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21.
《Journal of Molecular Catalysis #》1992,71(2):149-155
Hydroxylation or ketonization of alkanes is achieved using lithium or sodium hypochlorite in the presence of catalytic amounts of ruthenium(II) complexes in a biphasic dichloromethane—water system, at room temperature. The oxidation of cyclooctane is first order both in substrate and in catalyst: a kinetic isotope effect (kH/kD) = 5.6 was measured using cyclohexane-d12. A discussion is included concerning the origin of the different regioselectivities. 相似文献
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没食子酸磁性表面分子印迹聚合物的制备与选择性识别性能 总被引:1,自引:0,他引:1
羟基苯甲酸类化合物用途广泛,极性较强,在复杂水溶液体系中这些类似物的分离纯化与分析非常困难。 本文以磁性Fe3O4纳米颗粒为载体,没食子酸(GA)为模板分子,制备了磁性表面分子印迹聚合物(MIP)。 利用透射电子显微镜、红外光谱、磁强测定等检测手段对MIP进行了结构表征。 并对其吸附性能进行研究,比较了该MIP对GA及其它3种结构类似物的吸附性能差异。 结果表明,制备的以GA为模板的磁性分子印迹聚合物为核壳球形结构,键合牢固,对GA的吸附动力学符合准二级动力学方程模型,吸附过程属于Langmuir单分子层吸附。 该聚合物对GA表现出优异的选择性识别能力,其吸附量(318 K时37.736 mg/g)远远高于结构类似物。 该磁性分子印迹聚合物对模板分子不仅具有特异识别能力,而且能够磁控分离,分离效率高,可用于固相萃取。 相似文献
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We investigate modulational instability (MI) of a coupled two-component Bose-Einstein condensates in a rotating ring trap. The excitation spectrum and the MI condition of the system are presented analytically. We find that the coupling between the two components strongly modifies the MI condition, and the MI condition is phase-dependent. Furthermore, we discuss the effect of MI on both density excitation and spin excitation. If the inter- and intra-component interaction strengths are all equal, the MI causes density excitation but not spin excitation, and if the inter- and intra-component interaction strengths are different, the MI causes both density excitation and spin excitation. Our results provide a promising approach for controlling the stability and excitation of a rotating two-component Bose-Einstein condensates by modulating its coupling strength and interaction strength. 相似文献
25.
We consider an inertial two-level atom in interaction with a real massless scalar quantum field in a spacetime between two parallel reflecting plane boundaries, and calculate the contributions of vacuum fluctuations and radiation reaction to the rate of change of the atomic energy. Our results show that there exists a regime of the separation L between the two boundaries such that the excited atom's spontaneous emission is impossible. There also exist certain values of the atom's position such that the corrections due to the presence of boundaries balance each other, so that the atom's spontaneous emission rate is the same as if there were no boundaries at all. 相似文献
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通过静态吸附平衡和动态柱吸附试验,研究了自制大孔交联聚(对乙烯基苄基脲)树脂(简称PMVBU树脂)对银杏叶黄酮的吸附性能.结果表明,在pH=5.00时,该树脂对银杏叶黄酮有较好的吸附性能;PMVBU树脂对黄酮的吸附等温线符合Langmuir吸附等温方程,相关系数R^2〉0.99.308K时,PMVBU干树脂对黄酮的静态饱和吸附量达293.3mg/g.298K时,干树脂的动态吸附穿透容量为180mg/g.用75%的乙醇溶液对吸附在PMVBU树脂上的黄酮可进行有效洗脱.银杏叶提取液经过该树脂吸附柱吸附纯化后,黄酮纯度提高了18.6%,且树脂具有良好的重复使用性. 相似文献
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The product from reaction of lanthanum chloride seven-hydrate with salicylic acid and 8-hydroxyquinoline, La(C7H5O3)2·(C9H6NO), was characterized by IR, elemental analysis, molar conductance, and thermogravimetric analysis. The standard molar enthalpies of solution of [LaCl3·7H2O (s)], [2C7H6O3 (s)], [C9H7NO (s)] and [La(C7H5O3)2·(C9H6NO) (s)] in a mixed solvent of absolute ethyl alcohol, dimethyl formamide (DMF) and perchloric acid were determined by calorimetry to be [LaCl3·7H2O (s), 298.15 K] = −96.45 ± 0.18 kJ mol−1, [2C7H6O3 (s), 298.15 K] = 14.99 ± 0.17 kJ mol−1, [C9H7NO (s), 298.15 K] = −3.86 ± 0.06 kJ mol−1 and [La(C7H5O3)2·(C9H6NO) (s), 298.15 K] = −117.78 ± 0.11 kJ mol−1. The enthalpy change of the reaction
(1) 相似文献
28.
Zheng-Hua Tang Zheng-Sheng Jiang Tao Chen Chun-Zhi Jiang Da-Jun Lei Jian-Quan Huang Feng Qiu Min Yao Xiao-Yi Huang 《Physics letters. A》2018,382(2-3):106-110
Anisotropic piezoelectric superlattices (APSs) with the periodic arrangement of polarized anisotropic piezoelectric domains in a certain direction are presented, in which the coupled polaritonic band gaps (CPBGs) can be obtained in the whole Brillouin Zone and the maximum relative bandwidth (band-gap sizes divided by their midgap frequencies) of can be achieved. The general characteristics of the APSs are similar to those of the phononic crystals composed of two types of materials, with the main difference being the formation mechanism of the CPBGs, which originate from the couplings between lattice vibrations along two different directions and electromagnetic waves rather than from the periodical modulation of density and elastic constants. In addition, there are no lattice mismatches because the APSs are made of the same material. Thus, the APSs can also be extended to the construction of novel acousto-optic devices. 相似文献
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Long Huang Feng He Hai Huang Min Yao 《International Journal of Theoretical Physics》2014,53(6):1947-1952
Gravitation deflects light, which has been confirmed by a large number of observation data. f(R)-gravity is modification of Einstein’s gravity. According to the field equations obtained by the action of the f(R) form, a similar Schwarzschild metric is obtained. According to the condition that four-dimension momenta of the photon return to zero and conservation of covariant momenta, we obtain an equation of photon motion in a specific form of f(R)-gravity. We solve the equation to get gravitational deflection angle of light that grazes surface of sun and the calculation result is consistent with the experimental observation data. 相似文献