全文获取类型
收费全文 | 5089篇 |
免费 | 742篇 |
国内免费 | 696篇 |
专业分类
电工技术 | 113篇 |
技术理论 | 1篇 |
综合类 | 460篇 |
化学工业 | 89篇 |
金属工艺 | 87篇 |
机械仪表 | 311篇 |
建筑科学 | 136篇 |
矿业工程 | 31篇 |
能源动力 | 30篇 |
轻工业 | 41篇 |
水利工程 | 21篇 |
石油天然气 | 27篇 |
武器工业 | 25篇 |
无线电 | 716篇 |
一般工业技术 | 325篇 |
冶金工业 | 196篇 |
原子能技术 | 7篇 |
自动化技术 | 3911篇 |
出版年
2024年 | 36篇 |
2023年 | 128篇 |
2022年 | 173篇 |
2021年 | 266篇 |
2020年 | 244篇 |
2019年 | 208篇 |
2018年 | 202篇 |
2017年 | 227篇 |
2016年 | 303篇 |
2015年 | 284篇 |
2014年 | 341篇 |
2013年 | 294篇 |
2012年 | 273篇 |
2011年 | 270篇 |
2010年 | 198篇 |
2009年 | 230篇 |
2008年 | 279篇 |
2007年 | 243篇 |
2006年 | 254篇 |
2005年 | 236篇 |
2004年 | 219篇 |
2003年 | 167篇 |
2002年 | 163篇 |
2001年 | 140篇 |
2000年 | 153篇 |
1999年 | 107篇 |
1998年 | 102篇 |
1997年 | 110篇 |
1996年 | 86篇 |
1995年 | 93篇 |
1994年 | 86篇 |
1993年 | 63篇 |
1992年 | 73篇 |
1991年 | 61篇 |
1990年 | 40篇 |
1989年 | 32篇 |
1988年 | 21篇 |
1987年 | 13篇 |
1986年 | 20篇 |
1985年 | 22篇 |
1984年 | 16篇 |
1983年 | 9篇 |
1982年 | 10篇 |
1981年 | 4篇 |
1980年 | 7篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1974年 | 2篇 |
排序方式: 共有6527条查询结果,搜索用时 23 毫秒
71.
72.
73.
Recently, many local-feature based methods have been proposed for feature learning to obtain a better high-level representation of human behavior. Most of the previous research ignores the structural information existing among local features in the same video sequences, while it is an important clue to distinguish ambiguous actions. To address this issue, we propose a Laplacian group sparse coding for human behavior representation. Unlike traditional methods such as sparse coding, our approach prefers to encode a group of relevant features simultaneously and meanwhile allow as less atoms as possible to participate in the approximation so that video-level sparsity is guaranteed. By incorporating Laplacian regularization the method is capable to ensure the similar approximation of closely related local features and the structural information is successfully preserved. Thus, a compact but discriminative human behavior representation is achieved. Besides, the objective of our model is solved with a closed-form solution, which reduces the computational cost significantly. Promising results on several popular benchmark datasets prove the efficiency and effectiveness of our approach. 相似文献
74.
75.
76.
Image clustering methods are efficient tools for applications such as content-based image retrieval and image annotation. Recently, graph based manifold learning methods have shown promising performance in extracting features for image clustering. Typical manifold learning methods adopt appropriate neighborhood size to construct the neighborhood graph, which captures local geometry of data distribution. Because the density of data points’ distribution may be different in different regions of the manifold, a fixed neighborhood size may be inappropriate in building the manifold. In this paper, we propose a novel algorithm, named sparse patch alignment framework, for the embedding of data lying in multiple manifolds. Specifically, we assume that for each data point there exists a small neighborhood in which only the points that come from the same manifold lie approximately in a low-dimensional affine subspace. Based on the patch alignment framework, we propose an optimization strategy for constructing local patches, which adopt sparse representation to select a few neighbors of each data point that span a low-dimensional affine subspace passing near that point. After that, the whole alignment strategy is utilized to build the manifold. Experiments are conducted on four real-world datasets, and the results demonstrate the effectiveness of the proposed method. 相似文献
77.
78.
Piero Barone 《时间序列分析杂志》1987,8(2):125-130
Abstract. A method for generating finite independent realizations of a normal multivariate stationary ARMA( p, q ) process is proposed. It is based on an AR (1) representation of an ARMA( p, q ) process allowing for an exact generation of the initial values of the simulation algorithm. Input facilities are supplied in order to assure stationarity and invertibility of the considered process. 相似文献
79.
80.
《Advanced Engineering Informatics》2014,28(1):11-27
In this paper an evolutionary technique is proposed as a method for generating new design solutions with genotypes represented in the form of hierarchical hypergraphs. Such hypergraph-based evolutionary design requires the adaptation of traditional evolutionary operators like cross-over and mutation. This paper presents an attempt at defining modified cross-over and mutation operators that act on hierarchical hypergraphs. The application of the proposed transformations is illustrated on examples of designing floor layouts and furniture with the use of the evolutionary method. 相似文献