全文获取类型
收费全文 | 88958篇 |
免费 | 13877篇 |
国内免费 | 4156篇 |
专业分类
电工技术 | 5321篇 |
技术理论 | 3篇 |
综合类 | 6289篇 |
化学工业 | 17671篇 |
金属工艺 | 3833篇 |
机械仪表 | 4056篇 |
建筑科学 | 10831篇 |
矿业工程 | 6644篇 |
能源动力 | 3060篇 |
轻工业 | 10294篇 |
水利工程 | 3647篇 |
石油天然气 | 5666篇 |
武器工业 | 658篇 |
无线电 | 6534篇 |
一般工业技术 | 8060篇 |
冶金工业 | 6241篇 |
原子能技术 | 1060篇 |
自动化技术 | 7123篇 |
出版年
2024年 | 585篇 |
2023年 | 1975篇 |
2022年 | 5224篇 |
2021年 | 5708篇 |
2020年 | 4035篇 |
2019年 | 3376篇 |
2018年 | 3373篇 |
2017年 | 4126篇 |
2016年 | 5344篇 |
2015年 | 5801篇 |
2014年 | 6883篇 |
2013年 | 6345篇 |
2012年 | 5867篇 |
2011年 | 5282篇 |
2010年 | 4195篇 |
2009年 | 4177篇 |
2008年 | 3577篇 |
2007年 | 5031篇 |
2006年 | 4911篇 |
2005年 | 4170篇 |
2004年 | 2936篇 |
2003年 | 2720篇 |
2002年 | 2082篇 |
2001年 | 1519篇 |
2000年 | 1424篇 |
1999年 | 1080篇 |
1998年 | 735篇 |
1997年 | 598篇 |
1996年 | 573篇 |
1995年 | 479篇 |
1994年 | 466篇 |
1993年 | 317篇 |
1992年 | 254篇 |
1991年 | 239篇 |
1990年 | 252篇 |
1989年 | 204篇 |
1988年 | 131篇 |
1987年 | 102篇 |
1986年 | 85篇 |
1985年 | 72篇 |
1984年 | 85篇 |
1983年 | 49篇 |
1982年 | 48篇 |
1981年 | 43篇 |
1980年 | 63篇 |
1966年 | 32篇 |
1964年 | 48篇 |
1962年 | 70篇 |
1959年 | 32篇 |
1955年 | 25篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
On filter theory of residuated lattices 总被引:3,自引:0,他引:3
The aim of this paper is to develop the filter theory of general residuated lattices. First, we extend some particular types of filters and fuzzy filters in BL-algebras and MTL-algebras naturally to general residuated lattices, and further enumerate some relative results obtained in BL-algebras or MTL-algebras, which still hold in general residuated lattices. Next, we introduce the concepts of regular filters and fuzzy regular filters to general residuated lattices, which are two new types of filters and fuzzy filters, and derive some of their characterizations. Finally, we discuss the relations between (fuzzy) regular filters and several other special (fuzzy) filters, and also characterize some special classes of residuated lattices by filters or fuzzy filters. 相似文献
962.
Improving the spatio-temporal distribution of surface solar radiation data by merging ground and satellite measurements 总被引:2,自引:0,他引:2
Appropriate information on solar resources is very important for a variety of technological areas, such as: agriculture, meteorology, forestry engineering, water resources and in particular in the designing and sizing of solar energy systems. However, the availability of observed solar radiation measurements has proven to be spatially and temporally inadequate for many applications. In this paper we propose to merge the global solar radiation measurements from the Royal Meteorological Institute of Belgium solar measurements network with the operationally derived surface incoming global short-wave radiation products from Meteosat Second Generation satellites imageries to improve the spatio-temporal resolution of the surface global solar radiation data over Belgium. We evaluate several merging methods with various degrees of complexity (from mean field bias correction to geostatistical merging techniques) together with interpolated ground measurements and satellite-derived values only. The performance of the different methods is assessed by leave-one-out cross-validation. 相似文献
963.
