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   358篇
  免费   34篇
林业   20篇
农学   7篇
基础科学   5篇
  60篇
综合类   49篇
农作物   50篇
水产渔业   35篇
畜牧兽医   125篇
园艺   6篇
植物保护   35篇
  2023年   9篇
  2022年   13篇
  2021年   30篇
  2020年   22篇
  2019年   20篇
  2018年   26篇
  2017年   21篇
  2016年   18篇
  2015年   9篇
  2014年   23篇
  2013年   17篇
  2012年   27篇
  2011年   25篇
  2010年   17篇
  2009年   14篇
  2008年   16篇
  2007年   12篇
  2006年   12篇
  2005年   6篇
  2004年   7篇
  2003年   7篇
  2002年   10篇
  2001年   2篇
  2000年   3篇
  1999年   1篇
  1998年   1篇
  1995年   4篇
  1993年   1篇
  1987年   1篇
  1986年   3篇
  1985年   1篇
  1982年   1篇
  1981年   2篇
  1980年   1篇
  1979年   1篇
  1976年   3篇
  1975年   1篇
  1973年   1篇
  1970年   1篇
  1969年   1篇
  1966年   1篇
  1963年   1篇
排序方式: 共有392条查询结果,搜索用时 31 毫秒
1.
Environmental conditions influence phenology and physiological processes of plants. It is common for maize and sorghum to be sown at two different periods: the first cropping (spring/summer) and the second cropping (autumn/winter). The phenological cycle of these crops varies greatly according to the planting season, and it is necessary to characterize the growth and development to facilitate the selection of the species best adapted to the environment. The aim of this study was to characterize phenological phases and physiological parameters in sorghum and maize plants as a function of environmental conditions from the first cropping and second cropping periods. Two parallel experiments were conducted with both crops. The phenological characterization was based on growth analyses (plant height, leaf area and photoassimilate partitioning) and gas exchange evaluations (net assimilation rate, stomatal conductance, transpiration and water-use efficiency). It was found that the vegetative stage (VS) for sorghum and maize plants was 7 and 21 days, respectively, longer when cultivated during the second cropping. In the first cropping, the plants were taller than in the second cropping, regardless of the crop. The stomatal conductance of sorghum plants fluctuated in the second cropping during the development period, while maize plants showed decreasing linear behaviour. Water-use efficiency in sorghum plants was higher during the second cropping compared with the first cropping. In maize plants, in the second cropping, the water-use efficiency showed a slight variation in relation to the first cropping. It was concluded that the environmental conditions as degree-days, temperature, photoperiod and pluvial precipitation influence the phenology and physiology of both crops during the first and the second cropping periods, specifically cycle duration, plant height, leaf area, net assimilation rate, stomatal conductance and water-use efficiency, indicating that both crops respond differentially to environmental changes during the growing season.  相似文献   
2.
3.
4.
5.
6.
7.
8.
9.
Bovine tuberculosis is a contagious and zoonotic disease of animals and humans. In Europe, the number of reported cases of tuberculosis has decreased. Equidae are relatively rarely infected even in endemic areas. The presented report describes a case of chronic Mycobacterium bovis tuberculosis in a 30-year-old female donkey. The donkey initially presented with persistent lymphadenopathy; however, as the disease progressed, weight loss became apparent. To the authors' knowledge, this is the second confirmed case of tuberculosis in a donkey in Europe.  相似文献   
10.
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