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   1411525篇
  免费   26952篇
  国内免费   6826篇
电工技术   33743篇
综合类   6332篇
化学工业   251982篇
金属工艺   63520篇
机械仪表   40451篇
建筑科学   41348篇
矿业工程   11393篇
能源动力   49668篇
轻工业   100153篇
水利工程   14366篇
石油天然气   36840篇
武器工业   136篇
无线电   194256篇
一般工业技术   270146篇
冶金工业   131911篇
原子能技术   33978篇
自动化技术   165080篇
  2021年   14417篇
  2020年   11683篇
  2019年   14454篇
  2018年   15624篇
  2017年   15065篇
  2016年   21032篇
  2015年   17192篇
  2014年   28481篇
  2013年   87588篇
  2012年   33675篇
  2011年   45715篇
  2010年   41951篇
  2009年   50788篇
  2008年   42852篇
  2007年   39922篇
  2006年   42873篇
  2005年   38089篇
  2004年   40090篇
  2003年   39318篇
  2002年   37027篇
  2001年   33180篇
  2000年   31355篇
  1999年   30423篇
  1998年   32099篇
  1997年   30914篇
  1996年   28769篇
  1995年   27763篇
  1994年   26273篇
  1993年   26238篇
  1992年   25023篇
  1991年   22025篇
  1990年   22572篇
  1989年   21499篇
  1988年   19990篇
  1987年   18389篇
  1986年   17790篇
  1985年   21132篇
  1984年   21616篇
  1983年   19566篇
  1982年   18715篇
  1981年   18765篇
  1980年   17387篇
  1979年   17997篇
  1978年   17279篇
  1977年   16605篇
  1976年   16860篇
  1975年   15629篇
  1974年   15186篇
  1973年   15270篇
  1972年   12811篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Journal of Materials Science: Materials in Electronics - Sn–Zn–Cu is one of the most popular soldering alloys, especially when it has been doped with Bi, which has proved very...  相似文献   
92.

ResearchGate has emerged as a popular professional network for scientists and researchers in a very short span. Similar to Google Scholar, the ResearchGate indexing uses an automatic crawling algorithm that extracts bibliographic data, citations, and other information about scholarly articles from various sources. However, it has been observed that the two platforms often show different publication and citation data for the same institutions, journals, and authors. While several previous studies analysed different aspects of ResearchGate and Google Scholar, the quantum of differences in publications, citations, and metrics between the two and the probable reasons for the same are not explored much. This article, therefore, attempts to bridge this research gap by analysing and measuring the differences in publications, citations, and different metrics of the two platforms for a large data set of highly cited authors. The results indicate that there are significantly high differences in publications and citations for the same authors captured by the two platforms, with Google Scholar having higher counts for a vast majority of the cases. The different metrics computed by the two platforms also differ in their values, showing different degrees of correlation. The coverage policy, indexing errors, author attribution mechanism, and strategy to deal with predatory publishing are found to be the main probable reasons for the differences in the two platforms.

  相似文献   
93.
Filtration Waves     
Journal of Engineering Physics and Thermophysics - Equations and relations have been obtained for describing one-dimensional filtration waves in a homogeneous isotropic porous medium in plane,...  相似文献   
94.
Journal of Engineering Physics and Thermophysics - A laminar boundary layer in a gas flow near a disk rotating at a constant angular velocity under the conditions of a significant radial...  相似文献   
95.
Journal of Engineering Physics and Thermophysics - An overview of the development of mathematical models used to describe the relationship between the parameters of the state of real gases is...  相似文献   
96.
Kulemin  V. V.  Martynov  K. V.  Krasavina  E. P.  Rumer  I. A.  Kulyukhin  S. A. 《Radiochemistry》2022,64(2):158-163
Radiochemistry - The distribution of uranium between different phases of cast stone matrices fabricated by fusion of basalt and uranium-bearing SiO2-based collectors was investigated. It was found...  相似文献   
97.
Savruk  M. P.  Kravets  V. S.  Chornenkyi  A. B. 《Materials Science》2022,57(4):492-501
Materials Science - We develop an analytic-numerical algorithm for the determination of the optimal shape of smooth holes (with minimum stress concentration) in quasiorthotropic plates subjected to...  相似文献   
98.
Journal of Engineering Physics and Thermophysics - The possibility of intensifying the drying of materials by noncontact ultrasonic action at a frequency of 22 kHz at sound pressure levels up to...  相似文献   
99.
Yakunin  S. A. 《Radiochemistry》2022,64(4):482-490
Radiochemistry - As applied to the radioactive waste vitrification technology, published data on the behavior of cesium and its release into the gas phase are reviewed. The volatility of cesium...  相似文献   
100.
The aim of this study was to determine the effects of tumbling at different post-mortem times on the proteolytic features and quality attributes of beef loins (M. longissimus lumborum). Loins (n = 12) were cut into 4 sections and assigned to tumbling at 1, 6 or 11 days post-mortem or non-tumbled control. Upon tumbling, additional ageing was applied to a common post-mortem time of 16 days. In general, tumbling had no considerable impacts on water-holding ability of samples. Tumbling resulted in an immediate decrease in shear force values (WBSF) of beef samples. Tumbling at 1 day post-mortem with no ageing had similar WBSF compared to the non-tumbled controls at 16 days (P > 0.05). With ageing, tumbling increased amounts of protein degradation, myofibrillar fragmentation and calpain-1 autolysis of samples. These results suggest that early post-mortem tumbling coupled with ageing can synergistically impact the tenderness development of beef loins and shorten the necessary ageing period.  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