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61.
Ma?Peihua Dong?Jun Xiang?Shuangchun Xue?Saifeng Zhu?Qianjiang Tao?Zhu?Email author Zhang?Jianxin Zhou?Xin 《中国科学B辑(英文版)》2004,47(4):301-310
Three guests with two moiety probes for different Cucurbit[n = 6-8]urils have been synthesized. They are N-(2-methylenethiophen)-adamataneamine, N-(2-methylene pyrrole)-adamataneamine
and N-(2-methylenefurfuran)-adamataneamine. The probes are methyle-nepyridyl typically for Q[6] and adamataneamine typically
for Q[7]. The host-guest complexes of Cucurbit[n = 6-8]urils with these guests have been investigated by using NMR techniques
and ESMS method. Also, thermoanalysis has been used for exploring relationship of enthalpy and stability of the host-guest
complexes. 相似文献
62.
Jun-Ying Ge Sai-Feng Xue Qian-Jiang Zhu Zhu Tao Jian-Xin Zhang 《Journal of inclusion phenomena and macrocyclic chemistry》2007,58(1-2):63-69
The structures and optical properties of host–guest complexes produced from cucurbit[n = 6–8]urils and some benzimidazole derivatives have been investigated by 1H NMR spectroscopy, electronic absorption spectroscopy and fluorescence spectroscopy. The experimental results reveal that
calculations of A∼NQ[n]/Nguest and If∼NQ[n]/Nguest for the same association complex both support a good fit to an identical binding model. In particular, the A∼NQ[n]/Nguest, If∼NQ[n]/Nguest calculations and the 1H NMR determinations for three Q[6]–ge(1∼3) complexes and three Q[8]–ge(1∼3) complexes all support a binding model of 1:1
and 1:2 respectively. 相似文献
63.
1INTRODUCTIONInthe[Co(2,3-tri)(cmen)Cl]2 system,ame-thylgroupreplacinga-CH2-ofenshouldprovidechemistrysimilartothe[Co(2,3-tri)(en)Cl]2 com-plexes(en=ethylenediamine)[1~3].However,thenumberoftheisomersisincreasedfromfivetotwentyduetotwopossibleend-to-enda… 相似文献
64.
《Thermochimica Acta》1998,322(2):153-165
Water uptakes by the hydrocolloids gelatin, pectin and sodium carboxymethylcellulose (NaCMC) and their mixtures, following storage at 20°C and 93% relative humidity (RH), were investigated using differential scanning calorimetry. An increase in water uptake was observed for each sample on storage. The majority of the moisture sorption occurred in the initial 2 h. Only non-freezable, bound water was present in gelatin, pectin and gelatin/pectin or NaCMC/pectin/gelatin mixtures during storage for 28 h. Loosely bound freezable and non-freezable, bound water were detected in NaCMC stored for 2 h. Water in mixtures of NaCMC/gelatin or NaCMC/pectin was predominately loosely bound freezable and non-freezable bound. The order of water uptake was gelatin<pectin/gelatin<pectin<NaCMC/pectin/gelatin<NaCMC/gelatin<NaCMC/pectin<NaCMC. 相似文献
65.
66.
从声速的定义出发,由热力学基本关系给出了声速温度系数(偏微商)的一种计算方法,以顽火辉石为例,计算结果显示,在40~140 GPa压力范围内,其纵波、剪切波和体波的温度系数随压力的增大而逐渐减小,分别由40 GPa时的-0.386、-0.251、-0.255 m/(s·K)降至80 GPa时的-0.298、-0.188、-0.204 m/(s·K),120 GPa时的-0.244、-0.148、-0.175 m/(s·K)和140 GPa时的-0.197、-0.131、-0.162 m/(s·K)。将这一规律内推至零压得到(dK/dT)0=-0.027 9 GPa·K-1,与静高压下的实验值吻合很好。 相似文献
67.
用阻抗匹配法和压电探针技术测量了初始密度为1.714 g/cm3(孔隙率α=ρ0/ρ00=1.898/1.714=1.107)的水绿矾(FeSO4·7H2O)的冲击压缩线,发现其在0~100 GPa范围内存在两个明显相区:含有部分熔融的低压相和完全熔化的高压相。在两个相区内,冲击波速度D和波后粒子速度u可分别描述为:D=0.59+2.06u(u<3.12 km/s)和D=3.18+1.223u(u≥3.12 km/s)。从冲击压缩数据出发,用欧拉有限应变理论得到了其等熵状态方程。其熔化方程可用pm(GPa) =0.159(Tm(K)/1000)6.3371+0.69来近似描述。 相似文献
68.
《Comptes Rendus de l''Academie des Sciences Series IV Physics》2000,1(10):1245-1254
Infrared remote sensing is a powerful tool for studying the chemical composition and the thermal structure of planetary atmospheres. Infrared spectra, in particular, are used to derive molecular abundances and to infer elemental and isotopic ratios, which allow to constrain theoretical models of the formation and early evolution of the solar system, as well as the history of planetary atmospheres. Infrared imaging and spectroscopy have been performed from the ground but also from space planetary missions (Mariner 9 on Mars, Voyager on the giant planets, Galileo on Jupiter), and from the ISO Earth-orbiting infrared satellite. In the forthcoming decade, the Cassini mission will explore the Saturn system. Planetary exploration from Earth orbit will be performed by the FIRST and NGST space observatories. 相似文献
69.
《Tetrahedron: Asymmetry》2000,11(1):319-335
Reaction of 2,3:5,6-di-O-isopropylidene-d-mannofuranose 1 with C-2 lithio derivatives of glyoxylate mercaptal in the presence of MgBr2 afforded d-glycero-d-galacto-2-octulosonates 2 and 3, respectively. Their 3-O-deoxygenation led to Kdo. N-Iodosuccinimide treatment of 3 gave thioglycoside 11 directly, which was transformed into Ko derivative 12 via epimerisation of the 3-hydroxy group. 3-O-Benzoylation of 12 and then transformation into phosphite furnished 15, an efficient glycosyl donor. Reaction of 15 with 6-O-unprotected glucosamine derivative 22 as acceptor gave α-glycoside 23, which was successfully transformed either into Kdo-disaccharide 27 or into Ko-disaccharide 29. 相似文献
70.
Sheng Hong LI Hong Jie ZHANG* Ping YAO Han Dong SUN Phytochemistry Laboratory Kunming Institute of Botany Academia Sinica Kunming Guizhou Institute of Traditional Chinese Medicine Guiyang 《中国化学快报》2001,(1)
The ongoing study of our previous work1-4 led to the isolation of four new taxoids from the barks of Taxus yunnanensis. One of them belonged to a paclitaxel analogue named 7-xylosyl-taxol D, the others were 11(15?1)-abeotaxoids with an opened D-ring system, named taxuyunnanines P-R respectively. Their structures were determined by means of spectral method s including 1D and 2D NMR spectroscopy.7-Xylosyl-taxol D (1), white powder, has a molecular formula, C49H61NO18, from its positive HR… 相似文献