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   141篇
  免费   12篇
  2023年   1篇
  2022年   1篇
  2021年   4篇
  2019年   3篇
  2018年   7篇
  2017年   4篇
  2016年   6篇
  2015年   6篇
  2014年   10篇
  2013年   9篇
  2012年   15篇
  2011年   11篇
  2010年   6篇
  2009年   12篇
  2008年   12篇
  2007年   5篇
  2006年   4篇
  2005年   6篇
  2004年   9篇
  2003年   3篇
  2002年   2篇
  2001年   11篇
  1998年   1篇
  1997年   1篇
  1996年   1篇
  1995年   1篇
  1994年   1篇
  1990年   1篇
排序方式: 共有153条查询结果,搜索用时 15 毫秒
71.
Xyloglucan is the dominant hemicellulosic polysaccharide of the primary cell wall of dicotyledonous plants that plays a key role in plant development. It is well established that xyloglucan is assembled within Golgi stacks and transported in Golgi-derived vesicles to the cell wall. It is also known that the biosynthesis of xyloglucan requires the action of glycosyltransferases including α-1,6-xylosyltransferase, β-1,2-galactosyltransferase and α-1,2-fucosyltransferase activities responsible for the addition of xylose, galactose and fucose residues to the side chains. There is, however, a lack of knowledge on how these enzymes are distributed within subcompartments of Golgi stacks. We have undertaken a study aiming at mapping these glycosyltransferases within Golgi stacks using immunogold-electron microscopy. To this end, we generated transgenic lines of tobacco (Nicotiana tabacum) BY-2 suspension-cultured cells expressing either the α-1,6-xylosyltransferase, AtXT1, the β-1,2-galactosyltransferase, AtMUR3, or the α-1,2-fucosyltransferase AtFUT1 of Arabidopsis thaliana fused to green-fluorescent protein (GFP). Localization of the fusion proteins within the endomembrane system was assessed using confocal microscopy. Additionally, tobacco cells were high pressure-frozen/freeze-substituted and subjected to quantitative immunogold labelling using anti-GFP antibodies to determine the localization patterns of the enzymes within subtypes of Golgi cisternae. The data demonstrate that: (i) all fusion proteins, AtXT1-GFP, AtMUR3-GFP and AtFUT1-GFP are specifically targeted to the Golgi apparatus; and (ii) AtXT1-GFP is mainly located in the cis and medial cisternae, AtMUR3-GFP is predominantly associated with medial cisternae and AtFUT1-GFP mostly detected over trans cisternae suggesting that initiation of xyloglucan side chains occurs in early Golgi compartments in tobacco cells.  相似文献   
72.
73.
Hyperhomocysteinemia, characterized by an elevated plasma homocysteine concentration, leads to several clinical manifestations and particularly cardiovascular diseases. Experimental models of hyperhomocysteinemia revealed several tissue injuries including heart fibrosis and ventricular hypertrophy. In order to analyze the molecular mechanisms link to these morphological alterations, a mild hyperhomocysteinemia was induced in rats via a chronic methionine administration. Effects of methionine administration were examined by histological analysis with Sirius red staining, histomorphometric analysis, zymography, and immunoblotting. Hyperhomocysteinemia due to methionine administration produces an interstitial myocardial fibrosis and a ventricular cardiomyocyte hypertrophy, which were associated with increased expression of transforming growth factor-beta1 (TGFβ1), tissue inhibitors of metalloproteinase (TIMP) 2, and JNK activation. However, the matrix metalloproteinase 2 activity was decreased in the hearts of hyperhomocysteinemic rats. Moreover, the TIMP1 protein expression was decreased, and the TIMP1-MMP1 balance was shifted. Remodeling in cardiac tissue observed in rat model of mild hyperhomocysteinemia is associated with a dysregulation in extracellular matrix degradation which results, at least in part, from enhancement of TGFβ1 level.  相似文献   
74.
