全文获取类型
收费全文 | 1379篇 |
免费 | 42篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 66篇 |
综合类 | 2篇 |
化学工业 | 241篇 |
金属工艺 | 30篇 |
机械仪表 | 36篇 |
建筑科学 | 27篇 |
矿业工程 | 1篇 |
能源动力 | 109篇 |
轻工业 | 103篇 |
水利工程 | 12篇 |
石油天然气 | 13篇 |
武器工业 | 1篇 |
无线电 | 140篇 |
一般工业技术 | 237篇 |
冶金工业 | 189篇 |
原子能技术 | 9篇 |
自动化技术 | 212篇 |
出版年
2024年 | 5篇 |
2023年 | 22篇 |
2022年 | 46篇 |
2021年 | 70篇 |
2020年 | 43篇 |
2019年 | 57篇 |
2018年 | 56篇 |
2017年 | 34篇 |
2016年 | 52篇 |
2015年 | 28篇 |
2014年 | 40篇 |
2013年 | 86篇 |
2012年 | 40篇 |
2011年 | 58篇 |
2010年 | 34篇 |
2009年 | 41篇 |
2008年 | 37篇 |
2007年 | 38篇 |
2006年 | 25篇 |
2005年 | 20篇 |
2004年 | 32篇 |
2003年 | 21篇 |
2002年 | 21篇 |
2001年 | 19篇 |
2000年 | 22篇 |
1999年 | 19篇 |
1998年 | 60篇 |
1997年 | 39篇 |
1996年 | 36篇 |
1995年 | 26篇 |
1994年 | 29篇 |
1993年 | 21篇 |
1992年 | 14篇 |
1991年 | 27篇 |
1990年 | 25篇 |
1989年 | 24篇 |
1988年 | 18篇 |
1987年 | 13篇 |
1986年 | 10篇 |
1985年 | 12篇 |
1984年 | 12篇 |
1983年 | 13篇 |
1982年 | 12篇 |
1981年 | 9篇 |
1979年 | 9篇 |
1978年 | 9篇 |
1976年 | 6篇 |
1973年 | 4篇 |
1972年 | 7篇 |
1966年 | 4篇 |
排序方式: 共有1428条查询结果,搜索用时 15 毫秒
11.
Mechanical properties of high density polyethylene (HDPE) extended to draw ratios in the 20–40 range have been determined and compared with corresponding properties of the polymers containing particulates including rutile, carbon black, iron oxide, and mica. Shrinkage of drawn structures was studied to temperatures near the fusion of the polymer host. The degree of interaction at polymer/additive interfaces was varied by surface coating certain of the solids with standard coupling agents. Solids were found to increase tensile moduli and to decrease shrinkage, particularly at higher exposure temperatures. The magnitude of changes due to the presence of solids was shown to depend on the apparent interaction at contacts between host and additive. In a dispersion–force matrix, like HDPE, benefits were optimized when the particulates were amphoteric or neutral, rather than having pronounced acid or base interaction potentials. 相似文献
12.
13.
This paper presents a gravity optimised particle filter (GOPF) where the magnitude of the gravitational force for every particle is proportional to its weight. GOPF attracts nearby particles and replicates new particles as if moving the particles towards the peak of the likelihood distribution, improving the sampling efficiency. GOPF is incorporated into a technique for hand features tracking. A fast approach to hand features detection and labelling using convexity defects is also presented. Experimental results show that GOPF outperforms the standard particle filter and its variants, as well as state-of-the-art CamShift guided particle filter using a significantly reduced number of particles. 相似文献
14.
This paper investigates some limitations of the nonblocking property when used for supervisor synthesis in discrete event systems. It is shown that there are cases where synthesis with the nonblocking property gives undesired results. To address such cases, the paper introduces progressive events as a means to specify more precisely how a synthesised supervisor should complete its tasks. The nonblocking property is modified to take progressive events into account, and appropriate methods for verification and synthesis are proposed. Experiments show that progressive events can be used in the analysis of industrial-scale systems, and can expose issues that remain undetected by standard nonblocking verification. 相似文献
15.
Chlorendic anhydride based polyester ( I ,) tetrachlorophthalic anhydride based polyester ( II ), dibromoneopentyl glycol based polyester ( III ,) general purpose polyester ( IV ,) blend of dibromoneopentyl glycol based polyester with general purpose polyester ( V ,) chlorendic anhydride and dibromoneopentyl glycol based polyester ( VI ), and a blend of chlorendic anhydride based polyester and dibromoneopentyl glycol based polyester ( VII ) were prepared and their chemical resistance and moisture absorption studied in various reagents, acid, alkali, and water, at 25 and 65°C. It is found that the polyester ( III ) is the least affected in the presence of the acids. In 20% NaOH, there was a decrease in weight for all polyesters at both the temperatures compared to the control except the polyester ( VII ). Increase in weight of all the polyesters was observed during the absorption of moisture both at 25 and 65°C. The increase was higher at higher temperature. Polyester ( III ) thus shows the least absorption of moisture. 相似文献
16.
