全文获取类型
收费全文 | 9046篇 |
免费 | 319篇 |
国内免费 | 39篇 |
专业分类
电工技术 | 125篇 |
综合类 | 22篇 |
化学工业 | 2103篇 |
金属工艺 | 167篇 |
机械仪表 | 231篇 |
建筑科学 | 573篇 |
矿业工程 | 31篇 |
能源动力 | 171篇 |
轻工业 | 782篇 |
水利工程 | 54篇 |
石油天然气 | 11篇 |
武器工业 | 1篇 |
无线电 | 592篇 |
一般工业技术 | 1457篇 |
冶金工业 | 1534篇 |
原子能技术 | 70篇 |
自动化技术 | 1480篇 |
出版年
2023年 | 58篇 |
2022年 | 120篇 |
2021年 | 143篇 |
2020年 | 106篇 |
2019年 | 120篇 |
2018年 | 171篇 |
2017年 | 110篇 |
2016年 | 191篇 |
2015年 | 191篇 |
2014年 | 249篇 |
2013年 | 568篇 |
2012年 | 398篇 |
2011年 | 544篇 |
2010年 | 410篇 |
2009年 | 390篇 |
2008年 | 433篇 |
2007年 | 422篇 |
2006年 | 364篇 |
2005年 | 313篇 |
2004年 | 292篇 |
2003年 | 224篇 |
2002年 | 227篇 |
2001年 | 173篇 |
2000年 | 166篇 |
1999年 | 158篇 |
1998年 | 261篇 |
1997年 | 199篇 |
1996年 | 159篇 |
1995年 | 141篇 |
1994年 | 123篇 |
1993年 | 136篇 |
1992年 | 130篇 |
1991年 | 77篇 |
1990年 | 92篇 |
1989年 | 79篇 |
1988年 | 94篇 |
1987年 | 66篇 |
1986年 | 54篇 |
1985年 | 79篇 |
1984年 | 94篇 |
1983年 | 60篇 |
1982年 | 66篇 |
1981年 | 83篇 |
1980年 | 68篇 |
1979年 | 85篇 |
1978年 | 68篇 |
1977年 | 70篇 |
1976年 | 60篇 |
1975年 | 59篇 |
1973年 | 47篇 |
排序方式: 共有9404条查询结果,搜索用时 10 毫秒
161.
H-Infinity Static Output-feedback Control for Rotorcraft 总被引:1,自引:0,他引:1
Jyotirmay Gadewadikar Frank L. Lewis Kamesh Subbarao Kemao Peng Ben M. Chen 《Journal of Intelligent and Robotic Systems》2009,54(4):629-646
The problem of stabilization of an autonomous rotorcraft platform in a hover configuration subject to external disturbances
is addressed. Necessary and sufficient conditions are presented for static output-feedback control of linear time-invariant
systems using the H-Infinity approach. Simplified conditions are given which only require the solution of two coupled matrix
design equations. This paper also proposes a numerically efficient solution algorithm for the coupled design equations to
determine the output-feedback gain. A major contribution is that an initial stabilizing gain is not needed. The efficacy of
the control law and the disturbance accommodation properties are shown on a rotorcraft design example. The helicopter dynamics
do not decouple as in the fixed-wing aircraft case, so that the design of helicopter flight controllers with a desirable intuitive
structure is not straightforward. In this paper an output feedback approach is given that allows one to selectively close
prescribed multivariable feedback loops using a reduced set of the states. Shaping filters are added that improve performance
and yield guaranteed robustness and speed of response. This gives direct control over the design procedure and performance.
Accurate identification of the System parameters is a challenging task for rotorcraft control, addition of loop shaping facilitates
implementation engineers to counteract unmodeled high frequency dynamics. The net result yields control structures that have
been historically accepted in the flight control community. 相似文献
162.
This article deals with real-time critical systems modelling and verification. Real-time scheduling theory provides algebraic
methods and algorithms in order to make timing constraints verifications of these systems. Nevertheless, many industrial projects
do not perform analysis with real-time scheduling theory even if demand for use of this theory is large and the industrial
application field is wide (avionics, aerospace, automotive, autonomous systems, …). The Cheddar project investigates why real-time scheduling theory is not used and how its usability can be increased. The project was
launched at the University of Brest in 2002. In Lecture Notes on Computer Sciences, vol. 5026, pp. 240–253, 2008, we have presented a short overview of this project. This article is an extended presentation of the Cheddar project, its contributions and also its ongoing works. 相似文献
163.
Acar Esra Hopfgartner Frank Albayrak Sahin 《Multimedia Tools and Applications》2017,76(9):11809-11837
Multimedia Tools and Applications - In today’s society where audio-visual content such as professionally edited and user-generated videos is ubiquitous, automatic analysis of this content is... 相似文献
164.
