全文获取类型
收费全文 | 2997篇 |
免费 | 81篇 |
国内免费 | 13篇 |
专业分类
电工技术 | 46篇 |
综合类 | 2篇 |
化学工业 | 453篇 |
金属工艺 | 87篇 |
机械仪表 | 177篇 |
建筑科学 | 60篇 |
矿业工程 | 3篇 |
能源动力 | 119篇 |
轻工业 | 89篇 |
水利工程 | 27篇 |
石油天然气 | 9篇 |
无线电 | 536篇 |
一般工业技术 | 540篇 |
冶金工业 | 374篇 |
原子能技术 | 18篇 |
自动化技术 | 551篇 |
出版年
2023年 | 35篇 |
2022年 | 70篇 |
2021年 | 68篇 |
2020年 | 64篇 |
2019年 | 66篇 |
2018年 | 90篇 |
2017年 | 68篇 |
2016年 | 96篇 |
2015年 | 62篇 |
2014年 | 79篇 |
2013年 | 182篇 |
2012年 | 97篇 |
2011年 | 142篇 |
2010年 | 116篇 |
2009年 | 108篇 |
2008年 | 112篇 |
2007年 | 98篇 |
2006年 | 92篇 |
2005年 | 78篇 |
2004年 | 59篇 |
2003年 | 58篇 |
2002年 | 67篇 |
2001年 | 56篇 |
2000年 | 63篇 |
1999年 | 59篇 |
1998年 | 118篇 |
1997年 | 82篇 |
1996年 | 89篇 |
1995年 | 50篇 |
1994年 | 49篇 |
1993年 | 45篇 |
1992年 | 47篇 |
1991年 | 35篇 |
1990年 | 41篇 |
1989年 | 39篇 |
1988年 | 32篇 |
1987年 | 30篇 |
1986年 | 27篇 |
1985年 | 35篇 |
1984年 | 22篇 |
1983年 | 32篇 |
1982年 | 27篇 |
1981年 | 29篇 |
1980年 | 29篇 |
1979年 | 34篇 |
1978年 | 17篇 |
1977年 | 17篇 |
1976年 | 22篇 |
1975年 | 11篇 |
1973年 | 11篇 |
排序方式: 共有3091条查询结果,搜索用时 15 毫秒
41.
PVC-Based 2,2,2-Cryptand Sensor for Zinc Ions 总被引:1,自引:0,他引:1
A PVC-based membrane of 2,2,2-cryptand exhibits a very good response for Zn(2+) in a wide concentration range (from 2.06 ppm to 6.54 × 10(3) ppm) with a slope of 22.0 mV/decade of Zn(2+) concentration. The response time of the sensor is <10 s, and the membrane can be used for more than 3 months without any observed divergence in potentials. The proposed sensor exhibits very good selectivity for Zn(2+) over other cations and can be used in a wide pH range (2.8-7.0). It has also been possible to use this assembly as an indicator electrode in potentiometric titrations involving zinc ions. 相似文献
42.
Jain A 《Multibody System Dynamics》2011,26(3):335-365
This second part of a two part paper uses concepts from graph theory to obtain a deeper understanding of the mathematical
foundations of multibody dynamics. The first part (Jain in Graph theoretic foundations of multibody dynamics. Part I. Structural
properties, 2010) established the block-weighted adjacency (BWA) matrix structure of spatial operators associated with serial- and tree-topology multibody system dynamics, and introduced
the notions of spatial kernel operators (SKO) and spatial propagation operators (SPO). This paper builds upon these connections to show that key analytical results and computational algorithms are a direct
consequence of these structural properties and require minimal assumptions about the specific nature of the underlying multibody
system. We formalize this notion by introducing the notion of SKO models for general tree-topology multibody systems. We show that key analytical results, including mass-matrix factorization, inversion,
and decomposition hold for all SKO models. It is also shown that key low-order scatter/gather recursive computational algorithms
follow directly from these abstract-level analytical results. Application examples to illustrate the concrete application
of these general results are provided. The paper also describes a general recipe for developing SKO models. The abstract nature
of SKO models allows for the application of these techniques to a very broad class of multibody systems. 相似文献
43.
44.
This article addresses the issue of visual landmark recognition in autonomous robot navigation along known routes, by intuitively
exploiting the functions of the human visual system and its navigational ability. A feedforward–feedbackward architecture
has been developed for recognising visual landmarks in real time. It integrates the theoretical concepts from the pre-attentive
and attentive stages in the human visual system, the selective attention adaptive resonance theory neural network and its
derivatives, and computational approaches towards object recognition in computer vision. The architecture mimics the pre-attentive
and attentive stages in the context of object recognition, embedding neural network processing paradigm into a computational
template-matching approach in computer vision. The real-time landmark recognition capability is achieved by mimicking the
pre-attentive stage, where it models a selective attention mechanism for optimal computational resource allocation, focusing
only on the regions of interest to address the computational restrictive nature of current computer processing power. Similarly,
the recognition of visual landmarks in both clean and cluttered backgrounds is implemented in the attentive stage by developing
a memory feedback modulation (MFM) mechanism that enables knowledge from the memory to interact and enhance the efficiency
of earlier stages in the architecture. Furthermore, it also incorporates both top-down and bottom-up facilitatory and inhibition
pathways between the memory and the earlier stages to enable the architecture to recognise a 2D landmark, which is partially
occluded by adjacent features in the surroundings. The results show that the architecture is able to recognise objects in
cluttered backgrounds using real-images in both indoor and outdoor scenes. Furthermore, the architecture application in autonomous
robot navigation has been demonstrated through a number of real-time trials in both indoor and outdoor environments. 相似文献
45.
Clubfoot is a challenging structural foot abnormality in babies and generally occurs at birth or during childhood. Due to this the abnormal posturing of the foot causes the babies to turn the ankle inward and walk along the outside edges of the foot. In medical science it is known as “congenital talipes equino varus” (CTEV). Computer modeling of prosthesis and orthosis is a perspective method for optimal design and gait is a terminology related to walking patterns of human subject. 相似文献
46.
47.
48.
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
49.
Emergent semantics through interaction in image databases 总被引:9,自引:0,他引:9
Santini S. Gupta A. Jain R. 《Knowledge and Data Engineering, IEEE Transactions on》2001,13(3):337-351
In this paper, we briefly discuss some aspects of image semantics and the role that it plays for the design of image databases. We argue that images don't have an intrinsic meaning, but that they are endowed with a meaning by placing them in the context of other images and by the user interaction. From this observation, we conclude that, in an image, database users should be allowed to manipulate not only the individual images, but also the relation between them. We present an interface model based on the manipulation of configurations of images 相似文献
50.
Ansari N. Sakarindr P. Haghani E. Chao Zhang Jain A.K. Shi Y.Q. 《Security & Privacy, IEEE》2008,6(3):30-39
Despite their widespread deployment, questions about electronic voting systems' performance emerge following many elections. To encourage full public confidence in the electoral process, some researchers recommend equipping electronic voting machines with voter-verifiable audit trails that print out paper records that voters can read and verify. In this article, the authors report on their analysis and testing of one US state's criteria for direct-recording electronic (DRE) voting machines equipped with voter-verified paper-record (VVPR) systems. The criteria and analysis cover various categories, including privacy, security, verification, integrity, functionality, and examination. The authors describe their testing methodologies, discuss issues exhibited by different voting systems, and propose solutions to address those issues. 相似文献