查询词典 ionic bond

The results show that there are eight reaction channels, corresponding to eight transition states, in the reaction process. The main parts of all transition states are non-planar five-membered ring, in which the geometry of Z -benzaldoxime and E -benzaldoxime is maintained partially, but the bond length, bond angle and charge are all changed.

结果表明，在苯甲醛肟与炔丙醇加成反应过程中， 8个可能反应通道的过渡态中均形成非平面五元环结构，其中苯甲醛肟的 Z 、 E 构型特征得到了部分保留，但主要部分的键长、键角均发生了变化，电荷也进行了重新分布。

It isconfirmed by ~1H NMR,~(13)C NMR and X-ray crystallographic analysis that complexes 60-63are monopyridine complexes and show distorted square pyramid geometries; complexes 64and 65 are bispyridine complexes and show pseudo-octahedral geometries, where twopyridine ligands are in cis arrangement and trans to the NHC and the benzylidene ligandrespectively, the bond length between ruthenium and pyridine ligand trans to the benzylideneligand is 16 pm longer than the bond length between ruthenium and pyridine ligand trans tothe NHC ligand.

1H NMR、~(13)C NMR及X射线单晶衍射分析证明，配合物60-63是单吡啶衍生物配位的钌卡宾配合物，具有变形的四方锥构型；配合物64、65为双吡啶衍生物配位的钌卡宾配合物，具有变形的八面体构型，其中两个顺式配位的吡啶衍生物分别处于氮杂环卡宾和苯亚甲基的反位，处于苯亚甲基反位的吡啶衍生物对应的钌-氮键长要比处于氮杂环卡宾反位的长出16 pm。

The bond lengths,bond angles and molecular conformation indicate that:in these polyphenoxy benzene systems the conjugative polari...

的分子构象、键长和键角数据表明氧桥两边的苯环的共轭极化效应不能贯通，而苯氧基只是分子中的一个独立片断。

The result showed that Si--Si covalent bond eAsts in the melt of eutectic and hyper--eutectic alloy and Sr has capability to weaken the coto bond.

结果表明，在共晶及过共晶的合金的液态结构中，存在着Si—Si共价键，Sr有削弱这些共价键的倾向。

Compared with the double bond of cyclopentene ring, the double bond of the norbornene ring has much more lower activation energy in the hydrogenation and the main intermediate product is 14,15-DHTCPD.

非晶态合金催化剂晶化过程的原位分析结果表明，在热处理温度低于150°C条件下其结构基本保持稳定，而高于450°C条件下热处理后晶化度大于90%，600°C以上热处理后完全晶化。

The double bond in norbornene ring of TCPD was easily saturated at a low temperature, and an intermediate 12,13-dihydrotricyclopentadiene (12,13-DHTCPD) was formed. Higher temperature and hydrogen pressure were required for the saturation of remaining double bond in cyclopentene ring to generate a completely hydrogenated compound tetrahydrotricyclopentadiene.That is to say, the reaction occurred via the TCPD→12,13-DHTCPD→THTCPD route.

采用气质联用、红外光谱和核磁共振对加氢产物进行表征，发现在加氢反应中TCPD的降冰片烯双键首先被饱和，生成中间产物12，13-二氢三环戊二烯(12，13-DHTCPD)，残留的环戊烯双键需要在更高的温度和氢压下反应生成四氢三环戊二烯，即反应按照TCPD→12，13-DHTCPD→THTCPD的途径进行。

Plasma sprayed dicalcium silicate bond tightly to Ti-6Al-4V substrate, its bond strength is up to 38.9 MPa.

等离子喷涂硅酸二钙涂层与 Ti-6Al-4V 基体结合强度较高，其值可达38.9 MPa 。

Since the improper blue-shifted H-bond and dihydrogen bond were found,the unusual phenomena have attracted more and more attentions of scientists.

特别是反常蓝移氢键和双氢键的发现，更加引起了科学家们的广泛关注。

In chapter four, the preperation of ytterbium diiodide was examined. The reductive cleavage of Se-Se bond and S-S bond induced by ytterbium diiodide was investigated. The reaction of diselenides and disulfides with allylic bromide promoted by ytterbium diiodide was also examined. The intermolecular Barbier-type reaction induced by ytterbium diiodide was studied. In the last section of this chapter, the intermolecular reductive coupling of nitriles with azides induced by samarium diiodide was investigated.

第四章，研究了二碘化镱的制备方法，以及二碘化镱作为一种优良的单电子转移试剂在有机合成中的应用：二硒醚的Se--Se键和二硫醚S-S键的还原断裂，及其在合成烯丙基硒醚，硒代酯和烯丙基硫醚，硫代酯中的应用，实验结果表明二碘化镱也能促进分子间的Barbier反应，而文献认为二碘化镱不能促进分子间的Barbier反应；最后研究了二碘化钐促进的叠氮化合物与腈的交叉还原偶联反应，一步高收率地制备脒的方法。

for preparing n-boc or n-cbz derivatives of chiral alpha,alpha'-disubstituted pyrrolidines containing olefinic bond and acetylene bond

一种制备含烯键和炔键取代基的手性α，α'-二取代吡咯烷的n-boc或n-cbz衍生物的方法

There had been a moment during the breakfast meeting, though, after the backslapping and the small talk and when all of us were seated, with Vice President Cheney eating his eggs Benedict impassively and Karl Rove at the far end of the table discreetly checking his BlackBerry, that I witnessed a different side of the man.

那次早餐会期间，在表示过关心和寒暄以后，我们所有人坐了下来，我注意观察了一下，副总统切尼面无表情地吃着班尼迪克蛋（Eggs benedict，源自美国，以英式松饼、火腿、水煮蛋以及荷兰酱组合而成），卡尔。罗夫在餐桌的远端谨慎地经常查看他的黑莓手机，我目睹了他所不为人知的一面。

Talk Undelete failed; someone else may have undeleted the page first.

Talk 无法删除选定的页面或图像（它可能已经被其他人删除了）。