端羧基/羟基丙烯酸正丁酯聚合物的合成

研究了丙烯酸正丁酯在两种链转移剂巯基乙酸（TGA）和巯基乙醇（TEG）存在下的自由基聚合反应，合成了具有端羧基或端羟基的丙烯酸正丁酯聚合物，并用IR，NMR，GPC，酸碱滴定等方法对其进行了表征，以1／Pn对[S]／[M]作图求出了两种链转移剂在聚合条件下的链转移常数，讨论了端基官能团化的比率，滴定法和GPC法得到的TGA的链转移常数分别为0．64，0．67，滴定法得出TEG的链转移常数为0．67，保持单体和引发剂的摩尔比（100：1）不变，当单体与链转移剂的摩尔比大于0．02时，端基官能团化的比例可达85％以上。     

分次代数的分次Jacobson根

证明了对一般Monoid分次R－代数A（A未必有1，R是有1的交换环）的分次Jacobson根J'G（A）与作为分次环A的分Jacobson根相等，并给出了J'G（A）的几个特征。     

The reaction of acenaphthene with nitrobenzene

The reaction of acenaphthene with nitrobenzene was investigated in the presence of AlCl₃. The results showed that the reaction proceeded via carboncation-electrophilic substitution reaction and free radical substitution reaction pathway. The products of acenaphthenyl phenylamine and biacenaphthyl could be synthesized by this reaction. The influence of the amount of AlCl₃ and the temperature on the components of products were also studied in this reaction. Foundation item: Supported by the National Nature Science Foundation of China (No. 29676045) Biography: Wu Lin (1965-), male, Postdictor, research direction: PAHs catalytic conversion and its biologic toxicity.     

12-磷钼酸对苯乙烯自由基阻聚反应动力学影响的研究

用膨胀计法研究了12-磷钼酸的自由基阻聚反应动力学，实验证明，在苯乙烯自由基聚合过程中12-磷钼酸确实抑制了聚合反应速率，动力学数据表明，苯忆烯自由基聚合反应速率的改变值与12-磷钼酸浓度的0.16次幂成正比。     

无机盐熔点的一些变化规律

本文重点讨论酸根构型及其组成酸根的中心原子在周期表中的位置对无机盐熔点影响的一些规律。     

Bacterial suicide through stress

Outside of the laboratory, bacterial cells are constantly exposed to stressful conditions, and an ability to resist those stresses is essential to their survival. However, the degree of stress required to bring about cell death varies with growth phase, amongst other parameters. Exponential phase cells are significantly more sensitive to stress than stationary phase ones, and a novel hypothesis has recently been advanced to explain this difference in sensitivity, the suicide response. Essentially, the suicide response predicts that rapidly growing and respiring bacterial cells will suffer growth arrest when subjected to relatively mild stresses, but their metabolism will continue: a burst of free-radical production results from this uncoupling of growth from metabolism, and it is this free-radical burst that is lethal to the cells, rather than the stress per se. The suicide response hypothesis unifies a variety of previously unrelated empirical observations, for instance induction of superoxide dismutase by heat shock, alkyl-hydroperoxide reductase by osmotic shock and catalase by ethanol shock. The suicide response also has major implications for current [food] processing methods. Received 29 March 1999; received after revision 14 May 1999; accepted 17 May 1999     

反单根与Jacobson根的关系

本文讨论反单根与Jacobson根的关系,作为推论,我们给出文献[1]中问题100的肯定回答存在非诣零的反单环     

On The Impossibility Of Empirical Controls Of Scientific Theories – From The Point Of View Of A Psychologist

Standard considerations of philosophy of science are reformulated in psychological terms and arguments, suggesting a fundamental change in life perspective: subjective experiences or introspective data are subject to motivational biases and therefore not admitted as objective empirical facts in science, However, we never experience objects or events of the external world, i.e., so called objective facts, but exclusively subjective percepts or mental events. They are merely assumed to, but may or may not be accurate or distorted mental representations of objects or events of an external world. Accordingly, the latter are theoretical constructs, i.e., constructs of the fictitious but most successful predictive (implicit) theory, called external world, which seems to be constructed from regularities observed in mental events and serves as a reference fiction for, erroneously called empirical, tests of predictions of scientific theories.Relevant Publication: Micko, H.C.: 2001, Psychologie: Von der Geistes – zur Naturwissenschaft – und weiter wohin? Erkenntnistheoretische Erwägungen vor und nach dem Aufkommen des philosophischen Konstruktivismus. Ztschr. f. Psychologie, 209: 54–68.     

<Emphasis Type="Italic">In situ</Emphasis> generation and detection of methyl radical by voltammetry

The chemistry of free radicals is one of the advanced subjects of fundamental sciences such as biomedicine, environment protection, new energy sources and new material. The detection technique of free radicals is an essential tool for studying free radicals. Methyl radical is one of the representatives of alkyl radicals and the studies on it attract more attention. The current approaches to obtaining methyl radical are based on pulse radiolysis of organic substances that contain the methyl gro…     

4-Hydroxynonenal-modified amyloid-beta peptide inhibits the proteasome: possible importance in Alzheimer's disease

The amyloid β-peptide (Aβ) is a 4-kDa species derived from the amyloid precursor protein, which accumulates in the brains of patients with Alzheimer’s disease. Although we lack full understanding of the etiology and pathogenesis of selective neuron death, considerable data do imply roles for both the toxic Aβ and increased oxidative stress. Another significant observation is the accumulation of abnormal, ubiquitin-conjugated proteins in affected neurons, suggesting dysfunction of the proteasome proteolytic system in these cells. Recent reports have indicated that Aβ can bind and inhibit the proteasome, the major cytoslic protease for degrading damaged and ubiquitin-conjugated proteins. Earlier results from our laboratory showed that moderately oxidized proteins are preferentially recognized and degraded by the proteasome; however, severely oxidized proteins cannot be easily degraded and, instead, inhibit the proteasome. We hypothesized that oxidatively modified Aβ might have a stronger (or weaker) inhibitory effect on the proteasome than does native Aβ. We therefore also investigated the proteasome inhibitory action of Aβ _1–40 (a peptide comprising the first 40 residues of Aβ) modified by the intracellular oxidant hydrogen peroxide, and by the lipid peroxidation product 4-hydroxynonenal (HNE). H₂O₂ modification of Aβ _1–40 generates a progressively poorer inhibitor of the purified human 20S proteasome. In contrast, HNE modification of Aβ _1–40 generates a progressively more selective and efficient inhibitor of the degradation of fluorogenic peptides and oxidized protein substrates by human 20S proteasome. This interaction may contribute to certain pathological manifestations of Alzheimer’s disease Received 26 September 2000; accepted 26 September 2000