共查询到20条相似文献,搜索用时 93 毫秒
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在国外学习艺术玻璃这几年,谈起彩色玻璃镶嵌,自然会联想到欧洲教堂里的彩色玻璃窗。它是中世纪教堂装饰的一种独特方法,主要盛行于罗马式、哥特式和拜占庭式建筑。前两种建筑的窗户多而大,几乎布满整个建筑立面,便于采光。 相似文献
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通过对目前物理化学教材内容和讲授模式的分析,针对在概念著述和课堂讲授中存在的误区,结合物理化学家吉布斯的启发式教学典故,本文构建一种"立足客观自然、环环相扣启发"的概念教学模式,以"焓"概念的讲授为例,化抽象为直观,收了良好的教学效果。启发式模式对当前物理化学的概念教学有重要的参考价值。 相似文献
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<正>写美食专栏,纯手工做酱,义卖闲置物品帮助山区儿童……阿米,就这样,只做并坚持做自己喜欢的事情。生活宋:阿米,微博名"@amie阿米",四川人,颇有使气的关食作家,80后最美厨娘,著有《9分钟营养早餐》、《18分钟做便当》、《30分钟做晚餐》等。经营一家卖手工酱的淘宝店,店名:吃心望想食品小卖部。好生活理念:普从不预留,但可以用故事换你想要的酱,前提是打动阿米(故事可能被隐去真实身份分享出来)。"是厨娘更是小糯她娘,每日做饭、写文儿、带娃,充分享受做妈妈的乐趣。""做人不能太严肃,严肃症患者统统驱散……""做喜欢的事情,快乐就好。" 相似文献
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丁二酸酐的化学简式是C4H4O3丁二酸酐是医药、染料、涂料的主要原材料,同时还是重要的药物和化学试剂成分,另外丁二酸酐可以用于生胃酮、琥珀酸胺噻唑的生产,并且可以广泛的应用于树脂的合成和制备。目前工业上对丁二酸酐的制备主要有以下两种方法:第一种方法就是对顺丁烯二酸酐的直接催化加氢法。现在对顺丁烯二酸酐直接催化加氢的生产工艺流程研究的比较广泛,特别是对丁二酸酐生产工艺中的热力学以及探索新的催化研究体系等方面的研究更为广泛;第二种方法就是直接对丁二酸进行脱水。第二种方法的主要优点就在于它对环境污染较小且不使用苯类溶剂,所以国内外很多丁二酸酐生产厂家都普遍采用第二种方法。 相似文献
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今年两会期间,机场建设费遭到人大代表的强烈质疑。代表认为向乘客收取的数额不等的机场建设费违反宪法的有关原则。机场建设费的征收支配具有明显的垄断性、强制性、不公开性,具有“霸王条款”的种种特征。而早在2005年6月,在中国水泥协会召开的”关于散装水泥专项资金征收和使用办法座谈会”上,也有水泥企业的老总、十届全国人大代表提出:散装水泥专项资金应该取消。 相似文献
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异色满类香料化合物的合成及其进展 总被引:2,自引:0,他引:2
介绍了近年个异色满类香料化合物的研究进展,产品种类,香气特征,合成方法及其在香料中的应用。三聚氰胺和尿素经羟甲基化、醚化,生成甲醚化六羟甲基三聚氰胺和甲醚化羟甲基脲,再经浓缩脱醛,合成FH-衬布硬挺整理剂。用该产品整理出的衬布的综合性能指标,优于用脲醛树脂或六羟树脂整理出的衬布。是一种新型的复合树脂硬挺整理剂。 相似文献
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Electron-donating or electron-withdrawing substituents at the porphyrin rings considerably increase the catalytic activity of the manganese monomeric and μ-oxo porphyrins in the oxidation of cyclooctane with molecular oxygen without the use of sacrificial co-reductant. The change in the catalytic activity is due to the nature and number of the substituents in the porphyrin ring. 相似文献
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本工作合成了一系列取代的硝酮类化合物。其中部分化合物仅一侧的苯环上带有取代基,而另部分化合物则两个苯环上均带有取代基。研究工作表明:取代基处于一侧的硝酮类化合物,不论取代基是给出电子或接受电子的,均有利于化合物光环化反应的进行。而当两个苯环分别带有给电子及接受电子的取代基形成推拉结构时,则大大减弱了化合物光环化反应的发生。文章对上述结果进行了初步讨论。 相似文献
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戊二醛是一种有着广阔发展前景的精细化工产品,它的两个自由醛基非常活泼,能进行多种反应.被广泛应用在医药、油田、制革、食品、环境保护等领域。为了利用本公司具有丙烯醛原料的优势,积极开发高附加值的下游产品,进行了乙烯基乙醚和丙烯醛反应合成2-乙氧基-3,4-二氢吡喃及其水解制备戊二醛的研究.并在连续化吡喃合成和水解方面取得了一定的技术突破,形成了特有的戊二醛合成工艺。 相似文献
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M. F. Rey-Stolle F. Fernndez-Martín L. H. Tagle I. Hernndez-Fuentes 《Polymer International》1998,46(2):93-98
Glass transition temperatures and the corresponding activation energies of poly(carbonates) and poly(thiocarbonates) with different side-chain substituents obtained from diphenols with methyl groups in the 3-position in the phenyl rings have been determined by differential scanning calorimetry at several scanning speeds. Partial specific volume and specific refractive index increments have also been obtained by densimetry and refractometry measurements in benzene at 25°C. The effect of the different substituents on these properties has been analysed. © 1998 SCI. 相似文献
