欧盟禁用蓝染料

欧盟今年1月9日在官方刊物公布2003/3/EC指令,禁止使用一种俗称“蓝染料”的偶氮染料。有关法例于1月29日生效,但要到2004年6月30日才会落实推行。     

欧盟限制食品中禁用染料的含量

欧盟官员不久前表示，欧盟当局已对食品中含有可能致癌的禁用染料设定了严格界限。在欧盟成员国，任何工业染料(如苏丹红和对位红染料)含量超标的产品，都必须从市场撤出。检测界限设定为0．5～1mg／kg。今后这一指标还可能继续降低。苏丹红有致癌性和基因毒性，而调味品中出现的对位红染料也存在致癌风险。欧盟各国的科学家将共同研究改善检测染料的分析方法。     

关于电负性的几个问题

“电负性概念是化学领域中,特别是无机化学、有机化学中应用得最广泛的一个基本概念。在其他学科,例如地质化学、分子生物学,以及材料科学中也有较多应用。1932年鲍林根据经验事实给电负性下了一个定性的定义,并且提出了一个定量计算电负性值的公式。     

有关化学平衡的几个问题

化学平衡是化学反应的普遍现象,分析与了解化学平衡是具有重要意义的,它将有助于人们控制反应条件,使反应按预定的方向进行;或者了解在给定的条件下反应进行的最大限度等。     

几个无机化学问题的解答

应广大读者的需要,本刊特开辟"问题解答"栏.本栏拟选登一般教科书或参考书未简明解疑的、重要问题的答案.力求简明扼要.本期刊出的两则,我们认为确系中学教学中需要注意的问题.其他问题的解答将于本栏陆续发表.因限于人力,一般来问恕本刊不一一作覆.     

关于氢键的几个问题

氢键或称氢桥(hydrogen bridge),指在分子内或分子间两个电负性很强的原子,经过一个氢原子而相互连接起来;这是1887年俄国化学家М.А.Ильинский和Н.Н.Бекетов研究隣-亚硝基苯酚、吡啶醌的时候首先提出的。     

关于溶解性的几个问题

讨论了溶质和溶剂的极性与溶解度的关系;分子所含的极性基团与溶解度的关系;同素异形体和同分异构体的溶解性;在同一溶剂中2种溶质对溶解性的相互影响;溶质在混合溶剂中的溶解性;两亲（亲水、亲脂）溶质的溶解性;金属间的相互溶解。     

有关化学试剂的几个问题

解放以前,我国在生产、科学研究或教学上所用的化学试剂,主要是依靠进口货。那时候国内所生产的试剂的种类、产量都很少,质量也不可靠。当然,在国民党统治时期,民不聊生、工业生产陷于停顿的情况下,化学试剂的生产当然也不能例外。还有,当时科学工作者迷信外国,不相信自己的思想,也阻碍了试剂的推广。解放十年以来,我国的试剂工业有了很大的发展。目前国内能够生产的化学试剂种类很多。除最常用的酸、硷等以外,较复杂的有机试剂、许多种希有元素及其化合物、高纯度的试剂如光谱纯物质等等也能够生产。现在国内各方面所需要的各种试剂,除国内缺乏原料(如热带植物原料等)、需要量较少的及技术特别复杂的以外,大部分已能自已生产。在价值上,国产试剂占     

从几本外国教材想到的

笔者最近阅读了几本外国的中学化学教材,联想到我国的教材建设,觉得有几个地方,很值得我们借签。     

欧盟新化学品立法——REACH制度简介

REACH制度是欧盟提出的基于风险控制的化学品管理新框架。REACH制度不仅涵盖了化学品,而且也对纺织、机电等化学品的下游产品提出了注册要求。对REACH制度的产生背景及主要内容进行了介绍,着重分析了REACH提案所遵循的基本逻辑。     

关于气相色谱仪检定的几个问题

在对气相色谱仪进行检定的过程中,遇到了有关色谱柱,标准样品,积分仪和色谱数据工作站数据采集等实际问题,为了既不影响生产工艺分析任务的进行,又能及时完成对仪器性能的检定工作,采取了相应的措施和办法,较快地完成了对气相色谱仪的检定,并对某些测试数据进行了比较和讨论。     

AN APPROACH TO OLIGONUCLEOTIDE SYNTHESIS BY THE PHOSPHOTRIESTER METHOD

Abstract

A systematic approach to the chemical synthesis of oligoribo- and oligodeoxyribo-nucleotides is described. Synthesis in both series of oligonucleotides has been tackled as a two-stage problem. The first stage, which is concerned with the preparation of correctly-orientated, suitably-protected nucleoside building blocks, has been completed. The second stage, which is concerned with the development of an effective phosphorylation procedure for linking the building blocks together, is presently being investigated. From the results obtained so far, it is apparent that the phosphotriester approach to the synthesis of oligonucleotides, especially with phenyl (and other aryl) protecting groups, is superior to approaches which involve unprotected internucleotide linkages during synthesis.     