Experimental Evaluation and Formal Analysis of High‐Level Tasks with Dynamic Obstacle Anticipation on a Full‐Sized Autonomous Vehicle 下载免费PDF全文
Certifying the behavior of autonomous systems is essential to the development and deployment of systems in safety‐critical applications. This paper presents an approach to using a correct‐by‐construction controller with the probabilistic results of dynamic obstacle anticipation, and validates the approach with experimental data obtained from Cornell's full‐scale autonomous vehicle. The obstacle anticipation (used to calculate the probability of collision with dynamic obstacles around the vehicle) is abstracted to a set of Boolean observations, which are then used by the synthesized controller (a state machine generated from temporal logic task specifications). The obstacle anticipation, sensor abstraction, and synthesized controller are implemented on a full‐scale autonomous vehicle, and experimental data are collected and compared with a formal analysis of the probabilistic behavior of the system. A comparison of the results shows good agreement between the formal analysis and the experimental results. 相似文献
165.
Output synchronization of a network of heterogeneous linear state–space models under time-varying and directed interconnection structures is investigated. It is shown that, assuming stabilizability and detectability of the individual systems and imposing very mild connectedness assumptions on the interconnection structure, an internal model requirement is necessary and sufficient for synchronizability of the network to polynomially bounded trajectories. The resulting dynamic feedback couplings can be interpreted as a generalization of existing methods for identical linear systems. 相似文献
166.
167.
Martens et al. defined a pattern-based specification language equivalent in expressive power to the widely adopted XML Schema definitions (XSDs). This language consists of rules of the form where r and s are regular expressions and can be seen as a type-free extension of DTDs with vertical regular expressions. Sets of such rules can be interpreted both in an existential or universal way. In the present paper, we study the succinctness of both semantics w.r.t. each other and w.r.t. the common abstraction of XSDs in terms of single-type extended DTDs. The investigation is carried out relative to three kinds of vertical pattern languages: regular, linear, and strongly linear patterns. We also consider the complexity of the simplification problem for each of the considered pattern-based schemas. 相似文献
168.
Yi Zeng Ning Zhong Yan Wang Yulin Qin Zhisheng Huang Haiyan Zhou Yiyu Yao Frank van Harmelen 《Knowledge and Information Systems》2011,27(3):419-450
Under the context of large-scale scientific literatures, this paper provides a user-centric approach for refining and processing
incomplete or vague query based on cognitive- and granularity-based strategies. From the viewpoints of user interests retention
and granular information processing, we examine various strategies for user-centric unification of search and reasoning. Inspired
by the basic level for human problem-solving in cognitive science, we refine a query based on retained user interests. We
bring the multi-level, multi-perspective strategies from human problem-solving to large-scale search and reasoning. The power/exponential
law-based interests retention modeling, network statistics–based data selection, and ontology-supervised hierarchical reasoning
are developed to implement these strategies. As an illustration, we investigate some case studies based on a large-scale scientific
literature dataset, DBLP. The experimental results show that the proposed strategies are potentially effective. 相似文献
169.
In this paper we consider uncountable classes recognizable by ω-automata and investigate suitable learning paradigms for them. In particular, the counterparts of explanatory, vacillatory and behaviourally correct learning are introduced for this setting. Here the learner reads in parallel the data of a text for a language L from the class plus an ω-index α and outputs a sequence of ω-automata such that all but finitely many of these ω-automata accept the index α if and only if α is an index for L.It is shown that any class is behaviourally correct learnable if and only if it satisfies Angluin’s tell-tale condition. For explanatory learning, such a result needs that a suitable indexing of the class is chosen. On the one hand, every class satisfying Angluin’s tell-tale condition is vacillatorily learnable in every indexing; on the other hand, there is a fixed class such that the level of the class in the hierarchy of vacillatory learning depends on the indexing of the class chosen.We also consider a notion of blind learning. On the one hand, a class is blind explanatorily (vacillatorily) learnable if and only if it satisfies Angluin’s tell-tale condition and is countable; on the other hand, for behaviourally correct learning, there is no difference between the blind and non-blind version.This work establishes a bridge between the theory of ω-automata and inductive inference (learning theory). 相似文献
170.
Miniaturized interference filters were designed and fabricated using two different manufacturing technologies. Applying micromachined
ceramic masks during the coating processes interference filters with 1 mm lateral feature size and an alignment accuracy of
50 μm were arranged in an array consisting of three different filters. The filter edge definition obtained by this method
was smaller than 50 μm. By applying ion assisted deposition (IAD), a low-temperature coating process, the spectral sensitivity
of receiver cells has been modified by coating the cells directly. A combination of coating processes, microlithographic masking
procedures, and dry etching technologies made it possible to arrange three different stripe filters with minimum filter features
of about 5 μm side by side. The accuracy during mask alignment and the filter edge definition was also within 1 and 2 μm,
respectively.
Received: 20 March 1999/Accepted: 12 April 1999 相似文献