全文获取类型
收费全文 | 3532篇 |
免费 | 351篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 51篇 |
化学工业 | 929篇 |
金属工艺 | 137篇 |
机械仪表 | 103篇 |
建筑科学 | 91篇 |
矿业工程 | 20篇 |
能源动力 | 167篇 |
轻工业 | 756篇 |
水利工程 | 20篇 |
石油天然气 | 20篇 |
无线电 | 180篇 |
一般工业技术 | 692篇 |
冶金工业 | 112篇 |
原子能技术 | 9篇 |
自动化技术 | 600篇 |
出版年
2023年 | 31篇 |
2022年 | 28篇 |
2021年 | 133篇 |
2020年 | 120篇 |
2019年 | 142篇 |
2018年 | 228篇 |
2017年 | 213篇 |
2016年 | 250篇 |
2015年 | 202篇 |
2014年 | 255篇 |
2013年 | 427篇 |
2012年 | 239篇 |
2011年 | 190篇 |
2010年 | 164篇 |
2009年 | 180篇 |
2008年 | 133篇 |
2007年 | 119篇 |
2006年 | 77篇 |
2005年 | 40篇 |
2004年 | 55篇 |
2003年 | 50篇 |
2002年 | 45篇 |
2001年 | 15篇 |
2000年 | 34篇 |
1999年 | 20篇 |
1998年 | 44篇 |
1997年 | 26篇 |
1996年 | 17篇 |
1995年 | 16篇 |
1994年 | 19篇 |
1993年 | 18篇 |
1992年 | 11篇 |
1991年 | 8篇 |
1990年 | 20篇 |
1989年 | 12篇 |
1988年 | 14篇 |
1987年 | 13篇 |
1986年 | 10篇 |
1985年 | 24篇 |
1984年 | 31篇 |
1983年 | 35篇 |
1982年 | 21篇 |
1981年 | 27篇 |
1980年 | 20篇 |
1979年 | 18篇 |
1978年 | 8篇 |
1977年 | 12篇 |
1976年 | 13篇 |
1975年 | 11篇 |
1973年 | 9篇 |
排序方式: 共有3887条查询结果,搜索用时 609 毫秒
91.
We propose an efficient algorithm for computing a unit lower triangular n×n matrix with prescribed singular values of O(n
2) cost. This is a solution of the question raised by N. J. Higham in [4, Problem 26.3, p. 528].
Received July 21, 1999; revised November 4, 1999 相似文献
92.
S. Jaeger S. Manke J. Reichert A. Waibel 《International Journal on Document Analysis and Recognition》2001,3(3):169-180
This paper presents the online handwriting recognition system NPen++ developed at the University of Karlsruhe and Carnegie
Mellon University. The NPen++ recognition engine is based on a multi-state time delay neural network and yields recognition
rates from 96% for a 5,000 word dictionary to 93.4% on a 20,000 word dictionary and 91.2% for a 50,000 word dictionary. The
proposed tree search and pruning technique reduces the search space considerably without losing too much recognition performance
compared to an exhaustive search. This enables the NPen++ recognizer to be run in real-time with large dictionaries. Initial
recognition rates for whole sentences are promising and show that the MS-TDNN architecture is suited to recognizing handwritten
data ranging from single characters to whole sentences.
Received September 3, 2000 / Revised October 9, 2000 相似文献
93.
Bolesław Kacewicz 《Mathematics of Control, Signals, and Systems (MCSS)》2000,13(4):347-359
In contrast to the worst case approach, the average case setting provides less conservative insight into the quality of estimation
algorithms. In this paper we consider two local average case error measures of algorithms based on noisy information, in Hilbert
norms in the problem element and information spaces. We define the optimal algorithm and provide formulas for its two local
errors, which explicitly exhibit the influence of factors such as information, information (measurement) errors, norms in
the considered spaces, a subset where approximations are allowed, and “unmodeled dynamics.” Based on the error expression,
we formulate in algebraic language the problem of selecting the optimal approximating subspace. The solution is given along
with the specific formula for the error, which depends on the eigenvalues of a certain matrix defined by information and norms
under consideration.
Date received: November 25, 1999. Date revised: May 30, 2000. 相似文献
94.
Władysław Mantura 《人机工程学与制造业中的人性因素》2008,18(5):565-579
This article shows the results of research regarding the importance and the role of human factors in quality management in production enterprises. In creating the concept of systematizations of human factors in quality management an anthropocentrism rule was accepted and resulting from it a category of life quality. Acceptance of this rule led to a multiaspect and comprehensive approach to human factors in quality management. An interpretation of the notion of quality was made, adequate to needs, goals, and requirements of a human. Additionally, a cybernetic model of quality management system was elaborated. Human factors was exhibited in the manager's and executor's roles in quality management systems in enterprise as well as to the roles of creators, producers, and users (customers) in product life cycles. An existence of human factors in ISO norms regarding quality management, work safety, and hygiene management and environment management was also shown. The objective of this article is a comprehensive identification and systematization of aspects of human factors in quality management. © 2008 Wiley Periodicals, Inc. 相似文献
95.
The output of the human postural control system is studied by means of linear system theory. It is assumed that the act of maintaining an erect posture can be treated as an autoregressive system with white noise on input. The identification is performed on the basis of the centre of pressure trajectory and it is shown that the most important features of the postural signal are sufficiently well reproduced by a low order linear autoregressive model. It is shown that the parameters of a model depend on the human subject and in some way characterize his state. Poles of the transmitancy function lying close to the unit circle are discussed as parameters describing the response function and human reactions to external perturbations. In additionf, an analysis of the correlation function within the autoregressive model is performed and its scaling exponents are computed and compared to the experimental results. 相似文献
96.
97.
Pawe?czyk A 《Water science and technology》2012,66(3):666-672
This paper presents results of analyses of water in the river Ma?a Panew in South West Poland flowing through a rural area with some chemical industry developed. The aims of the work were to investigate the pollutants level in the river, compare the obtained results with obligatory drinking water standards and determine possible health effects when using the river as a source for drinking water production. Attention was given to nitrogen compounds as nitrate(V) ions (NO(3-)) and nitrite(III) ions (NO(2-)), mostly of anthropogenic origin, were detected in the monitored water. The average concentrations of NO(3-) and NO(2-) were 3.54 and 0.286 mg/dm(3), respectively. The chances for non-carcinogenic effects, namely methemoglobinemia, resulting from possible exposure to the examined chemicals were determined based on the analytical and toxicological data. As infants are the sub-population most susceptible to nitrate-induced methemoglobinemia, the assessment was limited to children aged 0-3 years. The determined values expressed by hazard quotient (HQ) and hazard index (HI) indicate that the water pollutants and their concentrations do not exceed unity; however, in the case of infants, the other nitrate sources should be controlled. 相似文献
98.
99.
100.