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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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产业及装饰用聚酰胺纤维产品的应用状况与开发前景 总被引:2,自引:1,他引:2
聚酰胺纤维以其强度、耐磨性、弹性恢复率、韧性等优良性能在产业用纺织品和装饰用纺织品方面的应用日趋扩大,如在轮胎帘子布、汽车用纺织品、过滤材料、BCF地毯膨体纱、特种和军用纺织品上都开发了新产品,受到了市场的欢迎。面对化纤品种结构和市场需求的不断变化,聚酰胺纤维产品应着眼于其性能特点,发展优势产品,拓宽应用面,在化纤市场中占据一定的位置。 相似文献
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根据近年来乙烯裂解发展趋势,以炼厂液化气和LNG凝析液等轻烃资源为主要原料,通过实例对比分析催化裂解和蒸汽裂解制烯烃的技术以及经济性,并提出石油石化公司应根据区域丙烯和丁二烯市场需求以及企业自身的发展定位,因地制宜地选取合理的烯烃裂解工艺。 相似文献
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GFRP门窗的综合应用性及经济性 总被引:1,自引:0,他引:1
门窗用玻璃纤维增强塑料(GFRP)拉挤中空型材的问世,为建筑业提供了一种新型材料。用型制作的GFRP门窗,其综合应用性能高于用木,钢,铝和PVC制成的门窗,具有广阔的发展前景。 相似文献
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A new kind of dimensional analysis, which uses two kinds of scales, provides a powerful tool for analyzing heat and mass transfer correlations as has been demonstrated by Ruckenstein (1986) in the case of forced convection of Newtonian fluids. In this work, the approach based on micro- and macro-scales is extended to free convection of Newtonian fluids, as well as to forced and free convection of power-law fluids.
As the micro-participation and macro-participation dominate in laminar and turbulent flow respectively, bounds on the exponents of the Reynolds number Re and the Grashof number Gr can be established in the case of forced and free convection respectively. An upper bound is obtained for laminar flow and a lower bound for turbulent flow. Thus, for free convection in Newtonian fluids, it is demonstrated that the bounds on the exponent of Gr for laminar and turbulent flow are 0.25 and 0.375 respectively. 相似文献
As the micro-participation and macro-participation dominate in laminar and turbulent flow respectively, bounds on the exponents of the Reynolds number Re and the Grashof number Gr can be established in the case of forced and free convection respectively. An upper bound is obtained for laminar flow and a lower bound for turbulent flow. Thus, for free convection in Newtonian fluids, it is demonstrated that the bounds on the exponent of Gr for laminar and turbulent flow are 0.25 and 0.375 respectively. 相似文献
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锦纶及其制品阻燃性能的研究概述 总被引:6,自引:0,他引:6
在综述有关锦纶燃烧过程文献的基础上,着重对锦纶的阻燃剂和有关工艺进行了回顾和评论,并对阻燃锦纶的毒性和发烟性等问题进行了一定的阐述,从而提出国内今后研究阻燃锦纶的一些方向,以供同行参考。 相似文献
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A sheet of paper is modelled as a network of cellulose fibres, either cylindrical or band-shaped. The equations for creeping flow through such structures are solved, and The calculated permeabilities are compared with measured values. Flow through some paper structures such as pulp sheets and handsheets of unbeaten sulphate pulp is adequately described by the structural model involving band-shaped fibres when a fibre aspect ratio of 3.5 is used. For newsprint sheets the measured permeability is lower than that predicted by the models when physically realistic values of the aspect ratio are taken. A total of 19 different paper grades have been characterised by measurement of the total specific surface area and The fibre orientation ratio in addition to the measurements of effective diffusivity, permeability and porosity. Permeability and effective diffusivity correlate with each other and permeability correlates with fibre orientation, so that at constant porosity, permeability decreases with increasing fibre orientation. 相似文献
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A comparison made between spouted-bed and two-impinging-streams reactors proved the superiority of the-impinging-streams dryer The latter device exhibited, on the one hand, relatively small energy requirements for pumping the phases through the reactor and, on the other hand, improved drying characteristics Thus the two-imping-streams reactor is recommended as a useful device for drying operations 相似文献
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微滤,超滤过程中的膜污染与清洗 总被引:80,自引:6,他引:80
本文综述了在微滤和超滤过程中,膜污染的影响因素,防止膜污染的措施的清洗方法的选择,指出料液粒子或溶质尺寸,膜结构以及膜与溶质间的相互作用都和膜污染程度有关;通过膜孔径,膜材料,膜结构,组件结构,料液温度,流速和压力的控制可以减轻或控制污染。 相似文献