查询词典 Closing the Ring

The low molacular hydrogenated bisphenol A epoxy resin was prepared by the ring-closing reaction of the chlorohydrin ether and alkali and high molecular hydrogenated bisphenol A epoxy resin was synthesis by the addition polymeration of the low one and hygenated bisphenol A.

氢化双酚A和环氧氯丙烷在催化剂作用下开环反应生成了氯醇醚，而后加碱进行闭环反应，制备了低分子质量氢化双酚A型环氧树脂，再将其进一步与氢化双酚A等进行加聚反应，得到高分子质量环氧树脂。

As one of the first manufacturers of bearing steel ring in China, the company is mainly engaged in such products as bearing steel ring for cotton spinning, nut, retaining ring, cotter pin, closing ring and flat pad etc.

经试验证明，"衰退钢领"内跑道的几何形态无显著变化，表面具备足够硬度，精抛光后（钢领可达到▽10-▽11级），上车使用效果非常好，可连续抛光使用能达到钢领使用寿命3-5年以上。

In addition, we studied the ring-closing metathesis of the diene intermediates to access helicenes by screening a wild reaction condition.

我们还对RCM反应关环得到螺旋化合物的方法进行了研究，筛选得到温和的RCM反应条件。

The optimum reaction conditions are obtained by orthogonal exptl. design; ring-opening reaction:n:n = 1:1.3, Hexamethylenetetramine catalyst 0.7%,reaction temp. is 80℃, reaction time is 7 h, and concentration of inhibitor is 0.3%. ring-closing reaction : n:n=1:0.9, reaction temp. is 40℃, reaction time is 5 h.

通过正交设计确定了最佳工艺条件为：开环反应：六次甲基四胺用量0.7%(占反应物总量的质量百分比)，阻聚剂用量0.3%(占反应物总量的质量百分比)，ECH：MAA的摩尔比为1.3：1，温度80℃，反应时间7h ；闭环反应：氯醇酯： NaOH的摩尔比为1：0.9，反应温度40℃，反应时间5h。

In this dissertation, we present the synthesis, structure and self-assembly of some novel calix [4] arene derivatives with multi-cavities.

本论文工作主要包括三个部分：(1)通过RCM(Ring-Closing Metathesis)方法设计合成了一系列桥连的双杯[4]及多杯[4]芳烃衍生物。

This dissertation is mainly focused on the reactivity of methylenecyclopropanes and comprises six parts. 1 The reactions of methylenecyclopropanes with phenylsulfenyl chloride, phenylselenyl chloride and diphenyl diselenide; 2 The coupling reactions of the ring-opening products derivated from methylenecyclopropanes; 3 The palladium-catalyzed ring-enlargement of mono-aryl group substituted methylenecyclopropanes to cyclobutenes. 4 The gold-catalyzed domino ring-opening and ring-closing hydroamination of methylenecyclopropanes with sulfonamides; 5 The Lewis acid-catalyzed reactions of mono-aryl group substituted methylenecyclopropanes with diethyl ketomalonate in the presence of water; 6 The iodobenzene diacetate mediated novel 1,3-dipolar cycloaddition of methylenecyclopropanes, vinylidenecyclopropanes, and methylenecyclobutane with phthalhydrazine.

本论文主要研究了亚甲基环丙烷类化合物的一些化学反应性能，共由以下六部分组成：1、亚甲基环丙烷类化合物与苯硫氯、苯硒氯及二苯基二硒的反应；2、亚甲基环丙烷类化合物开环产物的偶联反应；3、单芳基取代的亚甲基环丙烷类化合物在钯催化剂作用下的扩环反应；4、金化合物催化磺酰胺对亚甲基环丙烷类化合物的串联开环关环氨氢化反应；5、路易斯酸催化亚甲基环丙烷类化合物与丙酮二羧酸二乙酯在有水存在下的反应；6、醋酸碘苯促进的亚甲基环丙烷类化合物、亚乙烯基环丙烷类化合物及亚甲基环丁烷类化合物与邻苯二甲酰肼的新型1，3-偶极环加成反应。

The Metal seated butterfly valve adopts a double eccentric structure and a inclined cone seal. The seal-ring can be separated once open the disk, and the valve can be sealed once the seal-ring contacts the disk. This structure can decrease the friction torque when the butterfly valve opens and closes, and expanded the life time, and make opening and closing easily.

斜锥面金属密封蝶阀设计采用了一个双偏心和一个特殊斜锥椭圆密封结构，实现蝶板在开启瞬间密封面即分离，关闭接触即密封的效果，这种密封结构实现启闭无机械滑动摩擦，大大延长了密封件的使用寿命，并且达到启闭轻松自如目的，且具有密封自动补偿功能。

Taking CSL-102 and WXH-15 computer protection as examples,introduces the work principle of working frequency variable direction relay,analyzes the malfunction of closed abrupt direction high frequency protection on closing the ring ,and puts forward the material improvement measures.

以CSL-102和WXH-15型微机保护为例，介绍了工频变化量继电器的工作原理，对闭锁式突变量方向高频保护在系统合环时的误动情况进行了分析，并提出了具体的改进措施。

Investors so sought after because of the oil in the ring, the most direct or China Shenhua (601,088, the closing price of 18.58 yuan) in its interpretation prior to the listing for three consecutive days of trading wealth effect.

投资者如此追捧，除了因为中石油的光环外，最为直接的还是中国神华(601088，收盘价18.58元)在其之前演绎的上市连续三天涨停的财富效应。

Based on the-references on the thermal imidization of polyand the polymer composition analysis,the thermal imidization mechanism of SMA with aniline was demonstrated to be a two-stage consecutive reaction,in which a second-order reversible ring-opening reaction of SMA to produce poly(styrene-co-N-phenyl-maleamic acid)and a first-order irreversible intrachain ring-closing reaction to form SNPMI were involved.

论文首先参考聚酰胺酸热环化反应，并通过SMA酰亚胺化产物的组成分析，确定了SMA与苯胺的热酰亚胺化反应机理为一个包含由SMA生成苯乙烯—N-苯基马来酰胺酸共聚物的二级可逆开环反应以及由SNPMA生成苯乙烯—N-苯基马来酰亚胺共聚物的一级不可逆分子内闭环反应在内的串联反应过程，其中第二步SNPMA闭环反应为控制步骤。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。