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狄尔斯-阿尔德(Diels-Alder)可以构建结构丰富的有机化合物,被认为是现代有机化学中的基石反应之一。自1928年被发现以来,Diels-Alder (D-A)反应得到了深入发展,这主要是由于该反应能够产生六元环结构,可以一步反应得到具有四个立体中心的产物,从而大大增加分子的复杂性。这种特殊的转化已广泛应用于复杂天然产物的合成、药物化学以及材料科学等领域。近十年,大量天然生物酶(如SpnF、MaDA等)被发现可用于体外单独催化D-A反应,同时,大量的非酶催化剂(如路易斯酸、过渡金属与配体复合物等)也被应用于催化D-A反应。本文主要从D-A反应催化剂的类型分类,对近年来天然酶、酸、过渡金属、电催化等参与的D-A反应进行简要概述,同时对催化剂所存在的问题和局限性进行总结,并对今后发展做了展望。 相似文献
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通过对缺锌小儿服用锌剂和铁剂后发锌和外周血血红蛋白变化,研究了锌剂与铁剂在体内的相互作用。结果表明,低锌小儿贫血发生率与健康儿童无异,常规锌剂治疗对血红蛋白无明显影响。提示缺锌小儿合并贫血时可同时用常规剂量的锌剂和铁剂治疗,无锌、铁在体内相互拮抗问题。 相似文献
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A new Schiff base compound((NSBSH)2bipy·3H2O) based on 5-nitrosalicylal 4-methyl benzene-sulfonohydrazide(abbreviated as NSBSH), formulated as C38H40N8O13S2, has been synthesized by the condensation of 5-nitrosalicylaldehyde and 4-methylbenzenesulfonohydrazide, and structurally characterized by X-ray single-crystal diffraction analysis, elemental analysis and IR spectrum. It crystallizes in monoclinic system, space group P2/c with a = 13.7992(16), b = 7.1410(8), c = 21.403(2), β = 95.5660(10)o and V = 2099.1(4)3. X-ray analysis reveals that there are obvious π-π stacking interactions between two adjacent aromatic ring planes. The intermolecular hydrogen bonding interactions connect the adjacent Schiff base units into a binuclear unit, and further propagate these moieties into a two-dimensional(2D) supramolecular network. The title compound displays strong photoluminescence in the liquid state as well as high thermal stability. The experiment also shows that it has a good antibacterial activity in vitro antibacterial activity against Sarcina. 相似文献
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