首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1396399篇
  免费   26830篇
  国内免费   6827篇
电工技术   33721篇
综合类   6322篇
化学工业   259136篇
金属工艺   62709篇
机械仪表   38861篇
建筑科学   43473篇
矿业工程   11196篇
能源动力   50092篇
轻工业   97535篇
水利工程   13913篇
石油天然气   36810篇
武器工业   128篇
无线电   193186篇
一般工业技术   267173篇
冶金工业   117143篇
原子能技术   33639篇
自动化技术   165019篇
  2021年   15273篇
  2020年   11707篇
  2019年   14478篇
  2018年   13766篇
  2017年   12900篇
  2016年   20217篇
  2015年   17130篇
  2014年   28511篇
  2013年   87546篇
  2012年   32655篇
  2011年   43386篇
  2010年   40293篇
  2009年   49314篇
  2008年   41145篇
  2007年   37796篇
  2006年   42490篇
  2005年   36665篇
  2004年   39380篇
  2003年   39430篇
  2002年   38884篇
  2001年   35030篇
  2000年   33919篇
  1999年   32168篇
  1998年   30035篇
  1997年   30277篇
  1996年   29514篇
  1995年   27302篇
  1994年   26082篇
  1993年   26002篇
  1992年   25320篇
  1991年   21766篇
  1990年   22288篇
  1989年   21211篇
  1988年   19695篇
  1987年   18147篇
  1986年   17506篇
  1985年   20876篇
  1984年   21492篇
  1983年   19446篇
  1982年   18638篇
  1981年   18683篇
  1980年   17289篇
  1979年   17922篇
  1978年   17201篇
  1977年   16293篇
  1976年   16142篇
  1975年   15538篇
  1974年   15110篇
  1973年   15172篇
  1972年   12723篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
961.
ABSTRACT

This paper proposes the multiple-hypotheses image segmentation and feed-forward neural network classifier for food recognition to improve the performance. Initially, the food or meal image is given as input. Then, the segmentation is applied to identify the regions, where a particular food item is located using salient region detection, multi-scale segmentation, and fast rejection. Then, the features of every food item are extracted by the global feature and local feature extraction. After the features are obtained, the classification is performed for each segmented region using a feed-forward neural network model. Finally, the calorie value is computed with the aid of (i) food volume and (ii) calorie and nutrition measure based on mass value. The experimental results and performance evaluation are validated. The outcome of the proposed method attains 0.947 for Macro Average Accuracy (MAA) and 0.959 for Standard Accuracy (SA), which provides better classification performance.  相似文献   
962.
Single image super resolution (SISR) is an important research content in the field of computer vision and image processing. With the rapid development of deep neural networks, different image super-resolution models have emerged. Compared to some traditional SISR methods, deep learning-based methods can complete the superresolution tasks through a single image. In addition, compared with the SISR methods using traditional convolutional neural networks, SISR based on generative adversarial networks (GAN) has achieved the most advanced visual performance. In this review, we first explore the challenges faced by SISR and introduce some common datasets and evaluation metrics. Then, we review the improved network structures and loss functions of GAN-based perceptual SISR. Subsequently, the advantages and disadvantages of different networks are analyzed by multiple comparative experiments. Finally, we summarize the paper and look forward to the future development trends of GAN-based perceptual SISR.  相似文献   
963.
Telecommunication Systems - Signals from indoor access points in a wireless fidelity suffer from high attenuation as a result of the thick walls and metal structures in the multilevel-storey...  相似文献   
964.
Abdellah  W. M. 《Radiochemistry》2020,62(3):347-358
Radiochemistry - The study deals with separation of uranium, thorium, and yttrium with highest possible purity from El-Garaa El-Hamara sulfate leach liquor. From the latter, almost complete...  相似文献   
965.
The ability of bacterial species to colonize and infect host organisms is critically dependent upon their capacity to adhere to cellular surfaces of the host. Adherence to cell surfaces is known to be essential for the activation and delivery of certain virulence factors, but can also directly affect host cell signaling to aid bacterial spread and survival. In this review we will discuss the recent advances in the field of bacterial adhesion, how we are beginning to unravel the effects adhesins have on host cell signaling, and how these changes aid the bacteria in terms of their survival and evasion of immune responses. Finally, we will highlight how the exploitation of bacterial adhesins may provide new therapeutic avenues for the treatment of a wide range of bacterial infections.  相似文献   
966.
967.
968.
969.
970.
Itaconate (ITA) is an emerging powerhouse of innate immunity with therapeutic potential that is limited in its ability to be administered in a soluble form. A library of polyester materials that incorporate ITA into polymer backbones resulting in materials with inherent immunoregulatory behavior is developed. Harnessing hydrolytic degradation release from polyester backbones, ITA polymers result in the mechanism specific immunoregulatory properties on macrophage polarization in vitro. In a functional assay, the polymer-released ITA inhibits bacterial growth on acetate. Translation to an in vivo model of biomaterial associated inflammation, intraperitoneal injection of ITA polymers demonstrate a rapid resolution of inflammation in comparison to a control polymer silicone, demonstrating the value of sustained biomimetic presentation of ITA.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号