全文获取类型
收费全文 | 88456篇 |
免费 | 6206篇 |
国内免费 | 2926篇 |
专业分类
电工技术 | 4357篇 |
技术理论 | 9篇 |
综合类 | 4650篇 |
化学工业 | 15943篇 |
金属工艺 | 4485篇 |
机械仪表 | 5257篇 |
建筑科学 | 7102篇 |
矿业工程 | 1987篇 |
能源动力 | 2497篇 |
轻工业 | 5169篇 |
水利工程 | 1471篇 |
石油天然气 | 4545篇 |
武器工业 | 488篇 |
无线电 | 10502篇 |
一般工业技术 | 11566篇 |
冶金工业 | 5119篇 |
原子能技术 | 834篇 |
自动化技术 | 11607篇 |
出版年
2024年 | 326篇 |
2023年 | 1333篇 |
2022年 | 2343篇 |
2021年 | 3174篇 |
2020年 | 2365篇 |
2019年 | 2077篇 |
2018年 | 2310篇 |
2017年 | 2562篇 |
2016年 | 2409篇 |
2015年 | 2992篇 |
2014年 | 4075篇 |
2013年 | 5172篇 |
2012年 | 5347篇 |
2011年 | 5675篇 |
2010年 | 5025篇 |
2009年 | 4814篇 |
2008年 | 4597篇 |
2007年 | 4515篇 |
2006年 | 4717篇 |
2005年 | 4200篇 |
2004年 | 2842篇 |
2003年 | 2539篇 |
2002年 | 2240篇 |
2001年 | 2060篇 |
2000年 | 2308篇 |
1999年 | 2589篇 |
1998年 | 2402篇 |
1997年 | 1905篇 |
1996年 | 1763篇 |
1995年 | 1458篇 |
1994年 | 1235篇 |
1993年 | 896篇 |
1992年 | 672篇 |
1991年 | 544篇 |
1990年 | 423篇 |
1989年 | 373篇 |
1988年 | 322篇 |
1987年 | 187篇 |
1986年 | 171篇 |
1985年 | 118篇 |
1984年 | 102篇 |
1983年 | 67篇 |
1982年 | 63篇 |
1981年 | 56篇 |
1980年 | 41篇 |
1979年 | 33篇 |
1978年 | 14篇 |
1977年 | 36篇 |
1976年 | 19篇 |
1975年 | 16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 new method based on the discrete cosine transform (DCT), named as the DCT-based method, to detect oscillations for a single time series. The main idea is to isolate different frequency components of the time series via the DCT, and to detect oscillations by checking the regularity of zero-crossings of these isolated components. This method has the following features: (i) usage of only time series information of process variables without additional process knowledge, (ii) ability to deal with slowly varying trends, (iii) robustness to both white and colored noises, (iv) capability to handle the presence of multiple oscillations, and (v) amenability to complete automation without human intervention. Simulation examples and industrial case studies are presented to demonstrate the effectiveness and the above features of the DCT-based method. 相似文献
992.
Yun-Chuan Xie Yan Xu Kai-Leung Yung Long-Biao Huang Ming-Hong Lee 《Microsystem Technologies》2010,16(11):1887-1891
Finding out a rapid and reliable bonding method for plastic microfluidic chips with PCR functions is challenging for analytical
chemistry and biochemistry. A rapid, reliable covalent bonding method is introduced for fabricating PMMA PCR biochips with
long channels and thin walls. The bonding strength of ~5 MPa was obtained and bulk cohesive failure occurred during tensiling
tests. Preliminary leaking tests indicate that photolamination bonding can be implemented readily in the fabrication of PMMA
PCR biochips. 相似文献
993.
