全文获取类型
收费全文 | 1437篇 |
免费 | 49篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 67篇 |
综合类 | 3篇 |
化学工业 | 254篇 |
金属工艺 | 29篇 |
机械仪表 | 38篇 |
建筑科学 | 28篇 |
矿业工程 | 1篇 |
能源动力 | 113篇 |
轻工业 | 122篇 |
水利工程 | 12篇 |
石油天然气 | 13篇 |
武器工业 | 1篇 |
无线电 | 145篇 |
一般工业技术 | 244篇 |
冶金工业 | 195篇 |
原子能技术 | 9篇 |
自动化技术 | 219篇 |
出版年
2024年 | 5篇 |
2023年 | 25篇 |
2022年 | 53篇 |
2021年 | 77篇 |
2020年 | 46篇 |
2019年 | 62篇 |
2018年 | 65篇 |
2017年 | 39篇 |
2016年 | 54篇 |
2015年 | 29篇 |
2014年 | 46篇 |
2013年 | 90篇 |
2012年 | 41篇 |
2011年 | 58篇 |
2010年 | 36篇 |
2009年 | 42篇 |
2008年 | 36篇 |
2007年 | 38篇 |
2006年 | 27篇 |
2005年 | 20篇 |
2004年 | 32篇 |
2003年 | 22篇 |
2002年 | 21篇 |
2001年 | 21篇 |
2000年 | 22篇 |
1999年 | 19篇 |
1998年 | 62篇 |
1997年 | 40篇 |
1996年 | 36篇 |
1995年 | 26篇 |
1994年 | 29篇 |
1993年 | 22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 | 14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1493条查询结果,搜索用时 0 毫秒
21.
The effect of 0–12 wt% AlN addition on the electrical resistivity of SiC ceramics pressureless sintered with 0.7 wt% B4C and 2.5 wt% C additives was investigated. The elemental analysis of SiC grains revealed a codoping of Al and N in the SiC lattice with a higher N concentration with 1 wt% AlN addition and a higher Al concentration with 12 wt% AlN addition. The electrical resistivity decreased by four orders of magnitude (1.7 × 105 → 8.3 × 101 Ω cm) with 1 wt% AlN addition due to the increased carrier density (1.7 × 1010 → 2.3 × 1015 cm−3) caused by excess N-derived donors. However, subsequent AlN addition (4 → 12 wt%) led to an increase (2.9 × 103 → 1.2 × 104 Ω‧cm) in electrical resistivity due to (1) increased Al dopants which act as deep acceptors for trapping N-derived carriers causing a decrease in carrier density (2.3 × 1015 → 5.9 × 1013 cm−3), (2) the formation of electrically insulating SiC-AlN solid solution, and (3) the presence of electrically insulating AlN grains at the grain boundaries. 相似文献
22.
High-temperature oxidation and sulfidation studies were conducted on an oxide-dispersion-strengthened alloy of composition Fe-20Cr-16Ni-4Al-1Y2O3. The oxidation studies were conducted in air and low-PO2 environments over a temperature range of 650–1200°C. Results are also reported on the sulfidation resistance of preformed oxide scales and the influence of reoxidation of preformed sulfide scales. Detailed microstructural results and x-ray diffraction analysis data are presented to substantiate the corrosion behavior of the alloy over the wide range of conditions anticipated in fossil-energy systems. Data are also presented on the corrosion behavior of the alloy in oxygen/sulfur mixed gas atmospheres, and the results are used to compare the corrosion behavior of the present alloy with other chromia- and alumina-forming alloys. 相似文献
23.
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
24.
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
25.
Munsif Ali Jatoi Nidal Kamel Aamir Saeed Malik Ibrahima Faye Jose M. Bornot Tahamina Begum 《International journal of imaging systems and technology》2016,26(1):55-64
Electroencephalography (EEG) is widely used in variety of research and clinical applications which includes the localization of active brain sources. Brain source localization provides useful information to understand the brain's behavior and cognitive analysis. Various source localization algorithms have been developed to determine the exact locations of the active brain sources due to which electromagnetic activity is generated in brain. These algorithms are based on digital filtering, 3D imaging, array signal processing and Bayesian approaches. According to the spatial resolution provided, the algorithms are categorized as either low resolution methods or high resolution methods. In this research study, EEG data is collected by providing visual stimulus to healthy subjects. FDM is used for head modelling to solve forward problem. The low‐resolution brain electromagnetic tomography (LORETA) and standardized LORETA (sLORETA) have been used as inverse modelling methods to localize the active regions in the brain during the stimulus provided. The results are produced in the form of MRI images. The tables are also provided to describe the intensity levels for estimated current level for the inverse methods used. The higher current value or intensity level shows the higher electromagnetic activity for a particular source at certain time instant. Thus, the results obtained demonstrate that standardized method which is based on second order Laplacian (sLORETA) in conjunction with finite difference method (FDM) as head modelling technique outperforms other methods in terms of source estimation as it has higher current level and thus, current density (J) for an area as compared to others. 相似文献
26.
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
27.
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
28.
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
29.
S. Panda S.C. Swain P.K. Rautray R.K. Malik G. Panda 《Simulation Modelling Practice and Theory》2010,18(9):1199-1213
Power-system stability improvement by a static synchronous series compensator (SSSC)-based damping controller is thoroughly investigated in this paper. The design problem of the proposed controller is formulated as an optimization problem, and real coded genetic algorithm (RCGA) is employed to search for the optimal controller parameters. Both local and remote signals with associated time delays are considered in the present study and a comparison has been made between the two signals. The performances of the proposed controllers are evaluated under different disturbances for both single-machine infinite-bus power system and multi-machine power system. Simulation results are presented and compared with a recently published modern heuristic optimization technique under various disturbances to show the effectiveness and robustness of the proposed approach. 相似文献
30.
Khalida Inayat Noor Sarfraz Nawaz Malik 《Computers & Mathematics with Applications》2011,62(1):367-375
The aim of this paper is to generalize the conic domain defined by Kanas and Wisniowska, and define the class of functions which map the open unit disk E onto this generalized conic domain. A brief comparison between these conic domains is the main motivation of this paper. A correction is made in selecting the range interval of order of conic domain. 相似文献