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   809篇
  免费   39篇
林业   59篇
农学   26篇
基础科学   1篇
  130篇
综合类   75篇
农作物   15篇
水产渔业   38篇
畜牧兽医   440篇
园艺   8篇
植物保护   56篇
  2023年   10篇
  2022年   8篇
  2021年   11篇
  2020年   7篇
  2019年   15篇
  2018年   9篇
  2017年   18篇
  2016年   15篇
  2015年   12篇
  2014年   14篇
  2013年   46篇
  2012年   44篇
  2011年   33篇
  2010年   26篇
  2009年   23篇
  2008年   18篇
  2007年   31篇
  2006年   35篇
  2005年   30篇
  2004年   19篇
  2003年   24篇
  2002年   23篇
  2001年   11篇
  2000年   14篇
  1999年   14篇
  1996年   9篇
  1994年   6篇
  1993年   5篇
  1992年   14篇
  1991年   20篇
  1990年   19篇
  1989年   17篇
  1988年   13篇
  1987年   20篇
  1986年   23篇
  1985年   13篇
  1984年   11篇
  1983年   14篇
  1982年   8篇
  1981年   6篇
  1979年   7篇
  1977年   10篇
  1976年   5篇
  1975年   8篇
  1974年   11篇
  1973年   9篇
  1971年   10篇
  1970年   8篇
  1966年   11篇
  1938年   6篇
排序方式: 共有848条查询结果,搜索用时 0 毫秒
61.
Alcohol addiction and tetrahydropapaveroline   总被引:1,自引:0,他引:1  
  相似文献   
62.
Immune response restoration with macrophage culture supernatants   总被引:28,自引:0,他引:28  
Depression of the in vitro immune response of mouse spleen cell suspensions to sheep erythrocytes by removal of macrophages can be reversed by the addition of supernatants from peritoneal macrophage cultures. Supernatant activity can be absorbed by the red cell antigen, and supernatant-treated red cells are stimulatory in the absence of macrophages or supernatant.  相似文献   
63.
Drosophila host defense to fungal and Gram-positive bacterial infection is mediated by the Spaetzle/Toll/cactus gene cassette. It has been proposed that Toll does not function as a pattern recognition receptor per se but is activated through a cleaved form of the cytokine Spaetzle. The upstream events linking infection to the cleavage of Spaetzle have long remained elusive. Here we report the identification of a central component of the fungal activation of Toll. We show that ethylmethane sulfonate-induced mutations in the persephone gene, which encodes a previously unknown serine protease, block induction of the Toll pathway by fungi and resistance to this type of infection.  相似文献   
64.
65.
66.
A pattern noted in ecology is that diversity at one level begets diversity at other levels. In the case of consumers competing for similar resources, the diversity of those resources is thought to provide some degree of niche diversification in which a diverse set of consumer species can coexist. If, however, the diverse resources are not sufficiently distinct from one another, from the standpoint of the consumer species, such niche diversification will not exist. We experimentally show that a diverse array of twigs attracted 80% more species of twig-nesting ants than a monospecific collection of twigs. The specific tree species from which the twigs were derived did not explain the pattern. It appears that diversity per se at one level (twigs) creates conditions that promote diversity at another level (nesting ants).  相似文献   
67.
68.
69.
Data for six carrier gases of different thermal conductivities show a linear correlation between the logarithm of thermal conductivity and detector response. Carbon dioxide with a lower thermal conductivity than helium gives a ninefold increase in detector response.  相似文献   
70.
The first International Technical Conference on Animal Genetic Resources for Food and Agriculture, organized by the Food and Agriculture Organization of the United Nations, took place from 3 to 7 September, 2007, in Interlaken, Switzerland. The main achievement of the Conference was the adoption of the Global Plan of Action for Animal Genetic Resources, the first ever international framework for the promotion of the wise management of animal genetic resources for food and agriculture, endorsed by governments. The article describes the technical and intergovernmental processes developing the Global Plan of Action. The adoption of the Global Plan of Action has created unprecedented momentum for promoting the sustainable use, development and conservation of the world's livestock diversity. The international community is now facing the challenge to ensure that the Global Plan of Action is effectively implemented.  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