前体物质

新的研究成果表明多发性硬化症损害了身体自然修复神经鞘的机制：尽管出现了修复细胞的前体物质，但是还没有成熟到具有功能。

New research indicated that MS impairs the body 's natural mechanism for repairing myelin : Although precursors to the repair cells are present , they never mature enough to do their jobs .

初期合子内，核仁大量合成核糖体前体物质，胞质中多聚核糖体数目众多，细胞代谢活性较强；

At the early zygote stage , a large number of ribosomal precursors were produced by the nucleolus , and many polysomes appeared in the cytoplasm , which suggests a high level of metabolism .

多胺与乙烯具有共同的合成前体物质SAM。

SAM is a precursor not only of polyamines , the anti-senescence plant growth substances , but also of ethylene biosynthesis .

可通过控制两种前体物质的各种途径来降低烟草TSNA。

We can decrease TSNA by ways of reducing level of precursors .

凡影响前体物质的因素，都会影响烟草TSNA的形成、积累和含量。

All factors of effective precursors will affect their form and accumulation of TSNA .

烤烟烟叶中烟草特有亚硝胺（TSNA）及其前体物质积累规律的研究

The Studies on Rules of Accumulation of Tobacco-Specific Nitrosamines ( TSNA ) in Flue-Cured Tobacco Leaf

研究以鱿鱼皮酶水解液为基料结合其它前体物质进行Maillard反应，产生肉类香味料。

The synthesis of meat flavor aroma from enzymatic hydrolysate of squid skin and other precursors through Maillard reaction was studied in the experiment .

PDS基因沉默导致了叶片，花和果实组织中PDS基因mRNA水平的显著降低和前体物质八氢番茄红素的明显上升。

Silencing of PDS gene results in a dramatic reduction of the levels of PDS mRNA and the accumulation of phytoene in the leaves , flowers and fruits of PDS-silenced tomato plants .

Mg~（2+）作为许多酶的激活剂，可使酶活增强、代谢旺盛；Met通过促进次级代谢使产量提高，并很可能是前体物质；

Mg ~ ( 2 + ) was activator of many enzymes , Met could promote secondary metabolism and was probably a precursor of Nosiheptide , Ser promotes primary and secondary metabolism simultaneously , all these factors contributed to the increase of the productivity .

异柠檬酸脱氢酶（IsocitrateDehydrogenase，IDH）是三羧酸循环的关键性酶，为新陈代谢提供能量和生物合成前体物质。

Isocitrate dehydrogenase ( IDH ) is one of the key enzymes in the TCA cycle , which involves in providing energy and biosynthetic precursors for metabolism .

丙酮酸经过丙酮酸脱氢酶系（乙酰辅酶A羧化酶）催化生成乙酰CoA，乙酰CoA是合成脂肪酸的前体物质，最终进入脂肪酸合成代谢途径。

The pyruvate generate acetyl-CoA through the catalysis of pyruvate dehydrogenase , and acetyl-CoA is the precursor of fatty acid synthesis and ultimately into the fatty acid biosynthesis metabolism pathway .

南方红豆杉（TaxusChinensisvar.mairei）是提取紫杉醇及其前体物质的重要原料，由于针叶内此类物质含量低导致在生产过程中产生大量的废弃物。

Taxus chinensis var. mairei is a vital extracting material of taxol and its precursor substances . A lot of waste in the production process had been produced due to the low content of such substances in needles .

5-氨基乙酰丙酸（5-aminolevulinicacid，ALA）是生物合成卟啉、叶绿素、亚铁血红素和维生素B12等四吡咯化合物的共同前体物质，广泛存在于微生物、植物和动物细胞中。

5-Aminolevulinic acid ( ALA ) is a common precursor in the biosynthesis of tetrapyrrole compounds such as porphyrins , chlorophyll , heme and vitamin B12 , widely exists in the cells of microorganisms , plants and animals .

结论反复心理应激能够损害中枢DA神经元，导致TH阳性神经元数目减少，Fos蛋白表达增加，多巴胺前体物质Tyr的干预能够降低此种损害。

Conclusion Repeated psychological stress could impair central dopaminergic neurons , inducing a decrease in TH positive neuron and an increase in fos protein expression . Tyrosine , the precursor of dopamine may have the effects of reducing this damage .

因此，通过营养平衡来调控前体物质的积累，进而降低烟草TSNA的含量，对生产优质低害的烟叶原料具有重要的意义。

Therefore , it is great important to decrease the TSNA content through controlling the accumulation of nitrate and nitrite by nutrition balance in production of high quality and low harm tobacco leaves .

研究结果说明全氟前体物质的降解是环境中的PFSAs和PFCAs一个重要来源。

The results suggested that the biotic degradation of PFAS precursors is an important source of PFCAs and PFSAs in the environment .

目的：探讨慢性癫痫对大鼠空间记忆再生能力的影响，检测组胺前体物质组氨酸和胆碱酯酶抑制剂TAK-147对癫痫诱发记忆障碍的作用。

Objective : To investigate the influence of chronic epilepsy on spatial memory retrieval in rats , and to evaluate the effects of TAK-147 , an acetylcholinesterase inhibitor , and histidine , the precursor of histamine , on the amnesia induced by epilepsy .

初步探讨了加热过程中鸡肉风味前体物质变化的机理。

The mechanism of chicken flavor precursors concentration in heating was discussed .

酶法提取金华火腿中的风味前体物质

Immobilized enzymes Enzymatic extraction of flavor precursor from jinhua ham

烟草香味物质及其形成的前体物质研究进展

Development of the Research on Aroma Compositions of Tobacco and the precursor substances

不同茶树品种脂肪酸和糖苷类香气前体物质的研究

Studies on the Fatty Acid and Glycoside Aroma Precursors of Different Tea Varieties

上述研究结果暗示，紫杉醇及其前体物质在中国红豆杉体内存在转移现象。

Results indicated that taxol and its precursors translocated in intact yew plant .

烟叶成熟度及烘烤工艺对致香前体物质的影响研究

Studies on the Effects of Maturity and Flue-curing Process to Flue-cured Tobacco Aroma Precursors

金华火腿调味料风味前体物质酶解制备工艺研究

Study on the Preparation of Flavor Precursor of Jinhua Ham Seasoning by Enzymolysis Technology

加热过程对鸡肉风味前体物质的影响

Effect of Heating on the Chicken Flavor Precursors

亚硝胺可由其前体物质亚硝酸盐及二级胺在体内合成。

N-Nitrosamine can be formed in vivo by the interaction of nitrites with secondary amines .

白肋烟晾制中亚硝胺及前体物质的变化

Changes in the contents of nitrosamines and their precursors in Burley Tobacco during air curing

结论：腐殖酸是饮用水氯化消毒副产物的重要前体物质。

Conclusion : The humic acid is an important precursor substance of disinfection by products .

本文重点综述了鸡肉中重要的风味前体物质-脂肪酸的研究进展。

The article mainly overviews the research advance of aroma precursors-fatty acid in chicken meat .

薯蓣皂甙元是薯蓣皂甙的水解产物，它是许多重要甾体激素的前体物质。

Diosgenin is the hydrolyzed material of dioscin and the precursor substance of several important endogenous steroids .