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   607082篇
  免费   66883篇
  国内免费   324篇
  2018年   5447篇
  2016年   7453篇
  2015年   9962篇
  2014年   11710篇
  2013年   16497篇
  2012年   18993篇
  2011年   19571篇
  2010年   13122篇
  2009年   12035篇
  2008年   17303篇
  2007年   18009篇
  2006年   16477篇
  2005年   16037篇
  2004年   15923篇
  2003年   15309篇
  2002年   14789篇
  2001年   28207篇
  2000年   28571篇
  1999年   22406篇
  1998年   7834篇
  1997年   8117篇
  1996年   7752篇
  1995年   7029篇
  1994年   7001篇
  1993年   6925篇
  1992年   17957篇
  1991年   17504篇
  1990年   17045篇
  1989年   16891篇
  1988年   15316篇
  1987年   14654篇
  1986年   13434篇
  1985年   13422篇
  1984年   11185篇
  1983年   9641篇
  1982年   7230篇
  1981年   6493篇
  1980年   6187篇
  1979年   10569篇
  1978年   8236篇
  1977年   7478篇
  1976年   6941篇
  1975年   7676篇
  1974年   8472篇
  1973年   8229篇
  1972年   7544篇
  1971年   6975篇
  1970年   5882篇
  1969年   5728篇
  1968年   5159篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
132.
133.
134.
The selective action of the antibiotics chloramphenicol and cycloheximide on the synthesis of ferredoxin in liquid cultures of Chlamydomonas reinhardii was studied. Highly specific antibodies raised against Chlamydomonas ferredoxin were used to determine the in vivo synthesis of apoferredoxin and conversion into native protein. The results indicate that 80S ribosomes are involved in the synthesis. Chlamydomonas cells growing in the absence of iron did not synthesize immunologically detectable amounts of ferredoxin. We suggest that this is based upon feed-back inhibition of apoferredoxin synthesis at the translational level.Abbreviations CAP chloramphenicol - CHI cycloheximide - IgG Immunoglobulin G - PBS 140.4 mM NaCl. 9 mM Na2HPO4, 1.3 mM NaH2PO4 (pH 74) - SDS sodium dodecvl sulphate - Fd Ferredoxin - apoFd Apoferredoxin - CM-Fd Scarboxymethylated Fd - TCA-Fd Fd treated with trichloroacetic acid  相似文献   
135.
136.
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   
137.
138.
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   
139.
140.
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