CLIMATIC CHANGE SINCE LITTLE ICE AGE RECORDED BY DUNDE ICE CAP

The climatic change since the Little Ice Age recorded in the Dunde Ice Cap is presentedin this paper. There have been three cold periods and three warm periods since 1400AD.Among them, the coldest one was in the 17th century. Many evidences verified the three coldand warm variations recorded in the Dundc Ice Cap. But it was found from the comparison between the Dunde Icc Cap climatic record and thewinter temperature record in Shanghai that there was a temporal dfference in climatic changebetween East China and West China. The general trend is that the cooling and warmingprocesses in West China were earlier than that in East China. In the Dunde Ice Cap, it isnow in an anomalous warm period, while it is not as warm as in Dunde Ice Cap recordaccording to the winter temperature in Shanghai. In addition to the possible cause of temporaldifference in climatic change between West China and East China, another possible cause isthat the greenhouse effect of CO_2 may already be recognizable in the Dunde Ice Cap a     

CYTOLOGIC AND EMBRYOLOGIC STUDIES ON APOMICTS DISCOVERED FROM MALE STERILITY LINE C1001 IN RICE (Oryza sativa L.)

Cytologic and embryologic studies on the reproductive pattern of male sterility line C1001 in rice (Oryza saliva L.) indicated that several types of apomixis were discovered in partial strains of male sterility line C1001 in rice. Under a fully separate condition, two possible apomixis embryogenesis ways in the ovules were observed: One way was that the embryo was initiated from the somatic cells of the ovules, and then pushed against the embryo sac to develop into a mature embryo. The other way was that the embryo was from the unfertilized egg cell or one of synergids, and then developed into a mature embryo in the form of haploid parthenogenesis without forming endosperm. Besides, the antipodal cells migrated in the embryo sac, and their cytoplasm became thin and vacuolated while mitosis was taking place, giving rise to a multicellular structure or a group of large cells each containing several nuclei. This paper also discusses the significance and patterns of apomixis in rice C1001.     

The electrochemical reduction of perezone in the presence of benzoic acid in acetonitrile

An electrochemical study using transient techniques of a quinone-type natural product, perezone, has been performed in acetonitrile and in the presence of benzoic acid. Using linear sweep voltametry and single potential step chronoamperometry, it was possible to establish that the reduction mechanism of perezone involves a monoelectronic charge-transfer step, followed by a protonation step and homogeneous charge transfer due to disproportionation of the protonated intermediate. The mechanism for the homogeneous charge-transfer step was found to be of the type DISP1 (disproportionation order one) from the results of double potential step chronoamperometry experiments. The occurrence of the DISP1 mechanism was provoked by the mildly acidic medium used in this study.     

SYNTHESES OF THE SOLUBLE,HIGH MOLECULAR WEIGHT AND LADDERLIKE POLYPH ENYLSILSESQUIOXAN E AND COPOLYMETHYLPHENYLSILSESQUIOXANES BY PREAMMINOLYSIS METHOD

Soluble, high molecular weight (MW) and ladderlike polyphenylsilsesquioxane (LPPSQ) and its copolymers, ladderlike random and block copolymethyiphenylsilsesquioxanes(LR-PMPSQ and LB-PMPSQ)have been prepared by preamminolysis, hydrolysis and polycondensation reactions. The preparation method can be carried out easily at the temperature below 95℃with high yield of 95 %, instead of the conventional way by using high-boiling solvent and any reaction activator or by precipitation with methanol. Three kinds of ladderlike polymers have been characterized. The MW's of the polymers reached to 10~6 without noticeable gelling. The scheme for synthetic route has been proposed.     

三环己基锡芳氧乙酸盐的合成及其结构表征

三环己基锡衍生物(Cy_3SnX,Cy=环己基,X=配体或取代基)是一类具有较强生物活性的有机锡化合物,它们广泛用作杀螨剂,杀菌剂和海洋防污剂。有关三环己基锡芳氧乙酸盐的合成至今报道很少。Bubblitz 合成了两个三环已基锡芳氧乙酸盐,此后,Matsuda 等人制备了三环已基锡-2,4-二氯苯氧乙酸盐,它们都具有良好的杀螨、杀菌活性,后者还可应用于海洋     

一类新型的“三块板”式卟咻化合物的合成及光物理性质初探

在光合作用原初过程中,太阳能转化成电能的关键步骤为:在光引发下,电子从一个叶绿素给体 D 转移到泛醌受体 A,从而产生D~ 和 A~-。光合作用原初过程及其人工模拟是受到世界各国普遍重视的一个研究领域。特别是近年来。卟啉(D)-醌(A)类化合物引起了人们的广泛兴趣,其中三块板式化合物是目前最接近     

Analysis in terms of valence-bond structures of environmental effects on the electronic structure of molecules

Environmental effects on the electronic structure of molecules caused by external perturbations are studied by means of an expansion of molecular orbital wave functions into valence-bond (VB ) wave functions. Applications are carried out to the π system of butadiene, hydroxyethylene, acrolein, and carbonyl oxide and also to the full electronic system of water. The external perturbations considered are uniform electric fields, nonuniform electric fields, and reaction fields created by solvents. A different behavior is found between nonpolar and polar species in the presence of solvents. Some consequences on the behavior of molecules under the influence of the different electric fields are discussed.     

芥子气中毒人员尿液标记物谱分析及其临床诊断应用

该研究基于暴露生物标记物溯源思路,应用于解决芥子气(SM)临床早期诊断、溯源确证难题.建立了芥子气中毒患者尿液中7 种游离代谢产物的两步固相萃取/超高效液相色谱-串联质谱(SPE/UPLC-MS/MS)同时定量方法,检出限为5 pg/mL～1 ng/mL,定量下限为10 pg/mL～5 ng/mL;结合前期建立的4 种...     

中文化学名词醇醛酮醚酯之由来

1932年民国教育部颁布的《化学命名原则》为中文化学名词确立了统一的标准,并对于"元素及化合物定名取字"提出"取字应以谐声为主,会意次之,不重象形"的定名总则.它确立的中文化学名词醇、醛、酮、醚、酯是意译名,这似乎与其音译为主的命名原则相悖.本文讨论了醇、醛、酮、醚、酯的各种历史译名,并分析了它们被《原则》采纳的原因.     

Catalytic transfer hydrogenation of biomass-derived furfural to furfuryl alcohol with formic acid as hydrogen donor over CuCs-MCM catalyst

Catalytic transfer hydroge nation(CTH) of furfural(FF) to furfu ryl alcohol(FFA) has received great intere st in recent years.He rein,Cu-Cs bimetallic supported catalyst,CuCs(2)-MCM,was developed for the CTH of FF to FFA using formic as hydrogen donor.CuCs(2)-MCM achieved a 99.6% FFA yield at an optimized reaction conditions of 170℃,1 h.Cu species in CuCs(2)-MCM had dual functions in catalytically decomposing formic acid to generate hydrogen and hydrogenating FF to FFA.The doping of Cs made the size of Cu particles smaller and improved the dispersion of the Cu active sites.Impo rtantly,the Cs species played a favorable role in enhancing the hydrogenation activity as a promoter by adjusting the surface acidity of Cu species to an appropriate level.Correlation analysis showed that surface acidity is the primary factor to affect the catalytic activity of CuCs(2)-MCM.