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951.
In this paper, a two dimensional Voronoi cell element, formulated with creep, thermal and plastic strain, is applied for the numerical simulation of thermo-mechanical fatigue behavior for particulate reinforced composites. The relation between mechanical fatigue phases and thermal fatigue phases influences the thermo-mechanical fatigue behavior and cyclic creep damage. The topological features of micro-structure in particulate reinforced composites, such as the orientation, depth-width ratio, distribution and volume fraction of inclusions, have a great influence on thermo-mechanical behavior. Some related conclusions are obtained by examples of numerical simulation.The project supported by the Special Funds for the National Major Fundamental Research Projects (2004CB619304), the National Natural Science Foundation of China (10276020 and 50371042), the Key Grant Project of Chinese Ministry of Education (0306) 相似文献
952.
953.
纤维复合材料损伤过程的数值模拟 总被引:4,自引:0,他引:4
利用界面断裂力学和有限元法数值模拟纤维增强复合材料的细观损伤过程,研究各种主要破坏模式之间的相互转变和影响,指出以断裂能和混合度表示的界面性能是控制复合材料损伤过程的主要细观参数。分析了界面韧度对破坏性能的影响,探讨了基于破坏模式控制的复合材料韧度设计的新途径。 相似文献
954.
The present study aims at implementation of a strain rate dependent, non-linear, micro-mechanics material model for laminated, unidirectional polymer matrix composites into the explicit finite element code LSDYNA. The objective is to develop an accurate and simple micro-mechanical, rate dependent material model, which is computationally efficient. Within the model a representative volume cell is assumed. The stress-strain relation including rate dependent effects for the micro-model is derived for both shell elements and solid elements. Micro-failure criterion is presented for each material constituent and failure mode. The implemented model can deal with problems such as impact, crashworthiness, and failure analysis under quasi-static loads. The developed material model has a wide range of applications such as jet engine jackets, armor plates, and structural crashworthiness simulation. The deformation response of two representative composite materials with varying fiber orientation is presented using the described technique. The predicted results compare favorably to experimental values. 相似文献
955.
Hill condition and overall properties of composites 总被引:2,自引:0,他引:2
S. Hazanov 《Archive of Applied Mechanics (Ingenieur Archiv)》1998,68(6):385-394
Summary We discuss the Hill principle's role and applications in modern micromechanics of industrial composite materials. Uniform
boundary conditions, fundamental in micromechanics, are introduced as a class of Hill solutions. Mixed uniform conditions,
basic for experimental testing, are analysed. Domains of application of the Hill principle are reviewed, like homogeneization
of heterogeneous media, definition of effective properties and size effect in heterogeneous materials. Generalization of the
Hill condition is realized for arbitrary materials, in particular for nonlinear inelastic composites with imperfect interfaces.
Received 9 September 1997; accepted for publication 23 December 1997 相似文献
956.
S.R. Wang H.R. Geng Y.Z. Wang J.C. Zhang 《Theoretical and Applied Fracture Mechanics》2006,46(1):57-69
Magnesium matrix composites reinforced by three dimensional (3-D) network structure were fabricated by pressure-less infiltration technology. The 3-D network structure reinforcement and its composites exhibited special topology structure and different fracture characteristic. Metal matrix fractured in a ductile mode is manifested by small dimples and craters on the fracture surface. When the volume fraction of reinforcement is not in excess of 6%, the composite had an improved fracture toughness. This is because of the relatively homogeneous Si3N4 particles distributed in the metal matrix and the occurrence of interface reaction product such as MgAlO2 spinel phase. With the increases of volume fraction of reinforcement (>6%), the fracture toughness decreases slowly at the initial stages and then decreases rapidly towards the end. Therefore, the main fracture failure mechanisms consist of crack nucleation, growth, coalescence and crack propagation. 相似文献
957.
近年来发展的渐进结构优化方法是一种有前途的结构拓扑和形状优化方法.本文在渐进结构优化方法的框架内建立了统一敏感度的概念,并基于固定网格有限元技术,发展了一种新的增加材料技术,提出了双向固定网格渐进结构优化方法.将该方法应用于复合材料壳结构开孔形状优化,以孔周等Tsai-Hill强度值作为优化目标,可以得到合理的最优解,证明了双向固定网格渐进结构优化方法的适用性.不同的初始点能得到几乎相同的最优解,展示了本文方法良好的全局最优性. 相似文献
958.
从经典梁理论和弹性基础上的正交各向异性梁理论出发,分析了梁的弯曲剪切效应和弹性基础对用双悬臂梁试件测得的复合材料层合板Ⅰ型层间断裂韧性G_(IC)的影响,发现当试件的初始裂纹长度较短时,剪切效应和弹性基础对G_(IC)的影响是显著的,建议将初始裂纹长度取50毫米。实验结果表明,初始裂纹长度由20毫米增加到50毫米时,测得的G_(IC)值的离散系数降低20%~40%,数据趋于稳定,分散性减小。 相似文献
959.
This Note presents a new approximate scheme for nonlinear composites. The approximation which is made preserves certain features of the original second-order scheme of Ponte Castañeda, exactness to second-order in the contrast and existence of an effective energy, but improves on one drawback, which is the gap between the strain-energy formulation and the affine formulation. A numerical example shows the accuracy of the present method. To cite this article: N. Lahellec, P. Suquet, C. R. Mecanique 332 (2004). 相似文献
960.