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41.
Xuan Chuan Cao 《International Journal of Theoretical Physics》1997,36(6):1465-1474
It is shown that, starting from an exactly solvable potential and making use of the theory of a system of coupled differential
equations, it is possible to construct a new type of second-generation potential which is also exactly solvable. 相似文献
42.
Shangqing Li Jinglong Ma Xiaojun Wu Baolong Zhang Chen Ouyang Tianze Wang Dan Wang Xuan Wang Yutong Li 《中国光学快报(英文版)》2021,(5):60-64
We propose a spatial diffraction diagnostic method via inserting a millimeter-gap double slit into the collimated terahertz beam to monitor the minute variation of the terahertz beam in strong-field terahertz sources, which is difficult to be resolved in conventional terahertz imaging systems. To verify the method, we intentionally fabricate tiny variations of the terahertz beam through tuning the iris for the infrared pumping beam before the tilted-pulse-front pumping setups.The phenomena can be well explained by the theory based on the tilted-pulse-front technique and terahertz diffraction. 相似文献
43.
甲状腺内^(131)I放射性活度与辐射探测结果的比例关系与甲状腺几何尺寸、探测距离等因素相关,是估算甲状腺内^(131)I含量与其可能造成的辐照损伤的关键参数。基于MCPT辐射输运数值模拟算法器库开发了用于开展NaI探测器伽马辐射测量模拟的应用程序,进而建立了多组具有不同容积的甲状腺型容器和不同探测距离的物理模型,最终通过蒙特卡罗数值计算得到了不同测量状态下探测器的探测效率。在甲状腺型容器与探测器距离较远时,数值模拟给出的结果与理论计算结果一致,证明此应用程序可用于定量分析NaI的探测效率。数值模拟结果表明,小距离模型的结果受甲状腺样容器的大小和距离的显著影响,模拟给出的探测效率表为开展深入细致的实验研究奠定了基础。 相似文献
44.
We are concerned with the Cauchy problem of the quantum Landau equation in the whole space. The existence of local in time nearby quantum Maxwellian solutions is proved by the iteration method and generalized maximum principle. Based on Kawashima?s compensating function and nonlinear energy estimates, the global existence and the optimal time decay rate of those solutions are obtained under some conditions on initial data. 相似文献
45.
We report a systematic, experimental, and theoretical investigation on the surface plasmon resonance (SPR) sensing using optical disks with different track pitches, including Blu-ray disk (BD), digital versatile disk (DVD), and compact disk (CD). Optical reflection measurements indicate that CD and DVD exhibit much higher SPR sensitivity than BD. Both experiments and finite-difference time-domain simulations reveal that the SPR sensitivity is significantly affected by the diffraction order of the SPR peaks and higher diffraction order results in lower sensitivity. Numerical simulations also show that very high sensitivity (~1600 nm per refractive index unit) is achievable by CDs. 相似文献
46.
47.
A facile and efficient method has been developed for synthesis of β-iodocarboxylates in the presences of Ph3P/I2. Starting from epoxides, a series of β-iodocarboxylate compounds can be directly obtained in toluene media with excellent yields. Moreover, the method was successfully applied for the late-stage modification of natural products, such as isosteviol and vincamine derivatives, achieving the corresponding β-iodocarboxylates in good yields. 相似文献
48.
Xuan Zhang Xianhe Fang Miao Xu Yibo Lei Zibo Wu Xiangdong Hu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(23):7927-7931
Enantioselective total syntheses of pseudopteroxazole ( 1 ) and ileabethoxazole ( 2 ) are presented. The two original stereocenters were constructed in excellent enantioselectivity and good diastereoselectivity through Carreira's asymmetric dual catalytic allylation, which shows potential for accessing diastereoisomers at C2 and C3 of 1 and 2 . Cationic cyclizations of 13 and 24 demonstrated an effective pathway for the construction of the opposite configurations at C1 in 1 and 2 . Additionally, an approach for the introduction of methyl at C4 is a feasible solution for structural modifications at C4 in 1 and 2 . 相似文献
49.
Shu Ying Wu Xiao Min Zhang Hai Ou Tang Long Chen Bo Xuan Li 《Journal of solid state chemistry》2008,181(9):2171-2177
Ag/carbon hybrids were fabricated by the redox of glucose and silver nitrate (AgNO3) in the presence of imidazolium ionic liquid ([C14mim]BF4) under hydrothermal condition. Monodisperse carbon hollow sub-microspheres encapsulating Ag nanoparticles and Ag/carbon cables were selectively prepared by varying the concentration of ionic liquid. Other reaction parameters, such as reaction temperature, reaction time and the mole ratio of silver nitrate to glucose, play important roles in controlling the structures of the products. The products were characterized by XRD, TEM (HRTEM), SEM, energy-dispersive X-ray spectroscopy (EDX), FTIR spectroscopy and a Raman spectrometer. The possible formation mechanism was proposed. The catalytic property of the hybrid in the oxidation of 1-butanol by H2O2 was also investigated. 相似文献
50.
A new method of ionic liquids based cycle flow single drop microextraction combined with electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) was proposed for the determination of trace Co, Hg and Pb with 1-(2-pyridylazo)-2-naphthol (PAN) as both extractant and chemical modifier and 1-butyl-3-methylimidazolium hexafluorophosphate as the extraction solvent. Several factors that influence the microextraction efficiency, such as sample pH, sample flow rate, microdrop volume and extraction time, were investigated and the optimized microextraction conditions were established. Co, Hg and Pb in the post-extraction ionic liquids phase were directly determined by ETV-ICP-MS with the use of PAN as chemical modifier. The chemical modification of PAN in ETV-ICP-MS was studied and the factors affecting the vaporization behaviors of target analytes were investigated. Under the optimized conditions, the detection limits of the method were 1.5, 9.8 and 6.7 pg/mL for Co, Hg and Pb, with the relative standard deviations for 0.5 ng/mL (n = 7) of Co, Hg and Pb were 7.7%, 5.2% and 12.0%, respectively. After 10 min of extraction, the enrichment factors were 350 (Co), 50 (Hg) and 60 (Pb). The proposed method was successfully applied to the determination of trace Co, Hg and Pb in human serum and environmental water samples. In order to validate the developed method, a certified reference material of human hair (GBW07601) was analyzed and the determined values were in good agreement with the certified values. 相似文献