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   101039篇
  免费   8521篇
  国内免费   4385篇
电工技术   5773篇
技术理论   6篇
综合类   6377篇
化学工业   16845篇
金属工艺   6285篇
机械仪表   7129篇
建筑科学   8199篇
矿业工程   3450篇
能源动力   2941篇
轻工业   6392篇
水利工程   1714篇
石油天然气   7479篇
武器工业   821篇
无线电   10915篇
一般工业技术   11757篇
冶金工业   4946篇
原子能技术   1028篇
自动化技术   11888篇
  2024年   475篇
  2023年   1848篇
  2022年   3252篇
  2021年   4396篇
  2020年   3409篇
  2019年   2761篇
  2018年   2993篇
  2017年   3368篇
  2016年   3096篇
  2015年   4192篇
  2014年   4990篇
  2013年   5938篇
  2012年   6429篇
  2011年   6885篇
  2010年   5890篇
  2009年   5615篇
  2008年   5462篇
  2007年   5163篇
  2006年   5496篇
  2005年   4796篇
  2004年   3046篇
  2003年   2857篇
  2002年   2685篇
  2001年   2439篇
  2000年   2361篇
  1999年   2665篇
  1998年   2104篇
  1997年   1739篇
  1996年   1713篇
  1995年   1423篇
  1994年   1163篇
  1993年   748篇
  1992年   656篇
  1991年   441篇
  1990年   357篇
  1989年   306篇
  1988年   228篇
  1987年   151篇
  1986年   124篇
  1985年   70篇
  1984年   53篇
  1983年   44篇
  1982年   41篇
  1981年   29篇
  1980年   26篇
  1979年   16篇
  1978年   1篇
  1965年   1篇
  1959年   2篇
  1951年   2篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Multimedia Tools and Applications - To address the problems of insufficient detail extraction and long training time in the super-resolution reconstruction of chest X-ray images, a method of chest...  相似文献   
52.
53.
Zu  Guoqing  Lu  Yukuan  Yan  Yi  Zhang  Xiaoming  Zhao  Jingwei  Du  Wei  Ran  Xu  Jiang  Zhengyi 《Metals and Materials International》2020,26(2):248-259
Metals and Materials International - The flow behaviour and microstructure characteristics of a ferritic stainless steel were investigated using plain strain compression test on a Gleeble 3500...  相似文献   
54.
Stream ciphers based on linear feedback shift register (LFSR) are suitable for constrained environments, such as satellite communications, radio frequency identification devices tag, sensor networks and Internet of Things, due to its simple hardware structures, high speed encryption and lower power consumption. LFSR, as a cryptographic primitive, has been used to generate a maximum period sequence. Because the switching of the status bits is regular, the power consumption of the LFSR is correlated in a linear way. As a result, the power consumption characteristics of stream cipher based on LFSR are vulnerable to leaking initialization vectors under the power attacks. In this paper, a new design of LFSR against power attacks is proposed. The power consumption characteristics of LFSR can be masked by using an additional LFSR and confused by adding a new filter Boolean function and a flip-flop. The design method has been implemented easily by circuits in this new design in comparison with the others.  相似文献   
55.
56.
Cao  Zehui  Zhao  Jing  Sun  Shiliang 《Neural Processing Letters》2021,53(1):339-353
Neural Processing Letters - The beta processes (BP) is a powerful nonparametric tool in feature learning, which is often used as the prior of Bernoulli process for choosing features from a feature...  相似文献   
57.
58.
Abstract

Lignin biochar-catalytic depolymerization using biochar Fe-600, Fe-800, Ni-600, Ni-800 catalysts under microwave-heating (180?°C for 30?min) was explored in an ethanol/formic acid (1:1) media. Non-catalyst depolymerization was also studied and compared with the biochar-catalysts results. Characteristics of the bio-char catalysts were analyze by BET, XRD, and FT-IR. GPC, FT-IR, and MALDI-TOF MS spectrometry were also used to characterize the depolymerization products. The experimental results showed that the SBET, Vt, and Vmec and average pore diameter of the biochars are considerably dependent on the preparation temperature and type of cation (Ni2+ or Fe3+). The maximum yield of bio-oil product was obtained as 85?wt% with the addition of biochar Ni-600 and the total amount of oligomers or monomers with a molecular weight of 164 to 446 reaches 80.4%.  相似文献   
59.
60.
Research funding has been seen as one of the most important resource in the reward system of science. And usage of publications denotes an interesting perspective of user behavior in scientific communication. This study aims to address the relationship between funding and Usage Count, which is a new metrics item established on the platform of Web of Science. Full records of 300,010 articles published in 2013 were downloaded in October 2015, and divided into six disciplines, including information science library science, education educational research, economics, computer science, materials science, and chemistry. Seven indicators were proposed to measure the impact, including Funding rate, Citation per paper, Usage rate, Usage per paper, Citation difference, Usage difference, and Conversion rate. It concluded funding has impact on usage and citation, and funded papers attract more usage, but varying in different disciplines. Usage Count can be used in the extension of citation metrics but with limits. This study originally engages with usage metrics and detected that there is positive correlation between usage and funding.  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