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   253篇
  免费   10篇
  国内免费   1篇
林业   24篇
农学   13篇
  36篇
综合类   11篇
农作物   5篇
水产渔业   10篇
畜牧兽医   137篇
园艺   13篇
植物保护   15篇
  2022年   4篇
  2021年   6篇
  2020年   6篇
  2018年   10篇
  2017年   5篇
  2016年   6篇
  2015年   7篇
  2014年   6篇
  2013年   15篇
  2012年   12篇
  2011年   22篇
  2010年   4篇
  2009年   7篇
  2008年   19篇
  2007年   17篇
  2006年   9篇
  2005年   6篇
  2004年   7篇
  2003年   14篇
  2002年   9篇
  2001年   10篇
  2000年   1篇
  1999年   6篇
  1998年   2篇
  1996年   3篇
  1995年   2篇
  1993年   2篇
  1992年   6篇
  1991年   5篇
  1990年   2篇
  1989年   3篇
  1988年   2篇
  1987年   5篇
  1986年   4篇
  1985年   6篇
  1984年   5篇
  1983年   2篇
  1979年   1篇
  1974年   2篇
  1970年   1篇
  1969年   1篇
  1967年   2篇
排序方式: 共有264条查询结果,搜索用时 15 毫秒
261.
A high-pressure phase of TiO(2), which had been observed by shock-wave experiments and remained unresolved, has been studied by in situ x-ray diffraction. The single phase was formed at 20 gigapascals and 770 degrees C with the use of sintered-diamond multianvils; it has the same structure as baddeleyite, the stable phase of ZrO(2) at ambient conditions. The coordination number of Ti increases from six to seven across the rutile to baddeleyite transition, and the volume is reduced by approximately 9 percent.  相似文献   
262.
Amaranth seeds can be popped by heating. The traditional method of popping in a skillet is simple, but it is difficult to control the heating time and temperature. To overcome these disadvantages, we developed a fluidized bed continuous processing system based on hot air heating for producing popped amaranth seeds in bulk. Using this system, we evaluated the effects of heat treatment at 260 °C for 15 s on the contents of B-group vitamins and essential and trace elements in amaranth seeds. The results showed that the treatment did not affect the content of B-group vitamins, and the recovery for essential and trace elements was 97–196 %. This popping system is useful for processing amaranth seeds in terms of the product quality and nutrition.  相似文献   
263.
This study shows a method to easily develop suitable impregnation procedure of chemicals for preserving the archaeological waterlogged wood (WW) using diffusion constant. The steady-state diffusion coefficients of polyethylene glycol 4000 (PEG4000), trehalose, and keratin through eight archaeological waterlogged wood species were obtained from the total amounts of the chemicals diffused through the wood samples. The diffusion coefficients were strongly affected by the anatomical structures of the wood species and degree of wood deterioration. Within the same species of wood, the highest diffusion rates were measured in the longitudinal direction, followed by those in the radial and tangential directions. The longitudinal diffusion coefficients were 1.5- to 8.1-times higher than the radial diffusion coefficients, which were in turn approximately 1.1- to 5.7-times higher than the tangential diffusion coefficients. The diffusion rates were found to be inversely proportional to the molecular weight of the diffusing chemical. The diffusivity of trehalose through the waterlogged woods was found to be higher than those of keratin and PEG4000. This study provides a potential method to easily estimate chemical diffusion coefficients for dip-diffusion treatments.  相似文献   
264.
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