全文获取类型
收费全文 | 4666篇 |
免费 | 357篇 |
国内免费 | 92篇 |
专业分类
电工技术 | 193篇 |
综合类 | 181篇 |
化学工业 | 1091篇 |
金属工艺 | 106篇 |
机械仪表 | 150篇 |
建筑科学 | 273篇 |
矿业工程 | 117篇 |
能源动力 | 115篇 |
轻工业 | 421篇 |
水利工程 | 43篇 |
石油天然气 | 66篇 |
武器工业 | 8篇 |
无线电 | 498篇 |
一般工业技术 | 709篇 |
冶金工业 | 513篇 |
原子能技术 | 34篇 |
自动化技术 | 597篇 |
出版年
2024年 | 9篇 |
2023年 | 44篇 |
2022年 | 105篇 |
2021年 | 117篇 |
2020年 | 97篇 |
2019年 | 91篇 |
2018年 | 102篇 |
2017年 | 109篇 |
2016年 | 143篇 |
2015年 | 150篇 |
2014年 | 197篇 |
2013年 | 331篇 |
2012年 | 249篇 |
2011年 | 317篇 |
2010年 | 250篇 |
2009年 | 221篇 |
2008年 | 250篇 |
2007年 | 218篇 |
2006年 | 233篇 |
2005年 | 178篇 |
2004年 | 160篇 |
2003年 | 150篇 |
2002年 | 183篇 |
2001年 | 128篇 |
2000年 | 98篇 |
1999年 | 119篇 |
1998年 | 90篇 |
1997年 | 86篇 |
1996年 | 82篇 |
1995年 | 71篇 |
1994年 | 48篇 |
1993年 | 44篇 |
1992年 | 38篇 |
1991年 | 42篇 |
1990年 | 32篇 |
1989年 | 27篇 |
1988年 | 21篇 |
1987年 | 14篇 |
1986年 | 21篇 |
1985年 | 10篇 |
1984年 | 20篇 |
1983年 | 22篇 |
1982年 | 17篇 |
1981年 | 16篇 |
1979年 | 16篇 |
1978年 | 10篇 |
1976年 | 16篇 |
1975年 | 13篇 |
1974年 | 12篇 |
1970年 | 10篇 |
排序方式: 共有5115条查询结果,搜索用时 0 毫秒
71.
针对居民社区公共门窗管理不及时,耗费大量人力资源,且效率较低等问题,设计了一款基于STM32单片机的居民社区门窗禁控制系统.在传统的门禁控制系统的基础上,系统利用Zigbee无线传感网技术,实现门窗禁控制器之间的无线通讯.管理用户可以通过以太网远程控制系统,系统也可以根据传感器监测到的环境数据实现自动调节.同时,尝试采用一种基于频率捷变的分布式自适应干扰技术,解决系统在居民居住环境中遇到的Wifi网络信号干扰问题.最后,通过测试表明,该系统运行稳定,具有广泛的应用前景. 相似文献
72.
Lin HT Tai YW Brown MS 《IEEE transactions on pattern analysis and machine intelligence》2011,33(11):2329-2336
This paper addresses the problem of matting motion blurred objects from a single image. Existing single image matting methods are designed to extract static objects that have fractional pixel occupancy. This arises because the physical scene object has a finer resolution than the discrete image pixel and therefore only occupies a fraction of the pixel. For a motion blurred object, however, fractional pixel occupancy is attributed to the object’s motion over the exposure period. While conventional matting techniques can be used to matte motion blurred objects, they are not formulated in a manner that considers the object’s motion and tend to work only when the object is on a homogeneous background. We show how to obtain better alpha mattes by introducing a regularization term in the matting formulation to account for the object’s motion. In addition, we outline a method for estimating local object motion based on local gradient statistics from the original image. For the sake of completeness, we also discuss how user markup can be used to denote the local direction in lieu of motion estimation. Improvements to alpha mattes computed with our regularization are demonstrated on a variety of examples. 相似文献
73.
This paper proposes an improved variational model, multiple piecewise constant with geodesic active contour (MPC-GAC) model, which generalizes the region-based active contour model by Chan and Vese, 2001 [11] and merges the edge-based active contour by Caselles et al., 1997 [7] to inherit the advantages of region-based and edge-based image segmentation models. We show that the new MPC-GAC energy functional can be iteratively minimized by graph cut algorithms with high computational efficiency compared with the level set framework. This iterative algorithm alternates between the piecewise constant functional learning and the foreground and background updating so that the energy value gradually decreases to the minimum of the energy functional. The k-means method is used to compute the piecewise constant values of the foreground and background of image. We use a graph cut method to detect and update the foreground and background. Numerical experiments show that the proposed interactive segmentation method based on the MPC-GAC model by graph cut optimization can effectively segment images with inhomogeneous objects and background. 相似文献
74.
Studies in the literature indicate that many organizations have experienced a crisis of confidence in information systems (IS) functions and IS executives. We address the issue of joint chief executive/IT executive responsibility in building a corporate culture to overcome resistance to technological changes. This paper reports a study of differences in IT perceptions between chief executives and IS executives. The results suggest a similarity of views in three major dimensions of perception: IT vision, organizational IS issues and IT support for knowledge management. The study also suggests that national culture, industry type and the chief executive/IT executive relationship contribute to differences in IT perception. 相似文献
75.
76.
77.
Direct manipulation of FFD: efficient explicit solutions and decomposible multiple point constraints 总被引:8,自引:0,他引:8
Published online: 25 July 2001 相似文献
78.
79.
Many graphics applications require that 3D models automatically be presented upright and from a good view. We propose a method that simultaneously recognizes upright orientation and good view for 3D man-made models. The strategy is to determine the best base on which a 3D model can stand upright from a small set of candidate bases. Every candidate base is composed of clustered facets of the simplified convex hull of the given 3D model. Next, a proposed UV-measurement selects the best base from the candidate bases using weighted feature-based evaluation functions based on geometrical, physical, and visual aspects. Our method has been tested using a public 3D model database and compared with previous methods. As experimental results show, our method outperforms previous work in both efficiency and accuracy. 相似文献
80.
Carl Miller Helen Austin Larry Posorske Jesus Gonzlez 《Journal of the American Oil Chemists' Society》1988,65(6):927-931
The lipase-catalyzed synthesis of ester bonds has been well-documented lately and is of much current commercial interest.
Immobilization of a fungal lipase on a unique macroporous support allows not only the ability to operate in non-aqueous media
but to catalyze ester synthesis in quantitative yields, employing attractive commercial conditions. Catalyst dose and process
configurations will be illustrated. The capability of the catalyst to operate efficiently in reverse under a variety of unnatural,
hostile, solvent-containing environments will be discussed. The range of substrates for this immobilized lipase, Lipzome,
has been investigated. The enzyme will catalyze ester synthesis with saturated, unsaturated and a variety of branched carboxylic
acids. The alcohol specificity for this enzyme also is equally broad. A wide variety of straight-chain, branched and polar
alcohols can be substrates. In addition, some examples of alcohol specificity for kinetic isomer resolution will be cited.
Presented at the symposium “The Biology, Biotechnology and Technology of Lipases” at the 78th annual meeting of the American
Oil Chemists’ Society held May 17–21, 1987, in New Orleans, Louisiana. 相似文献