全文获取类型
收费全文 | 3367篇 |
免费 | 544篇 |
国内免费 | 267篇 |
专业分类
电工技术 | 181篇 |
综合类 | 352篇 |
化学工业 | 89篇 |
金属工艺 | 81篇 |
机械仪表 | 281篇 |
建筑科学 | 129篇 |
矿业工程 | 33篇 |
能源动力 | 21篇 |
轻工业 | 58篇 |
水利工程 | 24篇 |
石油天然气 | 16篇 |
武器工业 | 37篇 |
无线电 | 661篇 |
一般工业技术 | 469篇 |
冶金工业 | 58篇 |
原子能技术 | 16篇 |
自动化技术 | 1672篇 |
出版年
2024年 | 29篇 |
2023年 | 112篇 |
2022年 | 119篇 |
2021年 | 131篇 |
2020年 | 122篇 |
2019年 | 121篇 |
2018年 | 108篇 |
2017年 | 145篇 |
2016年 | 158篇 |
2015年 | 141篇 |
2014年 | 232篇 |
2013年 | 239篇 |
2012年 | 232篇 |
2011年 | 263篇 |
2010年 | 204篇 |
2009年 | 196篇 |
2008年 | 213篇 |
2007年 | 233篇 |
2006年 | 225篇 |
2005年 | 157篇 |
2004年 | 133篇 |
2003年 | 115篇 |
2002年 | 88篇 |
2001年 | 78篇 |
2000年 | 53篇 |
1999年 | 53篇 |
1998年 | 52篇 |
1997年 | 26篇 |
1996年 | 33篇 |
1995年 | 17篇 |
1994年 | 24篇 |
1993年 | 10篇 |
1992年 | 10篇 |
1991年 | 10篇 |
1990年 | 8篇 |
1989年 | 12篇 |
1988年 | 5篇 |
1987年 | 9篇 |
1986年 | 11篇 |
1985年 | 8篇 |
1984年 | 9篇 |
1983年 | 8篇 |
1982年 | 4篇 |
1981年 | 6篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1958年 | 1篇 |
排序方式: 共有4178条查询结果,搜索用时 15 毫秒
41.
为正确有效地分割出髋关节的外轮廓,提出了一种基于最佳分割线的股骨近端外轮廓的提取方法。该方法利用自底向上CT序列图像的帧间相似性找到一条分割目标股骨与其他骨骼的闭合分割线,从而利用该分割线来精确定位目标骨骼的位置,并搜索边缘点。实验结果表明,该方法能够准确地识别出股骨近端的外轮廓,自适应强,抗干扰性好。 相似文献
42.
For hyperspectral target detection, it is usually the case that only part of the targets pixels can be used as target signatures, so can we use them to construct the most proper background subspace for detecting all the probable targets? In this paper, a dynamic subspace detection (DSD) method which establishes a multiple detection framework is proposed. In each detection procedure, blocks of pixels are calculated by the random selection and the succeeding detection performance distribution analysis. Manifold analysis is further used to eliminate the probable anomalous pixels and purify the subspace datasets, and the remaining pixels construct the subspace for each detection procedure. The final detection results are then enhanced by the fusion of target occurrence frequencies in all the detection procedures. Experiments with both synthetic and real hyperspectral images (HSI) evaluate the validation of our proposed DSD method by using several different state-of-the-art methods as the basic detectors. With several other single detectors and multiple detection methods as comparable methods, improved receiver operating characteristic curves and better separability between targets and backgrounds by the DSD methods are illustrated. The DSD methods also perform well with the covariance-based detectors, showing their efficiency in selecting covariance information for detection. 相似文献
43.
Dynamic images that possess beauty and are user-friendly can increase the use of digital technology. In addition to information conveyance, dynamic images also act as a communication bridge in the human–machine interface. Dynamic images are widely used in the application of digital media. Therefore, understanding the visual effects of dynamic images on viewers is a very important issue. From a visual communication design perspective, dynamic images influence not only image quality, but also the viewers’ perception and impression of the displayed image. In the contemporary age characterized by universal usage of dynamic images, designers should attain synchronized knowledge and understanding of relevant media technology so as to present preferred design quality in the management of digital design such as animation design, Web page design, multimedia design, and so on. The current study noted that psychological effects such as viewers’ visual attention, preferences, and understanding were more important than image quality. Therefore, this study adopted the viewpoint of “visual design” and conducted a perceptual evaluation of grating frequency and grating velocity. The pair-comparison method and scale method were adopted in the research methodology to simplify perceptual evaluations and enhance their validity. The purpose of this study was: (1) To propose recommendations for displaying dynamic images and improving image performance using perceptual evaluation methods. (2) To examine the influence of psychological factors on viewer’s comfort when they experience dynamic images. (3) To identify the best grating feature combinations that meet viewer’s psychological characteristics and propose recommendations for dynamic images design. The study concludes that it is useful to establish criteria for evaluating users’ perception and to, develop perceptual evaluations of dynamic images. It is recommended that designers find a balance between watching a moving imaging display “clearly” and watching it “comfortably” for successful reception by the viewer. 相似文献
44.
