酸基

Second, using DBU as the base for enolization of propargylic esters of unsaturated acids 18e-k, we developed a tandem Ireland-Claisen rearrangement /isomerization reactions. It has been shown that the reaction sequence affords triene molecules 42a-b and 43a-b in moderated to high yields. Interestingly, with allyl hexa-3,5-dienoates 18i-j as the substrate, the rearranged products underwent further aromatization to give uniquely substituted benzyl acids 44a-b.

其次，以含有活泼质子的烯酸炔丙酯18e-k为底物，在DBU为烯醇化碱、TMSCl为硅试剂的条件下，底物18e-h发生了Ireland-Claisen重排/异构化串联反应，得到完全共轭的三烯类化合物42a-b及43a-b；而以己二烯酸炔丙基酯18i-j为底物时，重排/异构化后的产物进一步发生电环化等反应最终得到芳构化产物——取代苯甲酸类化合物44a-b。

The excess of ethyl orthosilicate should render the chain terminal unreactive toward the crosslinking...

降解是由于水在二月桂酸二丁基锡酯或它的水解产物月桂酸催化下使聚二甲基硅氧烷主链的Si—O—Si键水解所引起的。

Most of the org.impurities are nitro compds.They are mixed in DNS acid,turned to amino compds.in the reduction,and become the impurities of DSD acid,which result in important influences on the fluorescent whitener products,e.g.,yield,strength,shade,whiteness etc.

有机杂质主要是硝基物，混入产物DNS酸中，经还原后，生成氨基化合物，成为DSD酸中的有机杂质，对产品荧光增白剂的影响很大，如产品收率和强度、色光、白度等质量指标。

MethodsAfter acate liver injury model was induced by carbon tetrachloride (CCl4), mice were administrated intragastrically with Hypericum japonicum.The serum ALT, AST, SOD, NO, TNF-α, IL-6 were determined and pathological change of liver was observed.

方法以四氯化碳（CCl4）制备小鼠急性肝损伤的模型，田基黄水煎剂灌胃，检测小鼠血清中的丙氨酸氨基转移酶、天冬氨酸氨基转移酶、超氧化物歧化酶活力以及一氧化氮、肿瘤坏死因子-α、白介素-6的含量，观察肝组织的病理损伤程度。

After thecomplete genome extraction of the strain was performed, the genomic DNA was partiallydigested by restriction enzyme Sau3AⅠ, the DNA fragments from 1 to 5Kb was clonedinto prokaryote expression vector pET-28a-c, and transformed host bacteria. The resultsshowed that we succeeded in constructing the gene expression library of haemophilusparasuis serovar 5, which is fundamental for the study of advanced gene screening. Inaddition, primer design was performed based on haemophilus influenzae in this study. In addition, PCR was performed by using genomic DNA of haemophilus parasuisserovar 5 as the template. The results demonstrated that we obtained two neo-gene:23SrRNA gene(conserved gene belonging to the large-subunit of ribosome) and adenylatecyclase gene(encodes adenylate cyclase and participates in converting adenyl nucleosidetriphosphate to cyclic adenosine3",5"-monophosphate). Furthermore, the phylogeneticanalyses between the species was performed, and neighbor-joining tree was constructedbased on comparison of 23S rRNA gene sequences, so it was illuminated betweenHaemophilus parasuis and other species in molecular evolution relationship.

选择我国流行优势菌株副猪嗜血杆菌血清5型地方株为研究对象，提取细菌基因组DNA，用限制性内切酶Sau3AⅠ对基因组DNA进行部分酶切，回收大小为1～5Kb的DNA片段，将其连接入原核表达载体pET-28a-c，最后转化宿主菌，结果成功地构建了基因表达文库，为后续的基因筛选工作奠定基础；另外，本研究选择嗜血杆菌属的流感嗜血杆菌为参考对象进行引物的设计，以副猪嗜血杆菌血清5型地方菌株的基因组DNA为模板，进行PCR扩增反应，结果表明成功地获得两个新基因：23S rRNA基因(存在于核糖体大亚基中的保守性基因)和腺苷酸环化酶基因(负责将腺嘌呤核苷三磷酸转变为环腺苷酸)，并进一步做了不同物种之间的分子系统发育分析，构建了基于23S rRNA基因的邻接法系统发育树，阐明了副猪嗜血杆菌与其它菌种的分子进化关系。

The distribution, properties,structure and regulation of plant allantoinase were reviewed in detail.

文摘：全面综述植物酰脲降解代谢酶的研究现况，概述植物尿囊素酶的分布、性质、结构，以及调节控制，并简介植物尿囊酸酰胺水解酶和脲基乙醇酸酰胺水解酶的研究近况，同时指出待研究的方向。

By using antimonate potassium cytochemistry method, we found that antimonate calcium precipitates existed only in the cell wall rather than the protoplasm and showed a tip to base gradient in the cell wall of hyphal tips, i.

焦锑酸钾电镜细胞化学定位揭示焦锑酸钙沉淀颗粒仅存在菌丝细胞壁中，呈顶端到基部的极性分布。

Alpha-1 antitrypsin is the most abundant circulating protease inhibitor in the body, Dr. Lomas said. Its most common deficiency mutation is the Z allele, where the amino acid lysine is exchanged for glutamic acid at position 342 in the polypeptide chain (Glu342Lys). About 1 in 1700 whites of northern European descent are homozygotes for this mutation and thus have plasma antitrypsin levels that are 10% to 15% below normal, he said.

Lomas博士表示，甲一型抗胰蛋白酵素是身体内最充分的循环蛋白酶抑制剂，最常见的缺损突变在Z对偶基因，该处的胺基酸 lysine与麸氨酸在多胜肽链的第342位置交换(Glu342Lys)；北欧血统白人每1，700人有1人是此一突变的同合子，因此血浆抗胰蛋白酵素值比正常低10%到15%。

Bifluoro nitrobenzene was the raw material of synthesis of asymmetry chromotropic acid bisazo fluoroarsen reagent, By way of ammonia substitution, arsonation, reduction and coupled reactions, bisazo fluoroarsen was synthesized.

以2，4—二氟硝基苯为起始原料，经过氨取代、胂酸化、还原、偶联反应合成了偶氮氟胂Ⅰ，然后分别选择不同的取代苯胺与偶氮氟胂Ⅰ偶联，合成了一系列的不对称变色酸偶氮氟胂。

One of the major problems,however,remains the poor solubility and membrane permeation of pepstatin, as well as its lack of selectivity among aspartyl proteases.The amino acid statine can mimic the tetrahedral transition-state of amide bond hydrolysis but cannot itself be hydrolyzed by the enzyme.

分子中含有两个非天然氨基酸statine能模拟天冬氨酸蛋白酶底物活性部位的四面体水解过渡态，且本身不易被切割，通过氢键和酶的天冬氨酸残基结合。

With Death guitarist Schuldiner adopting vocal duties, the band made a major impact on the scene.

随着死亡的吉他手Schuldiner接受主唱的职务，乐队在现实中树立了重要的影响。

But he could still end up breakfasting on Swiss-government issue muesli because all six are accused of nicking around 45 million pounds they should have paid to FIFA.

不过他最后仍有可能沦为瑞士政府&议事餐桌&上的一道早餐，因为这所有六个人都被指控把本应支付给国际足联的大约4500万英镑骗了个精光。