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   818810篇
  免费   82713篇
  国内免费   2663篇
  2018年   19276篇
  2017年   17912篇
  2016年   17291篇
  2015年   14495篇
  2014年   15826篇
  2013年   22005篇
  2012年   29283篇
  2011年   38888篇
  2010年   29679篇
  2009年   24827篇
  2008年   32292篇
  2007年   34792篇
  2006年   20547篇
  2005年   21056篇
  2004年   20374篇
  2003年   19595篇
  2002年   18665篇
  2001年   30647篇
  2000年   30796篇
  1999年   24664篇
  1998年   9263篇
  1997年   9640篇
  1996年   9325篇
  1995年   8402篇
  1994年   8422篇
  1993年   8295篇
  1992年   19917篇
  1991年   19227篇
  1990年   18635篇
  1989年   18490篇
  1988年   16733篇
  1987年   16164篇
  1986年   14789篇
  1985年   14766篇
  1984年   12521篇
  1983年   10746篇
  1982年   8482篇
  1981年   7755篇
  1980年   7215篇
  1979年   11827篇
  1978年   9179篇
  1977年   8622篇
  1976年   8027篇
  1975年   8649篇
  1974年   9394篇
  1973年   9215篇
  1972年   8825篇
  1971年   8234篇
  1970年   6634篇
  1969年   6495篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
Systematic analysis of the long-chain components of Eubacterium lentum   总被引:1,自引:0,他引:1  
The cellular long-chain component patterns of 33 strains of Eubacterium lentum were determined by gas chromatography. Two main types of long-chain component patterns were distinguished. The first (26 strains) was characterized by saturated branched-chain fatty acids (br14:0, br15:0, br16:0 and br17:0). The second (7 strains) did not contain branched-chain fatty acids and was characterized by saturated straight-chain fatty acids (11:0, 12:0, 14:0 and 16:0). Both types contained fatty aldehydes and their respective dimethyl acetals (14ald and 14dma, 16ald and 16dma). br16dma was only found in the first type. The G + C content of the DNA (Tm) of the 33 strains varied between 63.7 and 69.1 mol %. Canonical correlation analysis distinguished three subtypes within the first main type.  相似文献   
142.
143.
144.
145.
146.
Chromatophores from Rhodopseudomonas capsulata cells grown semiaerobically in the dark oxidize NADH, succinate, and dichlorophenolindophenol. In the presence of N3? these activities are inhibited, but light induces oxidation of dichlorophenolindophenol with O2 as a terminal electron acceptor. Cyanide also inhibits electron transport but much higher concentrations are required to inhibit the photooxidation than the dark oxidation. The photooxidation was studied in a mutant strain of Rhodopseudomonas capsulata (YIV) which cannot grow anaerobically in the light, but similarly to the wild type, grows in the presence of oxygen. Chromatophores from YIV mutant catalyze photophosphorylation and dark oxidation activities with the same properties as those of the wild type. However, the rate of photooxidation in the mutant is only one-third that of the wild type. Based on the differential inhibitor sensitivity and on the mutation it is suggested that the photooxidase is different from the two respiratory oxidases and that this photooxidation activity might be essential for growth of the cells under anaerobic conditions in the light.  相似文献   
147.
148.
An apparatus for polyacrylamide slab gel electrophoresis is decribed which combines all parts into one integral unit. It eliminates several steps in the process of sealing, pouring, and setting the gels. Construction is easy with modest workshop facilities and the design easily adapted to suit most requirements. The apparatus provides a high degree of versatility and is suitable for use with many slab gel electrophoretic techniques.  相似文献   
149.
150.
Conditions for breaking various medically important yeasts using glass beads, 30 ml Corex centrifuge tubes, and a Vortex mixer were determined. From 75–95% ofCandida hyphal cells and all species of yeasts exceptSporothrix schenckii were broken when 10 g of 0.45–0.50 mm glass beads, 50–300 mg of wet cells in 5 ml of buffer, and 90 s of vortexing were employed. Yeasts ofSporothrix schenckii broke more efficiently when 0.25–0.30 mm beads were used.  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