Synthesis and characterization of biodegradable aliphatic polyesters using dibutylmagnesium as initiator

Aliphatic polyesters were synthesized via the ring opening polymerization of the corresponding lactones initiated with dibutylmagnesium both in bulk and in solution. The resulting polymers were characterized by 1H, 13C NMR, GPC and XRD. The results indicated that dibutylmagnesium is an effective initiator for the ring opening polymerization of lactones.     

Investigation of the interaction of DNA and neutral red by?uorescence spectroscopic analysis

The binding characteristics of neutral red (NR) with DNA were investigated by fluorescence spectrometry. Chemometrics approach as singular value decomposition (SVD) was used to evaluate the number of spectral species in the drug-DNA binding process, and then the intrinsic binding constant of 1.6 104 in base pairs and the binding site number of 0.97 were obtained from the Scatchard plot.     

Three Dimensional Identification of Zonal Flows in the HL-2A Tokamak

1 Introduction Zonal flows （ZF） have been studied in some fusion devices. For example, geodesic acoustic mode （GAM） is observed with the frequency of fGAM - 15 kHz, poloidal mode number （m〈3） and radial wave number （ krρi -0.2） using beam emission spectroscopy at plasma edge in the D Ⅲ- D tokamak.     

THE STRUCTURAL PROPERTIES OF THE DISCRETE POSITIVE REAL MATRIX

In this paper, the structural properties of the discrete positive real matrix (DPRM) are discussed by means of coprime fraction of a rational function matrix. Some structural properties of the DPRM are the same with the continuous positive real matrix (CPRM), but the other properties are unique with the DPRM.     

周期函数的付立叶分解与合成实验

周期函数的付立叶展开的分析问题方法,在自然科学的各个领域中有着广泛的应用,如果学生在数学基础知识的理解基础上,通过物理实验展现出这个数学展开的过程,对加深这种分析问题方法的理解及开阔它的应用领域,有着很重要的意义.近年来已有高校将它引入到学生课堂实验中来,但在实验仪器上还存在一些待研究改进的问题,效果不够理想,因此国家教委教学仪器研究所     

25米~3单砖建筑物应用爆炸减压板保护的爆炸试验

本文介绍了在25米~3单砖建筑物中进行的四次液化石油气-空气混气的爆炸试验。由于建筑物内壁装了爆炸减压板,爆炸最大压力被减低到8千帕之下,建筑物主体结构完好无损。 建筑物内的很多化学操作都含有可燃液体或者可燃气体。当工艺设备出现偶然的破碎时,燃气或者可燃液体的蒸气便能够播散在建筑物内,与空气混合后形成爆炸混合物。为了防止这种可燃混气爆炸对建筑物造成严重破坏,常规方法对建筑物设置泄压面积。文     

离子交换树脂在中草药化学上的应用

在中草药化学上,离子交换树脂不仅可以用于提取、分离那些可以离子化或能够转变成离子型的化学成分,而且可以对这些成分进行含量测定;还可用于寻找中草药的有效部位。一、用于寻找有效部位在研究一个中草药的有效成分时,首先需要寻找有效部位,给研究工作定向。若采用传     

对制定中学数学教师继续教育大纲的认识

在中学数学教师学历教育结束以后,继续教育将提到议事日程上来了,它也是目前各教育学院和广大中学教师普遍关心的问题。继续教育要不要搞?如何搞?对编制继续教育大纲的原则、指导思想是什么?它应有怎样的课程结构?对教学方式、方法应作怎样的改革等等都是值得研究与讨论的问题,本期发表的北京教育学院陈通鑫、王长沛,上海徐汇区教育学院分部陈永明的文章,发表了这方面的意见,希望引起读者讨论。本刊将设专栏对继续教育问题作进一步的讨论。     

THE RESEARCHES OF GLACIER LAKE OUTBURST FLOODS OF THE YARKANT RIVER IN XINJIANG

The Jokulhlaup of the Yarkant River (Yarkant He) is usually csused by the sudden discharge of the glacier-dammed lake and the mode of the discharge is the rapid expansion of the subglacial channel. Keyajir (Kyagar) Glacier and Telamukanli Glacier are on the upper reaches of the Keleqin (Shaksgam) River, the chief birthplaces of this kind of flood. Up to the end of this century, since the global climate has become warmer, the glaciers have accordingly shrunk and become thinner, with the result that the size and dimensions of the glacier-dammed lakes and their outburst floods have diminished. All these simply reveal the mystery of the Jokulhlaups of the Yarkant River in Xinjiang.