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排序方式: 共有346条查询结果,搜索用时 15 毫秒
81.
Eum WS Li MZ Sin GS Choi SY Park JB Lee JY Kwon HY 《Experimental & molecular medicine》2003,35(5):379-384
Dexamethasone converts pluripotent pancreatic AR42J cells into exocrine cells expressing digestive enzymes. In order to address molecular mechanism of this differentiation, we have investigated the role of mitogen-activated protein (MAP) kinase pathway and gene expressions of p21(waf1/cip1) and nuclear oncogenes (c-fos and c-myc) during AR42J cell differentiation. Dexamethasone markedly increased the intracellular and secreted amylase contents as well as its mRNA level. However, cell growth and DNA content were significantly decreased. With these phenotypic changes, AR42J cells induced transient mRNA expression of p21(waf1/cip1) gene, which reached maximal level by 6 h and then declined gradually toward basal state. In contrast to p21(waf1/cip1), c-fos gene expression was transiently inhibited by 6 h and then recovered to basal level by 24 h. Increased c-myc expression detected after 3 h, peaked by 12 h, and remained elevated during the rest of observation. Dexamethasone inhibited epidermal growth factor-induced phosphorylation of extracellular signal regulated kinase. Inhibition of MAP kinase pathway by PD98059 resulted in further elevation of the dexamethasone-induced amylase mRNA and p21(waf1/cip1) gene expression. These results suggest that p21(waf1/cip1) and nuclear oncogenes are involved in dexamethasone-induced differentiation and inhibition of MAP kinase pathway accelerates the conversion of undifferentiated AR42J cells into amylase-secreting exocrine cells. 相似文献
82.
Andrew G McDonald Sinéad Boyce Gerard P Moss Henry BF Dixon Keith F Tipton 《BMC biochemistry》2007,8(1):14
Background
We describe the database ExplorEnz, which is the primary repository for EC numbers and enzyme data that are being curated on behalf of the IUBMB. The enzyme nomenclature is incorporated into many other resources, including the ExPASy-ENZYME, BRENDA and KEGG bioinformatics databases. 相似文献83.
Cesare Oliva Marco Scavini Agusti Sin Yuri Dubitsky 《Journal of solid state chemistry》2004,177(11):4104-4111
EPR analysis is carried out with Ce1−xGdxO(4−x)/2 (x=0.1; 0.2) nanopowders aiming at obtaining information about their oxidation and reduction properties. The EPR spectrum of these systems is composed of a single feature. The first derivative peak-to-peak spectral intensity decreases at higher temperatures, but this trend deviates from that of Curie's law with the x=0.1 sample, at difference with the x=0.2 sample. This unexpected result is related to oxygen deficiency, due to gas-solid equilibrium, present in the former sample only. As a consequence, some Ce3+ ions would form providing it with conduction electrons propagating as small polarons in a percolative way. This would result in a thinner skin depth at higher temperatures, able to explain the deviation of the spectral intensity from its expected value. Indeed, this deviation from Curie's law is reduced or disappears at all after thermal treatment of the x=0.1 sample with O2. 相似文献
84.
Sze-Mun Lam Jin-Chung Sin Ahmad Zuhairi Abdullah Abdul Rahman Mohamed 《Chemical Papers》2013,67(10):1277-1284
Ag2O/ZnO heterostructure has been recently synthesized using a facile chemical-precipitation method. X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, and energy dispersive X-ray spectroscopy results confirmed the Ag2O nanoparticles loading on ZnO nanorods. The Ag2O addition increased the visible light absorption ability and a red shift for Ag2O/ZnO heterostructure appeared when compared to pure ZnO. Photoluminescence spectra showed lower emission yield on the Ag2O/ZnO heterostructure than on pure ZnO. Such a decrease in the emission yield represents the fraction of the excited state Ag2O sensitizer involved in the charge injection process. Under compact fluorescent lamp irradiation, the Ag2O/ZnO heterostructure demonstrated higher photocatalytic activity than pure ZnO in the degradation of resorcinol, which can be attributed to the high separation efficiency of the photogenerated electron-hole pairs based on the cooperative roles of Ag2O loading on ZnO nanarods. All these characteristics represent a significant contribution of the Ag2O/ZnO heterostructure to the practical applications in indoor environmental remediation. 相似文献
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Noor Abdulhussain Suhas H. Nawada Sinéad A. Currivan Peter J. Schoenmakers 《Journal of separation science》2022,45(8):1400-1410
In this work, devices for two-dimensional separations are considered. The device contains a flow distributor, a first-dimension channel, and 17 second-dimension outlets. In the design, all connections between the first-dimension channel, the flow distributor, and the second-dimension outlets were tapered, with a minimal diameter of 20 μm. The use of photo-masking is explored for the fabrication of monolithic frits in all tapered connections. Monolithic frits with optimized permeability and length were successfully fabricated in all 33 tapered channels through light-induced polymerization, photo-masking, and selective exposure. The efficacy of the monolithic frits was demonstrated by creating a packed bed of 15-μm particles, confined within the first-dimension channel. The outlet of the first-dimension channel was successfully connected to a mass spectrometer. Effective flow confinement was demonstrated with a reversed-phase separation of a mixture of five standard peptides. 相似文献
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