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   58898篇
  免费   5211篇
  国内免费   139篇
  2022年   426篇
  2021年   853篇
  2020年   558篇
  2019年   748篇
  2018年   919篇
  2017年   786篇
  2016年   1235篇
  2015年   1991篇
  2014年   2190篇
  2013年   3002篇
  2012年   3355篇
  2011年   3278篇
  2010年   2363篇
  2009年   1874篇
  2008年   2560篇
  2007年   2544篇
  2006年   2367篇
  2005年   2243篇
  2004年   2306篇
  2003年   2188篇
  2002年   2141篇
  2001年   1651篇
  2000年   1545篇
  1999年   1439篇
  1998年   761篇
  1997年   749篇
  1996年   652篇
  1995年   623篇
  1994年   492篇
  1993年   566篇
  1992年   1092篇
  1991年   963篇
  1990年   964篇
  1989年   913篇
  1988年   739篇
  1987年   749篇
  1986年   684篇
  1985年   718篇
  1984年   713篇
  1983年   598篇
  1982年   498篇
  1981年   478篇
  1980年   430篇
  1979年   574篇
  1978年   482篇
  1977年   522篇
  1976年   446篇
  1975年   462篇
  1974年   468篇
  1973年   430篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Laboratory Scale Activated Sludge Unit   总被引:1,自引:0,他引:1       下载免费PDF全文
  相似文献   
992.
993.
994.
A study was carried out to determine whether the double diffusion gel test when applied to the serum of patients with clear-cut penicillin reactions of various types, might be useful for demonstrating the presence of precipitating antibody. Results did not demonstrate the antibody.The difference in results with this test obtained by various workers was not explained by the observations in this study.Other approaches to determination of the mechanism of the penicillin reaction are discussed, and it is noted that the hemagglutination test, newly applied to the penicillin reaction problem, may be useful after further investigation.  相似文献   
995.
996.
Summary The formation of adipocere is a process occurring under virtually anaerobic conditions in which human fat is converted into a complex of saturated fatty acids by a great variety of bacterial species occurring in and on the decomposing body.  相似文献   
997.
SOME FEATURES OF A REMARKABLE ORGANELLE IN BACILLUS SUBTILIS   总被引:22,自引:7,他引:15       下载免费PDF全文
In thin sections of Bacillus subtilis certain organelles are observed situated either in the nuclear area from where they can extend into the cytoplasm, or in contact with the cell wall. Inside the nuclear area, the organelle is sometimes composed of concentric layers each seen to consist of two dense borders with a lighter interspace. In other instances, inside as well as outside the nuclear area, the organelles appear as clusters of delicately delimited vesicles. A typical site of occurrence is on the inner rim of the centripetally developing transverse septa, where it appears as a so called peripheral body (2). The micrographs strongly suggest that when the organelles are attached to the walls they have a function in cell wall formation.  相似文献   
998.
999.
Summary Some physiological and biochemical properties of several strains ofAcetobacter peroxydans have been studied. Their morphology, the aspects of growth on beer-gelatine slants and the colony type are described. The cells are catalase negative and acid resistant. The temperature optimum is 20–25°C. They grow readily on ethanol and on lactate, or on yeast extract alone, but not on carbohydrates and derivatives. They do not consume or oxidize glucose or gluconate. They are overoxidizers. None of these strains was able to grow as hydrogen bacteria. Resting cells oxidize lactate, pyruvate, ethanol, acetate, some Krebs cycle intermediates and several alcohols. Cell-free extracts oxidize glucose-6-phosphate, 6-phosphogluconate and ribose-5-phosphate in suitable conditions. These results favour the taxonomic position of this species as a member of the genusAcetobacter. The results are discussed.  相似文献   
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