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   516071篇
  免费   8298篇
  国内免费   2688篇
电工技术   10141篇
技术理论   5篇
综合类   1941篇
化学工业   77128篇
金属工艺   19753篇
机械仪表   15047篇
建筑科学   12749篇
矿业工程   2832篇
能源动力   12515篇
轻工业   44764篇
水利工程   5295篇
石油天然气   8567篇
武器工业   262篇
无线电   59331篇
一般工业技术   95701篇
冶金工业   107063篇
原子能技术   9924篇
自动化技术   44039篇
  2021年   4423篇
  2020年   3066篇
  2019年   3846篇
  2018年   6662篇
  2017年   6868篇
  2016年   7671篇
  2015年   5497篇
  2014年   8377篇
  2013年   21907篇
  2012年   14845篇
  2011年   19732篇
  2010年   14722篇
  2009年   16259篇
  2008年   17273篇
  2007年   17309篇
  2006年   15284篇
  2005年   15999篇
  2004年   14363篇
  2003年   13794篇
  2002年   12224篇
  2001年   12623篇
  2000年   11307篇
  1999年   11952篇
  1998年   32208篇
  1997年   22569篇
  1996年   16967篇
  1995年   12435篇
  1994年   11172篇
  1993年   11014篇
  1992年   7708篇
  1991年   7445篇
  1990年   7364篇
  1989年   7136篇
  1988年   6871篇
  1987年   5841篇
  1986年   5741篇
  1985年   6332篇
  1984年   5945篇
  1983年   5634篇
  1982年   5120篇
  1981年   5254篇
  1980年   4965篇
  1979年   4885篇
  1978年   4613篇
  1977年   5648篇
  1976年   7906篇
  1975年   4025篇
  1974年   3802篇
  1973年   3786篇
  1972年   3254篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
51.
Clean Technologies and Environmental Policy - Food production and consumption is one of the major causes of global environmental degradation. One way to address environmental impacts in the food...  相似文献   
52.
53.
54.
55.
The objective of this study was to determine the effect of temperature on whole milk density measured at four different temperatures: 5, 10, 15, and 20 °C. A total of ninety-three individual milk samples were collected from morning milking of thirty-two Holstein Friesian dairy cows, of national average genetic merit, once every two weeks over a period of 4 weeks and were assessed by Fourier transform infrared spectroscopy for milk composition analysis. Density of the milk was evaluated using two different analytical methods: a portable density meter DMA35 and a standard desktop model DMA4500M (Anton Paar GmbH, UK). Milk density was analysed with a linear mixed model with the fixed effects of sampling period, temperature and analysis method; triple interaction of sampling period x analysis method x temperature; and the random effect of cow to account for repeated measures. The effect of temperature on milk density (ρ) was also evaluated including temperature (t) as covariate with linear and quadratic effects within each analytic method. The regression equation describing the curvature and density–temperature relationship for the DMA35 instrument was ρ = 1.0338−0.00017T−0.0000122T2 (R2 = 0.64), while it was ρ = 1.0334 + 0.000057T−0.00001T2 (R2 = 0.61) for DMA4500 instrument. The mean density determined with DMA4500 at 5 °C was 1.0334 g cm−3, with corresponding figures of 1.0330, 1.0320 and 1.0305 g cm−3 at 10, 15 and 20 °C, respectively. The milk density values obtained in this study at specific temperatures will help to address any bias in weight–volume calculations and thus may also improve the financial and operational control for the dairy processors in Ireland and internationally.  相似文献   
56.
Theoretical Foundations of Chemical Engineering - New research results, as well as those published earlier by the authors, on the synthesis of azo compounds based on nitroanilines obtained by the...  相似文献   
57.
Polymer Bulletin - In this study, we synthesized a new ion-imprinted polymer (IIP) based on introduction of amidoxime groups in acrylonitrile, complexation with Cd2+ ions and polymerization with...  相似文献   
58.
At the hydroelectric unit No. 11 of the Nizhnekamsk hydroelectric power plant, the filling wedges of a rotor were investigated by ultrasound in the free st  相似文献   
59.
The bromodomain and extra terminal (BET) family of bromodomain-containing proteins (BCPs) have been the subject of extensive research over the past decade, resulting in a plethora of high-quality chemical probes for their tandem bromodomains. In turn, these chemical probes have helped reveal the profound biological role of the BET bromodomains and their role in disease, ultimately leading to a number of molecules in active clinical development. However, the BET subfamily represents just 8/61 of the known human bromodomains, and attention has now expanded to the biological role of the remaining 53 non-BET bromodomains. Rapid growth of this research area has been accompanied by a greater understanding of the requirements for an effective bromodomain chemical probe and has led to a number of new non-BET bromodomain chemical probes being developed. Advances since December 2015 are discussed, highlighting the strengths/caveats of each molecule, and the value they add toward validating the non-BET bromodomains as tractable therapeutic targets.  相似文献   
60.
Russian Journal of Non-Ferrous Metals - Rolling bearing rings comprise a large reserve for expanding powder metallurgy production. This reserve is being incompletely implemented. The hot forging of...  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