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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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为掌握佛山市顺德新城区降水中污染物的情况,2015年7月至8月,文章作者分别在雨天进行了降水取样,对降水中的pH、电导率、常见阴离子(F-、Cl~-、NO_3~(2-)、SO_4~(2-))及部分重金属(铅和镉)进行监测分析。选择有相关数据的珠江三角洲和石家庄、厦门等地的降水中污染物的情况进行对比。结果表明,顺德新城区降水中的p H和部分阴离子浓度优于珠江三角洲平均值,酸雨类型属于硫酸和硝酸混合型;其水体洁净程度略差于石家庄;铅和镉的浓度也高于厦门,甚至部分超出了人体能直接接触的安全范围。 相似文献
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Saturated very long chain fatty acids (fatty acids with greater than 22 carbon atoms; VLCFA) accumulate in peroxisomal disorders,
but there is little information on their turnover in patients. To determine the suitability of using stable isotope-labeled
VLCFA in patients with these disorders, the metabolism of 22-methyl[23,23,23-2H3]tricosanoic (iso-lignoceric) acid was studied in rats in vivo and in human skin fibroblasts in culture. The deuterated iso-VLCFA was degraded to the corresponding 16- and 18-carbon iso-fatty acids by rats in vivo and by normal human skin fibroblasts in culture, but there was little or no degradation in peroxisome-deficient (Zellweger’s
syndrome) fibroblasts, indicating that its oxidation was peroxisomal. Neither the 14-, 20-, and 22-carbon iso-fatty acids nor the corresponding odd-chain metabolites could be detected. In the rat, the organ containing most of the iso-lignoceric acid, and its breakdown products, was the liver, whereas negligible amounts were detected in the brain, suggesting
that little of the fatty acid crossed the blood-brain barrier. Our data indicate that VLCFA labeled with deuterium at the
ω-position of the carbon chain are suitable derivatives for the in vivo investigation of patients with defects in peroxisomal β-oxidation because they are metabolized by the same pathways as the
corresponding n-VLCFA. Moreover, as iso-VLCFA and their β-oxidation products are readily separated from the corresponding n-fatty acids by normal chromatographic procedures, the turnover of VLCFA can be more precisely measured.
A preliminary report of part of this work (Reference 18) was presented at the 5th International Symposium on the Synthesis
and Applications of Isotopes and Isotopically Labelled Compounds, Strasbourg, France, June 20–24, 1994. 相似文献
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H. Toda Y. Mochizuki T. Kawanishi H. Kawashima 《Nutrient Cycling in Agroecosystems》2002,63(2-3):167-173
In a coastal agricultural area in the central part of Japan (Shizuoka), we found decreasing nitrate concentration with depth in a shallow groundwater, where the depth to water table varied between 0.6 and 1.2 m below ground surface. High nitrate concentrations (5–29 mg N L–1) were often observed in the upper layer (0–2 m) of the groundwater, but the concentration decreased to less than 1 mg N L–1 in the deeper layer. Ammonium was scarcely detected, and the concentration of dissolved oxygen was usually low (< 1 mgO2 L–1) in the groundwater. Nitrate in the groundwater often had very heavy nitrogen stable isotope ratios (>20{}). There was a negative relationship between nitrogen stable isotope ratio of nitrate and its concentration. When nitrate was injected into the groundwater with acetylene and bromide (a conservative tracer), nitrate concentration decreased to 20% of the initial level within 5 days, accompanied by the increase in nitrite and nitrous oxide concentration and a little change in bromide concentration. These results indicate that microbial denitrification plays a potential role in the decrease of nitrate in shallow groundwater at the study site. 相似文献
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我国硝酸工业生产技术新进展 总被引:1,自引:0,他引:1
系统叙述了我国硝酸工业2000-2007年生产现状及主要技术成果,尤其指出了国产"四合一"机组的成功投运,使我国硝酸国产化装置取得较大的进步,表现在吨酸的铂耗、氨耗和能耗等方面接近国外引进装置水平,同时介绍了国外双加压法硝酸生产技术的进展.我国已成为硝酸生产大国,仍需以先进的技术改造和发展我国硝酸工业,确保我国硝酸工业健康有序地发展,加快从硝酸生产大国向强国迈进的步伐. 相似文献
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高效液相色谱法分析化妆品中微量成分的研究进展 总被引:1,自引:0,他引:1
综述了高效液相色谱法在化妆品中防腐剂、防晒剂中紫外线吸收剂以及性激素的检测等几个方面的应用;同时,介绍了分析所用的色谱柱、流动相、使用的检测手段以及样品的提取方法;最后针对目前存在的问题,提出了高效液相色谱用于化妆品中微量成分分析的研究方向和发展前景。 相似文献