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991.
Ai‐Ting Xing Jun‐Mian Tian Chun‐Mei Liu Hui‐Liang Li Wei‐Dong Zhang Lei Shan 《Helvetica chimica acta》2010,93(4):718-723
Three new monoterpene alkaloids, mairine A ( 1 ), mairine B ( 2 ), and mairine C ( 3 ), and a new caffeic acid ester, 2‐(1‐hydroxy‐4,4‐dimethoxycyclohexyl)ethyl caffeate ( 4 ), were isolated from the EtOH extract of the whole plants of Incarvillea mairei var. multifoliolata. The structures of these compounds were established on the basis of 1D‐ and 2D‐NMR and HR‐ESI‐MS analysis. 相似文献
992.
The reactions of Ln(NO3)3 with 1,4‐phenylenediacetic acid (H2PDA) under hydrothermal conditions produced two isostructural lanthanide coordination polymers with the empirical formula [Ln2(PDA)3(H2O)] · 2H2O [Ln = Nd ( 1 ), Sm ( 2 )]. Single‐crystal X‐ray diffraction analyses revealed that both contain one‐dimensionalmetal carboxylato chains, which are further connected by the–CH2C6H4CH2– spacers of PDA2– ligands to yield a three‐dimensional metal‐organic framework. Magnetic susceptibilities of 1 and 2 were measured. The experimental χmT value of both compounds decreases continuously with decreasing temperature over the whole temperature range. The best least‐squares fit of the experimental data of 1 to a theoretical equation in the temperature range of 70–300 K gives the zero‐field splitting parameter Δ = 2.21 cm–1 and the magnetic interaction between the NdIII ions 2zJ′ = –1.97 cm–1, which indicates the presence of antiferromagnetic interaction between the NdIII ions. The experimental χmT value of 2 at 2 K is much smaller than the expected value for two free SmIII ions (6H5/2, g = 2/7) in the ground state, indicating that an antiferromagnetic interaction possibly exists between SmIII ions at low temperature. Fitting the magnetic data of 2 above 110 K based on an equation deduced from the SmIII ion in a monomeric system with free‐ion approximation gave a spin‐orbit coupling parameter λ = 192(2) cm–1 相似文献
993.
Zhi‐Yong Xiao Xia‐Chang Wang Gui‐Ping Zhang Zhong‐Liang Huang Li‐Hong Hu 《Helvetica chimica acta》2010,93(4):803-810
Five new terpenoids, including four eudesmane‐type sesquiterpenoids, 1 – 4 , and one labdane‐type diterpenoid, 6 , together with ten known compounds, were isolated from the roots of Chloranthus spicatus. The structures and their relative configurations were mainly established by 1D‐ and 2D‐NMR spectra, and MS experiments. 相似文献
994.
From the whole plants of E. ritro L., the three new sesquiterpenoids (3α,4α,6α)‐3,13‐dihydroxyguaia‐7(11),10(14)‐dieno‐12,6‐lactone ( 1 ), (3α,4α,6α,11β)‐3‐hydroxyguai‐1(10)‐eno‐12,6‐lactone ( 2 ), and (11α)‐11,13‐dihydroarglanilic acid methyl ester (=(4β,6α,11α)‐4,6‐dihydroxy‐1‐oxoeudesm‐2‐en‐12‐oic acid methyl ester; 3 ), together with eight known sesquiterpenoids, were isolated. Their structures were elucidated through analysis of spectroscopic data including extensive 2D‐NMR. 相似文献
995.
Du‐Qiang Luo Wen‐Liang Zhu Xiao‐Long Yang Shu‐Juan Liang Zhi‐Ran Cao 《Helvetica chimica acta》2010,93(6):1209-1215
Two new daphniphyllum alkaloids named 2‐hydroxyyunnandaphnine D ( 1 ) and methyl 7‐hydroxyhomodaphniphyllate ( 2 ), together with eight known alkaloids, daphnioldhanin D, calyciphylline F, calyciphylline B, deoxycalyciphylline B, daphnicyclidin H, macropodumine C, 9,10‐epoxycalycine A, and yunnandaphnine A, were isolated from the stems and leaves of Daphniphyllum calycinum. Their structures and relative configurations were established on the basis of spectral evidence (including 2D‐NMR) and subsequently confirmed by a single‐crystal X‐ray crystallographic diffraction analysis. 相似文献
996.
