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991.
Three new alkaloids, longistylumphyllines A–C (1–3), together with the six known alkaloids deoxycalyciphylline B, deoxyisocalyciphylline B, methyl homosecodaphniphyllate, daphnicyclidin A, daphnicyclidin B, and daphnicyclidin F, were isolated from the stems and leaves of Daphniphyllum longistylum. Their structures and relative configuration were elucidated on the basis of spectroscopic data, especially 1D and 2D NMR techniques. 相似文献
992.
993.
大庆渣油族组分非等温热反应的研究 总被引:2,自引:0,他引:2
采用动态热重分析法在升温速率为6.2K·min ̄(-1)及惰性气流量100cm ̄3·min ̄(-1)的条件下,对大庆渣油族组分的热转化行为进行了考察,获得了族组分的热转化速率峰值、速率峰值处的反应温度、转化率和剧裂分解温度区间等动力学基本数据以及各族组分的生焦性能。数据分析表明,族组分的热反应活性顺序为:饱和分>胶质>芳香分>沥青质。在大庆渣油族组分热转化的两个温区内,采用分段一级动力学模型较好地拟合了实验数据,确定了各族组分在两个温区内的热反应动力学参数。 相似文献
994.
微分倒数示波计时电位法的研究—定量测试及滴定分析 总被引:3,自引:0,他引:3
首次利用微分倒数示波图定量测试微量金属离子并滴定分析药物,结果满意。 相似文献
995.
Xin‐Zhou Yang Li‐Gen Lin Chun‐Ping Tang Yong‐Qiang Liu Yang Ye 《Helvetica chimica acta》2007,90(2):318-325
Five new nonalkaloid constituents, a neolignan, japonin A ( 1 ), a macrocyclic lactone, japonin B ( 2 ), a (phenylethyl)benzoquinone, japonin C ( 3 ), a phenanthraquinone, japonin D ( 4 ), as well as a dihydrostilbene, stilbostemin M ( 5 ), were isolated from the roots of Stemona japonica, together with eight known compounds. Their structures were established by spectroscopic analyses. 相似文献
996.
Chen Luo Chenggang Zhou Jinping Wu T. J. Dhilip Kumar Naduvalath Balakrishnan Robert C. Forrey Hansong Cheng 《International journal of quantum chemistry》2007,107(7):1632-1641
Structures and physical properties of small palladium clusters Pdn up to n = 15 and several selected larger clusters were studied using density functional theory under the generalized gradient approximation. It was found that small Pdn clusters begin to grow 3‐dimensionally at n = 4 and evolve into symmetric geometric configurations, such as icosahedral and fcc‐like, near n = 15. Several isomers with nearly degenerate average binding energies were found to coexist and the physical properties of these clusters were calculated. For several selected isomers, relatively moderate energy barriers for structural interchange for a given cluster size were found, implying that isomerization could readily occur under ambient conditions. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 相似文献
997.
998.
Guang‐Fei Liu Lin‐Lin Li Yong Zhang Jian‐Ping Lang Seik Weng Ng 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(1):m1-m3
The title compound, [Cu(ClO4)2(C4H9N3O2)2][Cu(C4H9N3O2)2(CH4O)2](ClO4)2·2CH3OH, comprises two independent CuII species lying on different inversion sites. In the Cu complexes, a distorted octahedral geometry arises (from basic square‐planar N4 coordination) from the weak coordination of two perchlorate ions (as Cu—O) in one species and two methanol molecules in the other (also as Cu—O). Interactions between the O atoms of the perchlorate anions or methanol groups and the imide or amine NH groups afford an extensive intermolecular hydrogen‐bonding network. 相似文献
999.
Xiang‐Gao Meng Chun‐Shan Zhou Li Wang Chang‐Lin Liu 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(11):o667-o670
5‐Sulfosalicylic acid (5‐SSA) and 3‐aminopyridine (3‐APy) crystallize in the same solvent system, resulting in two kinds of 1:1 proton‐transfer organic adduct, namely 3‐aminopyridinium 3‐carboxy‐4‐hydroxybenzenesulfonate monohydrate, C5H7N2+·C7H5O6S−·H2O or 3‐APy·5‐SSA·H2O, (I), and the anhydrous adduct, C5H7N2+·C7H5O6S− or 3‐APy·5‐SSA, (II). Both compounds have extensively hydrogen‐bonded three‐dimensional layered polymer structures, with interlayer homo‐ and heterogeneous π–π interactions in (I) and (II), respectively. 相似文献
1000.
Xiao Ling WANG Wei JIAO Xun LIAO Shu Ling PENG Li Sheng DING 《中国化学快报》2006,17(7):916-918
The roots of Paeonia lactiflora Pall. is one of the most important traditional Chinese medicines, which has been used for the treatment of dizziness, spasm, menstrual disorder, spontaneous and night sweating, and as a general analgesic1. Chemical constitu… 相似文献