Memoona Malik Faraz Ahsan Sajjad Mohsin 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2016,20(3):925-938
This paper presents a novel denoising approach based on smoothing linear and nonlinear filters combined with an optimization algorithm. The optimization algorithm used was cuckoo search algorithm and is employed to determine the optimal sequence of filters for each kind of noise. Noises that would be eliminated form images using the proposed approach including Gaussian, speckle, and salt and pepper noise. The denoising behaviour of nonlinear filters and wavelet shrinkage threshold methods have also been analysed and compared with the proposed approach. Results show the robustness of the proposed filter when compared with the state-of-the-art methods in terms of peak signal-to-noise ratio and image quality index. Furthermore, a comparative analysis is provided between the said optimization algorithm and the genetic algorithm. 相似文献
17.
Andras Ferencz Erik G. Learned-Miller Jitendra Malik 《International Journal of Computer Vision》2008,77(1-3):3-24
Object identification is a specialized type of recognition in which the category (e.g. cars) is known and the goal is to recognize
an object’s exact identity (e.g. Bob’s BMW). Two special challenges characterize object identification. First, inter-object
variation is often small (many cars look alike) and may be dwarfed by illumination or pose changes. Second, there may be many
different instances of the category but few or just one positive “training” examples per object instance. Because variation
among object instances may be small, a solution must locate possibly subtle object-specific salient features, like a door
handle, while avoiding distracting ones such as specular highlights. With just one training example per object instance, however,
standard modeling and feature selection techniques cannot be used. We describe an on-line algorithm that takes one image from
a known category and builds an efficient “same” versus “different” classification cascade by predicting the most discriminative
features for that object instance. Our method not only estimates the saliency and scoring function for each candidate feature,
but also models the dependency between features, building an ordered sequence of discriminative features specific to the given
image. Learned stopping thresholds make the identifier very efficient. To make this possible, category-specific characteristics
are learned automatically in an off-line training procedure from labeled image pairs of the category. Our method, using the
same algorithm for both cars and faces, outperforms a wide variety of other methods. 相似文献
18.
K. Malik F. Ahmad N. A. Yunus T. Nakato E. Mouri S. Dawood I. R. Memon 《Materialwissenschaft und Werkstofftechnik》2023,54(9):1157-1166
This research aims to develop a method for the amalgamation of graphene nanoplatelets in glass/epoxy composites. The poor interface bonding between the fiber and matrix is critical and hinders the full performance of the composites. Glass fabric and epoxy were used as reinforcement and matrix in the composite, respectively. Graphene nanoplatelets were utilized as an additional nano-materials filler for the composites. Glass/graphene/epoxy and glass/epoxy composites were fabricated via vacuum infusion molding. The new method of applying graphene nanoplatelets as secondary reinforcement in the composite was developed based on proper functionalization in the sonication process. The physical, tensile, flexural, and short beam interlaminar properties of fabricated composites were examined to analyze the method's effectiveness. The results showed that density decreased by around 5 %; however, thickness increased by around 34 % after introducing graphene nanoplatelets into the composites. The tensile strength and modulus of the composites declined by approximately 19 %, on the other hand, flexural strength and modulus increased by around 63.3 % and 8.3 %, respectively, after the addition of graphene nanoplatelets into the composites. Moreover, interlaminar shear strength of the composite was enhanced by approximately 50 %. 相似文献
19.
Flynn Castles Stephen M. Morris Damian J. Gardiner Qasim M. Malik Harry J. Coles 《Journal of the Society for Information Display》2010,18(2):128-133
Abstract— The flexoelectro‐optic effect provides a fast‐switching mechanism (0.01–0.1 msec), suitable for use in field‐sequential‐color full‐motion‐video displays. An in‐plane electric field is applied to a short‐pitch chiral nematic liquid crystal aligned in the uniform standing helix (or Grandjean) texture. The switching mechanism is experimentally demonstrated in a single‐pixel test cell, and the display performance is investigated as a function of device parameters. A contrast ratio of 2000:1 is predicted. 相似文献
20.
The probabilistic visual tracking methods using color histograms have been proven to be robust to target model variations and background illumination changes as shown by the recent research. However, the required computational cost is high due to intensive image data processing. The embedded solution of such algorithms become challenging due to high computational power demand and algorithm complexity. This paper presents a hardware/software co-design architecture for implementation of the well-known kernel based mean shift tracking algorithm. The design uses color histogram of the target as tracking feature. The target is searched in the consecutive images by maximizing the statistical match of the color distributions. The target localization is based on gradient based iterative search instead of exhaustive search which makes the system capable of achieving frame rate up to hundreds of frames per second while tracking multiple targets. The design, which is fully standalone, is implemented on a low-cost medium-size field programmable gate array (FPGA) device. The hardware cost of the design is compared with some other tracking systems. The performance of the system in terms of speed is evaluated and compared with the software based implementation. It is expected that the proposed solution will find its utility in applications like embedded automatic video surveillance systems. 相似文献