全文获取类型
收费全文 | 53452篇 |
免费 | 7212篇 |
国内免费 | 4577篇 |
专业分类
电工技术 | 5493篇 |
技术理论 | 3篇 |
综合类 | 5772篇 |
化学工业 | 4324篇 |
金属工艺 | 1606篇 |
机械仪表 | 2586篇 |
建筑科学 | 3613篇 |
矿业工程 | 1342篇 |
能源动力 | 1968篇 |
轻工业 | 2170篇 |
水利工程 | 5005篇 |
石油天然气 | 2083篇 |
武器工业 | 740篇 |
无线电 | 7311篇 |
一般工业技术 | 5589篇 |
冶金工业 | 1871篇 |
原子能技术 | 811篇 |
自动化技术 | 12954篇 |
出版年
2024年 | 274篇 |
2023年 | 779篇 |
2022年 | 1555篇 |
2021年 | 1686篇 |
2020年 | 1976篇 |
2019年 | 1920篇 |
2018年 | 1744篇 |
2017年 | 2205篇 |
2016年 | 2376篇 |
2015年 | 2452篇 |
2014年 | 3319篇 |
2013年 | 3846篇 |
2012年 | 3812篇 |
2011年 | 3974篇 |
2010年 | 2910篇 |
2009年 | 3081篇 |
2008年 | 2923篇 |
2007年 | 3487篇 |
2006年 | 3209篇 |
2005年 | 2686篇 |
2004年 | 2228篇 |
2003年 | 2038篇 |
2002年 | 1835篇 |
2001年 | 1622篇 |
2000年 | 1361篇 |
1999年 | 1072篇 |
1998年 | 840篇 |
1997年 | 762篇 |
1996年 | 588篇 |
1995年 | 482篇 |
1994年 | 409篇 |
1993年 | 354篇 |
1992年 | 240篇 |
1991年 | 204篇 |
1990年 | 170篇 |
1989年 | 134篇 |
1988年 | 105篇 |
1987年 | 89篇 |
1986年 | 68篇 |
1985年 | 64篇 |
1984年 | 57篇 |
1983年 | 35篇 |
1982年 | 42篇 |
1981年 | 31篇 |
1980年 | 25篇 |
1979年 | 30篇 |
1978年 | 13篇 |
1977年 | 11篇 |
1964年 | 12篇 |
1956年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
This paper proposes a framework of fault estimation observer design in finite‐frequency domain for discrete‐time systems. First, under the multiconstrained idea, a full‐order fault estimation observer in finite‐frequency domain is designed to achieve fault estimation by using the generalized Kalman–Yakubovich–Popov lemma to reduce conservatism generated by the entire frequency domain. Then, a reduced‐order fault estimation observer is constructed, which results in a new fault estimator to realize fault estimation using current output information. Furthermore, by introducing slack variables, improved results on full‐order fault estimation observer and reduced‐order fault estimation observer design with finite‐frequency specifications are obtained such that different Lyapunov matrices can be separately designed for each constraint. Simulation results are presented to illustrate the advantages of the theoretic results obtained. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
992.
Observer‐based decentralized adaptive control for large‐scale pure‐feedback systems with unknown time‐delayed nonlinear interactions
下载免费PDF全文
![点击此处可从《国际强度与非线性控制杂志<br>》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Sung Jin Yoo 《国际强度与非线性控制杂志
》2015,25(8):1107-1125
》2015,25(8):1107-1125
This paper presents an approximation design for a decentralized adaptive output‐feedback control of large‐scale pure‐feedback nonlinear systems with unknown time‐varying delayed interconnections. The interaction terms are bounded by unknown nonlinear bounding functions including unmeasurable state variables of subsystems. These bounding functions together with the algebraic loop problem of virtual and actual control inputs in the pure‐feedback form make the output‐feedback controller design difficult and challenging. To overcome the design difficulties, the observer‐based dynamic surface memoryless local controller for each subsystem is designed using appropriate Lyapunov‐Krasovskii functionals, the function approximation technique based on neural networks, and the additional first‐order low‐pass filter for the actual control input. It is shown that all signals in the total controlled closed‐loop system are semiglobally uniformly bounded and control errors converge to an adjustable neighborhood of the origin. Finally, simulation examples are provided to illustrate the effectiveness of the proposed decentralized control scheme. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
993.
In this paper, the problem of finite‐time H ∞ control is addressed for a class of discrete‐time switched nonlinear systems with time delay. The concept of H ∞ finite‐time boundedness is first introduced for discrete‐time switched delay systems. Next, a set of switching signals are designed by using the average dwell time approach, under which some delay‐dependent sufficient conditions are derived to guarantee the H ∞ finite‐time boundedness of the closed‐loop system. Then, a finite‐time H ∞ state feedback controller is also designed by solving such conditions. Furthermore, the problem of uniform finite‐time H ∞ stabilization is also resolved. All the conditions are cast into linear matrix inequalities, which can be easily checked by using recently developed algorithms for solving linear matrix inequalities. A numerical example and a water‐quality control system are provided to demonstrate the effectiveness of the main results. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
994.
