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191.
Ruta Bariseviciute Justinas Ceponkus Alytis Gruodis Valdas Sablinskas 《Central European Journal of Chemistry》2006,4(4):578-591
Ozonization reaction of simple alkenes was studied by means of FT infrared absorption gas spectroscopy. The reaction was performed
at 95 K in neat films of the reactants. IR absorption spectra of the gaseous products were recorded. The spectra were analyzed
combining experimental results with theoretical calculations performed at B3LYP 6-311++G (3df, 3pd) level. We found that among
all theoretically predicted conformers of propene secondary ozonide, only one which has the O-O half-chair configuration for
the five membered ring and the radical attached in the equatorial position was present in the sample. Samples of 1-butene and 1-heptene secondary ozonides consist from two conformers of very
similar energy (ΔH=0.3 kJ/mol). The most stable conformer for both ozonides is the one with O-O half-chair configuration of the five membered
ring and the radical attached in equatorial position and the aliphatic chain in gauche position. The second stable conformer has the aliphatic chain in anti position. 相似文献
192.
为分析铁缺乏症(IDD)对婴幼儿智能发育的影响,随机抽取了6个月至3岁婴幼儿200例,按有否铁缺乏分组,比较了其与智能的关系。结果表明,铁缺乏症检出率为17.5%,铁缺乏组婴幼儿智能发育商(DQ)明显下降,与正常组比较差异有显著性,铁缺乏程度越重,DQ值越低。可见铁缺乏症对婴幼儿大脑发育造成不良影响,对该症无贫血阶段及轻度缺铁性贫血期(IDA)应予重视。 相似文献
193.
194.
《Arabian Journal of Chemistry》2022,15(11):104262
This review critically evaluates the plastic accumulation challenges and their environmental (primarily) and human (secondarily) impacts. It also emphasizes on their degradation and fragmentation phenomena under marine conditions. In addition, it takes into account the leachability of the various chemical substances (additives) embedded in plastic products to improve their polymeric properties and extend their life. Regardless of their effectiveness in enhancing the polymeric function of plastic products, these additives can potentially contaminate air, soil, food, and water. Several findings have shown that, regardless of their types and sizes, plastics can be degraded and/or fragmented under marine conditions. Therefore, the estimation of fragmentation and degradation rates via a reliable developed model is required to better understand the marine environmental status. The main parameter, which is responsible for initiating the fragmentation of plastics, is sunlight/UV radiation. Yet, UV- radiation alone is not enough to fragment some plastic polymer types under marine conditions, additional factors are needed such as mechanical abrasion. It should be also mentioned that most current studies on plastic degradation and fragmentation centered on the primary stages of degradation. Thus, further studies are needed to better understand these phenomena and to identify their fate and environmental effects. 相似文献
195.
含氟β-氨基酸及其衍生物具有特殊的生理活性, 其合成方法的研究近年来受到广泛关注. 以直接氟化法和间接氟化法分类, 概述了含氟β-氨基酸及其衍生物的合成方法及最新研究进展, 对一些已知化合物的生理活性及药用价值作了初步归纳. 相似文献
196.
Katarzyna Kaszyńska Ewa Banachowicz Genowefa Ślósarek Adrian Morawiec Iwona Gawrońska Jan Barciszewski 《Journal of solution chemistry》2002,31(12):987-993
We analyze the structure of napin (BngNAP1), a storage protein (m.w. 14.5 kDa) from Brassica napus. On the basis of the results of 1H NMR spectroscopy and dynamic light scattering (DLS) studies, the overall shape and secondary structure of the molecule are estimated. 相似文献
197.
简要回顾了色谱分析技术的发展史,厘清了某些中文文献中的不妥表述。通过分析色谱发展过程中的几个重要突破,总结了在科学技术创新方面给我们的启示:(1)基础研究始终是色谱技术进步的源泉;(2)社会发展的需求是各种色谱方法创新的驱动力;(3)学科交叉是色谱分析技术创新的重要途径;(4)不懈坚持和勇于探索是科学技术创新的必要条件。最后对色谱发展的前景作了展望。 相似文献
198.
The th Department 《有机化学》1985,5(1):107-112
本文评述了当前物理有机化学各个主要领域的研究工作,指出物理有机化学是甚为重要的基础学科,数十年来在深度和广度两方面皆有很大的发展。回顾了我国第一届和第二届物理有机讨论会情况,扼要地介绍了物理有机化学在我国的主要进展。 相似文献
199.
Ya. L. Kogan L. S. Fokeeva L. G. Shunina E. I. Knerel'man 《Russian Chemical Bulletin》1996,45(6):1380-1382
It has been found that thin polyaniline films doped with several zinc salts in solutions at pH 5.5 become electroconductive and electroactive in neutral aqueous electrolytes. The shape of the voltammetric characteristics depends on the initial state of the film. The effect of secondary doping withm-cresol is observed for polyaniline complexes with zinc salt of camphorsulfonic acid.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1450–1452, June, 1996. 相似文献
200.
Kazimierz Nikodem 《Aequationes Mathematicae》1991,42(1):182-189
Summary LetX be a real vector space,D a convex subset ofX and (Y, K) an order complete ordered vector space. The following sandwich theorem holds: Iff: D Y is midconvex,g: D Y {– } is midconcave andg f onD, then there exists a Jensen mappingh: D Y {– } such thatg h f onD. Using this theorem we show that a mappingf: D Y is midconvex if and only if it has Jensen support at every point ofD. Moreover, ifX is a Baire topological vector space and (Y, K) is an ordered topological vector space satisfying some additional conditions, then a mappingf: D Y is continuous whenever it has continuous Jensen support at every point ofD. As an application of these results we obtain the equality of some set-classes connected with additive and midconvex operators.Dedicated to the memory of Alexander M. Ostrowski on the occasion of the 100th anniversary of his birth 相似文献