环

It has been reported that some natural compounds containing α- methylene-γ-butyrolactone,α-methylenecyclopentanone,α- methylenecyclohexanone,α,β-unsaturated cyclic ketone moiety possessed significant antitumour activity and antiinflammatory activity as well.

在众多的天然产物中，一些含有α-亚甲基-γ-丁内酯，α-亚甲基环戊酮，α-亚甲基环己酮，α，β-不饱和环酮结构的天然化合物具有显著的抗癌、抗炎活性。

In this paper isopropyl -γ- chlorobutyrate was prepared from γ- butyrolactone by one - step. The effects of molar ratio of reactants, reaction temperature, reaction time on the yield of product were discussed, the optimum reaction condition was obtained.

一氯代丁酸异雨酯是合成新型拟除虫菊酯中间体环丙烷较酸及高效抗菌新药丙氟见酸和环丙氟院酸中间体环丙胺的重要原料［''］。

The influence of the opening ratio and the opening mode of the rectifying ring on the gas distribution effect was also measured with a calandria manometer.The flow through the pores of the center pipe could be uniformly distributed by adjusting the opening ratio of the rectifying ring.

利用压力排管研究了整流环开孔率和开孔方式对均布效果的影响，发现通过调整整流环周向开孔率可以实现内环射流流量均布。

The target compound was synthesized from clarithromycin via hydrolyzation,acetylation,cyclic carbonatation,oxidation,decarbonatation,acylation,cyclic carbamatation and cyclization.

方法以克拉霉素为起始原料，经水解、乙酰化、环碳酸酯化、氧化、脱碳酸酯化、酰化、环氨基甲酸酯化和环合等反应合成目标化合物。

In this dissertation, I will represent my studies on the nitration of Chalcone derivatives, reaction of epoxide ketone, and the aromatization of 3,5-disubstitued 2-isoxazolines with nitric oxide.

本文主要研究了：(1)NO与查尔酮及其衍生物的硝化反应，反应以较高的产率得到了a-硝基化合物；(2)NO对环氧酮的开环反应，反应生成了顺式羟基硝酸酯；(3)3，5-二取代的-2-异恶唑啉在NO作用下可以发生芳环化反应，生成了对应的2-异恶唑化合物。

While the diameter of an undirected chordal ring network has been well studied [1], the diameter of a directed chordal ring network and the diameter of a mixed chordal ring network are not known.

虽然「无向的弦环式网路」的直径已被完整地研究、并且可以运用公式得出，但是截至目前为止，「有向的弦环式网路」的直径、以及「混合的弦环式网路」的直径却还未被完全找出来。

In [8, 10, 11], Hwang, Chen, and Wright proposed the directed version of the undirected chordal ring network and derived the diameter of a directed chordal ring network.

在文献[8， 10， 11]中，黄光明老师、陈尚宽学长、以及Wright，将「无向的弦环式网路」推广成「有向的弦环式网路」，并给出计算「有向的弦环式网路」的直径的方法。

On the other hand, through the discussion on coronal density of flares, we found that the column mass density at the top of chromospheric flare model can not be represented the total mass above the chromosphere and the coronal density can be estimated from presure balance based on semiempirical model. Through estimations, the results show that the total mass above the chromosphere is about the same as the mass between the top of chromosphere and electron source, which so give an evidence that the source of electrons is situated at the top of flare loop.

另一方面，通过对日冕物质密度的讨论发现，半经验模型中色球顶部柱数密度不能用来代表耀斑环在日冕内的总物质，日冕物质密度可用日冕气压与半经验模型中色球顶部压力近似相等来进行估计，进而发现耀斑环在日冕内的总物质与前面估计的色球顶部到非热电子源之间的总物质近似相等，结果趋向于支持非热电子源位于环的顶部。

L-Azetidine-2-carboxylic acid, also named-Azetidine-2-carboxylic acid, commonly named L-Aze, was first isolated in 1955 by Fowden from Convallaria majalis and was the first known example of naturally occurring azetidine.

L-氮杂环丁烷-2-羧酸，又称-氮杂环丁烷-2-羧酸，简称为L-Aze.1955年，由Fowden从植物铃兰中分离得到，成为第一个被证实的植物中天然存在的氮杂环丁烷结构。

However, PARs in snow ice insoluble particulates, cryoconite and surface soil around the Qiyi Glacier are dominated by those of four to six rings.

雪冰和冰川融水样品中相对富集3环和4环，雪冰不溶微粒和冰尘以及七－冰川周围表层土壤样品主要以4-6环为主，这是由PAHs自身的物理化学性质决定的。

Do you know, i need you to come back

你知道吗，我需要你回来

Yang yinshu、Wang xiangsheng、Li decang,The first discovery of haemaphysalis conicinna.

1〕 杨银书，王祥生，李德昌。安徽省首次发现嗜群血蜱。