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   759篇
  免费   41篇
  800篇
  2023年   5篇
  2022年   8篇
  2021年   25篇
  2020年   17篇
  2019年   13篇
  2018年   16篇
  2017年   15篇
  2016年   19篇
  2015年   32篇
  2014年   34篇
  2013年   39篇
  2012年   50篇
  2011年   45篇
  2010年   28篇
  2009年   19篇
  2008年   38篇
  2007年   33篇
  2006年   36篇
  2005年   32篇
  2004年   28篇
  2003年   23篇
  2002年   22篇
  2001年   24篇
  2000年   28篇
  1999年   20篇
  1998年   5篇
  1997年   3篇
  1995年   6篇
  1993年   5篇
  1992年   11篇
  1991年   13篇
  1990年   8篇
  1989年   10篇
  1988年   9篇
  1987年   7篇
  1986年   6篇
  1985年   4篇
  1984年   4篇
  1983年   9篇
  1982年   3篇
  1981年   5篇
  1979年   4篇
  1978年   3篇
  1976年   3篇
  1974年   4篇
  1973年   3篇
  1972年   5篇
  1969年   5篇
  1968年   4篇
  1967年   2篇
排序方式: 共有800条查询结果,搜索用时 15 毫秒
771.
It is reported that an increase in aerobic bacteria, a lack of short-chain fatty acids (SCFAs), and immune disorders in the diverted colon are major causes of diversion colitis. However, the precise pathogenesis of this condition remains unclear. The aim of the present study was to examine the microbiota, intestinal SCFAs, and immunoglobulin A (IgA) in the diverted colon. Eight patients underwent operative procedures for colostomies. We assessed the diverted colon using endoscopy and obtained intestinal samples from the diverted colon and oral colon in these patients. We analyzed the microbiota and SCFAs of the intestinal samples. The bacterial communities were investigated using a 16S rRNA gene sequencing method. The microbiota demonstrated a change in the proportion of some species, especially Lactobacillus, which significantly decreased in the diverted colon at the genus level. We also showed that intestinal SCFA values were significantly decreased in the diverted colon. Furthermore, intestinal IgA levels were significantly increased in the diverted colon. This study was the first to show that intestinal SCFAs were significantly decreased and intestinal IgA was significantly increased in the diverted colon. Our data suggest that SCFAs affect the microbiota and may play an immunological role in diversion colitis.  相似文献   
772.
A synthesis of a new modified nucleoside isolated from tRNA2Gly of Bombyx mori was accomplished. This synthesis confirmed its structure and proved its absolute configuration to be 5-(S-carboxy(hydroxy)methyl)uridine.  相似文献   
773.
The nucleotide sequence of 5S rRNA from an extreme thermophile Thermusthermophilus HB8 has been re-examined and determined as [Formula: see text] The present study could resolve previously ambiguous residues and find two additional residues (G(8 3), C(9 7)), G at position 89 and two terminal heterogeneities which are exactly the same as reported with Thermusaquaticus 5S rRNA.Images  相似文献   
774.
Three kinds of low-molecular weight alginic acid fractions, Alg.A, B, and C, were prepared from a commercial alginic acid by acid hydrolysis using phosphoric acid. Alg.A was obtained as an insoluble fraction by the filtration of mixture. Alg.B was obtained as a precipitate by pouring the filtered solution into water. Alg.C was obtained as a precipitate by pouring the filtrate into methanol. Measurements with 13C NMR, GPC and WAXS were performed on the prepared fractions for characterization.

Alg.A was composed of rich M and G blocks, and had DPn and DPw/DPn values of 79 and 3.11, respectively. Alg.B was mainly composed of M block, and had DPn and DPw/DPn values of 38 and 2.57, respectively. Alg.C had a random structure including many alternating sequences, and had DPn and DPw/DPn values of 35 and 2.11, respectively. Alginic acid oligomers prepared in this study, Alg.B and C, were improved regarding in solubility in water and the viscosity of their aqueous solution.  相似文献   

775.
776.
777.
778.
  相似文献   
779.
Vancomycin-resistant Enterococcus faecalis (VRE) has become a significant threat in nosocomial settings. Bacteriophage (phage) therapy is frequently proposed as a potential alternative therapy for infections caused by this bacterium. To search for candidate therapeutic phages against Enterococcus faecalis infections, 30 Enterococcus faecalis phages were isolated from the environment. One of these, virulent phage phiEF24C, which has a broad host range, was selected for analysis. The plaque-forming ability of phiEF24C was virtually unaffected by differences in the clinical host strains. Furthermore, the phage had a shorter latent period and a larger burst size than ordinary tailed phages, indicating that phiEF24C has effective lytic activity against many Enterococcus faecalis strains, including VRE. Morphological and genomic analyses revealed that phiEF24C is a large myovirus (classified as family Myoviridae morphotype A1) with a linear double-stranded DNA genome of c. 143 kbp. Analyses of the N-terminal amino acid sequences of the virion proteins, together with the morphology and the genome size, speculated that phiEF24C is closely related to other myoviruses of Gram-positive bacteria that have been used experimentally or practically for therapy or prophylaxis. Considering these results, phiEF24C may be a potential candidate therapeutic phage against Enterococcus faecalis infections.  相似文献   
780.
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