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   950篇
  免费   22篇
  国内免费   3篇
电工技术   16篇
化学工业   194篇
金属工艺   29篇
机械仪表   26篇
建筑科学   14篇
矿业工程   3篇
能源动力   41篇
轻工业   74篇
水利工程   7篇
石油天然气   1篇
无线电   73篇
一般工业技术   259篇
冶金工业   124篇
原子能技术   3篇
自动化技术   111篇
  2024年   4篇
  2023年   8篇
  2022年   26篇
  2021年   39篇
  2020年   36篇
  2019年   40篇
  2018年   36篇
  2017年   30篇
  2016年   24篇
  2015年   26篇
  2014年   34篇
  2013年   65篇
  2012年   28篇
  2011年   39篇
  2010年   45篇
  2009年   40篇
  2008年   30篇
  2007年   28篇
  2006年   17篇
  2005年   20篇
  2004年   11篇
  2003年   18篇
  2002年   20篇
  2001年   14篇
  2000年   11篇
  1999年   10篇
  1998年   34篇
  1997年   23篇
  1996年   16篇
  1995年   8篇
  1994年   10篇
  1993年   16篇
  1992年   7篇
  1990年   10篇
  1989年   10篇
  1988年   9篇
  1987年   10篇
  1986年   6篇
  1985年   20篇
  1984年   10篇
  1983年   9篇
  1982年   10篇
  1981年   10篇
  1980年   15篇
  1979年   9篇
  1977年   3篇
  1976年   11篇
  1975年   3篇
  1974年   3篇
  1966年   2篇
排序方式: 共有975条查询结果,搜索用时 15 毫秒
11.
12.
This study examined the thermovinification technique using yeasts immobilized on calcium alginate for microvinification of the Cabernet Sauvignon and Pinot Noir grape varieties grown in Diamantina, Minas Gerais, Brazil. The wines obtained by thermovinification were characterized by their chemical and sensory aspects. The varietal wines from Cabernet Sauvignon and Pinot Noir had an alcohol content of 9.3 and 10.9 % (v/v), respectively. The total acidity, volatile acidity and the alcohol/reduced dry extract ratio were consistent with the Brazilian standards established for identity and quality of wines. There was a significant reduction in the levels of anthocyanins, flavonoids and total phenolic compounds after aging in the bottle. The sensory evaluation presented an acceptability exceeding 60 % for both wines.  相似文献   
13.
14.
During commercial sterilization, mild to severe breakage of individual potatoes sometimes occurs and the outer layers of potatoes disintegrate into a floury texture referred to as sloughing. Four cultivars of potatoes namely Kufri Badshah, Kufri Bahar, Kufri Chandramukhi and HPS-1/13 were either treated with CaCl2 or dehydrated before canning to reduce the sloughing. The extent of sloughing in terms of breakage observed visually depended on the cultivar of potatoes. Although CaCl2 treatment reduces sloughing, it causes turbidity of the brine. Partial dehydration of potatoes before canning was helpful in reducing sloughing and it allowed a higher filling of potato solids in the can thereby increasing drained weight. HPS-1/13 cultivar was found most suitable for dehydrocanning.  相似文献   
15.
This study was conducted in the Tafresh area of Iran to assess the dietary patterns, time allocation, and nutritional status of rural women in relation to their participation in mixed farming activities. We selected 75 women from 40 villages by applying a stratified random-sampling technique. Cereals and grains were the major source of energy intake. According to the recommended dietary allowance (RDA) tables of India, the United States, the United Kingdom, and the Food and Agriculture Organization (FAO), the respondents seemed to have no micronutrient and energy deficiencies during the spring season. They spent most of their time and energy on household, animal husbandry, and crop farming activities. According to measurements of body mass index (BMI), the respondents were well nourished. However, despite the high level of BMI, analysis suggested a negative energy balance. Nevertheless, analysis indicated that rural women with negative energy balance spent more time and energy in mixed farming and had a higher level of participation in related activities. Hence, it is evident from the results that the physical contribution of rural women in mixed farming activities has a detrimental effect on their nutritional status, at least during some parts of the year (e.g., spring or summer). Therefore, there is a need to adjust nutritional interventions to improve the sustainability of their food intake and to develop appropriate technologies in mixed farming to alleviate their work burdens.  相似文献   
16.
The idea of information improvement was introduced by Thiel [3]. This idea was further extended by the first author to information improvement due to 2 and N revisions and specifically states that different experimenters (a finite number) are required to proceed with given distributions P and U and are permitted to choose a suitable revision. We attempted to provide a measure of information corresponding to Theil's measure which reflected the effect of all revisions. In this paper, the authors have studied a joint characterization of information improvement of N revisions and its generalization by considering a suitable functional equation.  相似文献   
17.
The foliage of Chenopodium belonging to 10 species were analysed for selected nutritional and antinutritional components. The overall range of moisture was 757-910 g kg?1, carotenoid 78-190 mg kg?1, vitamin C 0.5-2.4 g kg?1, protein 26-64 g kg?1, nitrate 2.6-5.0 g kg?1 and oxalate 9-39 g kg?1 (fresh wt). Variation of all the six parameters with respect to leaf position from the apex showed the highest amount of carotenoid at 7-8, vitamin C at 9-10, protein at 5-6 and nitrate in the youngest leaves, followed by a continuous decrease with age (increasing position). However, oxalate contents always tended to increase with leaf position (age). The protein, fat and fatty acid composition in seeds of eight species were also analysed. Protein varied from 106 to 142 g kg?1 and fat from 30 to 62 g kg?1; palmitic, oleic and linoleic were the major fatty acids in the oils.  相似文献   
18.
The authors have axiomatically characterized the Shannon entropy using cyclic symmetry.  相似文献   
19.
The present study investigates the effect of Winkler-Pasternak elastic foundation parameters on the nonlinear dynamic response of shallow spherical shells. The values of foundation parameters ( and ) have been determined for the minimaximum central response of the shallow shells for both the clamped as well as simply supported immovable edge conditions. Donnell type partial differential equations governing the moderately large amplitude behaviour of shallow spherical shells resting on Winkler-Pasternak elastic foundations under step pressure loading, have been analysed. The space and time-wise integrations of governing equations have been carried out using Chebyshev series and Houbolt techniques, respectively. It is also shown that the present analysis can be extended to study the dynamic buckling of shallow shells resting on elastic foundations.  相似文献   
20.
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