全文获取类型
收费全文 | 825篇 |
免费 | 34篇 |
国内免费 | 11篇 |
专业分类
电工技术 | 18篇 |
综合类 | 3篇 |
化学工业 | 189篇 |
金属工艺 | 54篇 |
机械仪表 | 40篇 |
建筑科学 | 31篇 |
矿业工程 | 1篇 |
能源动力 | 40篇 |
轻工业 | 45篇 |
水利工程 | 9篇 |
石油天然气 | 11篇 |
无线电 | 89篇 |
一般工业技术 | 158篇 |
冶金工业 | 27篇 |
原子能技术 | 10篇 |
自动化技术 | 145篇 |
出版年
2024年 | 1篇 |
2023年 | 14篇 |
2022年 | 17篇 |
2021年 | 50篇 |
2020年 | 45篇 |
2019年 | 53篇 |
2018年 | 61篇 |
2017年 | 49篇 |
2016年 | 62篇 |
2015年 | 29篇 |
2014年 | 53篇 |
2013年 | 87篇 |
2012年 | 45篇 |
2011年 | 71篇 |
2010年 | 57篇 |
2009年 | 42篇 |
2008年 | 19篇 |
2007年 | 13篇 |
2006年 | 15篇 |
2005年 | 11篇 |
2004年 | 10篇 |
2003年 | 8篇 |
2002年 | 3篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 7篇 |
1998年 | 8篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1968年 | 2篇 |
排序方式: 共有870条查询结果,搜索用时 0 毫秒
1.
Massimiliano Corsini Elisa Drelie Gelasca Touradj Ebrahimi Mauro Barni 《Multimedia, IEEE Transactions on》2007,9(2):247-256
This paper addresses the problem of assessing distortions produced by watermarking 3D meshes. In particular, a new methodology for subjective evaluation of the quality of 3D objects is proposed and implemented. Two objective metrics derived from measures of surface roughness are then proposed and their efficiency to predict the perceptual impact of 3D watermarking is assessed and compared with the state of the art. Results obtained show good correlations between the proposed objective metrics and subjective assessments by human observers 相似文献
2.
This article raises various issues in the design of an efficient BCI system in multimedia applications. The main focus is on one specific modality, namely an electroencephalography (EEG)-based BCI. In doing so, we provide an overview of the most recent progress achieved in this field, with an emphasis on signal processing aspects. 相似文献
3.
Deconvolution methods for mitigation of transverse blurring in optical coherence tomography. 总被引:3,自引:0,他引:3
Tyler S Ralston Daniel L Marks Farzad Kamalabadi Stephen A Boppart 《IEEE transactions on image processing》2005,14(9):1254-1264
Imaging resolution in optical coherence tomography (OCT) is a key determinant for acquiring clinically useful optical biopsies of tissues. In contrast to light or confocal microscopy, the axial and transverse resolutions in OCT are independent and each can be analyzed individually. A method for mitigating transverse blurring and the apparent loss of transverse resolution in OCT by means of Gaussian beam deconvolution is presented. Such a method provides better representation of a specimen by using known physical parameters of a lens. To implement this method, deconvolution algorithms based on a focal-dependent kernel are investigated. First, the direct inverse problem is investigated using two types of regularization, truncated singular value decomposition, and Tikhonov. Second, an iterative expectation maximization algorithm, the Richardson-Lucy algorithm, with a beam-width-dependent iteration scheme is developed. A dynamically iterative Richardson-Lucy algorithm can reduce transverse blurring by providing an improvement in the transverse point-spread-function for sparse scattering samples in regions up to two times larger than the confocal region of the lens. These deblurring improvements inside and outside of the confocal region, which are validated experimentally, are possible without introducing new optical imaging hardware or acquiring multiple images of the same specimen. Implementation of this method in sparse scattering specimens, such as engineered tissues, has the potential to improve cellular detection and categorization. 相似文献
4.
Rezaei Afsaneh Mohajeri Farzad Hamzavi-Zarghani Zahra 《Journal of Computational Electronics》2021,20(6):2522-2529
Journal of Computational Electronics - In recent years, cloaking using materials with negative electric permittivity or magnetic permeability has been studied and researched. It has been... 相似文献
5.
Video indexing is employed to represent the features of video sequences. Motion vectors derived from compressed video are preferred for video indexing because they can be accessed by partial decoding; thus, they are used extensively in various video analysis and indexing applications. In this study, we introduce an efficient compressed domain video indexing method and implement it on the H.264/AVC coded videos. The video retrieval experimental evaluations indicate that the video retrieval based on the proposed indexing method outperforms motion vector based video retrieval in 74 % of queries with little increase in computation time. Furthermore, we compared our method with a pixel level video indexing method which employs both temporal and spatial features. Experimental evaluation results indicate that our method outperforms the pixel level method both in performance and speed. Hence considering the speed and precision characteristics of indexing methods, the proposed method is an efficient indexing method which can be used in various video indexing and retrieval applications. 相似文献
6.
