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   1508453篇
  免费   142710篇
  国内免费   1515篇
  2021年   17996篇
  2019年   16198篇
  2018年   18178篇
  2017年   17043篇
  2016年   28491篇
  2015年   42752篇
  2014年   50813篇
  2013年   77092篇
  2012年   41412篇
  2011年   30775篇
  2010年   44955篇
  2009年   45907篇
  2008年   28993篇
  2007年   27217篇
  2006年   31826篇
  2005年   32858篇
  2004年   31927篇
  2003年   29599篇
  2002年   27576篇
  2001年   42066篇
  2000年   39782篇
  1999年   37782篇
  1998年   26621篇
  1997年   26454篇
  1996年   25913篇
  1995年   23973篇
  1994年   23823篇
  1993年   23029篇
  1992年   33094篇
  1991年   31274篇
  1990年   30128篇
  1989年   30826篇
  1988年   28313篇
  1987年   27182篇
  1986年   25615篇
  1985年   27327篇
  1984年   26052篇
  1983年   23100篇
  1982年   22440篇
  1981年   21408篇
  1980年   20163篇
  1979年   22859篇
  1978年   20635篇
  1977年   19499篇
  1976年   18726篇
  1975年   18608篇
  1974年   19392篇
  1973年   19559篇
  1972年   16925篇
  1971年   15327篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
994.
995.
996.
The potential of nisin F as an antimicrobial agent in treating subcutaneous skin infections was tested in vivo by infecting C57BL/6 mice with a bioluminescent strain of Staphylococcus aureus (Xen 36). Strain Xen 36 has the luxABCDE operon located on a native plasmid. Mice were grouped into four groups: Infected with strain Xen 36 and treated with nisin F, infected with strain Xen 36 and treated with saline (placebo), not infected and treated with nisin (control) and not infected and not treated (control). The immune systems of the mice were suppressed with deksamethasone. Mice were treated with either nisin F or sterile physiological saline 24 and 48 h after infection with subcutaneously injected S. aureus Xen 36 (4 × 106 CFU). Histology and bioluminescent flux measurements revealed no significant difference between infected mice treated with nisin and saline, respectively. However, infected mice treated with nisin F had an increased number of polymorphonuclear cells when compared with infected mice treated with saline. Also, not infected mice treated with nisin F had an influx of polymorphonuclear cells. Nisin F is thus ineffective in combating deep dermal staphylococcal infections. The apparent immune modulation of nisin when subcutaneously injected has to be investigated.  相似文献   
997.
998.
999.
1000.
Cotton seedlings raised under glass from seed pre-soaked in a water suspension of Xanthomonas malvacearum , and watered by sub-irrigation only, developed atypical dull green flaccid areas extending from the periphery of the cotyledons. Later symptoms that variably developed were: vascular discoloration, not necessarily continuous, in the petioles of affected cotyledons, in the hypocotyl, and in parts of the plant above the cotyledonary node; premature withering of cotyledons; dull green flaccid areas in true leaves, not necessarily the lowest, later turning brown and drying, with usually a chlorotic margin; parenchymatous attack in stems, petioles and leaves. Evidence is adduced, from the progression of symptoms and from associations between them, and from isolations of the pathogen from various parts of the plant at different stages, that the course of this type of infection is primarily vascular, progressing from the edges of cotyledons into the hypocotyl and thence upwards in vascular tissues. Thence the infection may break out at any time into parenchymatous tissues, leading to the more characteristic forms of the disease, of greater or less severity according to the susceptibility of the parenchyma at the time of its invasion. Similar symptoms have been observed in field plantings, and it is suggested that vascular infection is of greater and wider significance in the epidemiology of bacterial blight than has hitherto been commonly accepted.  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