首页 | 官方网站   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   96篇
  免费   7篇
农业科学   103篇
  2019年   2篇
  2018年   3篇
  2016年   5篇
  2014年   4篇
  2013年   5篇
  2012年   3篇
  2011年   5篇
  2010年   2篇
  2009年   2篇
  2008年   1篇
  2007年   1篇
  2006年   3篇
  2005年   6篇
  2004年   2篇
  2003年   3篇
  2002年   3篇
  2001年   2篇
  2000年   1篇
  1999年   1篇
  1993年   1篇
  1991年   2篇
  1990年   1篇
  1988年   2篇
  1987年   2篇
  1986年   3篇
  1985年   2篇
  1984年   1篇
  1983年   1篇
  1981年   1篇
  1979年   2篇
  1976年   2篇
  1975年   2篇
  1971年   2篇
  1970年   1篇
  1969年   1篇
  1968年   3篇
  1967年   1篇
  1936年   1篇
  1927年   1篇
  1921年   1篇
  1918年   1篇
  1915年   1篇
  1908年   1篇
  1902年   1篇
  1899年   1篇
  1897年   1篇
  1896年   2篇
  1895年   2篇
  1886年   1篇
  1884年   2篇
排序方式: 共有103条查询结果,搜索用时 15 毫秒
1.
2.
3.
Preparations derived from plants were the original therapeutic interventions used by man to control diseases (including parasites), both within humans and livestock. Development of herbal products depended upon local botanical flora with the result that different remedies tended to develop in different parts of the world. Nevertheless, in some instances, the same or related plants were used over wide geographic regions, which also was the result of communication and/or the importation of plant material of high repute. Thus, the Nordic countries have an ancient, rich and diverse history of plant derived anthelmintic medications for human and animal use. Although some of the more commonly used herbal de-wormers were derived from imported plants, or their products, many are from endemic plants or those that thrive in the Scandinavian environment. With the advent of the modern chemotherapeutic era, and the discovery, development and marketing of a seemingly unlimited variety of highly efficacious, safe synthetic chemicals with very wide spectra of activities, herbal remedies virtually disappeared from the consciousness--at least in the Western world. This attitude is now rapidly changing. There is a widespread resurgence in natural product medication, driven by major threats posed by multi-resistant pest, or disease, organisms and the diminishing public perceptions that synthetic chemicals are the panacea to health and disease control. This review attempts to provide a comprehensive account of the depth of historical Nordic information available on herbal de-wormers, with emphasis on livestock and to provide some insights on potentially rewarding areas of "re-discovery" and scientific evaluation in this field.  相似文献   
4.
5.
6.
7.
为了探索烟叶生产过程中各机械的性能及工作效率,2013年在福建省建阳市莒口镇河坝新村开展了烟叶生产全程机械化作业试点研究。结果表明,起垄环节,碎土率方面邵武华友履带式起垄机表现最好(89.9%),沟底积土方面松溪永顺表现最好;覆膜环节,各测试机型表现中等,在效率方面优于人工覆膜;移栽环节,漏栽率上江苏久泰移栽机高于江苏井关移栽机;培土环节,漳州南冠培土机操作简便,掉头灵活,单人操作,单行双侧作业,深受烟农喜爱;拔杆环节,龙岩诚德拔杆机单人操作,操作简便,动力较足,拔杆顺畅,拔杆带土较少,效果较好,适应性较强。  相似文献   
8.
A new serotype of calicivirus was isolated from California sea lions (Zalophus californianus) with severe vesicular disease. Neutralizing antibodies were found in 27 of 82 (32.9%) serum samples from California sea lions and in 15 of 146 (10.3%) serum samples from Steller sea lions (Eumetopias jubatus) tested. The seropositive animals were widely dispersed along the margins of the eastern Pacific basin, from the Bering Sea to the Santa Barbara Channel. Seropositive samples were found from as early as 1976 through the present time. This new calicivirus serotype, San Miguel sea lion virus type 13, was inoculated into weaned pigs, resulting in induction of severe vesicular disease, which spread to all pigs, including uninoculated pen contacts. Virus was continually shed by most of the pigs throughout the 2-week duration of the experiment.  相似文献   
9.
Measurement from Christmas Island (2 degrees N, 157 degrees W) of long-term mean vertical motions in the tropical atmosphere using very-high-frequency wind-profiling Doppler radar show that there is a transition from downward motion in the free troposphere to upward motion in the upper troposphere and lower stratosphere. The observations in the free troposphere are consistent with a balance between adiabatic and diabatic heating and cooling rates in a clear atmosphere. Comparison of the results at Christmas Island during El Ni?o and non-El Ni?o conditions with earlier results obtained for stratiform rain conditions over Pohnpei, Federated States of Micronesia, show that cirrus clouds in the vicinity of the tropopause likely play an important role in determining the sense and magnitude of vertical motions in this region. These results have implications for the exchange of mass between the troposphere and stratosphere over the tropics.  相似文献   
10.
In muscle fibers which have been exposed for 1 hour to a Ringer solution containing 400 millimolar glycerol and then returned to plain Ringer solution, the transverse tubular system is disrupted. At the same time the membrane capacitance is markedly reduced and hyperpolarizing current pulses no longer produce a slow, progressive increase in potential (creep). The large capacitance of muscle and the phenomenon of "creep" must both depend on an intact transverse tubular system.  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-23

京公网安备 11010802026262号