四面体

Seeds obpyramidal, tetrahedral, or obovoid, narrowly winged along angles, transversely rugose, squamulose winged, lamellate, or concave reticulate.

种子倒金字塔形，四面体的，或倒卵球形，狭翅沿着棱，横向具皱纹的，具小鳞片具翅，片状，或凹网状的。

The total energies,ionization potentials and electron affinities of two geometric structures of O_4 are given.Compared with the calculated results of oxy...

与氧原子、普通氧分子O2和臭氧分子O3的计算结果比较，显示O4分子可以以正方形结构或正四面体结构形式存在，其中正方形结构更有可能是O4分子的真实空间结构。

ABSTRACT: Silicoaluminophosphate molecular sieves are microporous crystals with the structure of SiO2、AlO2－、PO2+ tetrahedral units.The physical—chemical properties of SAPO are not only similar to silicoalumino zeolites but also similar to some aluminophosphate zeolites.SAPO is a novel class of catalytic materials which exhibit excellent shape—selectivity、thermal and hydrothermal stability.

摘 要：磷酸硅铝分子筛是由SiO2、AlO2－、PO2＋三种四面体单元构成的微孔型晶体，它的物化性质不仅类似于硅铝沸石，同时具有某些铝磷酸盐分子筛的特性，是一种具有优异的择形选择性以及热稳定性和湿热稳定性的新催化材料。

Tetra-(8-hydroxy-quinolinato) boron complex with tetrahedral-like geometry and 3,3',4,4'-benzophenone tetracarboxylic anion with long-chain structure were successfully intercalated into layered double hydroxides with ion-exchange method.

我们首次选择了两种具有不同构型的光活性物种作为客体，即：具有四面体构型的四-(8-羟基喹啉)硼配合物和具有长链形状的3，3′，4，4′-苯酮四羧酸，得到了两种新的有机无机杂化光功能材料。

Tetrahexahedral Pt nanocrystals have been firstly prepared by the developed electrochemical method.

发展金属纳米晶体表面结构控制和生长的电化学方法，首次成功制备出二十四面体Pt纳米催化剂。

By developing the electrochemical method in this thesis to control surface structure and growth of metal nanocatalysts, we have prepared successfully not only platinum and palladium tetrahexahedral nanocatalysts, but also other nanocrystals of various shape enclosed by different high-index facets.

本文发展的金属纳米催化剂表面结构控制和生长的电化学方法，不仅制备出二十四面体Pt、Pd纳米催化剂，而且也用于成功制备其它高指数晶面围成的不同形状的金属纳米晶体。

The cellular structure of porous metal-bonded diamond wheel can be modeled by tetrakaidecahedron and their elastic modulus can be calculated by the finite element method. Furthermore, diamond is acted as reinforced particle.

利用十四面体模型描述开孔金属结合剂金刚石砂轮胎体的胞体结构，并用有限元方法确定材料的弹性模量，进而将金刚石以增强颗粒的形式加入胎体材料中，形成开孔结构的金属结合剂金刚石砂轮节块的有限元模型。

In this paper, material properties of the segment of the porous metal-bonded diamond grinding wheel were researched by finite element simulation. Segments were manufactured according to the design result and their elastic modulus was measured. The key points are as follows: The influence of the porosity on the elastic modulus was analyzed through a finite element method. In the FEM model, the design variable only includes the porosity, and the tetrakaidecahedron model is applied as the microstructure model of porous metal matrix. The corresponding porosity was decided in order to meet the requirement of the elastic modulus.

本文利用有限元软件对多孔金属结合剂金刚石砂轮节块的材料性能进行了数值模拟计算，依设计结果制备了节块试样，并测试了节块的弹性模量，主要内容有： 1、充分借鉴多孔材料结构设计和分析的方法，以十四面体模型为多孔金属胎体的微观结构模型，以孔隙率为设计变量，通过有限元分析，计算出满足一定弹性模量要求的多孔金属胎体的孔隙率范围。

L acted as tridentate ligand to chelate with metal atom in enol and ketone form respectively; In complex anion Co atom reside in tetrahedral coordination environment.

钴原子位于八面体配位环境中，配体L分别以烯醇式和酮式充当三齿配体与金属原子配位，配阴离子中Co原子位于四面体配位环境中。

Unstructural 2D triangle and 3D tetrahedron grids are generated using advancing front technology. The bidirectional chains are applied to accelerate some operations such as inserting, deleting and searching.

首先采用阵面推进法生成了二维三角形和三维四面体非结构网格，在生成过程中为了提高网格生成效率，采用双向链表和堆的数据结构，加快插入、删除和查找等单元操作。

Neither the killing of Mr Zarqawi nor any breakthrough on the political front will stop the insurgency and the fratricidal murders in their tracks.

在对危险的南部地区访问时，他斥责什叶派民兵领导人对中央集权的挑衅行为。

In fact,I've got him on the satellite mobile right now.

实际上 我们已接通卫星可视电话了