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   688547篇
  免费   8331篇
  国内免费   1160篇
电工技术   12316篇
综合类   524篇
化学工业   108854篇
金属工艺   30541篇
机械仪表   22506篇
建筑科学   15196篇
矿业工程   6002篇
能源动力   16883篇
轻工业   51725篇
水利工程   9025篇
石油天然气   20031篇
武器工业   48篇
无线电   70204篇
一般工业技术   146760篇
冶金工业   112415篇
原子能技术   18895篇
自动化技术   56113篇
  2021年   6612篇
  2019年   6294篇
  2018年   11245篇
  2017年   11418篇
  2016年   11957篇
  2015年   7328篇
  2014年   12504篇
  2013年   31253篇
  2012年   19014篇
  2011年   25307篇
  2010年   20318篇
  2009年   22714篇
  2008年   23019篇
  2007年   22579篇
  2006年   19412篇
  2005年   17506篇
  2004年   16784篇
  2003年   16451篇
  2002年   15921篇
  2001年   15382篇
  2000年   14816篇
  1999年   14335篇
  1998年   32108篇
  1997年   23531篇
  1996年   18298篇
  1995年   14150篇
  1994年   12958篇
  1993年   12686篇
  1992年   9986篇
  1991年   9816篇
  1990年   9688篇
  1989年   9379篇
  1988年   9029篇
  1987年   8335篇
  1986年   8066篇
  1985年   9025篇
  1984年   8298篇
  1983年   8027篇
  1982年   7287篇
  1981年   7441篇
  1980年   7187篇
  1979年   7406篇
  1978年   7386篇
  1977年   8045篇
  1976年   9721篇
  1975年   6670篇
  1974年   6579篇
  1973年   6647篇
  1972年   5820篇
  1971年   5399篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
93.
94.
This study aimed to evaluate the physicochemical characteristics and sensory attributes of beef burgers with the addition of pea fibre as a partial substitute of meat or fat. Three formulations were prepared: control (CON) – similar to the commercial formulation; fibre/less meat (FLM)—5% meat reduction and addition of 1% pea fibre; fibre/less fat (FLF)—7% fat reduction and addition of 1% pea fibre. Non-significant differences were obtained for pH, colour parameters (L* and b*), texture profile, cooking loss and size reduction among formulations. Moreover, sensory analysis with consumers of beef burgers did not indicate differences among the formulations for all the analysed attributes. Therefore, pea fibre is a promising partial replacer for meat and fat in beef burgers due to the preservation of technological parameters and sensory acceptance.  相似文献   
95.
96.
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   
97.
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   
98.
In the future, hydrogen will be an important energy carrier and industrial raw material. Catalytic steam reforming of bio-oils is a promising and economically viable technology for hydrogen production. However, during the reforming process, the catalysts are rapidly deactivated due to coke formation and sintering. Thus, maintaining the activity and stability of catalysts is the key issue in this process. Optimized operation conditions could extend the catalyst lifetime by affecting the coke morphology or promoting coke gasification. This article summarizes the recent developments in the field of catalytic steam reforming of bio-oils, focusing on the operation conditions, the properties of the catalysts, and the effects of the catalyst supports. The expected insights into the catalytic steam reforming of bio-oils will provide further guidance for hydrogen production from bio-oils.  相似文献   
99.
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   
100.
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   
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