全文获取类型
收费全文 | 23438篇 |
免费 | 2993篇 |
国内免费 | 1866篇 |
专业分类
电工技术 | 2627篇 |
技术理论 | 4篇 |
综合类 | 2426篇 |
化学工业 | 1123篇 |
金属工艺 | 350篇 |
机械仪表 | 1677篇 |
建筑科学 | 2428篇 |
矿业工程 | 378篇 |
能源动力 | 455篇 |
轻工业 | 3530篇 |
水利工程 | 491篇 |
石油天然气 | 1190篇 |
武器工业 | 247篇 |
无线电 | 2015篇 |
一般工业技术 | 1825篇 |
冶金工业 | 696篇 |
原子能技术 | 137篇 |
自动化技术 | 6698篇 |
出版年
2024年 | 190篇 |
2023年 | 532篇 |
2022年 | 983篇 |
2021年 | 1091篇 |
2020年 | 1182篇 |
2019年 | 979篇 |
2018年 | 880篇 |
2017年 | 1050篇 |
2016年 | 1032篇 |
2015年 | 1096篇 |
2014年 | 1590篇 |
2013年 | 1591篇 |
2012年 | 1780篇 |
2011年 | 1915篇 |
2010年 | 1394篇 |
2009年 | 1376篇 |
2008年 | 1237篇 |
2007年 | 1439篇 |
2006年 | 1220篇 |
2005年 | 955篇 |
2004年 | 781篇 |
2003年 | 675篇 |
2002年 | 596篇 |
2001年 | 426篇 |
2000年 | 367篇 |
1999年 | 288篇 |
1998年 | 257篇 |
1997年 | 219篇 |
1996年 | 159篇 |
1995年 | 154篇 |
1994年 | 122篇 |
1993年 | 97篇 |
1992年 | 84篇 |
1991年 | 72篇 |
1990年 | 62篇 |
1989年 | 56篇 |
1988年 | 38篇 |
1987年 | 35篇 |
1986年 | 31篇 |
1985年 | 18篇 |
1984年 | 30篇 |
1983年 | 15篇 |
1982年 | 24篇 |
1981年 | 27篇 |
1980年 | 35篇 |
1979年 | 16篇 |
1978年 | 14篇 |
1977年 | 8篇 |
1975年 | 8篇 |
1959年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
Keh-Shin Lii 《时间序列分析杂志》1985,6(3):153-169
Abstract. A distributed lag model with a rational transfer function is considered. We have demonstrated that the C -table can be used to determine the orders of the rational transfer function and the Padé table can be used to estimate the parameters of an identifiable transfer function. In case the model is not uniquely identified, the C -table reduces possible competing models to only a few for further examination. Padé approximant gives consistent initial values for possibly more efficient iterative procedures to estimate the coefficients of the identified model. Some asymptotic results on the estimation of the C -table and the Padé table are given. A few examples are presented to demonstrate the effectiveness of the method. 相似文献
13.
Akitoshi Iwata Shinji Ichikawa Mutuwo Tomita Shinji Doki Shigeru Okuma 《Electrical Engineering in Japan》2006,155(3):62-69
This paper presents a novel on‐line parameter identification method for sensorless control of Synchronous Reluctance Motors (SynRMs). Although conventional sensorless control methods based on mathematical models usually need some complex measurements of motor parameters in advance, the proposed identification method does not require them and can be realized on‐line. The proposed method identifies motor parameters under sensorless control, so rotor position and velocity cannot be used to identify these parameters. However, the proposed method does not need rotor position and velocity, and identified parameters are not affected by these estimation errors. The sensorless control using identified motor parameters is realized, and the effectiveness of the proposed method is verified by experimental results. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 155(3): 62–69, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20258 相似文献
14.
15.
