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   1566篇
  免费   92篇
  国内免费   23篇
电工技术   20篇
综合类   5篇
化学工业   378篇
金属工艺   40篇
机械仪表   58篇
建筑科学   57篇
矿业工程   1篇
能源动力   100篇
轻工业   143篇
水利工程   25篇
石油天然气   8篇
无线电   167篇
一般工业技术   340篇
冶金工业   74篇
原子能技术   47篇
自动化技术   218篇
  2024年   5篇
  2023年   29篇
  2022年   98篇
  2021年   134篇
  2020年   98篇
  2019年   106篇
  2018年   99篇
  2017年   93篇
  2016年   120篇
  2015年   47篇
  2014年   83篇
  2013年   119篇
  2012年   97篇
  2011年   104篇
  2010年   75篇
  2009年   58篇
  2008年   48篇
  2007年   32篇
  2006年   19篇
  2005年   16篇
  2004年   8篇
  2003年   10篇
  2002年   11篇
  2001年   8篇
  2000年   8篇
  1999年   5篇
  1998年   19篇
  1997年   11篇
  1996年   14篇
  1995年   8篇
  1994年   7篇
  1993年   8篇
  1992年   8篇
  1991年   11篇
  1990年   8篇
  1989年   9篇
  1988年   10篇
  1987年   3篇
  1986年   3篇
  1985年   3篇
  1984年   3篇
  1983年   3篇
  1982年   5篇
  1981年   5篇
  1980年   4篇
  1979年   5篇
  1977年   2篇
  1974年   1篇
  1972年   1篇
排序方式: 共有1681条查询结果,搜索用时 24 毫秒
41.
Multidimensional Systems and Signal Processing - Algebraic structures and their hardware–software implementation gain considerable attention in the field of information security and coding...  相似文献   
42.
Microgrids provide promising solution for integration of renewable energy sources in the electrical grid. To exploit the key benefits, achieving the economical operation of renewable aided microgrids has become necessary and is a challenging task. This paper presents an efficient optimization model to minimize the operational cost of a solar integrated microgrid. We formulate a joint optimization mixed integer problem for appropriate modeling of the system under various practical constraints. An efficient solution is obtained with a distributed approach such that the original problem is solved in two stages. Dual decomposition approach is adopted for cost, emissions, and solar share optimization. Lagrange relaxation, Lambda iteration method, and binary integer programming are employed to obtain the joint optimization solution. Finally, the performance of the proposed model is validated through simulations that show that an overall cost reduction of 4.2070e+04 $ and emission reduction of 7.2001e+03 kg are achieved with the proposed model.  相似文献   
43.
Shabir  Muhammad Yasir  Ullah  Ata  Mahmood  Zahid 《Wireless Networks》2019,25(8):5137-5150
Wireless Networks - Wireless sensor network (WSN) consists of small sized devices containing different sensors to monitor physical, environmental and medical conditions during surveillance of...  相似文献   
44.
The drive of this study is to develop a robust system. A method to classify brain magnetic resonance imaging (MRI) image into brain-related disease groups and tumor types has been proposed. The proposed method employed Gabor texture, statistical features, and support vector machine. Brain MRI images have been classified into normal, cerebrovascular, degenerative, inflammatory, and neoplastic. The proposed system has been trained on a complete dataset of Brain Atlas-Harvard Medical School. Further, to achieve robustness, a dataset developed locally has been used. Extraordinary results on different orientations, sequences of both of these datasets as per accuracy (up to 99.6%), sensitivity (up to 100%), specificity (up to 100%), precision (up to 100%), and AUC value (up to 1.0) have been achieved. The tumorous slices are further classified into primary or secondary tumor as well as their further types as glioma, sarcoma, meningioma, bronchogenic carcinoma, and adenocarcinoma, which could not be possible to determine without biopsy, otherwise.  相似文献   
45.
Wireless Personal Communications - The design of a fractal based slot antenna, to serve the dual-band communication applications, is proposed in this paper. The structure of the proposed antenna is...  相似文献   
46.
47.
48.
The occurrence of nocardial mastitis, mostly in the context of outbreaks, has been reported in many countries. However, there is a paucity of reports regarding detailed characterization of Nocardia cyriacigeorgica from bovine mastitis. Thus, herein we report characteristics, antimicrobial susceptibility patterns, molecular identification, and pathogenicity of N. cyriacigeorgica isolated from an outbreak of clinical mastitis in a dairy herd in northern China. A total of 182 (80.2%) lactating cows had clinical mastitis with severe inflammation and firmness of the udder, reduced milk production, and anorexia, with no apparent clinical response to common antibiotics. Out of 22 mastitic milk samples submitted to our laboratory, 12 N. cyriacigeorgica were isolated and characterized using standard microbiological analysis, 16S rRNA gene sequencing, random amplified polymorphic DNA PCR analysis, biochemical assays, and antibiotic susceptibility testing. Additionally, in vivo experiments were done to determine pathogenicity of these clinical mastitis isolates. All isolates were resistant to ampicillin, amoxicillin-clavulanic acid, ciprofloxacin, minocycline, rifampicin, and aminoglycosides (type VI pattern). Additionally, intramammary inoculation of mice with N. cyriacigeorgica caused chronic inflammatory changes, including hyperemia, edema, and infiltration of lymphocytes and neutrophils, as well as hyperplasia of lymph nodules in mammary glands. Therefore, we concluded that N. cyriacigeorgica was involved in the current outbreak of mastitis. To our best knowledge, this is the first report to characterize N. cyriacigeorgica isolated from cases of bovine mastitis in China.  相似文献   
49.
Abstract

Electrospinning of glass nanofibers, as one of the most important techniques for producing nanofibers, was the focus of the present research. This process was done using a carrying polymer in order to modify all important parameters of the process including the solution parameters, the electrospinning voltage, the electrospinning distance and feeding rate of the solution to achieve a desired nanofiber morphology. The produced nanofibers were pyrolyzed at a high temperature to remove the carrying polymer and the FTIR test approved that it was completely removed. The diameter of nanofibers and other details were investigated using SEM images and it was shown that the produced nanofibers have a finer diameter with an average of 228?nm and standard deviation of 46?nm in comparison to other works that reported 500?nm for these characteristics.  相似文献   
50.
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