环状的

The condensation reaction of levulinates with ethylene glycol brings about corresponding ketal , with respective productivity of 74%, 75% and 75%, and respective structure being verified by IRS.

由乙酰丙酸酯类化合物与乙二醇进行缩合反应，得到相应的环状缩酮化合物，产率分别为 74 %，75 %和 75 ，其结构为红外光谱所证

In 1903, D. Vorlander and co-workers found that treatment of dibenzylideneacetone with concentrated sulfuric acid and acetic anhydride followed by hydrolysis by sodium hydroxide yielded a cyclic ketol, the structure of which was unknown at the time.

1903年，D。 Vorlander和合作者发现，二苄基丙酮与浓硫酸及醋酸酐经过氢氧化钠水解后产生了当时还不知结构的环状酮醇。

The results indicated that DNase E belonging to endonuclease.Conclusion1. Established a preparation technics of rude extracts of Lumbricus Bimastus nucleases.

应用琼脂糖凝胶电泳对DNase E水解双链环状DNA后的产物进行鉴定，证明了DNase E属于核酸内切酶。

The two bright spots outside the ring are stars in the Large Magellanic Cloud.

这两个亮点以外的环状星在大麦哲伦云。

Can cause vomiting, neonatal diseases are congenital malrotation, annular pancreas and neonatal intracranial hemorrhage, but rare.

能引起新生儿呕吐的疾病还有先天性肠旋转不良，环状胰腺及新生儿颅内出血等，但较少见。

The cytogenetics of interspecific hybrids among the four cultivated cotton species were studied in this paper and results are as follows: The diploid interspecific hybrid (G. arboreum×G. herbacium) F〓 had a four-chromosome-ring at the meiotic metakinesis. The synapses of tetraploid hybrid (G. hirsutum ×G. barbadense) F〓 was found to be regular, which mainly formed bivalents, sometimes some univalents, multivalents and chromosome bridge.

四个栽培棉种间杂交种F〓的细胞学观察结果表明，F〓减数分裂中期Ⅰ，形成一个环状四价体，直接证明了亚洲棉与草棉之间存在一对相互易位；F〓减数分裂中期Ⅰ联会基本正常，主要形成二价体，偶尔出现一些单价体和多价体，以及染色体桥。

The density functional theory and MP2 method were employed to study the reaction pathways of methanolysis of 3-methyl cyclic ethylene phosphate: CH3O－＋MEP; CH3OH＋MEP; CH3O－＋HMEP; CH3OH＋HMEP.

采用密度泛函理论和MP2方法研究了3-甲基环状乙撑磷酸二酯与甲醇的反应途径： CH3O－＋MEP； CH3OH＋MEP； CH3O－＋HMEP； CH3OH＋HMEP。

We also consider a parabolic system in a three species mutualistic modelIt is shown that any solution with time delays is global.

我们还研究了另一类三种群单链环状互惠抛物模型并考虑了具时滞的问题。

The phosphine was quickly oxidized by triplet oxygen to phosphineoxide with a free radical chain reaction at relatively low temperature; while at high temperature, the phosphine react with singlet oxygen through a three member ring intermediate to form phosphineoxide and phosphinate as the product.

在相对较低温度时，膦化物与基态氧发生自由基链反应，膦化物很快被氧化为氧化膦；在相对较高的温度，膦化物与激发态氧直接作用，通过三元环状中间体而最终生成氧化膦和次磷酸酯。

Male flowers: sepals (4 or)5 or 6, membranous, round, imbricate; petals absent; disk annular, lobed or 5-glandular; stamens 10-20, or more; filaments free; anthers 2-locular, longitudinally dehiscent; pistillode absent.

雄花： 萼片(4或)5或6，膜质，圆形，覆瓦状；花瓣无；花盘环状，裂或具5腺；雄蕊10-20或更多；花丝离生花药2室，近纵向开裂的；无退化雌蕊。

It has been put forward that there exists single Ball point and double Ball points on the symmetrical connecting-rod curves of equilateral mechanisms.

从鲍尔点的形成原理出发，分析对称连杆曲线上鲍尔点的产生条件，提出等边机构的对称连杆曲线上有单鲍尔点和双鲍尔点。

The factory affiliated to the Group primarily manufactures multiple-purpose pincers, baking kits, knives, scissors, kitchenware, gardening tools and beauty care kits as well as other hardware tools, the annual production value of which reaches US$ 30 million dollars.

集团所属工厂主要生产多用钳、烤具、刀具、剪刀、厨具、花园工具、美容套等五金产品，年生产总值3000万美元，产品价廉物美、选料上乘、质量保证，深受国内外客户的青睐