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Huang JM Yang CS Zhao R Takahashi H Fukuyama Y 《Chemical & pharmaceutical bulletin》2004,52(1):104-107
Seven new seco-prezizaane-type sesquiterpenes were isolated from the methanol extract of the pericarps of Illicium merrillianum. Their structures were elucidated as 3-deoxypseudoanisatin (1), 2beta-hydroxy-3,6-dedioxypseudoanisatin (2), 8alpha-hydroxy-10-deoxycyclomerrillianolide (3), 10beta-hydroxypseudoanisatin (4), 10beta-hydroxycyclopseudoanisatin (5), 1,6-dihydroxy-3-deoxyminwanensin (6), and 8-deoxymerrilliortholactone (7) by analyses of their spectroscopic data and chemical transformation. Compounds 4 and 5 as well as 6 and 7 coexist as a keto/acetal equilibrated mixture in methanol solution. 相似文献
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Arylvinylidenecyclopropanes undergo a novel reaction upon heating at 150 °C with diaryl diselenide to give the corresponding 1,2-diarylselenocyclopentene derivatives in good to high yields within 1.5 h. The further transformation of 1,2-diarylselenocyclopentene derivatives has been disclosed. 相似文献
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基于密度泛函理论的第一性原理计算, 研究了硅烯饱和吸附碱金属元素原子的稳定性、微观几何结构和电子性质, 并与纯硅烯及其饱和氢化结构进行了对比分析. 研究发现复合物SiX(X=Li, Na, K, Rb)的形成能都是负的, 相对于纯硅烯来说可以稳定存在. Bader电荷分析表明, 电荷从碱金属原子转移至硅原子. 从成键方式来看, 硅烯与氢原子形成共价键, 而与碱金属原子之间形成的键主要是离子性成键, 但还存在部分共价关联成分. 能带计算表明, 锂原子饱和吸附在硅烯形成的复合物SiLi是直接带隙的半导体, 带隙大小为0.34 eV. 其他碱金属饱和吸附在硅烯上形成的复合物都表现为金属性. 相似文献
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配合物1由醋酸镉和Nahca(对羟基肉桂酸钠)在水溶液中反应得到,配合物2由醋酸铜,Hhca和phen在水和乙醇混合溶液中反应得到。配合物1属正交晶系,Pbcn空间群。配合物2属单斜晶系,C2/c空间群。配合物1和2中配体中的羧酸根与金属离子都是螯合配位的,末端羟基没有参与配位。配合物1和2的结构中都包含了丰富的氢键。通过氢键作用,配合物1形成了三维网状超分子结构,配合物2形成了二维层状超分子结构。 相似文献
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Han Luo Wei Qin Hong Zhang Fu-Cai Ren Wen-Tao Fang Qing-Hua Kong Liu Yang Jian-Mei Zhang Cheng-Wu Fang Jiang-Miao Hu Shou-Jin Liu 《Molecules (Basel, Switzerland)》2022,27(5)
The present study aimed to identify the composition of the aerial parts of Rubia cordifolia L. A chemical investigation on the EtOAc extracts from the aerial parts of Rubia cordifolia resulted in the isolation of four new anthraquinones, namely Cordifoquinone A–D (1–4), along with 16 known anthraquinones. Their structures were elucidated on the basis of NMR and HR-ESIMS data. All isolates were assessed for their inhibitory effects on NO production in LPS-stimulated RAW 264.7 macrophage cells. Compounds 1, 3 and 10 exhibited significant inhibitory activities with IC50 values of 14.05, 23.48 and 29.23 μmol·L−1, respectively. Their antibacterial activities of four bacteria, Escherichia coli (ATCC 25922), Staphylococcus aureus subsp. aureus (ATCC 29213), Salmonella enterica subsp. enterica (ATCC 14028) and Pseudomonas aeruginosa (ATCC 27853), were also evaluated. Our results indicated that the antibacterial activity of these compounds is inactive. 相似文献
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基于密度泛函理论的第一性原理计算方法,研究了宽度N=8的边缘氢化和非氢化条带的结构和电子性质. 研究表明,扶手形无氢化石墨纳米条带的边缘碳原子是以三重键相互结合,它在边缘的成键强度比氢化时要高,具有更强的化学活性,可作为纳米化学传感器的基础材料. 能带结构计算表明,无论是扶手形条带还是锯齿形条带,它们都是具有带隙的半导体,且无氢化条带的带隙要比氢化的条带带隙宽度大,氢化对于条带的电子性质具有显著修饰作用. 通过锯齿形石墨纳米条带顺磁性、铁磁性和反铁磁性的计算,发现反铁磁的状态最稳定,并且边缘磁性最强,这有利于条带在自旋电子器件中的应用.
关键词:
石墨纳米条带
成键机理
电子结构
自旋分布 相似文献
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Six new compounds: [M(dps)(dca)2]∞ (1, M = Cd; 2, M = Fe), [Cu(dps)(dca)2(CH3OH)2]∞ (3), [M(dps)2(SCN)2(H2O)2]∞ (4, M = Cd; 5, M = Fe), [Cu(dps)4(SCN)2]∞ (6), (dps = 4,4′-dipyridyl sulfide, dca = dicyanamide) were synthesized, characterized by FT-IR, element analysis and TG. Their structures were determined by single crystal X-ray diffraction. According to the structure analysis, compounds 1 and 2 are three-dimensional microporous frameworks constructed by Cu-dps-Cu and Cu-dca-Cu bridges; compound 3 shows a zigzag chain constructed by a Cu-dps-Cu bridge; compounds 4 and 5 show double-stranded chains constructed by a Cu-(dps)2-Cu bridge while thiocyanate anions act as terminal groups; compound 6 is a mononuclear compound. Moreover, compound 1 shows visible yellow luminescence under UV light irradiation and such phenomenon is mainly attributed to inter-ligand transitions. 相似文献
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采用微波溶样技术消解食品样品,用纳氏比色法测定食品中蛋白质。实验结果表明,用微波溶样技术消解食品具有节省时间、节约试剂、消解完全等优点。本方法的相对标准偏差为0.4%-5.3%;回收率为95.0%-102.0%。 相似文献