全文获取类型
收费全文 | 269篇 |
免费 | 32篇 |
国内免费 | 16篇 |
专业分类
化学 | 53篇 |
力学 | 127篇 |
综合类 | 1篇 |
数学 | 32篇 |
物理学 | 104篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 6篇 |
2021年 | 7篇 |
2020年 | 16篇 |
2019年 | 10篇 |
2018年 | 11篇 |
2017年 | 13篇 |
2016年 | 21篇 |
2015年 | 18篇 |
2014年 | 19篇 |
2013年 | 14篇 |
2012年 | 11篇 |
2011年 | 12篇 |
2010年 | 12篇 |
2009年 | 11篇 |
2008年 | 15篇 |
2007年 | 19篇 |
2006年 | 15篇 |
2005年 | 10篇 |
2004年 | 11篇 |
2003年 | 10篇 |
2002年 | 8篇 |
2001年 | 10篇 |
2000年 | 4篇 |
1999年 | 10篇 |
1998年 | 6篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1981年 | 1篇 |
排序方式: 共有317条查询结果,搜索用时 109 毫秒
11.
Optically driven actuators have a feature of a non-contact method supplied by light energy. A new method is proposed with
three poly(vinylidene difluoride) (PVDF) cantilevers as the legs and a polymer film as the body. The PVDF cantilevers are
coated with silver on one surface. When one side of the cantilever is irradiated by a laser beam, an electric field is produced
along a cross-section of the cantilever by the pyroelectric effect and a mechanical displacement occurs by the piezoelectric
effect. Its response time and its generated force are measured experimentally. Two types of optically driven actuators using
PVDF film are proposed to move using different characteristics. 相似文献
12.
We address the problem of inverse dynamics for flexible multibodies, which arises, in trajectory tracking control of flexible multibodies such as space manipulators and articulated flexible structures. Previous research has resolved this trajectory tracking problem by computing the system inputs for feedforward control of actuators at the joints. Recently, the use of distributed actuators like electro-strictive actuators in flexible structures has introduced a new dimension to this trajectory tracking problem. In this paper we optimally utilize such actuators to aid joint actuators for tracking control, and introduce a new inverse dynamics scheme for simultaneously (1) tracking a prescribed trajectory and (2) minimizing ensuing elastic deflections. We apply this scheme for trajectory tracking of a two-link two-joint planar manipulator with joint motors and distributed electro-strictive actuators. Experimental results are presented to contrast our new scheme with other existing methods. 相似文献
13.
Functionally graded piezoelectric cantilever beam under load 总被引:3,自引:0,他引:3
Summary In the present paper, the problem of a functionally graded piezoelectric cantilever beam subjected to different loadings is studied. The piezoelectric beam is characterized by continuously graded properties for one elastic parameter and the material density. A pair of stress and induction functions in the form of polynomials is proposed and determined. Based on these functions, a set of analytical solutions for the beam subjected to different loadings is obtained. As particular cases, series of solutions for some canonical problems can be directly obtained from the solutions of the present paper, such as for the problems of a piezoelectric cantilever beam with constant body force or without body forces, etc.This research work is supported by the National Natural Science Foundation of China (50272003). Support was also given by the Teaching and Research Award Fund for Outstanding Young Teachers in Higher Education Institutions of MOE, P.R.C. 相似文献
14.
15.
Thomas Hellweg 《Journal of polymer science. Part A, Polymer chemistry》2013,51(14):1073-1083
Core–shell microgels are of increasing interest as smart carriers of catalysts, as sensors, or as building blocks for colloidal superstructures. In the context of colloidal assemblies, photonic applications are probably the most promising ones. This progress report presents and discusses the most recent results in this area focusing on the last 2–3 years, and also gives some background information. In addition, potential perspectives of this area will be outlined. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1073–1083 相似文献
16.
17.
形状记忆合金作动器的设计及优化 总被引:11,自引:1,他引:11
采用Brision[1]等提出的SMA材料的本构关系,分析了形状记忆合金作动器在三种热交换方式(自然冷却、强制冷却和采用半导体热泵技术)下的动力特性,同时研究了SMA丝在恒载和载荷变化时对完成正逆相变所用时间的影响,并简单讨论了影响作动器响应的几个因素和改进方法 相似文献
18.
静电梳齿微驱动器因其结构简单、功耗低、灵敏度高、受温度影响小,成为硅微陀螺仪的主要驱动方式。静电梳齿微驱动器通常由活动梳齿和固定梳齿组成。理想情况下,活动梳齿平行地位于两固定梳齿中心位置。但由于加工误差、驱动结构不对称、扰动等因素,使得活动梳齿相对固定梳齿发生偏转。该文应用能量法及虚功原理,建立了梳齿之间的力与力矩平衡方程。得出了非理想情况下,偏离距离和转角的解析表达式,并分析得出了梳齿间的临界电压。经过数值仿真发现,梳齿面内既偏转又转动时的临界电压小于只发生偏转或转动时的临界电压。 相似文献
19.
Lyapunov exponents as a criterion for the dynamic pull-in instability of electrostatically actuated microstructures 总被引:1,自引:0,他引:1
Slava Krylov 《International Journal of Non》2007,42(4):626-642
The dynamic pull-in instability of double clamped microscale beams actuated by a suddenly applied distributed electrostatic force and subjected to non-linear squeeze film damping is investigated. A reduced order model is built using the Galerkin decomposition with undamped linear modes as base functions and verified through comparison with numerical finite differences solution. The stability analysis of a beam actuated by one and two electrodes symmetrically located at two sides of the beam and operated by a step-input voltage is performed by evaluating the largest Lyapunov exponent, the sign of which defines the character of the response. It is shown that this approach provides an efficient quantitative criterion for the evaluation of dynamic pull-in instability, especially when combined with compact reduced order models. Based on the Lyapunov exponent criterion, the influence of various parameters on the beam dynamic stability is investigated. 相似文献
20.
主动振动控制中传感/作动元件配置问题的全局优化方法研究 总被引:7,自引:0,他引:7
提出了一种主动振动控制中作动/传感元件位置的复合优化方法,它能有效地解决全局优化配置问题;通过对单点并置问题的优化,证明了该优化方法的有效性,并对多点配置问题也具有一定的参考价值。 相似文献