球形

In the single crystal of C60 with a FCC structure,positron mainly appears outside the C60 molecule.The main annihilation space is the interspace between molecules.The calculated positron bulk lifetime in C60 is 352ps, which agrees with experiment value of 356ps in literature.In carbon nanotube bundles with different dimeters,as the diameter of carbon nanotubes increases,the main space where positron appears changes from the interspace of carbon tubes to the space inside carbon tubes,the radio between positron annihilation with valence eletrons and core eletrons becomes larger,the positron bulk lifetime in carbon nanotube increase rapidly first and come to be a constant at the end.The calculated positron lifetime of carbon nanotube with a dimeter of 0.8～1.6ns is 332～470ps,which agrees with the experiment value of 394ps.Positron annihilation has been studied in widly used compound semiconductors.

计算结果表明：在片层结构的石墨晶体中，正电子主要在石墨层间的空隙中湮没，计算出的石墨中的正电子寿命为208 pS，与文献中的实验结果215 ps符合很好；在金刚石单晶中，正电子主要在碳原子之间的空隙中存在并发生湮没，计算出的金刚石中的正电子寿命为115 ps，文献中的实验结果110 ps左右符合；在面心立方结构的C60晶体中，正电子主要在C60分子球壳内外侧及分子之间存在，C60球形分子中心正电子分布很少，正电子的湮没区域集中在C60分子之间的空隙区域，计算出的C60中的正电子寿命为352 ps与文献中的实验结果356ps相符合；对于不同管径碳米管束中的正电子分布，随着碳纳米管直径的增加，碳纳米管束中的正电子由主要在碳纳米管管间的区域出现转变为主要在碳纳米管管内中心的区域出现：碳纳米管束中的正电子与碳原子的价电子的湮没概率变得越来越大，与核心电子的湮没概率变得越来越小；碳纳米管束中正电子的湮没寿命先迅速增大，而后趋于一定值。

Monoecism or dioecism, round cone, fruit 2 years ripe.

雌雄同株或异株，球果近圆球形，果需要2年成熟。

Two types of dark green three-leaf whorled leaves, Dioecism, rare monoecism, round cone.

雌雄异株，少同株，球果近圆球形。

Any of various paired spherical bacteria, including those of the genus Diplococcus, some of which are pathogenic.

双球菌一种成对球形细菌，包括双球菌属的细菌，其中一部分是致病的

It has been found that the inherent improved flow characteristics of spherical pellets result in improved dispensing performance.

研究发现球形颗粒的内部流动性改良会引起分配的优化。

Follicles divaricate, thick, narrowly ovoid, apex acuminate.

极叉开的蓇葖果，厚，狭卵球形，先端渐尖。

The results show that the particles character as the growth of anion coordination tetrahedron during solvent thermal treatment, where blende-type ZnS particle is in the shape of double cone or tetrahedron, blend-type CdS appears as the tetrahedron, but wurtzite-type CdS is in the shape of cone. In addition, the particles with the better crystallinity are obtained with the increase of solvent thermal treatment temperature and time.

结果表明：采用溶剂热处理，粉末形状呈现负离子配位多面体生长特征，闪锌矿型ZnS粉末由球形变为双锥状或四面体状，颗粒上有明显的电子衍射花纹；闪锌矿型CdS晶体粉末主要呈四面体形状，而纤锌矿型CdS晶体粉末则以锥状为主，并且粉末的晶型随溶剂热处理温度的升高和时间的延长更趋于完整。

A large hemispherical brass or copper drum with a drumhead that can be tuned by adjusting the tension on it.

带有可调整张力鼓膜的半球形铜鼓。

Drupe obovoid-globose, with 2 or 3 one-seeded stones, base with remnants of persistent calyx tube.

核果倒卵球形球状，具2或3 一种子的核，基部具宿存的萼筒的残余。

Drupe 1-1.5 cm. Stone ovoid, to 1.3 cm, conspicuously 4-6(-8)-ribbed.

核果1-1.5 厘米。核卵球形的，在1.3厘米，显著4-6(-8)棱的。

She gently rebuff ed him, but agreed that they could be friends

她婉言拒绝了，但同意作为朋友相处。

If in the penal farm, you were sure to be criticized.

要是在劳改农场，你等着挨绳子吧！