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Klaus Buttke Helmut Baumgrtel Hans-Joachim Niclas Matthias Schneider 《Advanced Synthesis \u0026amp; Catalysis》1997,339(1):721-728
Synthesis, Structure, and Photophysical Properties of Polyarylated Imidazoles and Oxazoles 23 tetraphenylimidazoles 1,2 and 11 triphenyloxazoles 4,5 with amino, nitro, methoxy, hydroxy, or halogeno substituents chiefly in the para position were prepared. The absorption and fluorescence emission properties were investigated in ethanolic solution. The effects of the substituents in 1,2 on the spectral shifts show that the arrangement of the phenyl rings in 1 position is not coplanar in relation to the heterocycle whereas the phenyl rings in 2 position are more coplanar. The spectral changes of compound 2a in solvents of various polarity (dielectric constants 2,02–47,24) are almost negligible. The Stokes shift is moderately increased. A remarkable increase in the fluorescence quantum yield is observed by chlorine substitution in phenyl ring 2. 相似文献
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Federico Marighetti Dr. Kerstin Steggemann Markus Hanl Prof. Dr. Michael Wiese 《ChemMedChem》2013,8(1):125-135
The breast cancer resistance protein (BCRP/ABCG2) is a member of the ABC transporter superfamily. This protein has a number of physiological functions, including protection of the human body from xenobiotics. The overexpression of BCRP in certain tumor cell lines causes cross‐resistance against various drugs used in chemotherapeutic treatment. In a previous work we showed that a new class of compounds derived from XR9576 (tariquidar) selectively inhibits BCRP. In this work we synthesized more members of this class, with modification on the second and third aromatic rings. The inhibitory activities against BCRP and P‐gp were assayed using a Hoechst 33342 assay for BCRP and a calcein AM assay for P‐gp. Finally, quantitative structure–activity relationships for both aromatic rings were established. The results obtained show the importance of the electron density on the third aromatic ring, influenced by substituents, pointing to interactions with aromatic residues of the protein binding site. In the second aromatic ring the activity of compounds is influenced by the steric volume of the substituents. 相似文献
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The results of the group structure analysis of asphaltenes, resins, and hydrocarbons in the liquid products obtained upon the thermolysis of vitrinites of different ranks are presented. The molecular weights of components decreased with the degree of vitrinite conversion: aromatic structures were predominant among ring compounds, and the lengths of alkyl substituents decreased. The molecules of asphaltenes predominantly consisted of two-block structures, whereas tars and oils mainly exhibited a single-block organization; in all cases, the alkyl substituents of aromatic rings had a length of C1–C4. 相似文献