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   15680篇
  免费   1321篇
  国内免费   1024篇
电工技术   3610篇
综合类   1572篇
化学工业   514篇
金属工艺   559篇
机械仪表   1877篇
建筑科学   240篇
矿业工程   454篇
能源动力   340篇
轻工业   247篇
水利工程   123篇
石油天然气   260篇
武器工业   199篇
无线电   2543篇
一般工业技术   414篇
冶金工业   357篇
原子能技术   132篇
自动化技术   4584篇
  2024年   56篇
  2023年   149篇
  2022年   195篇
  2021年   270篇
  2020年   383篇
  2019年   315篇
  2018年   276篇
  2017年   465篇
  2016年   472篇
  2015年   565篇
  2014年   860篇
  2013年   836篇
  2012年   1112篇
  2011年   1247篇
  2010年   931篇
  2009年   892篇
  2008年   979篇
  2007年   1241篇
  2006年   1136篇
  2005年   1036篇
  2004年   805篇
  2003年   718篇
  2002年   640篇
  2001年   488篇
  2000年   434篇
  1999年   376篇
  1998年   254篇
  1997年   190篇
  1996年   172篇
  1995年   124篇
  1994年   111篇
  1993年   59篇
  1992年   77篇
  1991年   45篇
  1990年   34篇
  1989年   27篇
  1988年   20篇
  1987年   8篇
  1986年   12篇
  1984年   2篇
  1983年   1篇
  1982年   3篇
  1981年   2篇
  1980年   2篇
  1979年   1篇
  1966年   1篇
  1961年   1篇
  1959年   2篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
针对动目标围捕过程对Multi-UUV编队结构的灵活性要求较高的问题,基于欠驱动UUV的数学模型,在目标轨迹能够准确预测的前提下,改进了协调编队运动控制器。协调编队运动控制器的控制目标是在Multi-UUV编队跟踪并围捕动目标过程中,避免Multi-UUV之间,UUV与障碍物以及UUV与动目标之间的碰撞并以稳定的编队结构围捕动目标。将控制器设计过程分解为运动学控制和动力学控制。在运动学控制部分,实现动目标跟踪、UUV之间避撞及UUV偏航角误差为零的控制目标。在动力学控制部分,应用反步法设计实际的控制输入。仿真案例验证了协调运动控制器在动目标围捕中的有效性。  相似文献   
72.
本文针对精馏塔不稳定时滞过程,提出一种基于设定值加权的分数阶PIλDμ控制器设计方法.首先采用比例环节构成内环反馈镇定不稳定时滞过程,然后基于等效的过程模型,依据设定值加权方法设计分数阶PIλDμ控制器,并进行了控制器参数整定.仿真结果表明:分数阶PIλDμ控制器可以使精馏塔不稳定时滞过程系统获得良好的动态响应特性,干扰抑制特性以及克服系统参数变化的鲁棒性.  相似文献   
73.
本文结合设计需求,提出了一种SPI主模式的接口电路设计,使其可以在多种SPI传输模式下进行数据的传输,且针对实时信息处理占用时间较长的不足,采取信息自动加载方法,有效降低了处理器占用时间.设计并搭建仿真验证平台对其进行验证.仿真测试结果表明,该SPI总线接口电路满足实际应用需求.  相似文献   
74.
This paper presents a timing controller embedded driver (TED) IC with 3.24‐Gbps embedded display port (eDP), which is implemented using a 45‐nm high‐voltage CMOS process for the chip‐on‐glass (COG) TFT‐LCD applications. The proposed TED‐IC employs the input offset calibration scheme, the zero‐adjustable equalizer, and the phase locked loop‐based bang‐bang clock and data recovery to enhance the maximum data rate. Also, the proposed TED‐IC provides efficient power management by supporting advanced link power management feature of eDP standard v1.4. Additionally, the smart charge sharing is proposed to reduce the dynamic power consumption of output buffers. Measured result demonstrates the maximum data rate of 3.24 Gbps from a 1.1 V supply voltage with a 7.9‐inch QXGA 60‐Hz COG‐LCD prototype panel and 44% power saving from the display system.  相似文献   
75.
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   
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.
In system identification, a data set needs to be informativeto ensure that the identification criterion has a unique global minimum asymptotically, and the parameter estimation is consistent. To guarantee a data set in a MIMO closed‐loop system with a switching controller to be informative, we develop a group of flexible conditions for the controller's switching rule and feedback laws, which provide a trade‐off between these two aspects through adjustable parameters. Compared with the results in the existing literature, our result includes all kinds of switching rules and therefore is not limited by the constraints on the switching rule.Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
78.
The position control system of an electro-hydraulic actuator system (EHAS) is investigated in this paper. The EHAS is developed by taking into consideration the nonlinearities of the system: the friction and the internal leakage. A variable load that simulates a realistic load in robotic excavator is taken as the trajectory reference. A method of control strategy that is implemented by employing a fuzzy logic controller (FLC) whose parameters are optimized using particle swarm optimization (PSO) is proposed. The scaling factors of the fuzzy inference system are tuned to obtain the optimal values which yield the best system performance. The simulation results show that the FLC is able to track the trajectory reference accurately for a range of values of orifice opening. Beyond that range, the orifice opening may introduce chattering, which the FLC alone is not sufficient to overcome. The PSO optimized FLC can reduce the chattering significantly. This result justifies the implementation of the proposed method in position control of EHAS.  相似文献   
79.
Discrete linear quadratic control has been efciently applied to linear systems as an optimal control.However,a robotic system is highly nonlinear,heavily coupled and uncertain.To overcome the problem,the robotic system can be modeled as a linear discrete-time time-varying system in performing repetitive tasks.This modeling motivates us to develop an optimal repetitive control.The contribution of this paper is twofold.For the frst time,it presents discrete linear quadratic repetitive control for electrically driven robots using the mentioned model.The proposed control approach is based on the voltage control strategy.Second,uncertainty is efectively compensated by employing a robust time-delay controller.The uncertainty can include parametric uncertainty,unmodeled dynamics and external disturbances.To highlight its ability in overcoming the uncertainty,the dynamic equation of an articulated robot is introduced and used for the simulation,modeling and control purposes.Stability analysis verifes the proposed control approach and simulation results show its efectiveness.  相似文献   
80.
CAN总线是一种成熟的串行通信总线,它具有可靠性高、稳定性好、抗干扰能力强、通信速率高、维护成本低、实时性强、很好的开放性及数据兼容性等优点。CAN总线这些众多的优点使其广泛应用于工业自动化控制等领域。其应用的广泛性则进一步对CAN总线IP提出了需求。同时以IP实现的CAN总线控制器所具有的通用处理器访问接口,良好的可移植性等优点使其可以集成于各种嵌入式SoC设计中。文中从CAN总线的规范和特点出发,提出了CAN总线控制器IP核的特点并定义了其功能,采用Verilog语言设计实现了CAN总线控制器IP核的功能,最后通过仿真和FPGA原型验证,证明了设计实现的正确性。目前CAN总线控制器IP核已经应用于SOPC和SoC的嵌入式应用设计中。  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