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991.
《Journal of Coordination Chemistry》2012,65(10):1545-1552
Lead(II) 4,4,4-trifluoro-1-naphthyl-1,3-butanedione (Htfnb) complexes of 1,10-phenanthroline (phen) and 2,2′-bipyridine (bpy), [Pb2(bpy)2(tfnb)2] (1) and [Pb2(phen)2(tfnb)2] (2), have been synthesized and characterized by elemental analysis, IR, spectroscopy and X-ray crystallography. The self-assembly of 1 and 2 is likely to be caused by C–H ··· F–C, C–H ··· O and π–π stacking interactions. 相似文献
992.
993.
Racha El Debs Maguy Abi Jaoudé Nicolas Morin Cécile Miege Jérôme Randon 《Journal of separation science》2011,34(15):1805-1810
In recent years, metal oxides such as titania have been commercially available as chromatographic beds that can potentially be used to achieve novel separations of polar compounds. For example β blockers, which are more often encountered in environmental sciences, have a wide range of polarity, and their basic character leads to difficult sample treatment and separation on conventional silica‐based sorbents. The contribution of titania to the selective analysis of nine β blockers was evaluated in terms of retention mechanisms observed in hydrophilic interaction LC using acetonitrile/water mobile phases with various additives. The mobile phase additives enabled to control the β blocker charge as well as the titania surface charge. Depending on their respective ionic state, various retention mechanisms were identified at low water contents (<40%), including mainly adsorption mixed with hydrophilic interaction LC partition, ion exchange and ion exclusion. An unexpected retention was also observed for high water content and high pH, changing the selectivity of the support. 相似文献
994.
HAN Jun DENG Chao FANG Ru LI YiZhi WANG LeYong& PAN Yi Key Laboratory of Mesoscopic Chemistry Ministry of Education School of Chemistry Chemical Engineering Nanjing University Nanjing China State Key Laboratory of Coordination Chemistry 《中国科学:化学》2010,(4)
Three tripod molecules, tris(2-methoxy-5-nitrobenzyl)phosphine oxide (1), tris(2-butoxy-3-methyl-5-nitrobenzyl)phosphine oxide (2), and tris(3-nitrobenzyl)amine (TNBA), were synthesized and crystallized. The structures of 1, 2, and their comparison (TNBA) were determined by X-ray crystallography. It is noteworthy that compound 1 interacted with adjacent molecules via π-π stacking and C-H···π interactions to yield an open supramolecular network with the porosity P in 8.9%, whereas compound 2 gathered closely... 相似文献
995.
We propose one possible mechanism,i.e.,the vector meson(VV)rescattering effects,to interpret the near threshold narrow enhancement observed in J/ψ→γp(p).The estimate indicates that these effects can give sizeable contributions to this channel,and a destructive interference between different rescattering amplitudes is required to reproduce the line shape of the data. 相似文献
996.
LI ZhengDong & FU YanNing Purple Mountain Observatory Chinese Academy of Sciences Nanjing China Graduate University of Chinese Academy of Sciences Beijing 《中国科学 数学(英文版)》2010,(2)
Consider a generalized 3-body problem. The attraction force between any two bodies is proportional to the two masses and the b-th power of the mutual distance. Albouy and Fu have obtained the optimal upper bound of the number of generalized Euler configurations for the cases b 1 and b = 2, 3. This paper obtains the optimal upper bound for the remaining real values of b in a systematic way. 相似文献
997.
A two‐dimensional multi‐phase model for immiscible binary fluid flow including moving immersed objects is presented. The fluid motion is described by the incompressible Navier–Stokes equation coupled with a phase‐field model based on van der Waals' free energy density and the Cahn–Hilliard equation. A new phase‐field boundary condition was implemented with minimization of the free energy in a direct way, to specifically improve the physical behavior of the contact line dynamics for moving immersed objects. Numerical stability and execution time were significantly improved by the use of the new boundary condition. Convergence toward the analytical solution was demonstrated for equilibrium contact angle, the Lucas–Washburn theory and Stefan's problem. The proposed model may be used for multi‐phase flow problems with moving boundaries of complex geometry, such as the penetration of fluid into a deformable, porous medium. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
998.
Yusuke Iwasaki Masato Goto Keisuke Mochizuki Emi Terayama Rie Ito Koichi Saito Norihiro Sugino Tsunehisa Makino Hiroyuki Nakazawa 《Biomedical chromatography : BMC》2011,25(4):503-510
A selective and sensitive HILIC‐MS/MS method for the simultaneous quantification of nicotine and its metabolites in human maternal and cord sera was developed and validated. After solid‐phase extraction, LC separation was achieved on a hydrophilic interaction chromatography. The validated method is capable of selective identification as well as accurate and sensitive quantification. Analyte recovery ranged from 86.2 to 107.7% and intra‐ and inter‐day assay precision were less than 15% relative standard deviation. This sensitive HILIC‐MS/MS method can be used to determine nicotine and its metabolic profile in smokers. This validated method is useful for the determination of nicotine and its metabolites in human serum in future studies of the effects of nicotine exposure on neonatal outcome. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
999.
1 INTRODUCTIONOrganophosphorus compounds are ubiquitous in nature and they have broad applications in the fields of agriculture and medicine. During the past two decades, (-ketophosphonates and their derivatives have attracted considerable attention because these compounds are endowed with special physical, chemical and pharmacological properties due to the proximity of the carbonyl and the phosphoryl groups[1~6]. For example, it is well known that phosphonoformic acid (PFA) is effectiv… 相似文献
1000.
In this article, the miscibility of poly(ε‐caprolactone) (PCL) with poly(styrene‐co‐acrylonitrile) (SAN) containing 25 wt % of acrylonitrile is studied from both a qualitative and a quantitative point of view. The evidences coming from thermal analysis (differential scanning calorimetry) demonstrate that PCL and SAN are miscible in the whole range of composition. The Flory interaction parameter χ1,2 was calculated by the Patterson approximation and the melting point depression of the crystalline phase in the blends; in both cases, negative values of χ1,2 were found, confirming that the system is miscible. The interaction parameter evaluated within the framework of the mean field theory demonstrates that the miscibility of PCL/SAN blends is due to the repulsive interaction between the styrene and acrylonitrile segments in SAN. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010 相似文献