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991.
JIANG Hua-Liang CHEN Kai-Xian TANG Yun CHEN Jian-Zhong JI Ru-YungShanghai Institute of Materia Medica Chinese Academy of Sciences Shanghai China 《中国化学》1995,13(2):131-140
In this paper theoretical studies were performed on artemisinin (qinghaosu) derivatives with semiempirical quantum chemical methods AMI and PM3. The antimalarial activity -logC has an obvious correlation with the net charge of C(16) and bond orders of bonds O(1)-C(10), O(2)-C(6), O(1)-O(2) and O(5)-C(16). According to the calculation results, we derived structure-activity relationship, presented the probable pharmacophore of qinghaosu derivatives and the interaction fashion between the drugs and the plasmodium receptor. 相似文献
992.
ZHAO Yun JIAO Qing-ze DING Xue-jia ZHANG Li-qun LIU Yuan-yuan 《高等学校化学研究》2007,23(5):622-624
Layered double hydroxides (LDHs) are a class of synthetic anion clays, characterized by the formula[MⅡ1-xMⅢx (OH)2]x (An- )x/n·yH2O (where M =metal and A = anion, usually carbonate)[1-3]. A large number of LDHs with a wide variety of M Ⅱ-M Ⅲ cation pairs including M Ⅰ-M Ⅲ ( e. g. , Li-Al ) and M Ⅱ-MⅣ( e. g. , Co-Ti) have been reported. Thus the identities of the cations(MⅠ , MⅡ , MⅢ and MⅣ) and the interlayer anion (An-) together with the value of the stoichiometric coefficient (x) may vary widely, giving rise to a large class of isostructural materials. 相似文献
993.
A convenient and efficient TfOH-catalyzed head-to-tail dimerization of vinylarenes has been realized under mild conditions. The present protocol provides an attractive approach to a diverse range of higher olefins in good to excellent yields. 相似文献
994.
995.
A new mercury iodide complex of dppf, [HgI2(dppf)] (adduct 1 , dppf = 1,1‐bis(diphenylphosphino)ferrocene) was prepared and characterized. Single crystal X‐ray diffraction analysis established that the compound crystallizes in the monoclinic system, space group C2c, with a = 34.992(3), b = 10.236(5), c = 18.765(4) Å, β = 99.410(2)°, Z = 8, V = 6631.2(9) Å3. The coordination about the mercury atom is tetrahedral with two equivalent Hg–I and Hg–P bonds. Dppf functions as a chelating ligand. The nonlinear optical (NLO) properties were studied with an 8 ns‐pulsed laser at 532 nm. Its optical responses to the incident light exhibit weak optical absorptive and strong refractive effects, with n2 = 6.86 × 10–18 m2 · W–1 in a 2.48 × 10–4 mol · dm–3 DMF solution. 相似文献
996.
In this paper, a highly birefringent index-guiding photonic crystal fiber with low confinement loss is proposed by enlarging the central row of air holes in the structure. By employing the multipole method, properties of this structure, including the effective index, birefringence and confinement loss, are investigated. Simulation results indicate that high birefringence of 1.65 × 10−3 can be reached at the wavelength of 1.55 μm, and a low confinement loss on the order of 10−6 dB/km can be achieved at the same wavelength. Moreover, the impacts of air hole sizes on birefringence and confinement loss are also analyzed in detail. 相似文献
997.
对于超细长弹性杆静力学的Kirchhoff方程,用动力学的概念和方法研究其常值特解 和稳定性问题.计算了Kirchhoff方程相对固定坐标系、截面主轴坐标系以及中心线Frenet 坐标系的常值特解,进行了Kirchhoff动力学比拟,用一次近似理论分别讨论了它们的Lyapu nov稳定性,导出了若干稳定性判据,并在参数平面上绘出了稳定域.
关键词:
超细长弹性杆
Kirchhoff方程
常值特解
Lyapunov稳定性 相似文献
998.
Ling Yun Wang 《European Polymer Journal》2006,42(2):322-327
Neutral nickel(II) and palladium(II) complexes bearing β-ketoiminato ligand have been synthesized. The two complexes have been investigated as catalyst for the polymerization. Using methylaluminoxane (MAO) as a cocatalyst, both complexes produce vinyl-addition polynorbornenes, but palladium(II) complex displays much higher activity up to 8.0 × 107 g/(molPd h). Furthermore, both Ni(II) and Pd(II)/MAO system can efficiently copolymerize norbornene and 5-norbornene-2-yl acetate (NB-OCOMe) in moderate yields and in relatively high molecular weights. The analyses of the product by FTIR, 1H NMR and 13C NMR spectra give the verification of vinyl addition copolymer. The copolymers show narrow molecular weight distribution and good solubility in common organic solvents. 相似文献
999.
1000.
湿热证动物模型微量元素、维生素E变化及清香散的调节作用 总被引:1,自引:0,他引:1
采用多因素造模方法复制成湿热证动物模型,观察了动物模型微量元素Zn、Cu、Fe、Se和维生素E代谢水平的变化。结果显示,模型动物血清Zn下降(P<0.05),Cu升高(P<0.05或P<0.01),Fe变化不大(P>0.05),血Se水平下降(P<0.05),血浆维生素E含量减少(P<0.01)。经清热祛湿的经验方清香散治疗后,治疗I组动物血清Zn、血Se、血浆维生素E明显升高(P<0.05),血清Cu下降(P<0.05);治疗Ⅱ组血浆血清Cu有变化(P<0.05)外,其余变化不大。 相似文献