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141.
Hongjian Lu 《Tetrahedron letters》2005,46(36):5983-5985
N-Acyltriazenes serve as a tin-free and initiator-free source for amidyl radicals. Thermal decomposition of N,N′-diaryl-N-(4-pentenoyl)triazenes in refluxing toluene led to the formation of monocyclic and tricyclic lactams in satisfactory yields via 5-exo amidyl radical cyclization. 相似文献
142.
143.
枸椽酸锗能明显提高小鼠血清溶血素抗体水平,增强二硝基氯苯(DNCB)致小鼠迟发型皮肤过敏反应。增加小鼠免疫器官胸腺和脾脏的重量,表明枸椽酸锗能增强小鼠体液免疫和细胞免疫水平。 相似文献
144.
吕明松 《广东微量元素科学》1997,4(7):52-54
以临床典型病案为例,探讨了中医中药传统理论和现代微量元素研究的关系,重点讨论了向量元素锌、宏量元素钙与高血压、风湿症的病因病机和治疗关系。 相似文献
145.
Joseph F. Chiang Raymond Chiang K.C. Lu Eun-Mo Sung Marlin D. Harmony 《Journal of Molecular Structure》1977,41(1):67-77
The molecular structure of norbornene has been investigated in the gas phase by combining electron diffraction data with microwave spectroscopic rotational constants. The interatomic distances (rg) and bond angles were obtained by applying a least squares program to the refined experimental molecular diffraction intensities. The CC bond length was found to be 1.336 ± 0.002 Å while the ) bond length was 1. 529 ± 0.007 Å. Other bond lengths and angles included (IUPAC numbering system was used for norbornene): C1-C6 = 1.550 ± 0.020 Å, C1-C7 = 1.566± 0.005 Å, C5-C6 = 1.556 ± 0.005 Å, C-Have. = 1.103 ± 0.003 Å, ∠C1C2C4 = 95.3°. The dihedral angle between planes C1C2C3C4 and C1C6C5C4 is 110.8 ± 1.5° while that between C1C2C3C4 and C1C7C4 is 122.3°. The moments of inertia calculated from ED structure are in good agreement with microwave spectroscopic values. 相似文献
146.
The molecular structure of 1,2,4-triazole has been determined by gas phase electron diffraction. The intemuclear distances and bond angles were obtained by applying a least-squares analysis to the experimental intensity. The bond distances (rg) and bond angles were N1-N2 = 1.380 ± 0.010 Å, N2C3 = 1.329 ± 0.009 Å, C3-N4 = 1.348 ± 0.009 Å, N1-C5 = 1.377 ± 0.004 Å, N4C5 = 1.305 Å (calculated value). N-H = 0.990 Å, C-H = 1.054 Å, ∠N1N2C3 = 102.7± 0.5°, ∠N2C3N4 = 113.8 ± 1.3°, ∠N2N1C5 = 108.9 ± 0.8°, ∠H1N1N2 = 110.9°, ∠H2C3N4 = 119.2°, ∠H3C5N1 = 131.0°, ∠C3N4C5 = 105.7° (calculated value) and ∠N4C5N1 = 108.7° (calculated value). 相似文献
147.
线性非理想条件下液相色谱柱末端峰形规律 总被引:2,自引:1,他引:2
色谱流出曲线的二阶中心矩μ2和三阶中心矩μ3以及描述峰形非对称程度的偏态系数∑k=μ3/μ1.52是反映色谱峰形的重要参数。从液相色谱过程动力学方程出发,运用电子计算机证明了在线性非理想条件下高效液相色谱体系中不同保留值组分在柱末端峰形的分布基本一致的结论。 相似文献
148.
An efficient synthesis of (+/-)-leporin A (1) has been developed using a tandem Knoevenagel condensation-inverse electron demand intramolecular hetero Diels-Alder reaction to construct the key tricyclic intermediate 3 from pyridone 5 and dienal 6 in one pot in 35% yield. Hydroxylation (71%) of 3 and methylation (77%) of the resulting hydroxypyridone 2 completed the first total synthesis of (+/-)-leporin A (1). 相似文献
149.
The equation of state (EOS) of Duh and Mier-y-Terán for one Yukawa potential is expanded to two Yukawa potentials to describe the nonidealities of the charged lysozyme and alpha-chymotrypsin solutions. Instead of the classical DLVO theory, the attractive dispersion and double-layer repulsion interactions are represented by two Yukawa potentials, respectively. For the aqueous lysozyme solutions, the only adjustable dispersion energy parameter epsilon/k is regressed and the average deviation is 1.76%. For the aqueous alpha-chymotrypsin solutions, two adjustable parameters (the molecular weight and dispersion energy parameter) are regressed and the average deviation is 7.62%. Some correlation and prediction results are discussed. 相似文献
150.
Alcohol sensing membranes coated on overhead transparency films for the continuous monitoring of ethanol, propanol and butanol are presented. Alcohol oxidation catalyzed by alcohol oxidase in conjunction with the fluorescence quenching reaction of oxygen-sensitive dye ion-pair, tris(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) didodecylsulphate was chosen for the determination. Alcohol oxidase was immobilized covalently on a plasticized carboxylated poly(vinyl chloride) membrane and the oxygen-sensitive dye ion-pair was entrapped in the same membrane. The sensing membrane relates oxygen consumption, as a result of enzymatic oxidation, to alcohol concentration. Measurements have been performed in air-saturated alcohol standard solutions of pH 7.0. Storage stability, reproducibility and the effect of pH on sensing membrane performance have been studied in detail. The alcohol sensing membrane proposed here is simple to prepare and has a fairly rapid response time of <1 min. It has been successfully applied to the determination of the ethanol contents in various spirits. 相似文献