文章通过分析武术视频的特点,提出了一种关于提取武术分段视频的关键帧的算法:图像颜色特征计算法与Ⅰ帧提取法相结合的方法,经仿真实验证明此算法对于武术分段视频的关键帧提取准确率高。在此算法的基础上,对关键帧的运动人体进行特征向量的概括。然后,对支持向量机进行了分析并利用得出的特征向量作为样本对分类器进行构造和训练。基于以上步骤设计的系统,可有效的实现对武术视频的分类检索。 相似文献
964.
为了避免连续数据离散化处理时造成的信息损失,降低样本属性邻域求解的复杂度,提高特征基因提取的效率。该文在单调度量空间上,提出了一种基于单调邻域粗糙集的特征基因提取方法。并在两个标准的基因表达数据上进行了实验,结果证明该方法是有效可行的。 相似文献
965.
T. Hoang Ngan Le Chia-Chen Lin Chin-Chen Chang Hoai Bac LeAuthor vitae 《Digital Signal Processing》2011,21(6):734-745
Many secret sharing schemes for digital images have been developed in recent decades. Traditional schemes typically must deal with the problem of computational complexity, and other visual secret sharing schemes come with a higher transmission cost and storage cost; that is, each shadow size is m times as big as the original secret image. The new (2,n) secret sharing scheme for grayscale images proposed in this paper is based a combination of acceptable image quality using block truncation coding (BTC), high compression ratio discrete wavelet transform (DWT) and good subjective performance of the vector quantization (VQ) technique. Experimental results confirm that our proposed scheme not only generates a high quality reconstructed original image but also generates small, random-like grayscale shadows. 相似文献
966.
967.
Veronika Šoltészová Daniel Patel Stefan Bruckner Ivan Viola 《Computer Graphics Forum》2010,29(3):883-891
In this paper, we present a novel technique which simulates directional light scattering for more realistic interactive visualization of volume data. Our method extends the recent directional occlusion shading model by enabling light source positioning with practically no performance penalty. Light transport is approximated using a tilted cone‐shaped function which leaves elliptic footprints in the opacity buffer during slice‐based volume rendering. We perform an incremental blurring operation on the opacity buffer for each slice in front‐to‐back order. This buffer is then used to define the degree of occlusion for the subsequent slice. Our method is capable of generating high‐quality soft shadowing effects, allows interactive modification of all illumination and rendering parameters, and requires no pre‐computation. 相似文献
968.
Juyong Zhang Chunlin Wu Jianfei Cai Jianmin Zheng Xue‐cheng Tai 《Computer Graphics Forum》2010,29(2):517-526
This paper considers the problem of interactively finding the cutting contour to extract components from a given mesh. Some existing methods support cuts of arbitrary shape but require careful and tedious input from the user. Others need little user input however they are sensitive to user input and need a postprocessing step to smooth the generated jaggy cutting contours. The popular geometric snake can be used to optimize the cutting contour, but it cannot deal with the topology change. In this paper, we propose a geodesic curvature flow based framework to overcome all these problems. Since in many cases the meaningful cutting contour on a 3D mesh is locally shortest in the sense of some weighted curve length, the geodesic curvature flow is an ideal tool for our problem. It evolves the cutting contour to the nearby local minimum. We should mention that the previous numerical scheme, discretized geodesic curvature flow (dGCF) is too slow and has not been applied to mesh segmentation. With a careful observation to dGCF, we devise here a fast computation scheme called fast geodesic curvature flow (FGCF), which only needs to solve a smaller and easier problem. The initial cutting contour is generated by a variant of random walks algorithm, which is very fast and gives reasonable cutting result with little user input. Experiment results on the benchmark mesh segmentation data set show that our proposed framework is robust to user input and capable of producing good results reflecting geometric features and human shape perception. 相似文献
969.
970.