首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   4056篇
  免费   526篇
  国内免费   391篇
电工技术   671篇
综合类   314篇
化学工业   307篇
金属工艺   210篇
机械仪表   941篇
建筑科学   44篇
矿业工程   33篇
能源动力   134篇
轻工业   16篇
水利工程   9篇
石油天然气   22篇
武器工业   96篇
无线电   685篇
一般工业技术   551篇
冶金工业   26篇
原子能技术   12篇
自动化技术   902篇
  2024年   9篇
  2023年   90篇
  2022年   73篇
  2021年   117篇
  2020年   150篇
  2019年   140篇
  2018年   145篇
  2017年   180篇
  2016年   213篇
  2015年   223篇
  2014年   227篇
  2013年   413篇
  2012年   209篇
  2011年   264篇
  2010年   206篇
  2009年   257篇
  2008年   252篇
  2007年   325篇
  2006年   282篇
  2005年   239篇
  2004年   195篇
  2003年   150篇
  2002年   114篇
  2001年   113篇
  2000年   104篇
  1999年   56篇
  1998年   51篇
  1997年   44篇
  1996年   27篇
  1995年   36篇
  1994年   18篇
  1993年   14篇
  1992年   14篇
  1991年   4篇
  1990年   8篇
  1989年   5篇
  1988年   3篇
  1987年   1篇
  1986年   1篇
  1985年   1篇
排序方式: 共有4973条查询结果,搜索用时 31 毫秒
71.
为精确控制采用燃爆直线型驱动器(combustion powered linear actuator,CPLA)的弹跳机器人,对影响CPLA驱动弹跳性能的因素进行了分析.首先根据CPLA的工作过程建立了CPLA的动力学模型,得到性能参数;然后试验分析氧化剂一氧化二氮(N2O)与燃料丙烷(C3H8)摩尔比、两者的充气压力对CPLA输出性能的影响.试验结果显示:影响确实存在,当摩尔比为9.91时,CPLA驱动弹跳高度最高,质量3.17 kg弹跳机构弹跳高度为3.2 m,CPLA能量利用率8.4%,弹跳效率7.01%.CPLA在驱动弹跳过程中输出很高的平均功率,并且具有很大的功率质量比.  相似文献   
72.
半球谐振陀螺仪频率裂解及固有刚性轴的测试方法   总被引:2,自引:0,他引:2  
半球谐振陀螺仪以其寿命长、可靠性高、体积小、重量轻、精度高而且可微型化的优点将在卫星、潜艇等导航领域有着广泛的应用前景。对半球谐振陀螺仪的而言,频率裂解值与固有刚性轴的位置是其关键的技术指标,因此设计测试方案对其进行精确测试是十分必要的。根据陀螺仪工作原理,从理论角度进行了推导,建立存在频率裂解及与固有刚性轴不重合时谐振子的运动方程,通过研究主驻波及辅助波的表达式,进而得到了振动位移的精确表达式,最后设计了在固定位置安装两组激励电极以及两组位移传感器对频率裂解以及固有刚性轴位置进行测试的测试方案,并给出了最佳的测试时间。  相似文献   
73.
This paper studies the problem of semi‐global leader‐following output consensus of a multi‐agent system. The output of each follower agent in the system, described by a same general linear system subject to external disturbances and actuator saturation, is to track the output of the leader, described by a linear system, which also generates disturbances as the exosystem does in the classical output regulation problem. Conditions on the agent dynamics are identified, under which a low‐gain feedback‐based linear state‐control algorithm is constructed for each follower agent such that the output consensus is achieved when the communication topology among the agents is a digraph containing no loop, and the leader is reachable from any follower agent. We also extend the results to the non‐identical disturbance case. In this case, conditions based on both the agent dynamics and the communication topology are identified, under which a low‐gain feedback‐based linear state‐control algorithm is constructed for each follower agent such that the leader‐following output consensus is achieved when the communication topology among the follower agents is a strongly connected and detailed balanced digraph, and the leader is a neighbor of at least one follower. In addition, under some further conditions on the agent dynamics, the control algorithm is adapted so as to achieve semi‐global leader‐following output consensus for a jointly connected undirected graph and the leader reachable from at least one follower. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
74.
