全文获取类型
收费全文 | 32446篇 |
免费 | 4747篇 |
国内免费 | 2471篇 |
专业分类
电工技术 | 17142篇 |
综合类 | 2656篇 |
化学工业 | 1070篇 |
金属工艺 | 816篇 |
机械仪表 | 1426篇 |
建筑科学 | 903篇 |
矿业工程 | 589篇 |
能源动力 | 1076篇 |
轻工业 | 444篇 |
水利工程 | 453篇 |
石油天然气 | 283篇 |
武器工业 | 162篇 |
无线电 | 5458篇 |
一般工业技术 | 1741篇 |
冶金工业 | 836篇 |
原子能技术 | 379篇 |
自动化技术 | 4230篇 |
出版年
2024年 | 139篇 |
2023年 | 467篇 |
2022年 | 730篇 |
2021年 | 951篇 |
2020年 | 1100篇 |
2019年 | 950篇 |
2018年 | 950篇 |
2017年 | 1355篇 |
2016年 | 1463篇 |
2015年 | 1689篇 |
2014年 | 2269篇 |
2013年 | 2130篇 |
2012年 | 2722篇 |
2011年 | 2856篇 |
2010年 | 2050篇 |
2009年 | 2161篇 |
2008年 | 2169篇 |
2007年 | 2416篇 |
2006年 | 2183篇 |
2005年 | 1669篇 |
2004年 | 1258篇 |
2003年 | 1110篇 |
2002年 | 874篇 |
2001年 | 837篇 |
2000年 | 661篇 |
1999年 | 483篇 |
1998年 | 329篇 |
1997年 | 299篇 |
1996年 | 263篇 |
1995年 | 227篇 |
1994年 | 204篇 |
1993年 | 162篇 |
1992年 | 123篇 |
1991年 | 99篇 |
1990年 | 72篇 |
1989年 | 48篇 |
1988年 | 41篇 |
1987年 | 21篇 |
1986年 | 22篇 |
1985年 | 15篇 |
1984年 | 24篇 |
1983年 | 16篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1978年 | 8篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1962年 | 3篇 |
1959年 | 3篇 |
1956年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 765 毫秒
1.
2.
This paper proposes a method for the coordinated control of power factor by means of a multiagent approach. The proposed multiagent system consists of two types of agent: single feeder agent (F_AG) and bus agent (B_AG). In the proposed system, an F_AG plays as an important role, which decides the power factors of all distributed generators by executing the load flow calculations repeatedly. The voltage control strategies are implemented as the class definition of Java into the system. In order to verify the performance of the proposed method, it has been applied to a typical distribution model system. The simulation results show that the system is able to control very violent fluctuation of the demands and the photovoltaic (PV) generations. 相似文献
3.
Dan Ye Kaiyu Wang Haijiao Yang Xingang Zhao 《International Journal of Adaptive Control and Signal Processing》2020,34(11):1677-1696
In this article, an adaptive fuzzy output feedback control method is presented for nonlinear time-delay systems with time-varying full state constraints and input saturation. To overcome the problem of time-varying constraints, the integral barrier Lyapunov functions (IBLFs) integrating with dynamic surface control (DSC) are applied for the first time to keep the state from violating constraints. The effects of unknown time delays can be removed by using designed Lyapunov-Krasovskii functions (LKFs). An auxiliary design system is introduced to solve the problem of input saturation. The unknown nonlinear functions are approximated by the fuzzy logic systems (FLS), and the unmeasured states are estimated by a designed fuzzy observer. The novel controller can guarantee that all signals remain semiglobally uniformly ultimately bounded and satisfactory tracking performance is achieved. Finally, two simulation examples illustrate the effectiveness of the presented control methods. 相似文献
4.
5.
In this paper, an adaptive control approach is designed for compensating the faults in the actuators of chaotic systems and maintaining the acceptable system stability. We propose a state‐feedback model reference adaptive control scheme for unknown chaotic multi‐input systems. Only the dimensions of the chaotic systems are required to be known. Based on Lyapunov stability theory, new adaptive control laws are synthesized to accommodate actuator failures and system nonlinearities. An illustrative example is studied. The simulation results show the effectiveness of the design method. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
6.
Volumetric mass transfer coefficients, kLa, just as power input are considered as essential parameters for mechanically agitated gas‐liquid contactors in relation to their optimization and design. The knowledge of power input is crucial for the prediction of other mass transfer characteristics. A power input correlation is created for the industrial design of the process with a non‐coalescent batch that would be appropriate for a broad range of operational conditions. The recommended resulting correlation is able to predict the power input for impellers in industrial‐scale design for a significant scope of operational conditions. 相似文献
7.
仪器仪表产品的脉冲耐压试验是产品型式试验、例行试验中的基本内容。通过对GB4793.1标准的整理,归纳了仪器仪表产品的脉冲耐压试验要求。通过对试验方法和设备特性的梳理,总结了特性参数,并介绍了应对脉冲耐压试验可采取的保护器件的类别及选用方法。 相似文献
8.
Frequency band selection (FBS) in rotating machinery fault diagnosis aims to recognize frequency band location including a fault transient out of a full band spectrum, and thus fault diagnosis can suppress noise influence from other frequency components. Impulsiveness and cyclostationarity have been recently recognized as two distinctive signatures of a transient. Thus, many studies have focused on developing quantification metrics of the two signatures and using them as indicators to guide FBS. However, most previous studies almost ignore another aspect of FBS, i.e. health reference, which significantly affect FBS performance. To address this issue, this paper investigates importance of a health reference and recognize it as the third critical aspect in FBS. With help of the health reference, the frequency band where the fault transient exists could be located. A novel approach based on classification is proposed to integrate all three aspects (impulsiveness, cyclostationarity, and health reference) for FBS. Classification accuracy is developed as a novel indicator to select the most sensitive frequency band for rotating machinery fault diagnosis. The proposed method (coined by accugram) has been validated on benchmark and experiment datasets. Comparison results show its effectiveness and robustness over conventional envelope analysis, the kurtogram, and the infogram. 相似文献
9.
为了减小传统的最差情况设计方法引入的电压裕量,提出了一种变化可知的自适应电压缩减(AVS)技术,通过调整电源电压来降低电路功耗.自适应电压缩减技术基于检测关键路径的延时变化,基于此设计了一款预错误原位延时检测电路,可以检测关键路径延时并输出预错误信号,进而控制单元可根据反馈回的预错误信号的个数调整系统电压.本芯片采用SMIC180 nm工艺设计验证,仿真分析表明,采用自适应电压缩减技术后,4个目标验证电路分别节省功耗12.4%,11.3%,10.4%和11.6%. 相似文献
10.
Madhab Chandra Tripathy Debasmita Mondal Karabi Biswas Siddhartha Sen 《International Journal of Circuit Theory and Applications》2015,43(6):776-792
The present work reports the realization of an analog fractional‐order phase‐locked loop (FPLL) using a fractional capacitor. The expressions for bandwidth, capture range, and lock range of the FPLL have been derived analytically and then compared with the experimental observations using LM565 IC. It has been observed that bandwidth and capture range can be extended by using FPLL. It has also been found that FPLL can provide faster response and lower phase error at the time of switching compared to its integer‐order counterpart. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献