Asanuma H Toda T Murayama K Liang X Kashida H 《Journal of the American Chemical Society》2010,132(42):14702-14703
A new foldamer, acyclic threoninol nucleic acid (aTNA), has been synthesized by tethering each of the genetic nucleobases A, G, C, and T to d-threoninol molecules, which were then incorporated as building blocks into a scaffold bearing phosphodiester linkages. We found that with its fully complementary strand in an antiparallel fashion, the aTNA oligomer forms an exceptionally stable duplex that is far more stable than corresponding DNA or RNA duplexes, even though single-stranded aTNA is rather flexible and thus does not take a preorganized structure. 相似文献
997.
Meriles CA Jiang L Goldstein G Hodges JS Maze J Lukin MD Cappellaro P 《The Journal of chemical physics》2010,133(12):124105
Magnetic resonance imaging can characterize and discriminate among tissues using their diverse physical and biochemical properties. Unfortunately, submicrometer screening of biological specimens is presently not possible, mainly due to lack of detection sensitivity. Here we analyze the use of a nitrogen-vacancy center in diamond as a magnetic sensor for nanoscale nuclear spin imaging and spectroscopy. We examine the ability of such a sensor to probe the fluctuations of the "classical" dipolar field due to a large number of neighboring nuclear spins in a densely protonated sample. We identify detection protocols that appropriately take into account the quantum character of the sensor and find a signal-to-noise ratio compatible with realistic experimental parameters. Through various example calculations we illustrate different kinds of image contrast. In particular, we show how to exploit the comparatively long nuclear spin correlation times to reconstruct a local, high-resolution sample spectrum. 相似文献
998.
Lei H Wang Y Su C Liang F Su W Hui M Shaw P Luo Y 《Natural product communications》2010,5(10):1673-1676
The essential oils from leaves, twigs and stems of large trees and shrub-like trees of Thuja sutchuenensis were extracted by hydrodistillation and supercritical fluid extraction, and analyzed by GC and GC-MS. The essential oil composition differed significantly among the three organs, as well as between large trees and shrub-like trees. Furthermore, consistent with the eastern Asia-North American disjunct distribution of the genus, many differences in the essential oil composition between T. sutchuenensis and other Thuja species were apparent. The essential oils exhibited a certain degree of antifungal activity against six strains of human pathogenic fungi. 相似文献
999.
A series of bipolar-transporting europium(III) complexes containing carbazole and oxadiazole units were synthesized and characterized. Two intense UV absorption bands at around 286 nm and 352 nm, and sharply red emissions peaked at 614 nm were observed for these europium complexes in dichloromethane. Importantly, the bipolar-transporting europium(III) complexes exhibited higher thermal stability, more intense UV absorption at 286 nm and twofold increased photoluminescent quantum yield compared to the reported red chromophore of tri(dibenzoylmethane) (1,10-phenanthroline) europium(III). 相似文献
1000.
Jinghong Ma Bing Fan Borun Liang Jian Xu 《Journal of colloid and interface science》2010,341(1):88-93
A novel pH- and temperature-sensitive nanocomposite microgel based on linear Poly(acrylic acid) (PAAc) and Poly(N-isopropylacrylamide) (PNIPA) crosslinked by inorganic clay was synthesized by a two-step method. First, PNIPA microgel was prepared via surfactant-free emulsion polymerization by using inorganic clay as a crosslinker, and then AAc monomer was polymerized within the PNIPA microgel. The structure and morphology of the microgel were confirmed by FTIR, WXRD and TEM. The results indicated that the exfoliated clay platelets were dispersed homogeneously in the PNIPA microgels and acted as a multifunctional crosslinker, while the linear PAAc polymer chains incorporated in the PNIPA microgel network to form a semi-interpenetrating polymer network (semi-IPN) structure. The hydrodynamic diameters of the semi-IPN microgels ranged from 360 to 400 nm, which was much smaller than that of the conventional microgel prepared by using N,N′-methylenebis(acrylamide) (MBA) as a chemical crosslinker, the later was about 740 nm. The semi-IPN microgels exhibited good pH- and temperature-sensitivity, which could respond independently to both pH and temperature changes. 相似文献