INHIBITION OF THE IMMUNE RESPONSE TO ALLOANTIGEN IN THE RAT BY EXPOSURE TO ULTRAVIOLET RADIATION

Exposure of mice to ultraviolet radiation (UV) followed by alloantigen sensitization can suppress the immune response to that alloantigen. In order to assess the applicability of using UV-induced immunosuppression in organ transplantation, the effectiveness of UV in prolonging the survival of vascularized organ allografts must be determined. Because, for technical reasons, rats are better suited than mice for such experiments, we first wanted to determine whether UV suppresses the immune response of inbred rats to alloantigens. The data presented here demonstrate that exposure of rats to UV (115-129 kJ/m2) prior to alloantigenic sensitization decreases the mixed lymphocyte response to alloantigen. The depression of the proliferative response to alloantigen was selective in that spleen cells from the UV-treated rats could respond to mitogenic stimulation. In contrast to previous results with mice, suppressor cells could not be demonstrated in the spleens of the UV-treated rats. In addition, UV treatment after sensitization inhibited the response to alloantigen. These data suggest that treatment of the recipient with UV before or after alloantigenic sensitization may provide a novel method of inhibiting immune responses to allogeneic antigens.     

硝酸氧化蒽制备蒽醌

蒽醌是用途广泛的化工原料和中间体,主要用于生产还原染料、分散染料、活性染料和酸性染料等。此外,用蒽醌制造变性剂,可以保护植物种子,蒽醌还可用于制造双氧水。近几年来,蒽醌在纸浆制造方面的需求也在迅速扩大。目前,蒽醌的制造方法基本上可分为两种类型。一类是...     

A NOVEL APPROACH TO SYNTHESIZE CHITOSAN BEADS CROSSLINKED BY EPICHLOROHYDRIN

The present investigation describes a novel method for preparing spherical chitosan particles based on crosslinking with epichlorohydrin.Certain amount of pre-crosslinking agent was added to form chitosan gels by traditional inverse phase suspension polymerization.Then the gels were crosslinked by epichlorohydrin at basic condition to obtain chitosan beads.The effects of reaction conditions,such as crosslinking time,the amount of crosslinking agent and the NaOH concentration,on the physical properties of the chitosan beads were investigated.The beads were found to have more amino groups in the polymer chains than the beads crosslinked by glutaraldehyde.The capacity for copper ions in as high as 40mg/g,The beads have good mechanical strength and can be reused.     

A NOVEL APPROACH TO SYNTHESIZE CHITOSAN BEADS CROSSLINKED BY EPICHLOROHYDRIN

1. INTRODUCTION Chitosan is the deacetylated chitin which is one of the most abundant natural polymers produced from crab, lobster and shrimp shells or fungal fermentation processes [1]. It is a family of deacetylated β1→4 D-glucosamine polymers. Chitosan has properties including bioactivity, biocompatibility and biodegradability, so it is potentially more useful than cellulose for developing advanced of attention not only as an unutilized biomass resource but also as a novel type of sp…     

INVESTIGATION OF DAMAGE TO FOREST BY EPR SPECTROSCOPY in vivo

Spruce needles collected from several trees of the Black Forest were investigaled by EPR spectroscopy. These needles show in the g = 2.00 region a signal II_S(Tyr D ₊) and a light-induced signal I(P700₊) and a Mn₂₊ hyperfine structure which superimposes the other absorptions. Difference spectra, light minus dark, partly eliminate the manganese hyperfine structure, and P700₊ can be observed. By comparison of these EPR signals with those of spinach chloroplast or thylakoid membranes described in the literature, significant deviations were observed, whereas several trees grown in the vicinity of Tubingen exhibit the well known D₊ and P700₊ EPR spectra. After treatment of branches of these 'normal' trees with herbicides like Amitrol and Roundup or chemicals like toluene or trichlormethane the EPR signals obtained are comparable with those observed with needles of the Black Forest.     

HOW TO USE MAJOR PARTS OF A PAPER PREVIOUSLY PUBLISHED BY OTHERS TO WRITE A NEW ONE. AN ALLEGATION OF PLAGIARISM BY INDIAN AUTHORS

ABSTRACT

In our present communication we prove the allegation that Indian authors plagarized the major parts and conclusions of our paper published in 1997 and used them in their paper published in this journal in 2000.     

HV-21型碳硫自动分析仪测定碳、硫常见问题及解决办法

采用HV－21型碳硫自动分析仪测定碳、硫时，经常出现空白值偏高，碳含量突然偏低或无检测信号等现象，对这些现象进行了分析并提出了解决办法。