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51.
代华云 《钢铁钒钛》2002,23(2):51-54
阐述了车轴坯皮下夹杂的分布,组成,形态及形成原因,据此采取了切实可行的改进措施,改善了车轴坯的皮下夹杂,稳定了车轴坯质量,使车轴坯磁探废品率控制在2%以下。  相似文献   
52.
The case studies focus on two types of enzyme applications for pharmaceutical development. Demethylmacrocin O-methyltransferase, macrocin O-methyltransferase (both putatively rate-limiting) and tylosin reductase were purified from Streptomyces fradiae, characterized and the genes manipulated for increasing tylosin biosynthesis in S. fradiae. The rate-limiting enzyme, deacetoxycephalosporin C (DAOC) synthase/hydroxylase (expandase/ hydroxylase), was purified from Cephalosporium acremonium, its gene over-expressed, and cephalosporin C biosynthesis improved in C. acremonium. Also, heterologous expression of penicillin N epimerase and DAOC synthase (expandase) genes of Streptomyces clavuligerus in Penicillium chrysogenum permitted DAOC production in the fungal strain. Second, serine hydroxymethyltransferase of Escherichia coli and phthalyl amidase of Xanthobacter agilis were employed in chemo-enzymatic synthesis of carbacephem. Similarly, echinocandin B deacylase of Actinoplanes utahensis was used in the second-type synthesis of the ECB antifungal agent.  相似文献   
53.
54.
热轧带肋钢筋22MnSiV的研制   总被引:1,自引:0,他引:1  
系统的研究了热轧带肋钢筋22MnSiV各项性能,其各项性能不仅达到GB1449-1998中HRB400的要求,还有其特性,脆性转变温度低于-40℃,抗形变时效,高应变低周疲劳性能好,因此,特别适用于地震区,寒冷地区,也适用于钢筋混凝土结构。  相似文献   
55.
56.
炉顶红外摄像监控系统在攀钢高炉上的应用   总被引:5,自引:0,他引:5  
通过在3#、4#高炉安装炉顶红外摄像监控系统,获得了对高炉操作具有指导意义的直观影像,便于监测炉内科面状况和气流分布,指导高炉的上、下部调剂及高炉特殊炉况的判断处理。  相似文献   
57.
L. N. Lai    A. A. Karim    M. H. Norziah    C. C. Seow 《Journal of food science》2004,69(4):FCT287-FCT29
ABSTRACT: Using differential scanning calorimetry and pulsed nuclear magnetic resonance (NMR), it was found that the presence of Na2CO3 and NaOH retarded retrogradation of aged starch (wheat, corn, waxy corn, rice, and waxy rice) gels during storage at 4°C. At the same level of addition (based on a fixed starch/water ratio), the effect of NaOH was observed to be more pronounced than that of Na2CO3. Kinetic studies using pulsed NMR showed a progressive reduction in rate of starch retrogradation with increasing concentration of alkali (up to a level of 1 g/100 starch).  相似文献   
58.
Syntaxin 1, synaptobrevins or vesicle-associated membrane proteins, and the synaptosome-associated protein of 25 kDa (SNAP-25) are key molecules involved in the docking and fusion of synaptic vesicles with the presynaptic membrane. We report here the molecular, cell biological, and biochemical characterization of a 32-kDa protein homologous to both SNAP-25 (20% amino acid sequence identity) and the recently identified SNAP-23 (19% amino acid sequence identity). Northern blot analysis shows that the mRNA for this protein is widely expressed. Polyclonal antibodies against this protein detect a 32-kDa protein present in both cytosol and membrane fractions. The membrane-bound form of this protein is revealed to be primarily localized to the Golgi apparatus by indirect immunofluorescence microscopy, a finding that is further established by electron microscopy immunogold labeling showing that this protein is present in tubular-vesicular structures of the Golgi apparatus. Biochemical characterizations establish that this protein behaves like a SNAP receptor and is thus named Golgi SNARE of 32 kDa (GS32). GS32 in the Golgi extract is preferentially retained by the immobilized GST-syntaxin 6 fusion protein. The coimmunoprecipitation of syntaxin 6 but not syntaxin 5 or GS28 from the Golgi extract by antibodies against GS32 further sustains the preferential interaction of GS32 with Golgi syntaxin 6.  相似文献   
59.
Double mutant cycles provide a method for analyzing the effects of a mutation at a defined position in the protein structure on the properties of an amino acid at a second site. This approach was used to map potential interactions between aspartates 69, 97, and 103 in the m2 muscarinic acetylcholine receptor transmembrane helices 2 and 3. Receptors containing single and double aspartate to asparagine mutants were expressed in Chinese hamster ovary cells and their effects on ligand binding, signal transduction, and thermal stability determined. Analysis of the double mutant cycles showed that the mutations had approximately additive effects on ligand binding, signal transduction, and thermal stability. Ligand binding and thermal inactivation results support the conclusion that aspartate-103 is the ligand amine counterion. Effector coupling properties of the mutant receptors showed that aspartate-103 was also required for signal transduction activity. The mutation of aspartate-69 to asparagine completely eliminated signal transduction by the agonists acetylcholine, carbachol, and pilocarpine but not oxotremorine M, which caused reduced but significant inhibition of adenylyl cyclase and stimulation of phospholipase C. In contrast, adenylyl cyclase stimulation by the asparagine-69 mutant was elicited only by acetylcholine and carbachol but not by oxotremorine M. The variation in agonist-dependent effector coupling properties provides evidence that the asparagine-69 mutant can exist in activated receptor states that are different from the wild-type m2 muscarinic receptor.  相似文献   
60.
现代转炉炼钢技术及对攀钢炼钢发展的建议   总被引:2,自引:1,他引:1  
回顾了转炉炼钢技术的发展历程及中个时期的主要技术进步,介绍了当代转炉炼钢的重要技术,结合具体实际情况,提出了攀钢炼钢技术发展的建议。  相似文献   
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