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   342207篇
  免费   37411篇
  国内免费   189篇
  2018年   3042篇
  2017年   2867篇
  2016年   4114篇
  2015年   5551篇
  2014年   6529篇
  2013年   9130篇
  2012年   10344篇
  2011年   10357篇
  2010年   7037篇
  2009年   6318篇
  2008年   9098篇
  2007年   9584篇
  2006年   8869篇
  2005年   8536篇
  2004年   8225篇
  2003年   8034篇
  2002年   7985篇
  2001年   18361篇
  2000年   18533篇
  1999年   14233篇
  1998年   4299篇
  1997年   4522篇
  1996年   4325篇
  1995年   4028篇
  1994年   3958篇
  1993年   3802篇
  1992年   11669篇
  1991年   11300篇
  1990年   10804篇
  1989年   10403篇
  1988年   9656篇
  1987年   9022篇
  1986年   8240篇
  1985年   8157篇
  1984年   6544篇
  1983年   5693篇
  1982年   4169篇
  1981年   3643篇
  1980年   3418篇
  1979年   6301篇
  1978年   4690篇
  1977年   4240篇
  1976年   3878篇
  1975年   4467篇
  1974年   4721篇
  1973年   4603篇
  1972年   4287篇
  1971年   3706篇
  1970年   3386篇
  1969年   3175篇
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
201.
202.
Pieces of brain are fixed in formalin ammonium bromide for about 4 days at room temperature, and given the following treatment: After washing, dehydrating and clearing, embed in paraffin, section and mount. Deparaffinize sections and pass through graded alcohols to water. Sensitize in 5% sodium sulfite for 2 hours, wash in distilled water and impregnate with silver diamminohydroxide solution 2-5 minutes at room temperature. Reduce in 2% formalin, wash in distilled water and tone in gold chloride. Fix in 5% hypo, counterstain with 1% picric acid, dehydrate and cover in balsam. Equally good results are obtained by impregnating with Hortega's strong silver carbonate. The microglia, oligodendroglia, fibrous and protoplasmic astrocytes in the cat, rabbit, newborn and adult human are successfully stained by this method.  相似文献   
203.
204.
205.
206.
Of 41 fungicides tested in the laboratory, copper carbonate, copper sulphate, mercuric chloride, Agrosan GN, quintozene, kasugamycin, carboxin, pyracar-bolid, carbendazim, chloroneb, benomyl, Ohric, RH 893 (2-n-octyl-4-isothiazole-3-one) and Terrazole were most inhibitory to the mycelial growth of Rhizoctonia solani on Czapek's agar plates and had EC50 values of less than 1 μg a.i./ml, while copper oxychloride, Udonkor, zineb, ziram, F 319 (3-hydroxy-5-methyl isoxazole) and anilazine were much less toxic, ziram being least inhibitory with an EC50 of 214 μg a.i./ml. Of 17 fungicides tested in the greenhouse as seed treatments, thiabendazole, carbendazim, benomyl, thiophanate-methyl, dichlozoline and Ohric gave 80–90% control of damping-off of mung bean seedlings. A single soil drench with thiophanate-methyl and two drenches with benomyl gave about 90% disease control, More seedlings with R. solani infection survived when thiophanate-methyl was used as a post-inoculation soil drench than when benomyl or chloroneb were used.  相似文献   
207.
When rats received glucagon or insulin every 2 h after partial hepatectomy (Hx), hepatic putrescine content was increased above control levels at 6 and 12 h, respectively. When the two hormones were combined, the increased levels were additive. Hepatic ornithine decarboxylase activity was above control levels at 12 h after insulin treatment. Hepatic spermidine N1-acetyltransferase activity was enhanced at 6 h only when glucagon was dosed. Putrescine administration from 0 to 4 h or from 6 to 10 h increased hepatic DNA synthesis to similar levels 22 h after Hx. These results suggest that glucagon and insulin additively stimulate hepatic putrescine production after Hx. This may explain the cooperative stimulation of liver regeneration by both hormones.  相似文献   
208.
209.
210.
The effects of chloroquine on the kinetics of the dark repair process were investigated by employing a cellular system. Lineweaver-Burke plots and Dixon plots of chloroquine inhibition, respectively, showed that there was an increase in slope with increasing concentration of inhibitor which followed an enzyme-like pattern. These results are consistent with a model for excision-repair in which chloroquine may block the excision repair pathway.  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