A study on the critical success factors for corporations embarking on knowledge community-based e-learning 总被引:1,自引:0,他引:1
Corporations have felt the pressure for fast-paced innovations and knowledge transfer as major driving forces in raising their sustainable competitive advantage and organizational total productivity. Thus, the development of the knowledge community through e-learning is an important strategy in implementing knowledge management policy. This paper illustrates an empirical study with which to conduct qualitative research of learning organization. From the case company’s real progress and practical experience, some core principles were extracted from four managerial aspects, such as: strategy, technology, process, and personnel. These aspects were analyzed in order to understand the value chain framework and the major concerns of knowledge community development. Further, the main benefits are addressed and certain critical factors are proposed and shown in this paper to ensure the success of corporations embarking on knowledge community-based e-learning. 相似文献
16.
Stirman Shannon Wiltsey; DeRubeis Robert J.; Crits-Christoph Paul; Brody Pamela E. 《Canadian Metallurgical Quarterly》2003,71(6):963
To determine the extent to which published randomized controlled trials (RCTs) of psychotherapy can be generalized to a sample of community outpatients, the authors used a method of matching information obtained from outpatient charts to inclusion and exclusion criteria from published RCT studies. They found that 80% of the patients in their sample who had diagnoses represented in the RCT literature were judged eligible for at least 1 published RCT; however, 58% of the patients had primary diagnoses such as adjustment disorder or dysthymia, which were not represented in the existing psychotherapy outcome literature. The most common reasons that patients in their sample did not match with published RCTs for psychotherapy are listed, and the implications of these findings for research and practice are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
17.
A model-based autotuning method consists of an identification and a regulator tuning phase. To achieve satisfactory performance and robustness, it is advisable that both phases be tailored a priori to the characteristics of the observed process dynamics. Such characteristics include, but are not limited to, the model structure. For example, overdamped and underdamped models with the same pole-zero structure are parametrised and controlled in different ways. Step response data, that are typically used for the identification phase in the autotuning context, can also be pre-processed to reveal those characteristics. This paper presents a step response classification method suitable for the above purpose. The method is based on a polygonal curve approximation technique for data pre-processing, followed by a neural network classifier. Only normalised I/O data are employed, so that the neural network can be trained off-line with simulated data. Simulation results are reported to show the effectiveness of the proposed classification method in terms of the achievable tuning results. 相似文献
18.
Marco Dalai Author Vitae 《Automatica》2007,43(8):1418-1425
In this paper we consider the problem of constructing confidence regions for the parameters of nonlinear dynamical systems. The proposed method uses higher order statistics and extends the LSCR (leave-out sign-dominant correlation regions) algorithm for linear systems introduced in Campi and Weyer [2005, Guaranteed non-asymptotic confidence regions in system identification. Automatica 41(10), 1751-1764. Extended version available at 〈http://www.ing.unibs.it/∼campi〉]. The confidence regions contain the true parameter value with a guaranteed probability for any finite number of data points. Moreover, the confidence regions shrink around the true parameter value as the number of data points increases. The usefulness of the proposed approach is illustrated on some simple examples. 相似文献
19.
Jane Pitcher 《Urban Policy and Research》2006,24(1):67-82
This article explores the role of qualitative and collaborative methods when undertaking evaluation research into local community safety partnerships and neighbourhood strategies. It draws on recent examples of research and evaluation studies of regeneration and community safety programmes in a number of cities and towns in England. The discussion is set against the background of the major changes in policy relating to crime and community safety, particularly the introduction of Crime and Disorder Partnerships and their engagement with local communities. The value of qualitative methods in exploring some key questions is discussed, particularly within a collaborative approach to policy research. 相似文献
20.
Lei Guo Lennart Ljung Pierre Priouret 《International Journal of Adaptive Control and Signal Processing》1993,7(6):525-537
An analysis is given of the performance of the standard forgetting factor recursive least squares (RLS) algorithm when used for tracking time-varying linear regression models. Three basic results are obtained: (1) the ‘P-matrix’ in the algorithm remains bounded if and only if the (time-varying) covariance matrix of the regressors is uniformly non-singular; (2) if so, the parameter tracking error covariance matrix is of the order O(μ + γ2/μ), where μ = 1 - λ, λ is the forgetting factor and γ is a quantity reflecting the speed of the parameter variations; (3) this covariance matrix can be arbitrarily well approximated (for small enough μ) by an expression that is easy to compute. 相似文献