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61.
Based on the hydrodynamic model theory and the transfer-matrix-method, we have reexamined the reflection properties by taking account of damping effects to the system of the metallic superlattice for the S-polarized soft X-rays and extreme ultraviolet. Fot the normal incidence, we find that the reflection intensity spectxm will decline monotonously with the increasing of the retardation, but for the regions of the higher frequencies and the smaller grazing angles, the damping effects could be neglected. 相似文献
62.
63.
用Hartrce-Fock-Relativistic(HFR)自洽场方法,计算类锂铝离子1s^2nl(n=2~7,l=0~5),1snln’l’(n,n’=2~3,l,l’=0~2)各能级值,电偶极跃迁谱线的光谱线性质(波长、振子强度和跃迁几率),其波长计算值和现有文献结果符合得较好。特别是实验中已观察到的软X射线激光跃迁(3d-4f,3d-5f)的波长值与我们的计算值符合得也很好。 相似文献
64.
J. -P. Deelchand Z. Naqvi C. Dubau J. Shearman M. -J. Lazaro A. A. Herod H. Read R. Kandiyoti 《Journal of chromatography. A》1999,830(2):3193-414
Vacuum distillation residues from two petroleum crudes, a coal liquefaction extract and a coal tar pitch have been fractionated by planar chromatography (PC) using two solvent sequences: pyridine–acetonitrile and tetrahydrofuran (THF)–toluene. Fractions recovered from PC were examined by UV-fluorescence spectroscopy (UV-F), size-exclusion chromatography (SEC). UV-F and SEC of the whole samples showed differences in aromatic cluster size and molecular mass (MM) ranges which could be related to the different origins of the samples. The MM ranges indicated by SEC were greater for the vacuum residues than for coal-derived materials. However, the UV-F spectra of the fractions indicated that the petroleum residue fractions contained similar aromatic types, whereas the fractions from coal liquids contained significantly different aromatic types. SEC profiles of the fractions indicated a separation of coal-derived samples by increasing molecular size with increasing immobility in PC, whereas for petroleum fractions, the same trend was not apparent. MALDI-mass spectra of the set of original samples showed broadly similar ranges of MM distributions but additional work is necessary to identify appropriate matrices and procedures in order to improve the MALDI spectra. 相似文献
65.
合成了一种有机-无机介孔二氧化硅杂化材料(SBA-15-Tpy),通过透射电镜显微镜、X射线衍射、热重分析和N_2吸附-解吸曲线对其进行表征,并基于该材料建立了在水中对Cu2+和Co2+的选择性识别。研究表明,SBA-15-Tpy与Cu2+和Co2+结合后会分别在800 nm和510 nm处产生新的吸收峰,加入其它金属离子后不发生明显的吸收峰值变化。在最优条件下,检测Cu2+和Co2+的线性范围分别为2.0~200.0μmol/L和10.0~200.0μmol/L,检出限分别为0.48μmol/L和4.28μmol/L。将上述方法用于江水中Cu2+和Co2+的测定,回收率在96.0%~108.5%之间。 相似文献
66.
Furqan Ahmad Saddique Sadia Faiz Syed Ali Raza Naqvi Muhammad Usman Matloob Ahmad 《合成通讯》2016,46(10):831-868
β-Amino alcohols are versatile intermediates in the synthesis of various biologically potent compounds, which can also be achieved by ring opening of epoxides by amines. In the present review, focus has been placed on the ring opening of epoxides with amines under a variety of reaction parameters reported during 2011–2015. All the factors that resulted in excellent yields and high regioselectivity, are environmentally benign, and use mild conditions have been discussed in detail. In addition, the applications of these methods in the synthesis of biologically active compounds such as β-blockers have also been described. 相似文献
67.
Summary Group-theoretical study of the vibrational modes of chlorosodalite [Na4Al3(SiO4)3]2 has been carried out for theT
d
1
space group. The Raman-active modes are evaluated and comparison is made with the experimental results on sodalite. It is
shown that the experimental Raman spectrum does not support the structure of sodalite to beT
d
1
but confirms it to beT
d
1
. Raman scattering studies were performed on X-ray irradiated As-grown single crystal of chloro-sodalite to identify the coloration
mechanism. Enhancement of oxygen twisting and stretching mode intensities on X-ray irradiation indicates the formation of
neutral sodium colloidal aggregate during the coloration process.
The authors of this paper have agreed to not receive the proofs for correction. 相似文献
68.
Interval exchange transformations (IETs) are piecewise isometries of the interval, obtained permuting a certain number of
subintervals. We give a condition on IETs in the special subclass of IETs with periodic Rauzy-Veech cocycle which guarantees
weak mixing, i.e. the continuity of the spectrum. The proof involves the study of the associated spectral measures. The condition
can be checked explicitly by computing a certain Galois group of a field related to the Ravzy-Veech cocycle. Explicit examples
of weakly mixing IETs are constructed in the Appendix.
*Dedicated to the memory of F.A. Berezin 相似文献
69.
70.
In this paper, the focussing of the transmitted electromagnetic field through a quadric inhomogeneous slab of lossless uniaxial chiral medium is derived using transmission coefficient under oblique incidence. The inhomogeneity in the uniaxial chiral slab has been incorporated through permittivity parameter. Asymptotic ray theory provides valid field everywhere except at focal point where it gives infinite value. Singularity of the field at focal point is addressed using Maslov's method. The derived analytical field expressions at caustic or focal point of uniaxial quadratic inhomogeneous slab have been solved numerically using MATHEMATICA. The effects of chirality parameter, axial permittivity, transvers permittivity, angle of incidence on the refracted field are discussed and the effects of Brewster angle on the focussed field are also discussed. The results obtained using Maslov's method are compared with Huygens–Kirchhoff's integral which are in good agreement. 相似文献