全文获取类型
收费全文 | 417593篇 |
免费 | 33845篇 |
国内免费 | 23392篇 |
专业分类
电工技术 | 44279篇 |
技术理论 | 58篇 |
综合类 | 51082篇 |
化学工业 | 36359篇 |
金属工艺 | 15770篇 |
机械仪表 | 29166篇 |
建筑科学 | 50672篇 |
矿业工程 | 20846篇 |
能源动力 | 12118篇 |
轻工业 | 18100篇 |
水利工程 | 18377篇 |
石油天然气 | 16061篇 |
武器工业 | 4865篇 |
无线电 | 28645篇 |
一般工业技术 | 25167篇 |
冶金工业 | 21847篇 |
原子能技术 | 3707篇 |
自动化技术 | 77711篇 |
出版年
2024年 | 898篇 |
2023年 | 3994篇 |
2022年 | 7111篇 |
2021年 | 9050篇 |
2020年 | 10091篇 |
2019年 | 8243篇 |
2018年 | 7538篇 |
2017年 | 10024篇 |
2016年 | 11790篇 |
2015年 | 13221篇 |
2014年 | 25023篇 |
2013年 | 22261篇 |
2012年 | 28765篇 |
2011年 | 30810篇 |
2010年 | 24008篇 |
2009年 | 24916篇 |
2008年 | 23918篇 |
2007年 | 30626篇 |
2006年 | 28448篇 |
2005年 | 24932篇 |
2004年 | 21018篇 |
2003年 | 18787篇 |
2002年 | 15311篇 |
2001年 | 12880篇 |
2000年 | 10943篇 |
1999年 | 8893篇 |
1998年 | 6766篇 |
1997年 | 5964篇 |
1996年 | 5140篇 |
1995年 | 4353篇 |
1994年 | 3812篇 |
1993年 | 2835篇 |
1992年 | 2418篇 |
1991年 | 1817篇 |
1990年 | 1542篇 |
1989年 | 1347篇 |
1988年 | 1039篇 |
1987年 | 686篇 |
1986年 | 512篇 |
1985年 | 446篇 |
1984年 | 480篇 |
1983年 | 348篇 |
1982年 | 321篇 |
1981年 | 234篇 |
1980年 | 180篇 |
1979年 | 170篇 |
1978年 | 107篇 |
1977年 | 118篇 |
1976年 | 63篇 |
1975年 | 63篇 |
排序方式: 共有10000条查询结果,搜索用时 407 毫秒
81.
ABSTRACTThis paper deals with asymptotic stabilisation of a class of nonlinear input-delayed systems via dynamic output feedback in the presence of disturbances. The proposed strategy has the structure of an observer-based control law, in which the observer estimates and predicts both the plant state and the external disturbance. A nominal delay value is assumed to be known and stability conditions in terms of linear matrix inequalities are derived for fast-varying delay uncertainties. Asymptotic stability is achieved if the disturbance or the time delay is constant. The controller design problem is also addressed and a numerical example with an unstable system is provided to illustrate the usefulness of the proposed strategy. 相似文献
82.
某出口型号交流电力机车牵引控制系统要求变流器控制逻辑具备接触器控制、牵引系统数据交互、变流器故障保护、变流器启动自检等功能。针对以上功能,基于MATLAB中的Simulink/Stateflow可视化编程工具进行牵引控制模型的搭建,遵循模块化编程理念,采用较少的程序代码编写实现复杂的逻辑控制模型,生成逻辑清晰的控制功能流程图,进行半实物仿真测试,增强控制模型的可靠性。通过该变流器产品型式试验检验,验证变流器控制逻辑的功能可以满足控制系统的需求。 相似文献
83.
84.
冯鹏一 《信息通信技术与政策》2020,(1):12-15
以电信用户入网协议为切入点,电信用户的携号转网行为应受到《合同法》《消费者权益保护法》等私法规范的保护与限制。该行为引起的格式条款解释、合同终止、违约责任、损失赔偿等问题,不能仅靠《电信条例》等公法规范来调整。应当积极引导广大消费者用户以私法领域相关规定为依据,转变争议解决思维,拓宽纠纷处理途径,合理选择维权手段,以保护自身合法民事权益,与行业监管部门共同推动电信行业有序发展。 相似文献
85.
86.
This paper investigates a renewable energy resource’s application to the Load–Frequency Control of interconnected power system. The Proportional-Integral (PI) controllers are replaced with Proportional-Integral Plus (PI+) controllers in a two area interconnected thermal power system without/with the fast acting energy storage devices and are designed based on Control Performance Standards (CPS) using conventional/Beta Wavelet Neural Network (BWNN) approaches. The energy storing devices Hydrogen generative Aqua Electroliser (HAE) with Fuel cell and Redox Flow Battery (RFB) are incorporated to the two area interconnected thermal power system to efficiently damp out the electromechanical oscillations in the power system because of their inherent efficient storage capacity in addition to the kinetic energy of the generator rotor, which can share the sudden changes in power requirements. The system was simulated and the frequency deviations in area 1 and area 2 and tie-line power deviations for 5% step- load disturbance in area 1 are obtained. The comparison of frequency deviations and tie-line power deviations of the two area interconnected thermal power system with HAE and RFB designed with BWNN controller reveals that the PI+ controller designed using BWNN approach is found to be superior than that of output response obtained using PI+ controller. Moreover the BWNN based PI+ controller exhibits a better transient and steady state response for the interconnected power system with Hydrogen generative Aqua Electroliser (AE) unit than that of the system with Redox Flow Battery (RFB) unit. 相似文献
87.
88.
Although hybrid Petri net (HPN) is a popular formalism in modelling hybrid production systems, the HPN model of large scale systems gets substantially complicated for analysis and control due to large dimensionality of such systems. To overcome this problem, a typical approach is to decompose the net into subnets and then control the plant through hierarchical or decentralized structures. Although this concept has been widely discussed in the literature for discrete PNs, there is a lack of research for HPNs. In this paper, a new method of decomposition of first-order hybrid Petri nets (FOHPNs) is proposed first and then the hierarchical control of the subnets through a coordinator is introduced. The advantage of using the proposed approach is validated by an existing example. A sugar milling case study is analysed by using a decomposed FOHPN model and the optimization results are compared against the results of the approaches presented in other papers. Simulation results show not only an improvement in production rate, but also show the ability to control the plant online. In addition, by using the hierarchical control structure for an FOHPN model, it is possible to reduce the cost of communication links, improve the reliability of the system, maintain the plant locally, and partially redesign the system. 相似文献
89.
同忻选煤厂采用重介质选煤技术,磁性介质的消耗较大,为此,相关技术人员针对介质回收系统设备进行了改造设计。改造后,设备运行稳定,介质消耗降低,提高了原煤的分选效率,创造了较好的安全经济效益。 相似文献
90.
利用模糊控制和比例积分微分(PID)控制相结合的手段对注塑机料筒温度进行了控制,同时以Matlab 6.0软件为仿真平台,对料筒温度控制进行了模拟仿真研究。实验发现,在注塑机料筒升温过程中利用CHR整定的PID控制手段和模糊控制手段,恒温过程中利用人工整定的PID控制手段,可保证快速的料筒升温响应速率和稳定的保温过程。通过实际注塑实验对该仿真结果进行了验证,在十组实验中,料筒温度误差不超过2%,产品翘曲变形量不超过0.059 mm。 相似文献