Contents and distribution of rare earth elements in wheat seeds

Contents of 15 rare earth elements (REEs) in the seeds of 60 breeds of wheat have been analyzed by the inductively-coupled plasma mass spectrometry (ICP-MS). The distribution pattern of contents of REEs in wheat seeds has been observed and compared with that in soils. Comparison with literature data has also been made. The results show that the background of REEs in wheat seeds is 10-11-10-8 g.g-1, 3-4 levels lower than in soils. The distribution pattern is light REEs higher in contents and slight Eu-anomaly, similar to that in soils. The data obtained in this study can accurately represent the background content of REEs in wheat seeds.     

Integrated Passive and Active Vibration Control of Ultra-precision Lathe

In ultra-precision cutting process, vibration is one of the key factors affecting the machining quality. In this paper, the damping methods of HCM-I Ultra-precision Lathe are discussed in both complete machine and slide. It is pointed out that integrated passive and active vibration control (IPAVC) by combining passive vibration control (PVC) and active vibration control (AVC) can not only eliminate high frequency vibration but also improve the damping effect to low frequency vibration. Experiment results show the effectiveness of the integrated passive and active vibration control.     

Asymmetric Information in Combating Terrorism: Is the Threat Just a Bluff?

<正>Introduction Terrorists now have international networks with terror-ism potentially having catastrophic effects. Worldwide, domestic, and transnational terrorists threaten public safety as they create disorder for political, religious or other reasons. Terrorist events, even a single terrorist     

Quantum Size Effect of the Magnetism of an Electron in a Metal Layer of the Layered Compounds M/I/M/I…

The energies and the magnetization of an electron in a piece of metal in the structure of Metal/Insulator/Metal/Insulator…(M/I/M/I…), in a magnetic field, at high temperature, and in range of quantum size thickness of the piece of metal layer have been obtained. The results show that when the thickness of the metal layer becomes smaller, the orbital magnetism of the charged particles which collide with the wall of the metal layer is to vary from diamagnetism to paramagnetism. The smaller the thickness of the metal layer becomes, the more particles will collide with the boundary of the metal layer, and then the paramagnetism becomes stronger. Finally, when the thickness of the metal layer becomes very small (＜100 nm), all of the orbital diamagnetism will reverse to paramagnetism, and then the paramagnetization will be almost a maximum constant.     

An atomistic simulation of site preference and vibrational properties of UMxAl12-x （M = Fe, Co, Ni, Cr and Mn） and UMxAl1z-xHx

A series of lattice inversion pair potentials are used to evaluate the phase stability and site preference for uranium intermetallics UMxAl12-x (M = Fe, Co, Ni, Cr and Mn) and their related hydrides. Calculated results show that Fe, Co, Ni, Cr or Mn atoms preferentially substitute Al at the 8f site. Interstitial H atoms only occupy 2b interstitial sites in UMxAl12-x. Calculated lattice constants are found to agree with a report in the literature. Elastic constants and bulk modulus of UMxAl12-x and UMxAl12-xH were also investigated. In particular, the phonon densities of states (DOS) of these actinide compounds were evaluated for the first time.     

Efficient polymerization of acrylonitrile catalyzed by divalent lanthanide complex/ sodium phenolate systems

Four divalent lanthanide complexes Sm(ArO)₂ - (THF)₄, Yb(ArO)₂(THF)₃, Eu(ArO)₂(THF)₃ (ArO = 2,6-di- tert-butyl-4-methylphenolate) and (Bu^tCp)₂Sm(THF)₂ were synthesized. Their catalytic activities on the polymerization of acrylonitrile were studied. The catalytic activities were influenced by the central metal ions involved. The catalytic activities of these divalent lanthanide complexes can be greatly increased by adding NaOC₆H₂-2,6-Bu^t₂-4-Me, NaOC₆H₄-4-Bu^t, or NaOC₁₀H₆-2-Me. The amount of additive has apparent effect on the catalytic activity, but the additive has no effect on the tacticity of the resulting polyacrylonitrile.     

“高师有机题库”应用软件钥匙盘的研制

研究了磁盘、磁盘控制器和ＲＯＭＢＩＯＳ软件的原理，并编制汇编程序，制作钥匙盘．     

西方政治思想史上的自由概念

在西方政治思想史上,自由是被人们讨论最多的概念之一.但对于什么是自由,众说纷纭.对之进行梳理,可以归纳出四种主要的自由概念：自由是一种免于强制的状态;自由是参与公共事务的权利;自由是一种精神状态,主要表现为对欲望的克制;自由是一种能力,特别是与必然有关的能力--或是对必然的认识,或是对必然的改造,或独立于必然.上述自由概念从不同的角度揭示了自由,但政治学意义上的自由主要包括前两种.     

论选择公理与2(※)0≥(※)1的关系

那汤松(HamaHcoH)在他所著的《实变函数》认为,不需要选择公理就可以证明20≥1.证明, 若ZF+AD是和谐的, 则没有选择公理,2(※)0≥(※)1不成立.从而说明那汤松所提示的证明是不严格的.     

VHDL硬件描述语言及其设计环境

VHDL硬件描述语言及其设计环境是一个形式化、层次化和规范化的计算机硬件描述与设计语言系统,它的出现为实现计算机设计领域的科学化迈出了重要的一步。本文较详细地介绍了VHDL的起因、历史和现状,概要地论述了VHDL语言及其语言特征,并讨论了VHDL的设计环境,最后提出了实现该系统的基本途径。