Understanding the factors that contribute to population genetic divergence across a species' range is a long‐standing goal in evolutionary biology and ecological genetics. We examined the relative importance of historical and ecological features in shaping the present‐day spatial patterns of genetic structure in two related plant species, Beta vulgaris subsp. maritima and Beta macrocarpa. Using nuclear and mitochondrial markers, we surveyed 93 populations from Brittany (France) to Morocco – the southern limit of their species' range distribution. Whereas B. macrocarpa showed a genotypic structure and a high level of genetic differentiation indicative of selfing, the population genetic structure of B. vulgaris subsp. maritima was consistent with an outcrossing mating system. We further showed (1) a strong geographic clustering in coastal B. vulgaris subsp. maritima populations that highlighted the influence of marine currents in shaping different lineages and (2) a peculiar genetic structure of inland B. vulgaris subsp. maritima populations that could indicate the admixture of distinct evolutionary lineages and recent expansions associated with anthropogenic disturbances. Spatial patterns of nuclear diversity and differentiation also supported a stepwise recolonization of Europe from Atlantic‐Mediterranean refugia after the last glacial period, with leading‐edge expansions. However, cytoplasmic diversity was not impacted by postglacial recolonization: stochastic long‐distance seed dispersal mediated by major oceanic currents may mitigate the common patterns of reduced cytoplasmic diversity observed for edge populations. Overall, the patterns we documented here challenge the general view of reduced genetic diversity at the edge of a species' range distribution and provide clues for understanding how life‐history and major geographic features interact to shape the distribution of genetic diversity.  相似文献   
75.
Septoria tritici blotch caused by Mycosphaerella graminicola (anamorph: Septoria tritici) is nowadays one of the most frequently occurring diseases on both bread and durum wheat crops. Two hundred and thirty isolates of the fungus were sampled from six distinct wheat-producing regions of Morocco in order to investigate the resistance of M. graminicola to strobilurins in this country, where this fungicide class is increasingly used in wheat-pest management. A subset of 134 isolates was first collected in 2008 from Meknes-Tafilalet, Tadla-Azilal, Gharb and Chaouia. Furthermore, 96 additional isolates were sampled in 2010 from the fourth regions investigated in 2008 plus Fes-Boulmane and Doukkala-Abda. Sensitivity or resistance within the isolates were determined by screening the G143A cytochrome b substitution conferring resistance. We used a mismatch amplification mutation assay allowing the amplification of either G143 (sensitive) or A143 (resistant) allele. All the 2008 isolates were found to be sensitive since they carry the wild-type allele G143. However, 9 (9%) out of the 2010 isolates were found to contain the resistant allele A143 and therefore to be resistant. Four of them were from Gharb and five from Fes-Boulmane. This study highlighted for the first time the occurrence of strobilurin-resistant isolates of M. graminicola in Morocco. Further genetic investigations should determine if the resistant isolates emerged independently in Morocco or traveled by wind-migration from Europe.  相似文献   
76.
77.
78.
Therapeutic antibodies are often engineered or selected to have high on-target binding affinities that can be challenging to determine precisely by most biophysical methods. Here, we explore the dynamic range of the kinetic exclusion assay (KinExA) by exploiting the interactions of an anti-DKK antibody with a panel of DKK antigens as a model system. By tailoring the KinExA to each studied antigen, we obtained apparent equilibrium dissociation constants (K(D) values) spanning six orders of magnitude, from approximately 100 fM to 100 nM. Using a previously calibrated antibody concentration and working in a suitable concentration range, we show that a single experiment can yield accurate and precise values for both the apparent K(D) and the apparent active concentration of the antigen, thereby increasing the information content of an assay and decreasing sample consumption. Orthogonal measurements obtained on Biacore and Octet label-free biosensor platforms further validated our KinExA-derived affinity and active concentration determinations. We obtained excellent agreement in the apparent affinities obtained across platforms and within the KinExA method irrespective of the assay orientation employed or the purity of the recombinant or native antigens.  相似文献   
79.
80.
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