全文获取类型
收费全文 | 856篇 |
免费 | 75篇 |
国内免费 | 240篇 |
专业分类
化学 | 120篇 |
晶体学 | 6篇 |
力学 | 714篇 |
综合类 | 33篇 |
数学 | 133篇 |
物理学 | 165篇 |
出版年
2024年 | 10篇 |
2023年 | 34篇 |
2022年 | 27篇 |
2021年 | 30篇 |
2020年 | 23篇 |
2019年 | 28篇 |
2018年 | 16篇 |
2017年 | 25篇 |
2016年 | 39篇 |
2015年 | 36篇 |
2014年 | 49篇 |
2013年 | 36篇 |
2012年 | 51篇 |
2011年 | 60篇 |
2010年 | 49篇 |
2009年 | 42篇 |
2008年 | 47篇 |
2007年 | 50篇 |
2006年 | 39篇 |
2005年 | 42篇 |
2004年 | 38篇 |
2003年 | 42篇 |
2002年 | 39篇 |
2001年 | 18篇 |
2000年 | 28篇 |
1999年 | 30篇 |
1998年 | 34篇 |
1997年 | 37篇 |
1996年 | 30篇 |
1995年 | 20篇 |
1994年 | 25篇 |
1993年 | 25篇 |
1992年 | 11篇 |
1991年 | 20篇 |
1990年 | 13篇 |
1989年 | 13篇 |
1988年 | 4篇 |
1987年 | 7篇 |
1986年 | 3篇 |
1982年 | 1篇 |
排序方式: 共有1171条查询结果,搜索用时 31 毫秒
991.
IntroductionIn the fracture mechanics studies for piezoelectric materials,differently electricboundary conditions at the crack surfaces have been proposed by many researchers.Forexample,for the sake of analytical simplification,the assumption that the cra… 相似文献
992.
本文设计了一种简单的双轴疲劳加载装置,将它安装在单轴疲劳试验机上可以实现双轴循环加载,在试样中产生具有一定应力比的同频率、同波形、同相位的双向拉-拉应力. 相似文献
993.
A new analytical model was established to describe the complex behavior of ceramic/metal armor under impact of deformable projectile by assuming some hypotheses. Three aspects were taken into account: the mushrooming deformation of the projectile, the fragment of ceramic tile and the formation and change of ceramic conoid and the deformation of the metal backup plate. Solving the set of equations, all the variables were obtained for the different impact velocities: the extent and particle velocity in rigid zone; the extent, cross-section area and particle velocity in plastic zone; the velocity and depth of penetration of projectile to the target; the reduction in volume and compressive strength of the fractured ceramic conoid; the displacement and movement velocity of the effective zone of backup plate. Agreement observed among analytical result, numerical simulation and experimental result confirms the validity of the model, suggesting the model developed can be a useful tool for ceramic/metal armor design. 相似文献
994.
本文运用瞬态激振的理论和方法,分析了火炮保险器杠杆轴过早破坏的原因,并通过实验给予验证。在此基础上,并提出了修改意见,为部队解决了一个实际问题。 相似文献
995.
A nonlinear finite element (FE) model based on domain switching was proposed to study the electromechanical behavior of ferroelectric ceramics. The incremental FE formulation was improved to avoid any calculation instability. The problems of mesh sensitivity and convergence, and the efficiency of the proposed nonlinear FE technique have been assessed to illustrate the versatility and potential accuracy of the said technique. The nonlinear electromechanical behavior, such as the hysteresis loops and butterfly curves, of ferroelectric ceramics subjected to both a uniform electric field and a point electric potential has been studied numerically. The results obtained are in good agreement with those of the corresponding theoretical and experimental analyses. Furthermore, the electromechanical coupling fields near (a) the boundary of a circular hole, (b) the boundary of an elliptic hole and (c) the tip of a crack, have been analyzed using the proposed nonlinear finite element method (FEM). The proposed nonlinear electromechanically coupled FEM is useful for the analysis of domain switching, deformation and fracture of ferroelectric ceramics.The project supported by the National Natural Science Foundation of China (10025209, 10132010 and 90208002), the Research Grants of the Council of the Hong Kong Special Administrative Region, China (HKU7086/02E) and the Key Grant Project of the Chinese Ministry of Education (0306) 相似文献
996.
997.
根据工程科研试验和生产的实际需要,本文提出了一种产生低周载荷,并把高周载荷与低周载荷复合起来的方法。 相似文献
998.
999.
本文应用弹塑性有限元计算技术结果,分析了目前疲劳寿命计算中常用的局部应力一应变法之一的Neuber 公式应用的局限性.文章指出:随着构件应力集中部位塑性区的扩大,Neuber 公式计算的结果误差 也随之扩大.因此,Neuber 公式只适合于小塑性区状态. 相似文献
1000.