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排序方式: 共有194条查询结果,搜索用时 15 毫秒
91.
92.
Two large DNA fragments overlapping the chicken ovalbumin gene have been isolated by molecular cloning. Analysis of these fragments provided a map of a 46,000-base pair region of the chicken genome. This region contains the complete ovalbumin gene (including its mRNA leader-coding sequence) and at least two other genes of unknown function. All three genes are orientated in the same direction and their expression in chicken oviduct is under hormonal control. The three genes share some sequence homologies, suggesting that duplications have occurred in the ovalbumin gene region in the course of evolution.  相似文献   
93.
Alcohol dehydrogenase 3 (ADH3) has been assigned a role in nitric oxide homeostasis due to its function as an S-nitrosoglutathione reductase. As altered S-nitrosoglutathione levels are often associated with disease, compounds that modulate ADH3 activity might be of therapeutic interest. We performed a virtual screening with molecular dockings of more than 40,000 compounds into the active site of human ADH3. A novel knowledge-based scoring method was used to rank compounds, and several compounds that were not known to interact with ADH3 were tested in vitro. Two of these showed substrate activity (9-decen-1-ol and dodecyltetraglycol), where calculated binding scoring energies correlated well with the logarithm of the k cat/K m values for the substrates. Two compounds showed inhibition capacity (deoxycholic acid and doxorubicin), and with these data three different lines for specific inhibitors for ADH3 are suggested: fatty acids, glutathione analogs, and cholic acids.  相似文献   
94.
在鼓泡反应装置上进行了尿素、碳酸氢铵/三乙醇胺溶液同时脱硫脱硝的试验研究,比较尿素和碳酸氢铵的脱硫脱硝性能,试验分别对液位、吸收剂组成以及SO2体积分数等参数对脱硝效率的影响规律进行了研究.结果表明:液位、吸收液中尿素/碳酸氢铵的比例及SO2入口浓度对NOx的脱除效率均有重要的影响,液位在459 mm时2种吸收液的脱硝...  相似文献   
95.
设计了一种具有自动功率控制功能的激光驱动器电路.为了获得良好的性能,该驱动器采用级联差分放大器和源极跟随器分别进行信号放大和级间阻抗匹配.该电路的实现采用了0.35 μm标准CMOS工艺.对该电路进行了测试,测试结果表明,在2.5和5 Gbit/s速率下,电路输出信号眼图清晰.在5 V电源电压、2.5 Gbit/s数据速率下,该驱动器可提供0~68 mA范围内的调制电流,满足长距离光纤通信系统的要求.电路典型功耗480 mW,芯片面积为0.57 mm2.  相似文献   
96.
具有催化活性TiO2薄膜的制备及表征   总被引:3,自引:0,他引:3  
采用溶胶法制备TiO2溶胶,用浸渍-提拉方式在普通玻璃表面制成锐钛矿相TiO2薄膜。实验结果表明:最佳镀膜次数为三次;掺杂Mo离子对于提高TiO2膜的光催化活性有明显的促进作用。用电镜分析(SEM)及X射线衍射法(XRD)确定了晶型及晶粒的大小;用光电子能谱(XPS)测定了其微观成分及其含量。  相似文献   
97.
Subendothelial retention of atherogenic lipoproteins in early atherosclerosis   总被引:27,自引:0,他引:27  
Complications of atherosclerosis are the most common cause of death in Western societies. Among the many risk factors identified by epidemiological studies, only elevated levels of lipoproteins containing apolipoprotein (apo) B can drive the development of atherosclerosis in humans and experimental animals even in the absence of other risk factors. However, the mechanisms that lead to atherosclerosis are still poorly understood. We tested the hypothesis that the subendothelial retention of atherogenic apoB-containing lipoproteins is the initiating event in atherogenesis. The extracellular matrix of the subendothelium, particularly proteoglycans, is thought to play a major role in the retention of atherogenic lipoproteins. The interaction between atherogenic lipoproteins and proteoglycans involves an ionic interaction between basic amino acids in apoB100 and negatively charged sulphate groups on the proteoglycans. Here we present direct experimental evidence that the atherogenicity of apoB-containing low-density lipoproteins (LDL) is linked to their affinity for artery wall proteoglycans. Mice expressing proteoglycan-binding-defective LDL developed significantly less atherosclerosis than mice expressing wild-type control LDL. We conclude that subendothelial retention of apoB100-containing lipoprotein is an early step in atherogenesis.  相似文献   
98.
The ultrafast timescale of electron transfer processes is crucial to their role in many biological systems and technological devices. In dye-sensitized solar cells, the electron transfer from photo-excited dye molecules to nanostructured semiconductor substrates needs to be sufficiently fast to compete effectively against loss processes and thus achieve high solar energy conversion efficiencies. Time-resolved laser techniques indicate an upper limit of 20 to 100 femtoseconds for the time needed to inject an electron from a dye into a semiconductor, which corresponds to the timescale on which competing processes such as charge redistribution and intramolecular thermalization of excited states occur. Here we use resonant photoemission spectroscopy, which has previously been used to monitor electron transfer in simple systems with an order-of-magnitude improvement in time resolution, to show that electron transfer from an aromatic adsorbate to a TiO(2) semiconductor surface can occur in less than 3 fs. These results directly confirm that electronic coupling of the aromatic molecule to its substrate is sufficiently strong to suppress competing processes.  相似文献   
99.
全面推进会计素质教育应加强会计职业道德教育和心理素质教育,提高会计从业人员的实践技能和综合能力,包括创新能力、终生学习能力,培养适应社会需要的高素质会计人才。  相似文献   
100.
纳米涂料研究概况   总被引:10,自引:0,他引:10  
概述了纳米材料的表面效应、小尺寸效应,量子隧道效应、量子效应等四大物理特性以及国内外纳米涂料的研究概况。  相似文献   
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