全文获取类型
收费全文 | 2638篇 |
免费 | 243篇 |
国内免费 | 140篇 |
专业分类
电工技术 | 621篇 |
综合类 | 237篇 |
化学工业 | 207篇 |
金属工艺 | 58篇 |
机械仪表 | 160篇 |
建筑科学 | 122篇 |
矿业工程 | 404篇 |
能源动力 | 85篇 |
轻工业 | 81篇 |
水利工程 | 49篇 |
石油天然气 | 53篇 |
武器工业 | 22篇 |
无线电 | 317篇 |
一般工业技术 | 48篇 |
冶金工业 | 251篇 |
原子能技术 | 14篇 |
自动化技术 | 292篇 |
出版年
2024年 | 9篇 |
2023年 | 21篇 |
2022年 | 60篇 |
2021年 | 62篇 |
2020年 | 59篇 |
2019年 | 45篇 |
2018年 | 43篇 |
2017年 | 92篇 |
2016年 | 77篇 |
2015年 | 84篇 |
2014年 | 127篇 |
2013年 | 138篇 |
2012年 | 188篇 |
2011年 | 192篇 |
2010年 | 162篇 |
2009年 | 157篇 |
2008年 | 138篇 |
2007年 | 172篇 |
2006年 | 167篇 |
2005年 | 93篇 |
2004年 | 137篇 |
2003年 | 115篇 |
2002年 | 91篇 |
2001年 | 90篇 |
2000年 | 89篇 |
1999年 | 75篇 |
1998年 | 41篇 |
1997年 | 42篇 |
1996年 | 48篇 |
1995年 | 37篇 |
1994年 | 36篇 |
1993年 | 26篇 |
1992年 | 17篇 |
1991年 | 14篇 |
1990年 | 20篇 |
1989年 | 8篇 |
1988年 | 15篇 |
1987年 | 12篇 |
1986年 | 2篇 |
1984年 | 3篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1977年 | 2篇 |
排序方式: 共有3021条查询结果,搜索用时 46 毫秒
81.
82.
基于LDO限流技术的辐射闩锁防护技术 总被引:2,自引:0,他引:2
讨论了CMOS器件受辐射感生的闩锁与电气感生的闩锁的异同点,研究并提出了一种基于限流型低压降线性调整器的闩锁防护方法,给出了卫星用线性调整器电路的地面总剂量摸底试验数据及空间飞行试验验证结果和解决星载计算机的闩锁防护与恢复问题的有效方法. 相似文献
83.
调节阀中不同阀瓣型线构成的通道,其局部流阻是不一样的。通过应用ANSYS2软件对DN50mmZVF型调节阀几种阀瓣型线在不同开度下构成的通道结构模型进行计算,从而得出流阻系数与开度的关系,并通过比较得到最佳阀瓣型线。该方法有很好的工程应用价值。 相似文献
84.
85.
介绍了CDW43S-80X4000S特大型七辊板料校平机电气控制系统,并对系统中直流调速装置的主从控制方式作了说明。 相似文献
86.
This paper focuses on the control of a low temperature ethanol steam reformer for in-situ hydrogen production. For this purpose, three optimization-based control configurations are proposed, namely, a linear model-based predictive controller, a linear quadratic regulator with output error integral action and a cascade control combining the two previous configurations. In all cases, control objectives aim at obtaining the desired flow of hydrogen while keeping the carbon monoxide at its nominal working point under input and output operational constraints. Output tracking and robustness of each configuration are compared using two key performance indicators that evaluate the output errors and the smoothness of the control signals. Simulation results allow to compare the characteristics of each control configuration when applied to the non-linear model of the ethanol steam reformer. 相似文献
87.
88.
Abstract In this paper, a simple practical analytic method is proposed for designing multiloop‐controlled pulse width modulation (PWM) switching regulators. First, an equivalent single loop gain is presented and an approximate optimal set of closed‐loop poles is suggested according to the given specification such that the familiar design concept of a single‐loop second order system can be applied directly. In particular, closed form expressions of the feedback gains and the unknown parameters of the standard implemented circuit are derived. This renders the implementation problem surprisingly simple. Finally, some experimental results are also presented to demonstrate the effectiveness of the proposed method. 相似文献
89.
This paper presents novel power system stabilizers (PSS) tuning approach with particles swarm optimization (PSO) driven knowledge domain states mapping for multi area power system. Tuning of PSS parameters has been done by PSO technique offline at different operating conditions as load dynamics change. The objective function for PSS parameters tuning is integral time multiplied by absolute error (ITAE). The sets of tuned parameters at different operating conditions thus obtained are termed as knowledge domain. The process is viewed as knowledge domain mapping. The dynamical system response has been linked with states, and if there is any violation from desired limits, control action is initiated and thus retuned control parameters obtained straight away from the respective knowledge domain helps to provide quick response and precise damping of signals of interest. Proposed concept also demonstrates that if one controller (PSS) fails to stabilize the system at certain operating condition then another controller (UPFC) connected in the system acts as supplementary controller in automation which assists PSS functioning and thus entire system operation improves by way of modulating the signal dynamics at interface points which quickly damps oscillations. The system study has been performed on a sample six area power systems comprising of UPFC connected between area two and three and PSS to all areas. The proposed concept demonstrates auto tuning of PSS for quick oscillation damping as the operating conditions change and also under situations of PSS failure due to relatively larger perturbation, UPFC acts as supplementary controller by assisting the entire system PSS to recover ensuring stability. 相似文献
90.
The present work presents teaching–learning based optimization (TLBO) algorithm as an optimization technique in the area of tuning of the classical controller installed in automatic voltage regulator (AVR). The proposed TLBO algorithm is applied with an aim to find out the optimum value of proportional integral derivative (PID) controller gains with first order low pass filter installed in the AVR. The voltage response of the AVR system, as obtained by using the proposed TLBO based PID controller with first order low pass filter, is compared to those offered by the other algorithms reported in the recent state-of-the-art literatures. The advantage of using this control strategy may be noted by providing good dynamic responses over a wide range of system parametric variations. For on-line, off-nominal operating conditions, fast acting Sugeno fuzzy logic technique is applied to obtain the on-line dynamic responses of the studied model. Furthermore, robustness analysis is also carried out to check the performance of the designed TLBO based PID controller. An analysis, based on voltage response profile, has been investigated with the variations of the model parameters. The simulation results show that the proposed TLBO based PID controller is a significant optimization tool in the subject area of the AVR system. The essence of the present work signifies that the proposed TLBO technique maybe, successfully, applied for the AVR of power system. 相似文献