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萜类化合物具有可观的经济价值,但是目前的生产过程复杂、产量低。酿酒酵母甲羟戊酸途径为萜类化合物的合成提供直接前体,因此酿酒酵母细胞具有合成异源萜类化合物的天然优势。对酿酒酵母甲羟戊酸途径的清晰认识是对其进行有效利用的基础,本文从代谢途径、关键酶的特点和全局调控机制3个方面对该途径进行了介绍。从代谢途径的构建和优化、模块与底盘细胞的适配、模块构建及组装方式的角度概述了酿酒酵母细胞异源合成单萜、倍半烯萜、二萜、三萜类化合物的研究进展。指出实现酿酒酵母高效合成萜类化合物所需要解决的基础问题是对酿酒酵母甲羟戊酸途径进行更为全面了解和对萜类化合物的天然代谢途径进行明确解析;另外,合成生物学的进一步发展也将为此提供应用基础。 相似文献
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1胶原纤维巴西Novaprom胶原纤维是以精选的牛皮内剖层(真皮)组织提取的,它不同于明胶或明胶的衍生物。它的生产是在严格控制的时间和温度范围内进行的,从而确保其主要成分──胶原蛋白的活性不变,并以天然纤维的形式存在。它在肉制品中的结构呈纤维状而不是一般的胶冻,因而这种结构是非常稳定的,是不可逆的。它是很好的功能性动物纤维蛋白,在肉制品及鱼糜制品等相关的食品中得到广泛的应用。2胶原纤维的性能及相关指标(1)蛋白质含量:胶原纤维中的动物蛋白质(M×6.25)高达98%,含有人体必需的氨基酸。(2)吸水、持水性:胶原纤维结构良好,呈矩… 相似文献
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玻璃纤维池窑拉丝生产线配合料的制备中,原料是形成优质玻璃液的基础,因此可以说配合料的稳定性、均匀性和准确性对玻璃纤维的质量起着决定的作用.生产实践证明:组分和粒度均匀的配合料,不但能强化玻璃液的熔化和澄清过程,而且还能减少或消除影响玻璃质量的各种弊病.所以认真拟定玻璃纤维原料的成分和选择玻璃纤维的种类和化学性质:严格控制进厂原料化学成分、粒度和水份;做好原料的分堆、存放、加工、称量、混合、输送是优质配合料制备不可缺少的手段,这也是做好玻璃纤维池窑配合料的基本任务. 相似文献
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1前言 随着池窑生产的发展,原有的浸润剂在快速浸润性和快速浸透性方面无法得到满足.意大利DSM公司聚酯乳液是公认的喷射纱浸润剂最好的成膜剂.本项目的目的是研制出能工业化生产的与DSM公司产品质量相当的聚酯乳液,替代进口,节约外汇,满足我国池窑发展需要,争创良好的经济社会效益. 相似文献
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通过长期跟踪涤纶短纤维生产过程控制及产品质量指标,对纺丝成形过程中产生的疵点及染色疵点形态进行了考查,分析了环吹筒组装使用、组件组装及压力控制等主要工艺操作条件对疵点产生的影响,总结了降低针织专用涤纶短纤维产品疵点含量的纺丝工艺及操作改进措施。 相似文献
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针对聚丙烯(PP)塑料梳的主要成型缺陷,分析了缺陷产生的原因,然后根据现有条件主要通过调整PP塑料梳的注射成型工艺参数消除了缺陷,为解决类似制品的成型缺陷提供一定的借鉴. 相似文献
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SSAW焊管超声检测试验研究 总被引:1,自引:0,他引:1
分析了脉冲反射法和TOFD法的检测原理,对缺陷进行了定位、定量的方法研究。然后制作了模拟SSAW焊管缺陷试块,用两种方法对这些缺陷进行深度和长度测量,对检测结果进行分析得知,对于坡口未熔合等方向性缺陷,TOFD检测精度远大于常规超声波检测精度。最后,用手动检测模拟SSAW自动检测,发现超声检测存在漏检现象,对焊缝中部的漏检缺陷可以采用TOFD法进行补充检测。TOFD法定量精度高,但不适合测定表面缺陷,两种方法结合对SSAW焊管进行缺陷检测,则获得了理想的检测效果。 相似文献
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Incidence of defects in MoSi2 rods prepared by continuous extrusion is dependent on the viscosity of binder. Generally, low viscosity results in surface defects while high viscosity is responsible for inner defects. Cross-section observations indicated that the typical inner defects in sintered MoSi2 rods were large fissure cavity, multiple small holes and single small cavity, of which the characteristic ultrasonic reflection patterns have been experimentally established. Formation of the inner defects is attributed to the inhomogeneous feedstock moving behavior in die, which is aggravated with increasing viscosity of binder. Defect free MoSi2 rods were prepared successfully via continuous extrusion by carefully controlling the viscosity of binder. 相似文献
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In this study, three different ultrasonic nondestructive methods (NDT) used to characterize porosity and identify defects in ceramic materials were employed as alternative approaches to conventional systems. A contact ultrasound technique, based on the A-scan, and measurements of the material frequency response were found to be useful for the characterization of porosity in porcelain tiles. Ceramic specimens with two types of simulated defects (a piece of paper and aluminum foil) were prepared and studied. The defects were readily identified in the ultrasonic A-scan and the location depth was measured. The technique, based on air-coupled ultrasound, was shown to be applicable for non-contact detection and imaging of defects in ceramic tiles. 相似文献
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GAO Jianying JIANG Wan 《中国耐火材料》2007,16(4):3-7
Incidence of defects in MoSi2 rods prepared by con- tinuous extrusion is dependent on the viscosity of binder. Generally, low viscosity results in surface defects while high viscosity is responsible for inner defects. Cross-section observations indicated that the typical inner defects in sintered MoSi2 rods were large fissure cavity, multiple small holes and single small cavity, of which the characteristic ultrasonic reflection patterns have been experimentally established. Formation of the inner defects is attributed to the inhomogeneous feedstock moving behav- ior in die, which is aggravated with increasing viscosity of binder. Defect free MoSi2 rods were prepared successfully via con. tinuous extrusion by carefully controlling the viscosity of binder. 相似文献
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对35 MN旋转料室电极挤压机由于初始安装等方面存在不足而导致运行中的部分缺陷进行了简要分析,并对影响压机稳定运行的这些缺陷的改进和修复办法进行了阐述. 相似文献