研究分析老、中、青年肾移植患者服用普乐可复天数、总胆红素、尿酸的三维图像,使临床指标形象化显现,为预测疾病提供信息。将60岁以上老年患者、40~59岁中年患者与小于40岁青年患者分三组,采用MATLAB7.0做三维图像,分析图像特征并且对老年、中年、青年组图像进行比较。三维图像显示出各项指标间存在内在关系与个体差异。体内指标与服药天数相关,体内指标对临床预防疾病具有重要意义。 相似文献
45.
YUAN Da 《计算机辅助绘图.设计与制造(英文版)》2014,(2):1-5
This paper presents a new model for edge extraction of MR images, based on curve evolution and edgeflow techniques. At first the model for curve evolution is constructed, which automatically detect boundaries, and change of topology in terms of the edgeflow fields, and then the numerical approximation of the model is introduced, which is based on semi-implicit scheme to speed up the proposed approach. Finally, the numerical implementation is present and the experimental results show that the proposed model successfully extracts the edge contours, regardless of the heavy noise. 相似文献
46.
Tiff文件格式是一个丰富的图像格式,可以支持多种图像,现在已经成为存储档案数字化图像的标准格式.现有的应用程序都可以很好的支持Tiff图像格式.本文从Tiff的结构、特性、分类等几个方面,对Tiff文件进行了详细的分析.在支持传真的Class-F分类基础上,通过配置Tiff标签和在图像数据区域附加图像描述信息,对基于Tiff图像的数字化档案进行研究,并把此研究应用于焊接培训中,并取得了预期的效果. 相似文献
47.
刘杰 《网络安全技术与应用》2014,(12):20-21
为了达到特定目标跟踪的目的,对视频帧进行匹配算法的处理。通过利用灰度匹配的算法在平台上对简单背景下的目标进行跟踪,来显示进行目标基本跟踪过程。对目标坐标系的转换、运算的速度和使用的范围进行讨论。 相似文献
48.
宋艳萍 《网络安全技术与应用》2014,(11):153-154
AUTO CAD是一款交互式计算机辅助设计以及绘图的软件,在传统的教学中很多学生都认为这款软件的学习十分困难,所以很难提起学习兴趣,还有一些学生学习了后面的知识就会忘记前面的知识,这就使得教学质量与效率很难提升。为此,教师应积极主动探索有效的教学方式,激发学生的ATUO CAD软件的学习兴趣,提升教学和学习的质量。本文就探讨ATUO CAD在图形图像教学领域的多元结合应用。 相似文献
49.
Yinling Wang Yuan Hu Xinglong Gong Wanquan Jiang Peiqiang Zhang Zuyao Chen 《应用聚合物科学杂志》2007,103(5):3143-3149
Magnetorheological (MR) elastomers, which are mainly composed of magnetic particles and elastic polymer, are a new kind of smart materials whose modulus can be controlled by changing the strength of magnetic fields. In this article, MR elastomers based on immiscible silicon rubber/polystyrene (SR/PS) blend matrix were fabricated successfully via cosolvent method and the MR effect, electric and mechanical properties, and the microstructures of the corresponding materials were studied. SEM studies showed that the dispersion of iron particles in blend matrix were different from that in single polymer, which could be further proved by the different electric conductivity. The MR effect of MR elastomers based on blend matrix varied with the different ratios of SR and PS, which was discussed in detail from the special dispersion of iron particles and of zero‐modulus of MR elastomers. In addition, the MR elastomers based on SR/PS blend matrix had enhanced mechanical properties, which made them more hopeful to be applied in practice. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3143–3149, 2007 相似文献
50.
New Algorithm for Binary Connected-Component Labeling Based on Run-Length Encoding and Union-Find Sets 总被引:1,自引:0,他引:1
Based on detailed analysis of advantages and disadvantages of the existing connected-component labeling (CCL) algorithm, a new algorithm for binary connected components labeling based on run-length encoding (RLE) and union-find sets has been put forward. The new algorithm uses RLE as the basic processing unit, converts the label merging of connected RLE into sets grouping in accordance with equivalence relation, and uses the union-find sets which is the realization method of sets grouping to solve the label merging of connected RLE. And the label merging procedure has been optimized: the union operation has been modified by adding the "weighted rule" to avoid getting a degenerated-tree, and the "path compression" has been adopted when implementing the find operation, then the time complexity of label merging is O(nα(n)). The experiments show that the new algorithm can label the connected components of any shapes very quickly and exactly, save more memory, and facilitate the subsequent image analysis. 相似文献