This work provides a framework for nominal and robust stability analysis for a class of discrete-time nonlinear recursive observers (DNRO). Given that the system has linear output mapping, local observability and Jacobian matrices satisfying certain conditions, the nominal and robust stability of the DNRO is defined by the property of estimation error dynamics and is analyzed using Lyapunov theory. Moreover, a simultaneous state and parameter estimation scheme is shown to be Input-to-State Stable (ISS), and adaptively reduce plant-model mismatch on-line. Three design strategies of the DNRO that satisfy the stability results are given as examples, including the widely used extended Kalman filter, extended Luenberger observer, and the fixed gain observer. 相似文献
994.
In this paper, a controller performance monitoring technology is introduced with a focus on its industrial implementation and applications. The technology to be introduced in this paper is known as Performance Analysis Toolbox and Solutions (PATS). The main components are discussed, which include data collection, closed-loop systems identification, control valve stiction monitoring, univariate control performance monitoring, multivariate control performance monitoring, model predictive control performance monitoring, etc. It is shown, through a thorough industry case study with various components of PATS, that the integration of the technology provides more convincing diagnosis results and facilitates identification of control improvement opportunities. Some components of the developed technology can be downloaded from the website http://www.ualberta.ca/~bhuang/research/research.htm. 相似文献
995.
Performance monitoring of model predictive control (MPC) systems has received a great interest from both academia and industry. In recent years some novel approaches for multivariate control performance monitoring have been developed without the requirement of process models or interactor matrices. Among them the prediction error approach has been shown promising, but it is based on single-step prediction and may not be compatible with the MPC objective that is based on multi-step prediction. This paper develops a multi-step prediction error approach for performance monitoring of model predictive control systems, and demonstrates its application in a real industrial MPC performance monitoring and diagnosis problem. 相似文献
996.
IEEE 802.15.4a工业无线标准的研究与应用 总被引:1,自引:1,他引:0
对目前常用的几种工业无线标准进行了简单比较,并着重介绍了低速无线个人区域网络的新标准IEEE802.15.4a及其关键技术MDMA和CCS。新标准采用Chirp扩频物理层技术作为物理层标准,对工业环境中的干扰等具有很强的鲁棒性。以IEEE802.15.4a为基础,在现场总线测控系统中构建了无线子网段,实验表明系统处于稳定运行状态,且满足一般流程工业要求。该实例为工业无线网络接入到有线网络提供了一种解决方案,新标准在工业现场的短距离传输方面将会有广阔的应用前景。 相似文献
997.
998.
为提高电力故障诊断系统的性能,介绍了一种嵌入式电力故障录波器的设计方案.该故障录波器采用了DSP与ARM双微处理器协同工作的方式;数据采集系统采用了DSF芯片TMS320F2812、A/D芯片ADS8364及硬件同步采样技术;数据管理系统包括S3C44B0X芯片、以太网接口、LCD接口、USB接口.录波器具有数据采集精度高、处理速度快、系统容量大、以太网接口数据远传等优点,这对交流电参量检测装置的设计具有一定的参考价值. 相似文献
999.
1000.
This paper investigates robust observer‐controller compensator design using Vidyasagar's structure (VS). VS has a unit matrix parameter H similar to the Q parameter for the Youla–Kucera parameterization. VS can be designed based on the left coprimeness of the central controller in the H∞‐loop shaping design procedure (H∞‐LSDP) and therefore can preserve the intrinsic properties of the H∞‐LSDP. This paper introduces algebraic methods to simplify the design of H in the VS controller by solving specific algebraic equations. In particular, the algebraic design of H can achieve two things. First, a dynamic H adjusts the tracking performance and yields the integral action. Second, a dynamic H rejects the input and output sinusoidal disturbances with known frequencies. These attributes are indications of the flexibility of the proposed method since the output‐feedback controller design of the H∞‐LSDP cannot easily deal with such conditions. This paper discusses the achieved loop and the closed‐loop behavior of the system with VS, and also gives two numerical examples. The first example shows that the proposed method results in a better design in many aspects than the resulting from H∞‐LSDP. The second example shows the application of the proposed method to rejecting input and output step disturbances, and input and output multiple sinusoidal disturbances, for which the H∞‐LSDP can hardly be used. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献