This paper is concerned with the stability and L2‐gain problems for a class of continuous‐time linear switched systems with the existed asynchronous behaviors, where ‘asynchronous’ means that the switching of the controllers to be designed has a lag to the switching of the system modes. Firstly, a new sufficient condition on the asymptotic stability and weighted L2‐gain analysis is obtained by using multiple Lyapunov functions combined with the average dwell time technique. Moreover, a result that is formulated in form of linear matrix inequalities is derived for the problem of asynchronous H ∞ control. Based on the result, the mode‐dependent controllers can be designed. Finally, an illustrative numerical example is presented to show the effectiveness of the obtained results.Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
995.
The problem of the stability of a linear system with an interval time‐varying delay is investigated. A new Lyapunov–Krasovskii functional that fully uses information about the lower bound of the time‐varying delay is constructed to derive new stability criteria. It is proved that the proposed Lyapunov–Krasovskii functional can lead to less conservative results than some existing ones. Based on the proposed Lyapunov–Krasovskii functional, two stability conditions are developed using two different methods to estimate Lyapunov–Krasovskii functional's derivative. Two numerical examples are given to illustrate that the two stability conditions are complementary and yield a larger maximum upper bound of the time‐varying delay than some existing results. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
996.
Neural Network and Classification Approach in Identifying Customer Behavior in the Banking Sector: A Case Study of an International Bank
下载免费PDF全文
![点击此处可从《人机工程学与制造业中的人性因素》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Francisca Nonyelum Ogwueleka Sanjay Misra Ricardo Colomo‐Palacios Luis Fernandez 《人机工程学与制造业中的人性因素》2015,25(1):28-42
The customer relationship focus for banks is in development of main competencies and strategies of building strong profitable customer relationships through considering and managing the customer impression, influence on the culture of the bank, satisfactory treatment, and assessment of valued relationship building. Artificial neural networks (ANNs) are used after data segmentation and classification, where the designed model register records into two class sets, that is, the training and testing sets. ANN predicts new customer behavior from previously observed customer behavior after executing the process of learning from existing data. This article proposes an ANN model, which is developed using a six‐step procedure. The back‐propagation algorithm is used to train the ANN by adjusting its weights to minimize the difference between the current ANN output and the desired output. An evaluation process is conducted to determine whether the ANN has learned how to perform. The training process is halted periodically, and its performance is tested until an acceptable result is obtained. The principles underlying detection software are grounded in classical statistical decision theory. 相似文献
997.
连接界面的黏滑、摩擦行为不仅是引起结构刚度和阻尼非线性的主要原因,而且是结构无源阻尼的主要来源.Iwan模型能够较好地复现连接界面的黏滑、摩擦行为.本文采用时频域交替法(Alternating Frequency/Time Domain Method,AFT)研究含Iwan非线性模型的单自由度振子系统的稳态响应.时频域交替法具有频域法求解线性系统响应的高效性和时域法判断非线性力的便捷性特点,采用离散傅里叶变换和傅里叶逆变换,在频域和时域内分别求解系统响应和对应的非线性恢复力,再反复迭代计算系统的稳态响应.将时频域交替法计算结果和中心差分法计算的结果进行对比,并研究激励幅值对系统非线性特征的影响.结果表明,时频域交替法计算的结果与中心差分计算的结果具有较好的一致性,且求解效率较高,计算耗时减少50%;随着激励幅值的增加,系统的能量耗散增加,刚度降低,固有频率降低. 相似文献
998.
选取带有控制系统的旋转弹为研究对象,考虑到控制环节不可避免的时滞及气动非线性效应,从理论上进一步完善了旋转弹动力学模型.从模型的特征方程出发,以时滞、控制增益为分岔参数,对系统的零平衡点稳定性进行了分析,得到平衡点失稳后发生Hopf分岔的临界参数值,并在理论预测的情况下数值模拟了攻角和侧滑角在不同情况下的失稳情况以及Hopf分岔周期解振幅随分岔参数的变化情况.数值结果表明了理论预测的正确性,时滞虽未改变旋转弹锥形运动方式,但是却大幅度的减小了稳定飞行控制增益的取值范围,因此在旋转弹姿态稳定性系统设计过程中时滞的影响不可忽略. 相似文献
999.
1000.
基于Hamilton原理建立了受控压电梁的参数振动方程,研究了轴向激励压电梁时滞速度反馈控制的主参数共振.采用非线性振动的多尺度法研究了压电梁的亚谐波主参数共振,并对其稳定域进行分析.通过算例分析得到了不同时滞,控制增益,轴力影响下压电梁参数共振的稳定域和时程曲线.结果表明:时滞值增大,系统承受轴向力减小,相对于控制增益则反之.同时,随着轴向力增大,在一定范围内主动阻尼增加,时滞反馈能有效降低响应幅值.随着时滞值增大,减振效果变差. 相似文献