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   131284篇
  免费   7308篇
  国内免费   64篇
林业   5995篇
农学   4542篇
基础科学   859篇
  15996篇
综合类   21672篇
农作物   4962篇
水产渔业   6633篇
畜牧兽医   67512篇
园艺   1620篇
植物保护   8865篇
  2018年   1825篇
  2017年   1979篇
  2016年   1877篇
  2015年   1582篇
  2014年   1978篇
  2013年   4973篇
  2012年   3575篇
  2011年   4242篇
  2010年   2911篇
  2009年   2989篇
  2008年   4438篇
  2007年   4194篇
  2006年   3953篇
  2005年   3734篇
  2004年   3655篇
  2003年   3756篇
  2002年   3451篇
  2001年   4105篇
  2000年   4059篇
  1999年   3301篇
  1998年   1478篇
  1997年   1412篇
  1996年   1308篇
  1995年   1556篇
  1994年   1436篇
  1993年   1355篇
  1992年   2699篇
  1991年   2870篇
  1990年   2923篇
  1989年   2792篇
  1988年   2633篇
  1987年   2535篇
  1986年   2629篇
  1985年   2518篇
  1984年   2159篇
  1983年   1893篇
  1982年   1266篇
  1979年   2002篇
  1978年   1548篇
  1977年   1439篇
  1976年   1345篇
  1975年   1421篇
  1974年   1653篇
  1973年   1748篇
  1972年   1690篇
  1971年   1574篇
  1970年   1528篇
  1969年   1524篇
  1968年   1257篇
  1967年   1380篇
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
51.
Summary Acute febrile diseases are characterized by specific and non-specific symptoms. The non-specific responses are presented under the headings: fever, inflammation and pain, experimental models for investigating febrile reactions, haematologic changes, blood biochemical changes, cardiovascular effects, changes in gastric function, and the effects of fever upon pharmacokinetics of drugs. It was the purpose of this review to describe present concepts of thermoregulation and fever, the associated reactions produced by bacterial pyrogens and the mechanisms of these reactions. The available data illustrate, that many questions have not yet been clearly answered. However, the entire field of research involving endogenous substances, such as interleukin-1, is now moving ahead with great speed. Furthermore, there is some evidence which suggests that fever and the associated lower plasma zinc and iron levels act together as a co-ordinated non-specific host defence mechanism. Since experimental fever has a distinct effect upon the pharmacokinetics of drugs, more attention should be given to this aspect.  相似文献   
52.
Characterization of monoclonal antibodies directed against swine leukocytes   总被引:3,自引:0,他引:3  
Hybridomas were produced from fusions of the SP2/0 mouse myeloma with splenic cells from: 1) an outbred Sprague Dawley rat immunized with swine peripheral blood mononuclear (PBM) cells; 2) a (CBA/NDub X BALB/c Dub) F1 mouse immunized with concanavalin A (Con A) activated swine PBM cells and 3) a (BALB/c Dub X C3H/He Dub) F1 mouse immunized with swine thymocytes. The resulting supernatants were screened by a microcytotoxicity assay for activity against swine PBM cells. Four hybridomas (MSA1, MSA2, MSA3 and MSA4) were selected, cloned and characterized by their cell reactivity and effect on mitogenic assays. MSA1 and MSA2 belong to the rat IgG2b subclass. MSA3 and MSA4 are of the mouse IgG2a subclass. These monoclonal antibodies reacted in the following manner: MSA1 with monocytes, granulocytes, red blood cells and bone marrow cells; MSA2 with subset of T cells; MSA3 with B cells and subsets of T cells and monocytes (class II molecule) and MSA4, a pan-T cell reagent (E-rosette receptor). The involvement of the various cell types reactive to the different monoclonal antibodies in the mitogenic response of swine PBM cells to Con A, phytohemagglutinin (PHA) or pokeweed mitogen (PWM) was investigated by cellular depletion with monoclonal antibody plus complement. Cellular depletion of PBM cells with the following monoclonal antibodies plus complement treatment resulted in: MSA1, almost total reduction in the mitogenic response to low doses of Con A or PWM; MSA2, partial reduction in the proliferative responses to any concentration of Con A, PHA or PWM; MSA3, partial reduction in proliferative responses to low concentrations of Con A or PWM and 4) MSA4, total elimination of any proliferative response to Con A, PHA or PWM.  相似文献   
53.
54.
55.
56.
57.
58.
59.
60.
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