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   416篇
  免费   30篇
林业   21篇
农学   8篇
基础科学   1篇
  62篇
综合类   42篇
农作物   20篇
水产渔业   27篇
畜牧兽医   178篇
园艺   7篇
植物保护   80篇
  2023年   2篇
  2022年   2篇
  2021年   11篇
  2020年   16篇
  2019年   8篇
  2018年   10篇
  2017年   14篇
  2016年   14篇
  2015年   9篇
  2014年   15篇
  2013年   17篇
  2012年   27篇
  2011年   35篇
  2010年   13篇
  2009年   14篇
  2008年   43篇
  2007年   32篇
  2006年   22篇
  2005年   30篇
  2004年   17篇
  2003年   20篇
  2002年   11篇
  2001年   2篇
  2000年   4篇
  1999年   2篇
  1998年   3篇
  1997年   3篇
  1996年   5篇
  1995年   6篇
  1994年   1篇
  1992年   1篇
  1991年   1篇
  1990年   1篇
  1989年   2篇
  1987年   2篇
  1985年   1篇
  1984年   3篇
  1983年   2篇
  1982年   1篇
  1981年   6篇
  1980年   3篇
  1978年   6篇
  1977年   1篇
  1976年   5篇
  1975年   2篇
  1955年   1篇
排序方式: 共有446条查询结果,搜索用时 15 毫秒
441.
442.
Ctenocephalides felis were killed and collected from 92 cats in Alabama, Maryland, and Texas. The fleas and blood from the corresponding cat were digested and assessed in polymerase chain reaction assays that amplify DNA of Ehrlichia species, Anaplasma phagocytophilum, Neorickettsia risticii, Mycoplasma haemofelis, 'Candidatus M haemominutum' and Bartonella species. DNA consistent with B henselae, B clarridgeiae, M haemofelis, or 'Candidatus M haemominutum' was commonly amplified from cats (60.9%) and their fleas (65.2%). Results of this study support the recommendation to maintain flea control on cats in endemic areas.  相似文献   
443.
444.
445.
Among contact fungicides, dithiocarbamates have remained successful and are used worldwide. These organic sulfur fungicides, viz. mancozeb, maneb, zineb, ziram, thiram, metiram and propineb, have helped growers manage several economically important plant diseases. Their multi‐site mode of action and broad‐spectrum disease control make them some of the most common partners in mixtures of a number of single‐site fungicides as part of resistance management strategies. Indeed, it was the part played by ethylene‐bis‐dithiocarbamates such as mancozeb in delaying the evolution of phenylamide resistance in several oomycete phytopathogens that laid the groundwork for mixture strategies to become a cornerstone of anti‐resistance management in plant disease control. Dithiocarbamates, however, do not have systemic action, are only surface protectants and have to be applied prior to pathogen infection. Dithiocarbamates will likely continue play a key role as reliable resistance management tools to prolong the efficacy of single‐site fungicides. The primary metabolite ethylene thiourea produced by some of these fungicides is considered a reproductive and endocrine disrupter in animals. Therefore, dithiocarbamates need to be used at reduced rates or in slow‐release formulations. © 2017 Society of Chemical Industry  相似文献   
446.
The optimisation of plant nitrogen-use-efficiency (NUE) has a direct impact on increasing crop production by optimising use of nitrogen fertiliser. Moreover, it protects environment from negative effects of nitrate leaching and nitrous oxide production. Accordingly, nitrogen (N) management in agriculture systems has been major focus of many researchers. Improvement of NUE can be achieved through several methods including more accurate measurement of foliar N contents of crops during different growth phases. There are two types of methods to diagnose foliar N status: destructive and non-destructive. Destructive methods are expensive and time-consuming, as they require tissue sampling and subsequent laboratory analysis. Thus, many farmers find destructive methods to be less attractive. Non-destructive methods are rapid and less expensive but are usually less accurate. Accordingly, improving the accuracy of non-destructive N estimations has become a common goal of many researchers, and various methods varying in complexity and optimality have been proposed for this purpose. This paper reviews various commonly used non-destructive methods for estimating foliar N status of plants.  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