中壳

According to the principle of strontium isotope stratigraphy, we attempt to determine the age of the boundaries for Campanian/Santonian and Maastrichtian/Campanian by 87Sr/86Sr ratios for Gamba section in southern Tibet.

在与国际上同期海相地层锶同位素演化曲线对比的基础上，研究了晚白垩世海相碳酸盐锶同位素组成与主要地质事件的关系；在将本研究锶同位素数据融入到全球中新代海水锶同位素曲线的基础上，综合作出了中新生代海平面变化和锶同位素对照曲线，讨论了全球风化速率，造山事件，气候，海平面变化以及灾变性事件对中新生代海水锶同位素的控制作用；根据锶同位素地层学原理，本研究尝试将碳酸盐锶同位素组成用于海相地层定年上，利用已有的全球海水87Sr/86Sr值-年龄数据库和测试的藏南晚白垩海相碳酸盐的87Sr/86Sr值，确定了岗巴剖面Campanian/Santonian和Maastrichtian/Campanian阶界线，标定了广泛分布于白垩纪的厚壳蛤化石的年龄；本研究还将这些方法推广到了塔里木盆地井下奥陶纪地层的年龄标定，确定了中/上，中/下奥陶统界线，从锶同位素角度获得了古岩溶作用证据，显示锶同位素地层学在解决海相地层对比，年龄确定及在岩溶型油气储层研究中的潜在价值和良好应用前景。

A study was conducted in the lab from April to June in 2000. Mnipponense were fed in different vitamin D3 diets for four weeks and in vitamin D2 and D3 (70001U/ I OOg) for three weeks. After four weeks, we measured the effect of vitamin D3 in diet on survival, moult, length and weight gain, and the effect of the content of Ca P in plasma, in curst, in muscle, and also measured the effect of vitamin D3 on RNA/DNA value, on protein content in plasma and AEC of muscle.

本研究于2000年4-6月间在实验室条件下，用不同含量的维生素D_3投喂日本沼虾(Macrobrachium，nipponense)，饲养4周；用7000IU/100g饵料的维生素D_2和维生素D_3投喂日本沼虾，饲养3周后，测定了饵料中添加维生素D_3 对其存活率、蜕皮率、体长和体重的增长率等形态指标的影响；同时测定了虾血、虾壳和虾肌肉中的钙含量、磷含量以及维生素D对RNA/DNA值、血中蛋白含量和肌肉中的能荷的影响；并从上述指标的测定中，比较了饵料中添加维生素D_2和维生素D_3对日本沼虾生长的影响。

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。

This may be due to hydrolytic chelating, precipitation and the sediment or hydrobioes attachment, absorption etc. The honewort had stronger ability of accumulating La because of its large leaf surface that could attach La. The accumulating ability of snail and fish to La was relatively weaker but some organs of them had higher contents of La especially in the intestines, shell of snail, and in gill, internal organs, scales, head, bone of fish, rare in muscle. The total accumulating quantities of La in each component of simulated aquatic ecosystem were a decreasing order of: sediment ＞honewort＞snail＞fish, and the sequence of bio-concentration facter was as follows: honewort＞snail＞fish.

2金鱼藻对La有较强的富集能力，主要通过枝叶表面吸附、吸收而富集；螺蛳对La也有一定的富集，并主要分布于肠、壳中，螺头中积累相对较少；草鱼对La的富集能力相对较弱，进入鱼体的La主要集中在鳃、内脏、鳞及头、骨中，肌肉中积累量较少；按质量计，稀土元素La在模拟水生态系统各部分中的积累量依次为：底泥＞金鱼藻＞螺蛳＞草鱼；各水生生物对稀土La的生物富集因子依次为：金鱼藻＞螺蛳＞草鱼。

However, relating to investigate the modes, courses and characteristics of the orogenetic process in Paleozoic and after orogenetic process, the cognitive divergence have still occurred.

通过对新疆北东部地区不同构造区带构造作用的方式、过程和特点的研究，确定：①南天山榆树沟高压麻粒岩地体的正变质原岩是一个基本完整的蛇绿岩套，其经历了俯冲至下地壳的高压麻粒岩相、构造抬升至深地壳麻粒岩相以及快速构造折返至角闪岩相的变质过程，代表了南天山洋壳俯冲、变质、随后折返的过程，并首次确定了变质过程的PTt轨迹；②奥陶纪末期中天山北缘发生洋盆俯冲、地体增生作用，此时萨日达拉地区处于岛弧活动带；中石炭世晚期中天山小型洋盆关闭，准噶尔地块与伊犁—中天山板块斜向对接随后发生脆韧性质近水平高温低速右行走滑剪切；③根据巴音沟地区不构成蛇绿岩套有效成分的硅质岩具有与活动大陆边缘密切相关的地球化学特征以及洋中脊玄武岩显示其岩浆源区受到消减带流体交代作用的影响，结合区域地质资料，首次提出巴音沟蛇绿岩带所代表的洋盆古构造环境为弧后盆地，并于早石炭世至中石炭世末期间，经历了扩张、收缩和闭合过程；④首次在克拉麦里蛇绿混杂岩带中分解出具有N-MORB、T-MORB与OIB三种不同类型的火山岩岩石组合，反映了洋盆俯冲

The efficiency of shell and tube heat exchanger is a core to design of a shell and tube heat exchanger .

管壳式换热器是广泛应用于各个领域的工业设备，在国民经济中具有非常重要的作用，管壳式换热器的效率问题是设计工作的核心。

The ventilation system screamed into high gear, airlocks slammed into place where the chemical breached the hull--leaving parts of the ship effectively dead--and in the chilling near-vacuum the remaining chemical couldn't react to completion with the metal on the hull.

通风制度进入高速档之内尖叫，airlocks 猛然地撞进化学者突破了壳的地方--有效地完全地离开船的部份--和在无情者中接近-用吸尘器打扫那剩余的化学无法由於在壳上的金属对完成产生反应。

The levels of blood urea nitrogen and concentrations of some biogenic amines were also reduced in pigs given the diet with oat hulls, suggesting that oat hulls changed fermentation characteristics in the hindgut, possibly by altering the balance of the microbiota.

给仔猪饲喂燕麦壳也可以降低一些生物氨在血液中尿素氮的水平和浓度，得出燕麦壳很可能通过改变微生物的平衡来改变后肠的发酵特性。

Though 37 years passed after the double arch and flat shell structure applied in the water power engineering, the rubber canvas faceplate has never been used.

薄壳空间结构具有很多优点，我国在水工闸门中使用双曲扁壳结构的历史已有 37年，但尚未见到采用橡胶布面板的。

Themapping function sequences including circular cutouts and elliptical cutouts aregiven in this chapter.

然后为方便地满足圆柱壳大开孔的边界条件，通过复变函数方法中的用来求解多边形映射问题的Schwarz-Christoffel积分表达式，将圆柱壳展开面上的非圆非椭的开孔边界曲线保角映射成为单位圆，给出了在不同开孔率情况下的关于圆孔和椭圆孔的保角映射函数的具体形式。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。