晶核中心

The surface morphology of the nacreous layer on different parts of Pteria Penguin and blister pearl from Sanya, Hainan Province, are observed directly by using environmental scanning electron microscope.

研究结果表明，该地区海水成因的珍珠层中有机质薄膜对珍珠层的螺旋生长成核和结晶取向起到了严格的调控作用，它为文石或方解石晶体的生长提供一个有效的定位或成核中心；有机质与文石微晶在时间和空间上的螺旋交互生长具有周期性，从而产生珍珠层表面的这种结构形态。

In order to improve present Monte Carlo methods, method changing the node to optimistical orientation corresponding to the system having the lowest energy was proposed, which ensures the grain boundary moving to its curvature center. The new method avoided re-nucleation, and increased simulation efficiency, and made the simulation process more approaching the physics foundation of grain growth. The results show that the grain growth exponent, n=0.478, is close to its theoretic value, and the topological structure accorded with the normal grain growth of the real material.

简要回顾了晶粒长大理论并分析了现有Monte Carlo模拟方法的不足，提出了一个"择优转换"方法，确保节点转换时晶界向其曲率中心移动，以致模拟过程更接近物理基础，避免了重新形核的发生，使模拟效率大大提高，模拟的晶粒长大指数达到0.478，已接近理论值，组织形貌和实际材料正常晶粒长大组织基本一致。

The longer fluorinatd alkyl chain on the three-ring was advantageous to the formation of smectic phase. The mesogens with chiral center located between fluorinated tail and mesogenic core exhibited chiral smectic C phase and other smectic phases when the alkoxyl adhering to the other side of the mesogenic core was of intermediate length.

三环系液晶化合物中较长的氟烷基边链有利于近晶相的形成，且当液晶核另一端的烷氧基链的长度适中时，在氟烷基边链和液晶核之间具有手性中心的液晶分子显示了手性近晶C相和其它液晶相。

Symmetrical six-horn nickel diselenide nanostars were firstly synthesized with selenium powder as precursor but without any external reducing agents. Each nanostar consisted of a central core and six symmetrical nanohorns.

以硒粉为硒源，在无外加还原剂的条件下首次合成了六角星状二硒化镍纳米晶，每个纳米星具有一个中心核和六个对称纳米角。

In this thesis, a series of complexes based on aromatic multicarboxylic acids have been successfully synthesized in solutions or under hydrothermal conditions. Their structure and properties are investigated.(1) Eight complex compounds have been synthesized and characterized by X-ray single crystal diffractive technology: The eight complexes are listed as following: [Cu242] complex 1 [Cd22(H2O)4]·4H2O complex 2 [Co(H2btc)(H2O)3] complex 3 [Co2(H2O)2]·H2O complex 4 [Ni22(H2O)4] complex 5 [Cu22(H2O)4] complex 6 [Co(H2biim)2(H2O)2](H2btc) complex 7 [Zn(H2biim)2(H2O)2](H2btc) complex 8 The structure of complex 1 is dinuclear complex resulted from weak interactions（0-D chain）; complex 2 is 1-D chain stucture result from interactions of water molecules; complex 3、4、5、6 are coordination polymers using hydrothermal synthses, where the first kind ligand is H4btc, the second kind ligand is phen and Co2+、Ni2+、Cu2+ as center ions, respectively. While the coordination enviroment of Co2+ is the same in complex 3, the coordination geometries around the Co atoms in complex 4 are obviously different because of the different reaction conditions. In complex 4, the 1-D chains are connected into 2-D layer through carboxy groups of ligand H4btc. The structures of complex 5、6 are 1-D chain stucture result from interactions of carboxy groups in ligand H4btc. Complex 7、8 are homeomorphy compounds. Either of them are linked to the 3-D chains through intermolecular hydrogen bonds. Each H4btc lose two protons and H2btc2- acts as negative electron balance.

合成了8个结构新颖的配合物，并用X-射线单晶结构分析方法确定了晶体结构，分别为： [Cu242] 配合物1 [Cd22(H2O)4]·4H2O 配合物2 [Co(H2btc)(H2O)3] 配合物3 [Co2(H2O)2]·H2O 配合物4 [Ni22(H2O)4] 配合物5 [Cu22(H2O)4] 配合物6 [Co(H2biim)2(H2O)2](H2btc)配合物7 [Zn(H2biim)2(H2O)2](H2btc)配合物8 配合物1是一个依靠弱作用连接的双核铜结构；配合物2借助水分子形成一维链状结构；配合物3、4、5、6是以H4btc为第一配体、phen为第二配体，通过水热法合成的配合物，其中，Co2+、Ni2+、Cu2+为中心离子；配合物3中的二价钴离子具有相同的配位环境，不同反应条件下得到的配合物4中的二价钴离子存在不同的配位环境，在配合物4中，一维链通过H4btc上的羧基形成一个二维层结构；配合物5、6是借助H4btc上的羧基形成的一维链状结构；配合物7、8属于异质同晶结构，它们的分子通过分子间氢键形成三维网状结构，H4btc上的羧基失去2个质子，作为一个二价负离子起到电荷平衡作用。

Al (OC3H7)3 was added to an excess of distilled water (Al : H2O = 1:60-100 ) under vigorous stirring. Nitric acid [HNO3] was then added to peptize the hydroxide precipitate (Al: HNO3 = 1: 0.16). The reaction vessel was then closed and maintained for 48h at 90° C to get clear boehmite sol.

水解和缩聚反应的最终产物为非晶态的一水氢氧化铝，由许多 AlOOH 相互聚合交联形成的胶核处于中心位置，其外层是紧密吸附的同种离子 Al2O22+，它们共同构成了胶粒。

Consequently, they continued to grow and connected with each other to form the skeletal crystal for the porphyroblast.

本区石榴石、十字石等变斑晶的生长过程有多种形式，多数单晶不是一开始就环绕一个晶核不断增长，而是以多结晶中心聚集生长为特征。

As the alkyl chain moving from the terminal position to the lateral position near the central of the rigid core, the stability of the smectic A phase would be decreased.

当烷基链从端位移向靠近棒状刚硬核的中心侧位时，近晶A相的稳定性降低。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。