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   245054篇
  免费   22500篇
  国内免费   257篇
  267811篇
  2018年   2636篇
  2017年   2580篇
  2016年   3430篇
  2015年   3663篇
  2014年   4577篇
  2013年   6558篇
  2012年   7208篇
  2011年   7908篇
  2010年   5382篇
  2009年   4790篇
  2008年   6876篇
  2007年   7085篇
  2006年   6724篇
  2005年   6417篇
  2004年   6320篇
  2003年   6159篇
  2002年   6017篇
  2001年   12008篇
  2000年   11965篇
  1999年   9145篇
  1998年   2669篇
  1997年   2748篇
  1996年   2692篇
  1995年   2476篇
  1994年   2424篇
  1993年   2320篇
  1992年   7178篇
  1991年   6987篇
  1990年   7060篇
  1989年   6843篇
  1988年   6360篇
  1987年   6012篇
  1986年   5358篇
  1985年   5665篇
  1984年   4465篇
  1983年   3863篇
  1982年   2672篇
  1981年   2500篇
  1980年   2313篇
  1979年   4137篇
  1978年   3147篇
  1977年   2887篇
  1976年   2828篇
  1975年   3268篇
  1974年   3498篇
  1973年   3525篇
  1972年   3062篇
  1971年   2843篇
  1970年   2530篇
  1969年   2299篇
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
941.
Using two-dimensional polyacrylamide gel electrophoresis, the GroEL homologue ofBacillus subtilis was shown to be induced upon infection with Ø105clz, a clear plaque mutant of the temperate bacteriophage Ø105. Western blotting of one dimensional polyacrylamide gels also showed the induction of the GroEL homologue when cells were infected with Ø105clz.  相似文献   
942.
943.
944.
Outer membrane proteins of Pseudomonas   总被引:26,自引:0,他引:26  
In this review, we describe the outer membrane proteins of Pseudomonas aeruginosa and related strains from the Pseudomonas fluorescens rRNA homology group of the Pseudomonadaceae, with emphasis on the physiological function and biochemical characteristics of these proteins. The use of opr (for outer membrane protein) is proposed as the genetic designation for the P. aeruginosa outer membrane proteins and letters are assigned, in conjunction with this designation, to known outer membrane proteins. Proteins whose primary functions involve pore formation, transport of specific substrates, cell structure determination and membrane stabilization are discussed. The conservation of selected proteins in the above Pseudomonas species is also examined.  相似文献   
945.
The results of complementation analysis of nitrosoguanidine-induced mutants of F-like drd-plasmid pAP18-1 (Tc, ColV) testified to the existence of at least 3 tra regions (tra1, tra2, tra3) and regulating locus fin V in the genome of this plasmid. By means of molecular cloning of tra2 region and locus fin V of plasmid pAP18-1drd were located in Sall-fragment f5 (3.9 MD).  相似文献   
946.
Ombuin (7,4′-dimethyl quercetin) (10 μg ml-1, for 12 wk), glycyrrhizin/quercetin (80 μg ml-1and 10 μg ml-1respectively, for 18 wk), ribavirin (10 μg ml-1, for 12 wk) and quercetin/ribavirin (10 μg ml-1each, for 9–12 wk) reduced the titre of apple stem grooving virus (ASGV) when applied in vitro to infected tissue cultures of Nicotiana occidentalis obliqua Wheeler, and/or Malus domestica. ASGV was not detectable in both plant species after the quercitin/ribavirin treatment when tested by ISEM, herbaceous host indexing, RT-PCR, and immunocapture RT-PCR. A sensitive immunocapture RT-PCR procedure for the detection of ASGV was developed for the screening of treated samples to assess antiviral activity.  相似文献   
947.
948.
The phytocenotic diversity of the Altai steppe piedmont is described. Plant communities were ordinated along the moisture gradient. The results were used to analyze the structure of vegetation of steppe hill massifs. Distribution of steppe vegetation over an ideal hill was simulated, and the main patterns of distribution were typified.  相似文献   
949.
Lipid synthesis in permeabilized cultured rat hepatocytes   总被引:1,自引:0,他引:1  
Hepatic lipid synthesis was verified and studied in lysolecithin-permeabilized cultured rat hepatocytes and compared to that of intact liver cells. Triacylglycerol synthesis in permeabilized cells incubated in the presence of glycerol 3-phosphate and long chain fatty acids approached that of intact hepatocytes. Similarly, phosphatidylcholine synthesis in permeable cells incubated in the presence of exogenous CDP-choline was similar to that of intact hepatocytes and at the expense of microsomal neutral lipid synthesis. Phosphatidic acid accumulation in lysolecithin-permeabilized liver cells was remarkably increased as compared to that of intact cells, and its synthesis was mostly accounted for by the activity of mitochondrial glycerol-3-phosphate acyltransferase. Mitochondrial-generated phosphatidate was found to migrate to the endoplasmic reticulum, thus establishing a novel lipid esterification pathway which begins in mitochondrial glycerol 3-phosphate acylation and results in microsomal triacylglycerol and phospholipid synthesis. The free access of permeabilized liver cells to substrates and modulators of lipid synthesis, while maintaining an overall synthetic pattern similar to that of intact hepatocytes, makes them a system of choice for studying hepatic lipid synthesis in general and the microsomal/mitochondrial distribution of fluxes in particular.  相似文献   
950.
N.C. Lee 《CMAJ》1990,142(11):1176-1177
  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