三氯偶氮胂直接光度法测定金属材料中铈组稀土元素

研究了三氯偶氮胂在盐酸－草酸介质中与钢铁及合金材料中铈组稀土元素的显色反应。试验表明，在盐酸（２Ｍ）－草酸（０．０８Ｍ）介质中，铈组稀土元素与三氯偶氮胂形成稳定的络合物。其最大吸收波长λｍａｘ＝６３０ｎｍ，表现摩尔吸光系数ε＝１．１×１０４Ｌ／ｍｏｌ·ｃｍ，铈组稀土元素与三氯偶氮胂的络合比为１：２。用本法测定了球墨铸铁、合金钢、铝合金、镁合金和钴合金等金属材料中的铈组稀土元素，其结果令人满意。     

稀土矿中吸附性稀土总量的重量分析法

用７％ＮａＣｌ水溶液淋洗稀土矿，使吸附性稀土离子进入溶液，经氢氧化物沉淀后，用草草酸盐重量法测定稀土矿中吸附性稀土总量，方法有较好的选择性，适合勘探普查稀土矿床时对含量很人低的吸附性稀土总量的测定。     

由递推关系式确定数列的阶

在一些由递推关系式所决定的数列中,通常需要对数列的阶进行估计。由于数列的显式表达式一般很难求出,因此要判定它们的阶并不是一件容易的事。本文对两种不同类型的递推关系式采用不同的方法得到数列极限的细致刻画。     

Determining the architectures of macromolecular assemblies

To understand the workings of a living cell, we need to know the architectures of its macromolecular assemblies. Here we show how proteomic data can be used to determine such structures. The process involves the collection of sufficient and diverse high-quality data, translation of these data into spatial restraints, and an optimization that uses the restraints to generate an ensemble of structures consistent with the data. Analysis of the ensemble produces a detailed architectural map of the assembly. We developed our approach on a challenging model system, the nuclear pore complex (NPC). The NPC acts as a dynamic barrier, controlling access to and from the nucleus, and in yeast is a 50 MDa assembly of 456 proteins. The resulting structure, presented in an accompanying paper, reveals the configuration of the proteins in the NPC, providing insights into its evolution and architectural principles. The present approach should be applicable to many other macromolecular assemblies.     

由递推关系式确定数列的阶

在一些由递推关系式所决定的数列中,通常需要对数列的阶进行估计.由于数列的显式表达式一般很难求出,因此要判定它们的阶并不是一件容易的事.本文对两种不同类型的递推关系式采用不同的方法得到数列极限的细致刻画.     

非奇异M矩阵的判定

给出了Ｍ矩阵的几个新的判定准则，这些准则具有简单、方便的特点，且与已有的判定准则相比，具有更为广泛的适用范围。     

From digital Earth to smart Earth

This article will analyze the achievements of the digital Earth concept and further introduce two key technologies,the internet of things and cloud computing.Both these technologies are accelerating the development of digital Earth toward a new concept—smart Earth.The objective of this article is to discuss the architecture,infrastructure,and typical applications for smart Earth and to elaborate on trends of the movement from digital Earth to smart Earth.     

稀土配合物与基质材料的复合(一)

稀土配合物与基质材料复合既具有稀土离子特殊性能,又具有高分子材料质量轻、抗冲击力强和易加工成型的优良性能,具有极其广阔的应用前景,特别是稀土离子在有机介质中的光吸收和受激发射受到人们的重视。稀土有机高分子材料主要有两大类：一类是将稀土化合物作为掺杂剂均匀地分散到单体或聚合物中,制成以掺杂方式存在的稀土高分子聚合物;另一类是稀土化合物以单体形式参与聚合或缩合,或与大分子链上的官能团进行络合,直接配位在聚合物的侧链上,获得以键合方式存在的稀土高分子聚合物。文中以这两大类稀土高分子聚合物的复合方法及研究状况为主要内容进行综述,并介绍了稀土高分子聚合物的主要应用。     

接地相的判断方法

在矿井三相供电系统中，中性点不接地系统中单相故障接地相的判断法：三相电压中以指示值最高相为依据，按相序顺序往下推移一相才是故障相。     

Volatile accretion history of the Earth

It has long been thought that the Earth had a protracted and complex history of volatile accretion and loss. Albarède paints a different picture, proposing that the Earth first formed as a dry planet which, like the Moon, was devoid of volatile constituents. He suggests that the Earth's complement of volatile elements was only established later, by the addition of a small veneer of volatile-rich material at ～100 Myr (here and elsewhere, ages are relative to the origin of the Solar System). Here we argue that the Earth's mass balance of moderately volatile elements is inconsistent with Albarède's hypothesis but is well explained by the standard model of accretion from partially volatile-depleted material, accompanied by core formation.     

Determining the position of the cell division plane

Proper positioning of the cell division plane during mitosis is essential for determining the size and position of the two daughter cells--a critical step during development and cell differentiation. A bipolar microtubule array has been proposed to be a minimum requirement for furrow positioning in mammalian cells, with furrows forming at the site of microtubule plus-end overlap between the spindle poles. Observations in other species have suggested, however, that this may not be true. Here we show, by inducing mammalian tissue cells with monopolar spindles to enter anaphase, that furrow formation in cultured mammalian cells does not require a bipolar spindle. Unexpectedly, cytokinesis occurs at high frequency in monopolar cells. Division always occurs at a cortical position distal to the chromosomes. Analysis of microtubules during cytokinesis in cells with monopolar and bipolar spindles shows that a subpopulation of stable microtubules extends past chromosomes and binds to the cell cortex at the site of furrow formation. Our data are consistent with a model in which chromosomes supply microtubules with factors that promote microtubule stability and furrowing.     

实代数数的代数表达式的符号判定

将符号计算方法与数值计算方法结合起来应用于计算机代数领域,构造了一种判定实代数数的代数表达式的符号的算法,并在计算机数学系统上加以实现,算法的基本思想是对每一个实代数数ａ定义了一个二元组（Ｉ,ｆ（ｘ））,其中Ｉ是包含ａ的区间,ｆ（ｘ）是ａ所满足的多项式,并将代数数的运算转化为对应的二元组的运算,同时结合多项式的根的最短距离估计式,从而达到对代数数的代数表达式进行符号判定的目的。     

确定负荷中心的一种解析法

运用重心原理．导出求解平面或空间负荷中心位置的解析式。     

追捕逃逸型微分对策问题的识别域判别

研究了仿射非线性控制系统下的单目标两人追捕逃逸型微分对策问题,解决了该类控制系统在不等式约束区域上系统识别域的判别问题,给出了判别识别域的充分必要条件.首先利用生存理论及非光滑分析工具得到了仿射非线性控制系统的识别域判别定理,从而把对该非线性控制系统识别域的判别问题转化为求解凸不等式组的相容性问题.基于凸可行问题的求解方法给出了此问题的投影算法,并给出算法相应的收敛性定理.最后得到了仿射非线性系统下的两人追捕逃逸型微分对策问题的选择定理.     

生产氟化稀土新工艺的理论浅析

对稀土草酸盐转化成氟化物进行了理论探讨 ,导出了从稀土草酸盐转化成氟化物的平衡常数 ,由平衡常数可知 ,一些稀土草酸盐可定量地转化成氟化物 ,生产实践证明了这种转化的可行性。