This paper investigates the problems of controller design and stability analysis for singularly perturbed switched systems subject to actuator saturation. A set of well‐defined sufficient conditions for the existence of state feedback controllers is proposed, under which the closed‐loop system is locally asymptotically stable for arbitrary switching law as long as the singular perturbation parameter is sufficiently small. With the obtained controller, the estimation problem of stability bound and basin of attraction of the closed‐loop system is reduced to solving a convex optimization problem. A numerical example and a hydraulic servo position system are used to illustrate the obtained results. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
75.
A feedback linearization‐based adaptive control scheme is developed for multivariable nonlinear systems with redundant actuators subject to uncertain failures. Such an adaptive controller contains a direct adaptive actuator failure compensator to compensate the uncertain actuator failure, a nonlinear feedback to linearize the nonlinear dynamics, and a linear feedback to stabilize the linearized system. The key new design feature is the estimation of both the failure patterns and the failure values, for direct adaptive actuator failure compensation, newly developed for multivariable feedback linearizable nonlinear systems. With direct control signal adaptation, the adaptive failure compensation design ensures closed‐loop stability and asymptotic output tracking in the presence of actuator failure uncertainties. Simulation results from an application to attitude control of a near‐space vehicle dynamic model are presented to verify the desired system performance with adaptive actuator failure compensation. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
76.
In this paper, an adaptive fuzzy PD+ controller is proposed for the attitude maneuver of rigid spacecraft. The novel controller adjusts the gains of the PD+ attitude controller online according to attitude errors and angular velocity errors during the maneuver procedure. Therefore, quick response and avoidance of actuator saturation can be achieved simultaneously. Furthermore, the adaptation mechanism is designed, based on Lyapunov theory, to guarantee the stability of the closed‐loop system. To achieve good performance of the closed‐loop system under the constraint of actuator saturation, controller parameter optimization is developed on the basis of a genetic algorithm. Simulation results show that the transient performance and robustness against parametric uncertainty and environmental disturbance of the adaptive fuzzy PD+ controller are better than those of a constant PD+ controller.  相似文献   
77.
针对双余度舵机不同控制通道间速度环输出指令存在偏差、电流冲击和输出转矩波动等问题,本文提出了一种带温度补偿的双余度舵机伺服控制算法。首先,采用积分均衡的方法抑制传感器和双通道控制器解算误差引起的速度环输出指令的差异,然后采用电流截止负反馈的方法减小负载扰动和电机过渡过程带来的电流冲击,最后通过对电机进行温度补偿来减小环境温度和本体升温对输出转矩的影响。仿真结果表明,该算法能够有效抑制速度环输出指令误差和减小电流冲击,使电机在不同的工作温度下保持良好的性能。  相似文献   
78.
This paper presents an approach to design robust non‐fragile HL2 ? L static output feedback controller, considering actuator time‐delay and the controller gain variations, and it is applied to design vehicle active suspension. According to suspension design requirements, the H and L2 ? L norms are used, respectively, to reflect ride comfort and time‐domain hard constraints. By employing a delay‐dependent Lyapunov function, existence conditions of delay‐dependent robust non‐fragile static output feedback H controller and L2 ? L controller are derived, respectively, in terms of the feasibility of bilinear matrix inequalities. Then, a new procedure based on LMI optimization and a hybrid algorithm of the particle swarm optimization and differential evolution is used to solve an optimization problem with bilinear matrix inequality constraints. Simulation results show that the designed active suspension system still can guarantee their own performance in spite of the existence of the model uncertainties, the actuator time‐delay and the controller gain variations. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
79.
为有针对性地根据不同干扰类型选择正确的抗干扰措施,有必要对无人机数据链所处环境的干扰信号进行分析和分类识别。本文以变换域通信系统(Transform Domain Communication System,TDCS)为载体,对无人机数据链常面临的干扰类型的自动识别进行研究,采用时域、频域、时频联合分析的方法,提出了一组对干信比变化不敏感的特征参数,并利用这组参数提出一种基于决策树理论的干扰分类识别方法,仿真结果表明,该方法能够快速准确地识别出干扰类型,具有很好的鲁棒性,并且在干信比和干噪比在0dB以上时,正确识别率均在90%以上。  相似文献   
80.
蔡军 《自动化应用》2013,(11):22-25
介绍光电编码器的工作原理,提出电动执行机构电子行程部件的设计方法,分析光电编码器在电动执行机构应用中遇到的问题,并提出了解决方案.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号