Oscar Ljungkrantz Knut Åkesson Martin Fabian Amir Hossein Ebrahimi 《Empirical Software Engineering》2014,19(3):655-677
This paper presents an empirical study of control logic specifications used to document industrial control logic code in manufacturing applications. More than one hundred input/output related property specifications from ten different reusable function blocks were investigated. The main purpose of the study was to provide understanding of how the specifications are expressed by industrial practitioners, in order to develop new tools and methods for specifying control logic software, as well as for evaluating existing ones. In this paper, the studied specifications are used to evaluate linear temporal logic in general and the specification language ST-LTL, tailored for functions blocks, in particular. The study shows that most specifications are expressed as implications, that should always be fulfilled, between input and output conditions. Many of these implications are complex since the input and output conditions may be mixed and involve sequences, timer issues and non-boolean variables. Using ST-LTL it was possible to represent all implications of this study. The few non-implication specifications could be specified in ST-LTL as well after being altered to suit the specification language. The paper demonstrates some advantages of ST-LTL compared to standard linear temporal logic and discusses possible improvements such as support for automatic rewrite of complex specifications. 相似文献
7.
Water uptake characteristics and some mechanical properties of polypropylene composites containing three types of natural fillers, purified α‐cellulose, wastepaper fibers, and wood flour were studied. The fiber contents were 15, 25, and 35% by weight. Two percent maleic anhydride polypropylene (MAPP) was also added to the mix, as the compatibilizer agent. Mixing process was performed in a Brabender Plasticorder until a constant torque was reached. Composites made out of these combinations were then pressed in a laboratory press and ASTM standard test specimens were cut out of the sheets. Water absorption and tensile tests were performed on these specimens. The results showed a significant difference between the various filler types regarding water uptake. Water uptake also increased by the increase in filler content. Tensile strength and elongation at break in composites declined when compared with pure polypropylene, but their modulus of elasticity increased. Among the three types of fillers, no significant discrepancies were observed in terms of improving mechanical properties in composites. Filler content increase had no drastic effect regarding strength improvement. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 941–946, 2003 相似文献
8.
Mehdi Bidabadi Farzad Faraji Dizaji Hossein Beidaghy Dizaji Moslem Safari Ghahsareh 《中南工业大学学报(英文版)》2014,(1):326-337
In this work, the effect of various effective dimensionless numbers and moisture contents on initiation of instability in combustion of moisty organic dust is calculated. To have reliable model, effect of thermal radiation is taken into account. One- dimensional flame structure is divided into three zones: preheat zone, reaction zone and post-flame zone. To investigate pulsating characteristics of flame, governing equations are rewritten in dimensionless space-time ((, r/, ~) coordinates. By solving these newly achieved governing equations and combining them, which is completely discussed in body of article, a new expression is obtained. By solving this equation, it is possible to predict initiation of instability in organic dust flame. According to the obtained results by increasing Lewis number, threshold of instability happens sooner. On the other hand, pulsating is postponed by increasing Damk6hler number, pyrolysis temperature or moisture content. Also, by considering thermal radiation effect, burning velocity predicted by our model is closer to experimental results. 相似文献
9.
Rajabali Ebrahimi 《应用聚合物科学杂志》2021,138(37):50931
The powerful waves of ultrasound are used in polymerization reactions in the absence of initiator. In the present research, the hydrogel was obtained by water-soluble acrylic monomers, starch, and the crosslinking agent of methylene bis acrylamide dissolved in water/glycerol dual. The hydrogel is formed by these waves only in viscous environments such as glycerol, heat, or initiator is not required. In the presence of ultrasound, the time of product formation is reduced to a few minutes. Moreover, the resulting hydrogels have more uniform microscopic structure and are more swollen. The structure of the grafted hydrogel was examined meanwhile the hydrogel swelling in three environments of pure water, saltwater, and under pressure was measured. It was found that the grafted hydrogel has double swelling rate in the pure. Also, after loading the ciprofloxacin into the synthesized hydrogel, this drug is released 99% in initial 20 min. 0.1 g starch in 1.5 g acrylic hydrogel has the most drug release. The high swelling capacity in the pH ranges of 5–9 shows the extension of drug application in acidic or alkaline environments, and also after several using the gel and the capacity of water absorbency, which was about 70% of its initial water, indicates the perfect reusability capacity of the gel. 相似文献
10.
Morteza Nikooghadam Author VitaeAuthor Vitae Mohsen Ebrahimi Moghaddam Author Vitae 《Journal of Systems and Software》2010,83(10):1917-1929
The elliptic curve cryptosystem (ECC) has recently received significant attention by researchers due to its high performance, low computational cost, and small key size. In this paper, an efficient key management and derivation scheme based on ECC is proposed to solve dynamic access problems in a user hierarchy. Compared to previous ECC based works, the proposed method does not require constructing interpolate polynomials, therefore, the computational complexity of key generation and key derivation is significantly reduced. At the same time, time complexity of adding/deleting security classes, modifying their relationships, and changing of secret keys is decreased in the proposed method. 相似文献