羟基

Cephalotaxine ester of 2-oxo-6-methylheptanoic acid was treated with lithium diisopropylamide and Me O-(1-methoxyisopropyl)glycolate to give a mixture of homoisoharringtonine and its stereoisomers with 56% yield. The four stereoisomers separated by TLC showed identical mass spectra and almost superimposed IR but with different 1H NMR spectra. The configuration of the 2'-C and 3'-C of the four isomers were postulated based upon their 1H NMR spectra as compared with the 1H NMR spectra of isoharringtonine and its stereoisomers.

2-氧代-6-甲基庚酰基三尖杉碱(3)与0-(1-甲氧基异丙基)羟基乙酸甲酯(4)在强碱性试剂二异丙胺锂存在下，起亲核加成反应，反应中间体5在室温用酸性丙酮水解，得到一种新的三尖杉酯类生物碱一一高异三尖杉酯碱(6c)及其立体异构体(6a、6b、6d)的混合物，产率56%、通过制备薄层层析分得这四个立体异构体，它们的1H NMR和异三尖杉酯碱及其立体异构体的1H NMR类似，推定了它们的绝对构型。

Second, among the seven yeast strains investigated, Rhodotorula gracilis AS 2.499 exhibited the highest activity and stereo-selectivity to tert-butyl-6-chloro-5-hydroxy-3-oxohexanoate.

其次，从实验室保藏的七株酵母菌株中筛选出对-6-氯-5-羟基-3-羰基己酸叔丁酯具有较高还原能力的菌株——Rhodotorula gracilis AS 2.499。

In the scheme,the key reactions were Grignard reaction, dihydroxylation,S_N2 substitution of hydroxyl and epoxide under acidic conditions and etc.

合成过程中的关键反应为Grignard反应，双羟化反应，质子酸催化的羟基与环氧的S_N2亲核取代成环反应。

Polyphenol compounds were extracted from the sorghum groats by water and methanol. Total phenolic content, reducing power, chelating activity, DPPH radical scavenging activity, ABTS radical cation scavenging activity and inhibition of hydroxyl radical-mediated 2-deoxy-D-ribose degradation of the extracts from the sorghum groats were determined.

以水和甲醇为溶剂提取高粱籽粒中的多酚类化合物，测定了提取物中的总酚含量、还原力、Fe~(2+)络合能力以及提取物对DPPH、ABTS、羟基自由基的清除能力。

In order to obtain 3-methoxy-4-hydroxymandelic acid with high quality and high yield, guaiacol was condensed with glyoxylic acid in an alkaline aqueous solution using solid acid as catalyst. The reaction temperature and reaction time was 15℃ and 18 hours respectively.

为了得到高质量和高收率的3-甲氧基－4-羟基苯乙醇酸，使愈创木酚和乙醛酸在碱性水溶液中在固体酸催化剂存在下进行缩合反应，反应温度15℃，反应时间18h。

The probable reactions of the adamantane,for example halogenation , alcoholization, nitration and alkylation,are summarized.

文章从分子设计的角度综述了金刚烷可能发生的化学反应，如卤化、羟基化、硝化、烷基化等；同时探讨了金刚烷化学反应的机理，为金刚烷在精细化工领域的深层次应用打下基础。

DMBQ, resorcin, ferulic acid, and hydroxybenzoic acid were effective chemical signal substances in the inducement of haustorium, but the haustorium formation rate was only 3.3%.

适当浓度的2，6-二甲氧基对苯醌、间苯二酚、阿魏酸和对羟基苯甲酸均可诱导肉苁蓉种子萌发形成吸器，吸器形成率最高为3.3%。

Resveratrol (3,5,4'- trihydroxystilbene) was first isolated from the roots of white hellebore Veratrum grandiflorum O.

白藜芦醇( 3，5，4'三羟基二苯乙烯)最早是于1940年从白藜芦的根茎中分离所得。

However, the activity of HO-1 was increased after hematin and phenylhydrazine induction, while the activity of HO-2 was fully refractory to these inducers.

采用离子交换层析、羟基磷灰石交换、分子筛层析、酶活性检测、SDS-PAGE和Western印迹技术手段来提取、纯化这些大白鼠不同组织HO的同工酶。

It appears to be a complication of chronic hemolysis, is resistant to hydroxyurea 40 therapy, and confers a high risk of death.

肺动脉高压似乎是慢性溶血的一个并发症，对羟基脲治疗耐药，并具有很高的死亡危险。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。