全文获取类型
收费全文 | 19001篇 |
免费 | 338篇 |
国内免费 | 177篇 |
专业分类
电工技术 | 247篇 |
综合类 | 23篇 |
化学工业 | 2310篇 |
金属工艺 | 592篇 |
机械仪表 | 276篇 |
建筑科学 | 621篇 |
矿业工程 | 31篇 |
能源动力 | 203篇 |
轻工业 | 775篇 |
水利工程 | 72篇 |
石油天然气 | 19篇 |
武器工业 | 1篇 |
无线电 | 898篇 |
一般工业技术 | 1537篇 |
冶金工业 | 1570篇 |
原子能技术 | 159篇 |
自动化技术 | 10182篇 |
出版年
2023年 | 59篇 |
2022年 | 120篇 |
2021年 | 143篇 |
2020年 | 105篇 |
2019年 | 132篇 |
2018年 | 173篇 |
2017年 | 110篇 |
2016年 | 191篇 |
2015年 | 192篇 |
2014年 | 456篇 |
2013年 | 730篇 |
2012年 | 1154篇 |
2011年 | 3589篇 |
2010年 | 1535篇 |
2009年 | 1385篇 |
2008年 | 1093篇 |
2007年 | 991篇 |
2006年 | 803篇 |
2005年 | 876篇 |
2004年 | 806篇 |
2003年 | 795篇 |
2002年 | 496篇 |
2001年 | 176篇 |
2000年 | 167篇 |
1999年 | 177篇 |
1998年 | 342篇 |
1997年 | 215篇 |
1996年 | 173篇 |
1995年 | 142篇 |
1994年 | 125篇 |
1993年 | 138篇 |
1992年 | 137篇 |
1991年 | 80篇 |
1990年 | 101篇 |
1989年 | 85篇 |
1988年 | 102篇 |
1987年 | 72篇 |
1986年 | 65篇 |
1985年 | 85篇 |
1984年 | 117篇 |
1983年 | 71篇 |
1982年 | 71篇 |
1981年 | 89篇 |
1980年 | 68篇 |
1979年 | 85篇 |
1978年 | 68篇 |
1977年 | 67篇 |
1976年 | 56篇 |
1975年 | 58篇 |
1973年 | 47篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Backlash is one of the most important non-linearities that limit the performance of speed and position control in industrial, robotics, automotive, automation and other applications. The control of systems with backlash has been the subject of study since the 1940s. This survey reveals that surprisingly few control innovations have been presented since the early path breaking papers that introduced the describing function analysis of systems with backlash. Promising developments are however taking place using adaptive and non-linear control strategies. 相似文献
52.
53.
H.A. Barker Author Vitae A.H. Tan Author Vitae K.R. Godfrey Author Vitae 《Automatica》2003,39(1):127-133
Analysis of systems with direction-dependent dynamics is currently limited to cases in which the dynamics in the two directions of the output are first order; results for such systems have been published for both pseudo-random maximum-length binary (MLB) and inverse-repeat maximum-length binary (IR-MLB) inputs. These relatively limited analytical results make it useful to examine alternative ways of modelling such systems and in this paper, Wiener models are considered for this purpose. Methods for optimising the Wiener model parameters by matching the system and model cross-correlation functions, outputs, and discrete Fourier transforms of the outputs are considered, and the results are compared. These methods are also applied to a first-order direction-dependent system with a maximum-length ternary (MLT) input, for which no analytical results are currently available, and to a second-order system with an IR-MLB input. 相似文献
54.
Terry WindeattAuthor Vitae 《Pattern recognition》2003,36(12):2743-2756
Various measures, such as Margin and Bias/Variance, have been proposed with the aim of gaining a better understanding of why Multiple Classifier Systems (MCS) perform as well as they do. While these measures provide different perspectives for MCS analysis, it is not clear how to use them for MCS design. In this paper a different measure based on a spectral representation is proposed for two-class problems. It incorporates terms representing positive and negative correlation of pairs of training patterns with respect to class labels. Experiments employing MLP base classifiers, in which parameters are fixed but systematically varied, demonstrate the sensitivity of the proposed measure to base classifier complexity. 相似文献
55.
This article reviews the steps necessary to configure and implement a complex router internetwork. This article will specifically concentrate on Cisco routers, and since they support Transmission Control Protocol/Internet Protocol (TCP/IP) natively, it will concentrate on a backbone network employing that protocol. 相似文献
56.
Matthew John M. Krane Frank P. Incropera 《Metallurgical and Materials Transactions A》1995,26(9):2329-2339
Numerical calculations based on a continuum model are used to examine the effects of solidification shrinkage on the redistribution
of solute in a Pb-19.2 pct Sn mixture which is convectively cooled at a sidewall. For each of three different cooling rates,
separate calculations are performed for shrinkage and buoyancy-induced flows, as well as for the combined influence of shrinkage
and buoyancy effects. The calculations reveal that flow and macrosegregation patterns are more strongly influenced by buoyancy
effects over a wide range of solidification rates. Although extremely large solidification rates yield small regions near
the chilled wall in which shrinkage-induced flows control the redis-tribution of solute, the overall effect on macrosegregation
is small relative to that associated with buoyancy. Scaling analysis of the governing equations produces reference shrinkage
and buoyancy velocities which can be used to extend the current numerical results to other binary systems. 相似文献
57.
TheSpecial Issue on Applications of Temporal Models raises many issues of time: What are the important properties of time? How can time be best represented? How can one reason about time-dependent properties? What are the important directions of temporal research? This introductory piece very briefly surveys the current wide variety of temporal models, temporal reasoning methods, and applications to time-varying phenomena. Promising areas of investigation such as the verification of concurrent systems, knowledge-base representation methods, and dealing with theFrame Problem pass in fleeting review. Brief introductions to each of the works in the volume close the section. 相似文献
58.
Extending the Kernighan/Lin Heuristic for Hardware and Software Functional Partitioning 总被引:5,自引:0,他引:5
The Kernighan/Lin graph partitioning heuristic, also known as min-cut or group migration, has been extended over several decades very successfully for circuit partitioning. Those extensions customized the heuristic and its associated data structure to rapidly compute the minimum-cut metric central to circuit partitioning; as such, those extensions are not directly applicable to other problems. In this paper, we extend the heuristic for functional partitioning, which in turn can solve the much investigated codesign problem of partitioning a system's coarse-grained functions among hardware and software components. The key extension customizes the heuristic and data structure to rapidly compute execution-time and communication metrics, crucial to hardware and software partitioning, and leads to near-linear time-complexity and excellent resulting quality. Another extension uses a new criteria for terminating the heuristic, eliminating time-consuming and unnecessary fine-tuning of a partition. Our experiments demonstrate extremely fast execution times (just a few seconds) with results matched only by the slower simulated annealing heuristic, meaning that the extended Kernighan/Lin heuristic will likely prove hard to beat for hardware and software functional partitioning. 相似文献
59.
60.