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111.
RB Calder RS Williams G Ramaswamy CO Rock E Campbell SE Unkles JR Kinghorn S Jackowski 《Canadian Metallurgical Quarterly》1999,274(4):2014-2020
Pantothenate kinase (PanK) is the key regulatory enzyme in the CoA biosynthetic pathway. The PanK gene from Escherichia coli (coaA) has been previously cloned and the enzyme biochemically characterized; highly related genes exist in other prokaryotes. We isolated a PanK cDNA clone from the eukaryotic fungus Aspergillus nidulans by functional complementation of a temperature-sensitive E. coli PanK mutant. The cDNA clone allowed the isolation of the genomic clone and the characterization of the A. nidulans gene designated panK. The panK gene is located on chromosome 3 (linkage group III), is interrupted by three small introns, and is expressed constitutively. The amino acid sequence of A. nidulans PanK (aPanK) predicted a subunit size of 46.9 kDa and bore little resemblance to its bacterial counterpart, whereas a highly related protein was detected in the genome of Saccharomyces cerevisiae. In contrast to E. coli PanK (bPanK), which is regulated by CoA and to a lesser extent by its thioesters, aPanK activity was selectively and potently inhibited by acetyl-CoA. Acetyl-CoA inhibition of aPanK was competitive with respect to ATP. Thus, the eukaryotic PanK has a distinct primary structure and unique regulatory properties that clearly distinguish it from its prokaryotic counterpart. 相似文献
112.
本文介绍了通型金属封闭开关设备的上总体水平,目前产品的结构与特点,国内产品的自行才引进以及今后产品的发展前景。 相似文献
113.
采用80C196单片机为控制核心,解决了窄间隙埋弧焊机的微机控制问题。所研制的控制系统由主机和智能操作盒组成,具有焊接参数预置、焊接参数显示,焊接参数打印等功能,在焊接过程中,对电弧电压主、焊接电流、接速度实现闭环控制,系统抗干扰能力强,性能可靠,功能齐全。 相似文献
114.
The effect of the composition of an epoxy blend based on a cycloaliphatic (CAE) and diglycidyl ether of bisphenol A (DGEBA) epoxides containing N‐benzylpyrazinium hexafluoroantimonate (BPH) as a thermal or UV latent initiator was investigated in the context of their thermal stability and mechanical properties. The compositions of a CAE–DGEBA blend were varied within 100:0, 80:20, 60:40, 20:80, and 0:100 by mole percent. Latent properties were measured by the degree of conversion. As a result, the thermal stability characterized from the initial decomposition temperature (IDT), the temperature of maximum weight loss (Tmax), the integral procedural decomposition temperature (IPDT), and the decomposition activation energies by TGA increased when the DGEBA composition was increased. According to the mechanical measurements, the flexural and tensile strengths increased with an increase of the DGEBA composition because of the compact hydrogen bond, long repeat unit, and bulky side groups of the DGEBA, while both the elastic and tensile moduli decreased. This latter result was attributed to the DGEBA intermolecular interaction, resulting in a toughened three‐dimensional network, which dispersed the internal stress. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 290–297, 2000 相似文献
115.
Zhang Haicun Liu Mingxia Liu Daoxin Guo Wenyong Zhi Jinhua Zhou Yafeng Xi’an Shaangu Power CO. LTD Xi’an China 《稀有金属材料与工程》2012,(Z1):78-80
0Cr17Ni4Cu4Nb powder was used to investigate the same-stuff laser repair(LR)technology on the semishrounded impeller.To improve the repaired effect,heat treatment was used after LR forming process.By means of optical microscopy,scan electron microscopy(SEM),micro-hardness tester and tensile tests,the microstructure of the coating was investigated and mechanical properties were measured.The experimental results show that cladding layer is well bonded to the substrate,the microstructure of the laser repaired zone(LRZ)is coarse martensite which will be refined after heat-treatment.The mechanical property experiments indicate that the micro-hardness and toughness would be increased after heat-treatment,the strength of LRZ after heat-treatment is 1050~1200 MPa,while the strength of normal laser repaired sample is 1000~1050 MPa.The refinement effect due to the heat treatment plays an important role in the improvement of the mechanical properties of samples.Overspeed examination and the real operation of the impeller after repairing also confirmed the reliability of this same-stuff and equal-strength laser cladding technology. 相似文献
116.
LED照明亮度控制新技术特征与应用 总被引:1,自引:0,他引:1
随着LED应用的不断增加,大功率LED的驱动控制日显重要。本文分析介绍了LED照明亮度控制的新技术特征与应用。 相似文献
117.
A mixed-integer programming (MIP) problem is formulated to address the flexible manufacturing system (FMS) batching, loading, and tool configuration problems concurrently. This model results in a great many variables, making its mathematical solution impractical. We introduce a four-pass approach using submodels of the original MIP problem. The approach assumes that the need for batching is primarily that of tool magazine capacity constraints, with balancing and maximizing flexibility as secondary objectives. 相似文献
118.
Kimberly D. Grimes Dr. Ying‐Jie Lu Dr. Yong‐Mei Zhang Dr. Vicki A. Luna Dr. Julian G. Hurdle Dr. Elizabeth I. Carson Dr. Jianjun Qi Dr. Sucheta Kudrimoti Dr. Charles O. Rock Dr. Richard E. Lee Dr. 《ChemMedChem》2008,3(12):1936-1945
PlsY is a recently discovered acyltransferase that executes an essential step in membrane phospholipid biosynthesis in Gram‐ positive bacteria. By using a bioisosteric replacement approach to generate substrate‐based inhibitors of PlsY as potential novel antibacterial agents, a series of stabilized acyl phosphate mimetics, including acyl phosphonates, acyl α,α‐difluoromethyl phosphonates, acyl phosphoramides, reverse amide phosphonates, acyl sulfamates, and acyl sulfamides were designed and synthesized. Several acyl phosphonates, phosphoramides, and sulfamates were identified as inhibitors of PlsY from Streptococcus pneumoniae and Bacillus anthracis. As anticipated, these inhibitors were competitive inhibitors with respect to the acyl phosphate substrate. Antimicrobial testing showed the inhibitors to have generally weak activity against Gram‐positive bacteria with the exception of some acyl phosphonates, reverse amide phosphonates, and acyl sulfamates, which had potent activity against multiple strains of B. anthracis. 相似文献
119.
120.
文章根据管道指数评价法所建立的风险评价模型,对上海市燃气中环线(大柏树至共和新路)段高压管(0.8MPa)进行了实际应用,提出了风险缓解措施。 相似文献