全文获取类型
收费全文 | 4926篇 |
免费 | 436篇 |
国内免费 | 304篇 |
专业分类
电工技术 | 250篇 |
综合类 | 1019篇 |
化学工业 | 372篇 |
金属工艺 | 200篇 |
机械仪表 | 474篇 |
建筑科学 | 175篇 |
矿业工程 | 165篇 |
能源动力 | 144篇 |
轻工业 | 213篇 |
水利工程 | 55篇 |
石油天然气 | 121篇 |
武器工业 | 32篇 |
无线电 | 414篇 |
一般工业技术 | 437篇 |
冶金工业 | 98篇 |
原子能技术 | 21篇 |
自动化技术 | 1476篇 |
出版年
2024年 | 9篇 |
2023年 | 52篇 |
2022年 | 76篇 |
2021年 | 122篇 |
2020年 | 102篇 |
2019年 | 98篇 |
2018年 | 90篇 |
2017年 | 102篇 |
2016年 | 150篇 |
2015年 | 149篇 |
2014年 | 279篇 |
2013年 | 295篇 |
2012年 | 310篇 |
2011年 | 361篇 |
2010年 | 254篇 |
2009年 | 298篇 |
2008年 | 255篇 |
2007年 | 304篇 |
2006年 | 269篇 |
2005年 | 245篇 |
2004年 | 185篇 |
2003年 | 197篇 |
2002年 | 166篇 |
2001年 | 142篇 |
2000年 | 175篇 |
1999年 | 119篇 |
1998年 | 123篇 |
1997年 | 103篇 |
1996年 | 63篇 |
1995年 | 98篇 |
1994年 | 110篇 |
1993年 | 57篇 |
1992年 | 53篇 |
1991年 | 55篇 |
1990年 | 42篇 |
1989年 | 44篇 |
1988年 | 31篇 |
1987年 | 24篇 |
1986年 | 9篇 |
1985年 | 16篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 7篇 |
1980年 | 6篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有5666条查询结果,搜索用时 218 毫秒
1.
2.
For industrial chemical process, preliminary-summation-based principal component analysis (PS-PCA), an amended PCA method was recently provided for coping with both Gaussian and non-Gaussian characteristics. By summing the training and monitoring data respectively, PS-PCA is capable of resolving the issue of non-Gaussian processes and achieves higher fault detection rate than the traditional PCA. However, in the PS-PCA summation operation, all data samples are regarded as the same weight, which results in the fault information of newly-samples may be diluted, leading to significant detection delays. To address this challenge, in this paper, we propose a novel weighted PS-PCA (WPS-PCA) method that employs an exponential weighting scheme to put more emphasis on recent information. Subsequently, a mathematical argument demonstrates that when the number of variables is enough plentiful, the obtained summation combined with the generalized central limit theorem conforms to approximately a Gaussian distribution. The kurtosis relationships indicate this conversion will bring out well-pleasing feasibility for conventional PCA. Ultimately, the proposed technique verifies detection performance using the Tennessee Eastman process, which is compared with the existing PCA and PS-PCA schemes, in terms of the fault detection time and fault detection rate. The simulation studies reveal that the proposed method is efficient and superior. 相似文献
3.
A. K. Roy 《Journal of Modern Optics》2019,66(4):448-454
Two ways of constructing analytic phase function for a polydispersion of small spherical non-absorbing particles have been investigated. First one is a straightforward procedure emanating from the implementation of single particle scattering input into the defined polydisperse phase function. This results in an analytic phase function in terms of moments of the distribution. The second approach is a new strategy, based on the Lagrange mean value theorem. A clear understanding of the relationship between these two approaches has been developed. The efficacy and accuracy of the scattering phase functions is illustrated by applying it to a power-law size distributed sphere ensemble. 相似文献
4.
5.
Marcus Weyd Christian Pflieger Andy Vogel Hannes Richter Volker Prehn Christiane Günther Frank Splittgerber Alessa Gäbler Daniel Kaulbars Patrick Bräutigam Marcus Franke Samira Lambertz Julian Schlechtweg Ingolf Voigt 《化学,工程师,技术》2021,93(9):1432-1439
Reducing micropollutant pollution of water bodies is an important objective of water management and an integral part of environmental policy. Ceramic nanofiltration membranes were developed as multichannel membranes of increased membrane area and rotating disk filters. The membranes developed show retention of over 80 % for PEG 400. The membranes are currently being tested for the separation of micropollutants from wastewater contaminated with pharmaceuticals. With the help of a downstream oxidative process, the trace substances remaining in the permeate are degraded. 相似文献
6.
7.
针对异源图像提出一种基于多尺度密集结构特征的快速匹配算法。算法首先利用Gabor滤波器逐像素提取图像中的结构响应,再根据主方向响应对多尺度结构特征融合,然后使用快速傅里叶变换在频域计算各特征分量图像之间的卷积,最后将卷积生成的系数矩阵求和计算出图像之间的相似性并选择相似性最大位置作为匹配结果输出。本文算法能有效适应异源图像间的非线性灰度变化和噪声干扰问题。测试使用可见光、红外、雷达图像组成的异源图像数据集对本文算法和现有算法进行测试比较,结果表明:本文算法的平均误匹配率最低,并且计算速度有明显优势。 相似文献
8.
Hitoshi Tonomura Masateru Nagae Ryota Takatori Hidenobu Ishibashi Tomonori Itsuji Kenji Takahashi 《International journal of molecular sciences》2020,21(22)
This paper aims to provide a comprehensive review of the changing role of hepatocyte growth factor (HGF) signaling in the healthy and diseased synovial joint and spine. HGF is a multifunctional growth factor that, like its specific receptor c-Met, is widely expressed in several bone and joint tissues. HGF has profound effects on cell survival and proliferation, matrix metabolism, inflammatory response, and neurotrophic action. HGF plays an important role in normal bone and cartilage turnover. Changes in HGF/c-Met have also been linked to pathophysiological changes in degenerative joint diseases, such as osteoarthritis (OA) and intervertebral disc degeneration (IDD). A therapeutic role of HGF has been proposed in the regeneration of osteoarticular tissues. HGF also influences bone remodeling and peripheral nerve activity. Studies aimed at elucidating the changing role of HGF/c-Met signaling in OA and IDD at different pathophysiological stages, and their specific molecular mechanisms are needed. Such studies will contribute to safe and effective HGF/c-Met signaling-based treatments for OA and IDD. 相似文献
9.
《The Electricity Journal》2020,33(7):106816
Using mean value theorem for integrals we show that the well-known LCOE definition is incorrect. 相似文献
10.