全文获取类型
收费全文 | 436篇 |
免费 | 19篇 |
国内免费 | 24篇 |
专业分类
电工技术 | 27篇 |
综合类 | 13篇 |
化学工业 | 22篇 |
金属工艺 | 52篇 |
机械仪表 | 67篇 |
建筑科学 | 19篇 |
矿业工程 | 5篇 |
能源动力 | 7篇 |
轻工业 | 2篇 |
水利工程 | 2篇 |
石油天然气 | 5篇 |
武器工业 | 5篇 |
无线电 | 74篇 |
一般工业技术 | 58篇 |
冶金工业 | 11篇 |
自动化技术 | 110篇 |
出版年
2023年 | 3篇 |
2022年 | 1篇 |
2021年 | 8篇 |
2020年 | 6篇 |
2019年 | 6篇 |
2018年 | 3篇 |
2017年 | 8篇 |
2016年 | 16篇 |
2015年 | 2篇 |
2014年 | 28篇 |
2013年 | 32篇 |
2012年 | 23篇 |
2011年 | 35篇 |
2010年 | 14篇 |
2009年 | 25篇 |
2008年 | 18篇 |
2007年 | 33篇 |
2006年 | 42篇 |
2005年 | 30篇 |
2004年 | 35篇 |
2003年 | 19篇 |
2002年 | 14篇 |
2001年 | 11篇 |
2000年 | 11篇 |
1999年 | 10篇 |
1998年 | 11篇 |
1997年 | 9篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 6篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1984年 | 1篇 |
排序方式: 共有479条查询结果,搜索用时 0 毫秒
31.
水电、核电、风电是目前全球倡导优先开发的绿色能源,而在这三大能源资源中,水能又是我国最丰富的能源资源,也是中国现有能源中唯一可以大规模开发的清洁、可再生能源,大力开发利用水能对实现可持续发展具有重要的现实意义。 相似文献
32.
33.
机器视觉系统中摄像机定标策略 总被引:1,自引:0,他引:1
摄像机定标是从拍摄的二维图像中获取三维信息必不可少的步骤,一直为机器视觉领域的研究热点之一。本文阐述了几种定标方法的基本原理,并论述了如何在工业视觉系统中根据不同的任务来选择不同的定标方法问题。 相似文献
34.
运用有限元软件ABAQUS对薄壁件的实际加工过程进行了模拟三维仿真,研究了多点柔性工装系统支撑单元的密度、间距和吸附装置吸附力对薄壁件加工变形的影响。总结出3种因素对加工变形的影响规律以及为减少占用较多资源和调配时间最优的装夹布局,对多点柔性工装系统控制薄壁件的加工变形问题给出了建议。 相似文献
35.
S. Sarafan J.-B. Lévesque P. Wanjara J. Gholipour H. Champliaud 《Science & Technology of Welding & Joining》2013,18(6):473-478
Heavy-section assembly of hydroelectric turbine runner materials using single-pass, autogenous EBW was demonstrated to penetrate a 90-mm-thick butt joint. The welding-induced distortions and residual stresses were characterised to understand the impact of the materials and process conditions (e.g. preheating and/or PWHT). Using 3D optical measurements, the angular distortions of EB-welded UNS S41500 and CA6NM steels were determined to be 0.13° and 0.38°, respectively. The longitudinal residual stresses, measured through the contour method, had a M-shaped distribution throughout the thickness with minimum (~?500?MPa) compressive stresses in the FZ and maximum (~600?MPa) tensile stresses in the HAZ. After PWHT, the tensile and compressive stresses reduced to ~100?MPa. 相似文献
36.
《Science & Technology of Welding & Joining》2013,18(8):636-642
AbstractA new technique of in situ rolling friction stir welding (IRFSW) has been developed to reduce the residual stress and distortion. It can eliminate the weld flashes and improve corrosion resistance of the FSW seam. A new kind of FSW tool consisting of rolling balls was designed to achieve IRFSW. The residual stresses across the weld were measured by ultrasonic stress measurement experimental installation. The 3·5%NaCl solution was used to corrode the surface of welded joint, and corrosion current and potential were determined by an electrochemical analyser. The results shown that the residual tensile stress was reduced, the weld flashes were eliminated, and the corrosion resistance was improved. By applying IRFSW, the reduction of distortion was ~34·4% compared with that of conventional FSW joint for aluminium plant with 3 mm in thickness and 300 mm in length. 相似文献
37.
38.
In this paper we propose an effective watermark scheme for embedding and extracting based on the JPEG2000 Codec process. Our embedding algorithm applies the torus automorphisms (TA) technique to break up and scramble a watermark. The scrambled watermark was embedded into the quantized bitstreams of JPEG2000 before the entropy coding stage. Distortion reduction (DR) was applied to the compressed image to lessen image degradation caused by the embedding process. Our watermark scheme is simple and easy to implement. Furthermore, it is robust to attacks like blurring, edge enhancement, and other image processing manipulations.Corespondence to: J. Chen (P.O. Box 63-146, Taichung, Taiwan 406, R.O.C.) 相似文献
39.
无中继长线传输会出现信宿端信号严重失真的现象,矫正器是长线传输系统中的重要一环。本文提出一种对长线传输系统中HDB_3编码的失真信号进行矫正的算法。该算法采用先进先出队列并结合HDB_3编码规律进行码元矫正。最后给出了仿真结果。结果表明,误判率得到有效控制。 相似文献
40.
This paper addresses the estimation of a small gallery size that can generate the optimal error estimate and its confidence on a large population (relative to the size of the gallery) which is one of the fundamental problems encountered in performance prediction for object recognition. It uses a generalized two-dimensional prediction model that combines a hypergeometric probability distribution model with a binomial model and also considers the data distortion problem in large populations. Learning is incorporated in the prediction process in order to find the optimal small gallery size and to improve the prediction. The Chernoff and Chebychev inequalities are used as a guide to obtain the small gallery size. During the prediction, the expectation–maximization (EM) algorithm is used to learn the match score and the non-match score distributions that are represented as a mixture of Gaussians. The optimal size of the small gallery is learned by comparing it with the sizes obtained by the statistical approaches and at the same time the upper and lower bounds for the prediction on large populations are obtained. Results for the prediction are presented for the NIST-4 fingerprint database. 相似文献