全文获取类型
收费全文 | 10146篇 |
免费 | 999篇 |
国内免费 | 461篇 |
专业分类
电工技术 | 672篇 |
技术理论 | 3篇 |
综合类 | 707篇 |
化学工业 | 1792篇 |
金属工艺 | 614篇 |
机械仪表 | 651篇 |
建筑科学 | 760篇 |
矿业工程 | 303篇 |
能源动力 | 349篇 |
轻工业 | 925篇 |
水利工程 | 247篇 |
石油天然气 | 549篇 |
武器工业 | 109篇 |
无线电 | 1058篇 |
一般工业技术 | 1152篇 |
冶金工业 | 398篇 |
原子能技术 | 98篇 |
自动化技术 | 1219篇 |
出版年
2024年 | 52篇 |
2023年 | 230篇 |
2022年 | 400篇 |
2021年 | 558篇 |
2020年 | 407篇 |
2019年 | 333篇 |
2018年 | 378篇 |
2017年 | 399篇 |
2016年 | 361篇 |
2015年 | 522篇 |
2014年 | 651篇 |
2013年 | 684篇 |
2012年 | 662篇 |
2011年 | 832篇 |
2010年 | 629篇 |
2009年 | 566篇 |
2008年 | 532篇 |
2007年 | 456篇 |
2006年 | 464篇 |
2005年 | 317篇 |
2004年 | 282篇 |
2003年 | 226篇 |
2002年 | 224篇 |
2001年 | 184篇 |
2000年 | 222篇 |
1999年 | 217篇 |
1998年 | 144篇 |
1997年 | 119篇 |
1996年 | 107篇 |
1995年 | 94篇 |
1994年 | 89篇 |
1993年 | 71篇 |
1992年 | 65篇 |
1991年 | 31篇 |
1990年 | 23篇 |
1989年 | 26篇 |
1988年 | 19篇 |
1987年 | 4篇 |
1986年 | 7篇 |
1985年 | 2篇 |
1984年 | 10篇 |
1983年 | 1篇 |
1982年 | 4篇 |
1979年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Kaixuan Rong Shuyuan Yang Licheng Jiao 《International journal of remote sensing》2016,37(6):1315-1318
This study clarifies the implicit potential deficiency caused by the sparse cardinality parameter k in Rong et al. (2014). In addition, k = β × W × M × N (0.9 ≤ β < 1) is suggested to avert this potential deficiency, where β is a ratio controlling the amount of sparse cardinality, W is the number of multispectral bands and M × N is the size of panchromatic image. With the choice of k suggested in this study, the low rank matrix L and sparse matrix S obtained by Go Decomposition (Zhou and Tao 2011) can be iteratively optimized and solved. Thus, instead of choosing k as W × M × N in Rong et al. (2014), the potential deficiency that L is directly obtained as an analytic solution can be averted. 相似文献
52.
53.
we present a novel polarimetric synthetic aperture radar (PolSAR) image compression scheme. PolSAR data contains lots of similar redundancies in single-channel and massively correlation between polarimetric channels. So these features make it difficult to represent PolSAR data efficiently. In this paper, discrete cosine transform (DCT) is adopted to remove redundancies between polarimetric channels, simple but quite efficient in improving compressibility. Sparse K-singular value decomposition (K-SVD) dictionary learning algorithm is utilized to remove redundancies within each channel image. Double sparsity scheme will be able to achieve fast convergence and low representation error by using a small number of sparsity dictionary elements, which is beneficial for the task of PolSAR image compression. Experimental results demonstrate that both numerical evaluation indicators and visual effect of reconstructed images outperform other methods, such as SPIHT, JPEG2000, and offline method. 相似文献
54.
Region-driven distance regularized level set evolution for change detection in remote sensing images
Change detection is a fundamental task in the interpretation and understanding of remote sensing images. The aim is to partition the difference images acquired from multitemporal satellite images into changed and unchanged regions. Level set method is a promising way for remote sensing images change detection among the existed methods. Unfortunately, re-initialization, a necessary step in classical level set methods is known a complex and time-consuming process, which may limits their practical application in remote sensing images change detection. In this paper, we present an unsupervised change detection approach for remote sensing image based on an improved region-based active contour model without re-initialization. In order to eliminate the process for re-initialization and reduce the numerical errors caused by re-initialization, we describe an improving level set method for remote sensing images change detection. The proposed method introduced a distance regularization term into the energy function which could maintain a desired shape of the level set function and keep a signed distance profile near the zero level set. The experimental results on real multi-temporal remote sensing images demonstrate the advantages of our method in terms of human visual perception and segmentation accuracy. 相似文献
55.
56.
57.
58.
Feature scaling for kernel fisher discriminant analysis using leave-one-out cross validation 总被引:1,自引:0,他引:1
Kernel fisher discriminant analysis (KFD) is a successful approach to classification. It is well known that the key challenge in KFD lies in the selection of free parameters such as kernel parameters and regularization parameters. Here we focus on the feature-scaling kernel where each feature individually associates with a scaling factor. A novel algorithm, named FS-KFD, is developed to tune the scaling factors and regularization parameters for the feature-scaling kernel. The proposed algorithm is based on optimizing the smooth leave-one-out error via a gradient-descent method and has been demonstrated to be computationally feasible. FS-KFD is motivated by the following two fundamental facts: the leave-one-out error of KFD can be expressed in closed form and the step function can be approximated by a sigmoid function. Empirical comparisons on artificial and benchmark data sets suggest that FS-KFD improves KFD in terms of classification accuracy. 相似文献
59.
通过数值计算的方法分析了色散、自相位调制和激光器啁啾等因素对10Gb/s100kmG.652光纤通信系统的综合效应。对10Gb/sG.652光纤系统中用色散补偿光纤(Dispersion Compensation Fiber,即DSF)的两种方案进行了比较,然后简单讨论了色散补偿光纤在密集波分复用(DWDM)中的应用,最后给出通过以上分析得出的结论。 相似文献
60.
甚小孔径卫星(VSAT)的数据传输应用 总被引:1,自引:0,他引:1
简单分析了甚小孔径卫星通信的技术特点和优缺点。重点讨论用它来解决数据传输问题,通过举例对目前采用VSAT卫星通信解决数据传输问题的技术做进一步的讨论。 相似文献