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   1449658篇
  免费   135970篇
  国内免费   1492篇
  2021年   17865篇
  2019年   16143篇
  2018年   17816篇
  2017年   16551篇
  2016年   28053篇
  2015年   42414篇
  2014年   50513篇
  2013年   76693篇
  2012年   38623篇
  2011年   27401篇
  2010年   43990篇
  2009年   45256篇
  2008年   26084篇
  2007年   24093篇
  2006年   29320篇
  2005年   30489篇
  2004年   29528篇
  2003年   27353篇
  2002年   25308篇
  2001年   41597篇
  2000年   39252篇
  1999年   37176篇
  1998年   26237篇
  1997年   26142篇
  1996年   25594篇
  1995年   23632篇
  1994年   23484篇
  1993年   22663篇
  1992年   32099篇
  1991年   30506篇
  1990年   28795篇
  1989年   29549篇
  1988年   27372篇
  1987年   25960篇
  1986年   24352篇
  1985年   26111篇
  1984年   25041篇
  1983年   22182篇
  1982年   21841篇
  1981年   20873篇
  1980年   19453篇
  1979年   21488篇
  1978年   19585篇
  1977年   18614篇
  1976年   17699篇
  1975年   17523篇
  1974年   18198篇
  1973年   18455篇
  1972年   15782篇
  1971年   14515篇
排序方式: 共有10000条查询结果,搜索用时 22 毫秒
991.
992.
993.
994.
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   
995.
996.
997.
998.
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   
999.
1000.
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