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   769篇
  免费   36篇
林业   67篇
农学   27篇
基础科学   3篇
  95篇
综合类   77篇
农作物   12篇
水产渔业   28篇
畜牧兽医   442篇
园艺   4篇
植物保护   50篇
  2023年   8篇
  2022年   9篇
  2021年   11篇
  2019年   12篇
  2018年   12篇
  2017年   15篇
  2016年   8篇
  2015年   13篇
  2014年   14篇
  2013年   37篇
  2012年   37篇
  2011年   31篇
  2010年   23篇
  2009年   21篇
  2008年   24篇
  2007年   30篇
  2006年   31篇
  2005年   28篇
  2004年   12篇
  2003年   30篇
  2002年   27篇
  2001年   15篇
  2000年   11篇
  1999年   15篇
  1998年   5篇
  1996年   8篇
  1992年   13篇
  1991年   19篇
  1990年   19篇
  1989年   16篇
  1988年   15篇
  1987年   17篇
  1986年   22篇
  1985年   12篇
  1984年   10篇
  1983年   14篇
  1982年   6篇
  1981年   6篇
  1979年   7篇
  1977年   10篇
  1976年   6篇
  1975年   9篇
  1974年   11篇
  1973年   9篇
  1972年   4篇
  1971年   10篇
  1970年   8篇
  1968年   4篇
  1966年   11篇
  1938年   6篇
排序方式: 共有805条查询结果,搜索用时 15 毫秒
71.
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   
72.
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   
73.
74.
75.
76.
77.
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   
78.
T lymphocytes are generated in the thymus, where developing thymocytes must accept one of two fates: They either differentiate or they die. These fates are chiefly determined by signals that originate from the T cell receptor (TCR), a single receptor complex with a remarkable capacity to decide between distinct cell fates. This review explores TCR signaling in thymocytes and focuses on the kinetic aspects of ligand binding, coreceptor involvement, protein phosphorylation, and mitogen-activated protein kinase (MAPK) activation. Understanding the logic of TCR signaling may eventually explain how thymocytes and T cells distinguish self from nonself, a phenomenon that has fascinated immunologists for 50 years.  相似文献   
79.
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   
80.
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