,获得了比经典公式更精确的结果。对特殊模型,可以得到许多有意义的问题(如二相模型)的解答。 相似文献
452.
We present a comparison of computational results from light scattering by spherical particles with inclusions. The different simulation methods like the T-matrix method, multiple multipole method and the method of separation of variables are presented shortly. Exemplary numerical simulations involve scattering by particles with one or two spherical inclusions and scattering by particles with non-spherical inclusions. 相似文献
453.
基于不可逆热力学理论和内变量理论,提出平均意义下的Clausius_Duhem不等式方程·与以往弹塑性空洞损伤研究不同,本文旨在利用自洽分析法建立起既考虑空洞形状影响又考虑空洞之间相互作用的场方程,并使之能够处理空洞体积比较大的弹塑性损伤问题· 相似文献
454.
We study the sweeping processes in a Hilbert space which are generated by a closed not necessarily convex moving set. A technique is developed, based on measurability properties of normal cones, in order to prove existence of solutions. Some existence results are proved, with or without hypothesis of compactness; moreover, under suitable assumptions, uniqueness and regularity properties are established. In particular, the well-known results of Moreau are extended to a class of not necessarily convex (called -convex) sets. 相似文献
455.
H. Frankowska 《Journal of Optimization Theory and Applications》1989,60(2):277-296
We prove sufficient conditions for the instantaneous local controllability of nonlinear (nonsmooth) control systems with feedback. We introduce for that purpose the high-order variations of the reachable map, which is related strongly to its shape. It is a direction in which the reachable map evolves. The cone of variations is convex. This allows one to prove the following theorem: if there exist variationsv
1, ...,v
p
such that int co{v
1, ...,v
p
}, then the system is small-time locally controllable at the point of equilibrium. We provide a short proof of the main result of Sussmann (Ref. 12) and extend it to differential inclusions.This work was supported in part by FCAR of Canada. 相似文献
456.
A methodology for bulk analysis of Al and Ti and for determination of soluble and total Al and Ti concentration in steel samples by laser ablation inductively coupled plasma mass spectrometry was developed. The spatial distribution (both at surface and within the sample) of the insoluble fraction of Al and Ti was also qualitatively estimated. Certified reference materials (CRMs) SS-451 to 460 (carbon steel) and 064-1 (Nb/Ti interstitial free steel), from BAS, and JK 2D (carbon steel) and JK 37 (highly alloyed steel), from SIMR, were studied. It was demonstrated that the insoluble fraction of Al and Ti is heterogeneously distributed. A series of nine glass samples (fused beads) with fixed Fe content and different Al and Ti contents was prepared by melting appropriate amounts of Fe2O3, Al2O3 and TiO2 with a lithium tetraborate–sodium carbonate mixture. Quantitative determinations were performed by using calibration graphs obtained from the synthetic fused beads, with 57Fe as internal standard; line scan laser sampling mode was used, focusing the laser beam at the sample surface. The optimized laser operating parameters were: laser pulse energy of 1.5 mJ, pulse repetition rate of 5 Hz, scanning speed of 5 μm s−1 and preablation time of 20 s. The concentrations obtained for bulk analysis of CRM samples corresponded with the certified values within the experimental uncertainty. An acceptable concordance between certified and found values was attained for the determination of soluble and total Al and Ti in CRM 064-1 sample. 相似文献
457.
宋福民 《应用泛函分析学报》2005,7(1):13-21
旨在Banach空间中研究微分包含的周期边值问题(PBVP).假设F(t,u)仅满足弱Carathèodory条件,并不使用紧性条件,然而仍证明了该PBVP的唯一解能通过迭代序列的一致极限得到,并且还给出了解的误差估计. 相似文献
458.
Analyzing non-smooth mechanical systems requires often the solution of inclusion problems of normal cone type. These problems arise for example in the event-driven or time-stepping simulation approaches. Such inclusion problems can be written as non-linear equations, which can be solved iteratively. In this paper we discuss three different methods to derive the non-linear equations representing the inclusions arising in the event-driven simulation approach. First, we formulate inclusions describing the individual non-smooth constraints and solve them successively. Secondly, we interpret the non-linear equations as the conditions for the saddle point of the augmented Lagrangian function. As a third possibility we discuss the exact regularization of set-valued force laws. All three methods lead to the same numerical scheme, but give different insight into the problem. Especially the factor r occurring in the non-linear equations is discussed. Two iterative methods for solving the non-linear equations are presented together with some remarks on convergence. 相似文献
459.
In this paper, we introduce and study a new system of generalized mixed quasi-variational inclusions with (H,η)-monotone operators which contains variational inequalities, variational inclusions, systems of variational inequalities
and systems of variational inclusions in the literature as special cases. By using the resolvent technique for the (H,η)-monotone operators, we prove the existence of solutions and the convergence of some new p-step iterative algorithms for this system of generalized mixed quasi-variational inclusions and its special cases. The results
in this paper unifies, extends and improves some known results in the literature. 相似文献
460.
In this paper we consider second order differential inclusions in real Hilbert space, namely p(t)⋅x″(t)+r(t)⋅x′(t)∈Ax(t)+F(t,x(t)), a.e. on [0,T], under the nonlinear boundary conditions. Using techniques from multivalued analysis and the theory of operators of monotone type, we prove the existence of solutions for both the ‘convex’ and ‘nonconvex’ problems. Finally, we present a special case of interest, which fit into our framework, illustrating the generality of our results. 相似文献