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   1392244篇
  免费   129748篇
  国内免费   1456篇
  2021年   17964篇
  2019年   16204篇
  2018年   17753篇
  2017年   16330篇
  2016年   28181篇
  2015年   42712篇
  2014年   50806篇
  2013年   77080篇
  2012年   39682篇
  2011年   28479篇
  2010年   44133篇
  2009年   45410篇
  2008年   26901篇
  2007年   24941篇
  2006年   29639篇
  2005年   30665篇
  2004年   29929篇
  2003年   27416篇
  2002年   25297篇
  2001年   38077篇
  2000年   35410篇
  1999年   34216篇
  1998年   25997篇
  1997年   25840篇
  1996年   25298篇
  1995年   23380篇
  1994年   23220篇
  1993年   22367篇
  1992年   28952篇
  1991年   27081篇
  1990年   25682篇
  1989年   26433篇
  1988年   24117篇
  1987年   22920篇
  1986年   21652篇
  1985年   23311篇
  1984年   23155篇
  1983年   20475篇
  1982年   20876篇
  1981年   20067篇
  1980年   18717篇
  1979年   19263篇
  1978年   17917篇
  1977年   17224篇
  1976年   16430篇
  1975年   15775篇
  1974年   16224篇
  1973年   16541篇
  1972年   13895篇
  1971年   12871篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
Y. Avi-Dor  R. Rott  R. Schnaiderman 《BBA》1979,545(1):15-23
The interrelation was studied between the phototransient absorbing maximally at 412 nm (M412) and light-induced proton release under steady-state conditions in aqueous suspensions of ‘purple membrane’ derived from Halobacterium halobium. The decay of M412 was slowed down by the simultaneous application of the ionophoric antibiotics valinomycin and beauvericin. The former had only slight activity alone and the latter was effective only in conjunction with valinomycin. The steady-state concentration of M412 which was formed on illumination was a direct function of the concentration of valinomycin. Maximum stabilization of M412 was obtained when the valinomycin was approximately equimolar with the bacteriorhodopsin. Addition of salts to the medium increased the number of protons released per molecule of M412 without affecting the level of M412 which was produced by continuous illumination. The effectiveness of the salts in this respect depended on the nature of the cation. Ca2+ and their antagonists La3+ and ruthenium red were found to have especially high affinity for the system. The extent of light-induced acidification could not be enhanced by increasing the pH of the medium from 6.5 to 7.8. The possible mechanism of action of the ionophores and of the cations on the photocycle and on the proton cycle is discussed.  相似文献   
992.
In order to evaluate the effectiveness and selectivity of various reagents in the solubilization of bacterial membranes, membranes of Micrococcus lysodeikticus were treated with detergents and chaotropic agents. The composition of the extracts so obtained was analyzed by rocket and two-dimensional immunoelectrophoretic techniques. Recovery of succinate-, malate-, and reduced nicotinamide adenine dinucleotide- (NADH) dehydrogenases, ATPase, succinylated lipomannan and cytochromes in the extracts was measured. Treatment with a variety of non-denaturing detergents produced extracts that were generally qualitatively uniform although quantitative differences were observed. The degree of extraction of various components was correlated with the hydrophile-lipophile balance. Several chaotropic agents were also evaluated as reagents for membrane solubilization. These agents were less effective in extraction of bulk protein, but produced extracts enriched in some membrane components.  相似文献   
993.
994.
W. H. B. Aikins 《CMAJ》1923,13(2):131-132
  相似文献   
995.
J. A. Nutter 《CMAJ》1923,13(3):182-184
  相似文献   
996.
997.
998.
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