金属环

Generally speaking, the reaction types involvingα-oxoketene--acetals mainly include the regioselective addition-aromatization with organometallic reagents, conjugate addition-cyclization with nitrogen nucleophilicspecies, nucleophilic reactions ofα-carbon, acting as odorless dithiol equivalentsin thioacetalization, Michael additions and [5+1] annulation, as well as the synthetic applications based on the above reactions.

一般来说，基于α-羰基二硫缩烯酮化学的反应主要为：与金属有机试剂的选择性加成反应，与氮亲核体的共轭加成反应，α-碳原子的亲核性及相关反应，烷硫基作为硫醇的替代试剂的应用，α-羰基二硫缩烯酮在碳环、杂环化合物合成中的应用等。

The accumulation of asphaltene in the system depends on the physical structure of ...

在沥青质分子单元叠积过程中，由沥青质的杂原子因素、过渡金属因素、芳香环结构因素和脂肪性侧链因素共同决定的化学作用的影响是第一位的，其中芳香环结构因素和杂原子因素的影响最为显著，而由稠油体系不稳定性构成的物理作用的影响则居于次要地位。

Metal cock ring soft seat surface pressure to the bearing surfaces, such as the valve core and valve seat is concentric ring surface can be a double tight closure.

金属旋塞表面压向阀座环软支座表面，如阀芯和阀座环表面是同心的，就能得到双重严密的关闭。

The sulphur atom in the intermediate has sp2 hybridization, and the remaining p orbital is symmetrical to the d orbital of the metal center. Thus, the lone pair on the p orbital can have interaction with the d orbital to form a π bond, which leads to the coplanarity of the center of Cp ring, Ru, P, S and Si atoms, rather than the deviation of P, S and Si atoms from the plane.

该中间体中，硫原子采取sp2杂化，硫原子剩余的一个p轨道与金属中心上的d轨道具有相同的对称性，因而该p轨道上的孤电子对可与金属中心上的d轨道形成π键，导致Cp环中心， Ru， S1， P和Si原子在同一平面内，而不是S1， P和Si原子偏离该平面。

A process for preparing cycloolefin features that in the presence of catalyst slurry containing metal Ru catalyst, water and metallic sulfate, the mononuclear aromatics is partially hydrogenated by hydrogen, and includes a step to control the activity of catalyst.

一种生产环烯烃的方法，该方法是在含有金属钌催化剂、水和金属硫酸盐的催化剂浆液存在下用氢部分加氢单环芳烃进行该方法，其中包括控制催化剂活性的步骤。

A catalyst composition for the polymerization of propylene comprising one or more Ziegler-Natta procatalyst compositions comprising one or more transition metal compounds and one or more esters of aromatic dicarboxylic acid internal electron donors; one or more aluminum containing cocatalysts; a selectivity control agent comprising at least one silicon containing compound containing at least one C1-10 alkoxy group bonded to a silicon atom, and one or more activity limiting agent compounds comprising one or more aliphatic or cycloaliphatic carboxylic acids; alkyl-, cycloalkyl- or alkyl-ester derivatives thereof; or inertly substituted derivatives of the foregoing.

一种用于丙烯聚合的催化剂组合物，所述催化剂组合物包括：一种或多种齐格勒-纳塔主催化剂组合物，该主催化剂组合物包括一种或多种过渡金属化合物和一种或多种芳族二羧酸酯内部电子给体；一种或多种包含铝的助催化剂；选择性控制剂，该选择性控制剂包括至少一种包含硅的化合物，该化合物包括至少一种与硅原子连接的C 1-10 烷氧基；和一种或多种活性限制剂化合物，该活性限制剂包括一种或多种脂族或脂环族的单或聚羧酸类、其烷基-、环烷基-或烷基-衍生物、或上述惰性取代的衍生物。

Herein the latest developments of olefin aqueous polymerization which are mainly promoted by late- transition metal catalysts are reviewed including ethylene,α-olefins, cyclo-olefins and dienes polymerization, along with ROMP of cyclo-olefins and CO/olefins copolymerization.

本文综述了后过渡金属催化剂水相催化烯烃配位聚合的一些新进展，内容包括烯、α-烯烃、环烯烃、二烯烃的聚合反应和环烯烃的开环聚合反应以及CO/烯烃的共聚反应等方面。

The series of computerized automatic welder for portal ring seam is applicable for both of wire-drive and butt-weld ring seams at M direction for various casket cylindrical metal materials with plate thickness of 0.8mm~2.5mm and lmm8mm, due to silver or golden welding seam, beautiful and clear appearance, high strength, continuous and stepless weld-speed regulating and non corrosion in crystalline, this equipment is mainly suitable for ring-seam butt-weld to SS compressing components and various inners concerning solar water heater, enamel water container, electric heater and turkey boiler, and for ring-seam wire-drive and butt-weld to barrel and tank for large industry production.

该系列龙门式环缝电脑自动焊接设备可对板厚0.8mm—2.5mm和1mm—8mm的各种圆桶形金属件实施M向位置的环缝对接和送丝焊接，为两用型设备。焊缝颜色呈银白色或金黄色，焊接美观光洁、强度高、无晶间腐蚀，焊接速度连续无级可调，主要适用于不锈钢承压或太阳能热水器内胆、搪瓷水箱内胆、电热水器内胆、火鸡锅和对大型工业制桶、罐等产品的环缝对接、送丝焊接。

Electrocatalysts, such as metals, metal alloys, transition metal oxides, transition metal macrocycle etc, for oxygen reduction reaction in fuel cells and metal-air batteries were reviewed .

主要综述了近几年燃料电池、金属-空气电池中氧还原反应催化剂的发展状况，包括发展成熟的贵金属及合金；过渡金属复合氧化物、简单氧化物；过渡金属大环化合物以及双功能电催化剂研究现状。

It is discovered that there is a satisfied linear relationship between the experimental impact sensitivity and the activation energy of the ring breaking reaction.

首次提出并运用&取代基模型&(即将金属原子视为四唑环上的取代基、对金属配合物的处理采取与计算衍生物完全相同的模式)较为简便地计算研究了系列四唑金属配合物的热解反应，发现开环形成叠氮化物的活化能与它们的实验撞击感度之间存在良好的线性关系。

I didn't watch TV last night, because it .

昨晚我没有看电视，因为电视机坏了。

Since this year, in a lot of villages of Beijing, TV of elevator liquid crystal was removed.

今年以来，在北京的很多小区里，电梯液晶电视被撤了下来。