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41.
Dan Archdeacon C. Paul Bonnington Joanna A. Ellis-Monaghan 《Discrete and Computational Geometry》2007,38(3):573-594
Steinitz's theorem states that a graph is the 1-skeleton of a convex polyhedron if and only if it is 3-connected and
planar. The polyhedron is called a geometric realization of the embedded graph. Its faces are bounded by convex polygons whose
points are coplanar. A map on the torus does not necessarily have such a geometric realization. In this paper we relax the
condition that faces are the convex hull of coplanar points. We require instead that the convex hull of
the points on a face can be projected onto a plane so that the boundary of the convex hull of the projected points is the
image of the boundary of the face. We also require that the interiors of the convex hulls of different faces do not intersect.
Call this an exhibition of the map. A map is polyhedral if the intersection of any two closed faces is simply connected. Our
main result is that every polyhedral toroidal map can be exhibited. As a corollary, every toroidal triangulation has a geometric
realization. 相似文献
42.
43.
A simple and sensitive method was conducted for the determination of trace amounts of proteins with benzeneazo-8-acetylamino-1-naphthol-3,6-disulfonic acid sodium salt (azophloxine, AP) using a Rayleigh light-scattering (RLS) technique. At pH 2.60 and in the presence of an emulsifier OP microemulsion, the RLS of AP can be greatly enhanced by proteins, owing to the interaction between AP and protein. The enhanced intensity is proportional to the concentration of proteins. Four proteins, including bovine serum albumin (BSA), human serum albumin (HSA), lysozyme (Lys) and gamma globulin (gamma-G) have been tested. For example, the linear range of BSA was 0 - 0.06 microg mL(-1) with detection limits of 2.38 ng mL(-1). The method was applied to the analysis of protein in human urine and penicillin samples with satisfactory results. The relative standard deviation was in all instances less than 4.0%, and the recovery was in the range of 97.5 - 104%. 相似文献
44.
The newton filtration and d-determination of bifurcation problems related to C
0 contact equivalence
In this paper, from the Newton filtration’s point of view, we construct the singular Riemannian metric and use the method in singular theory to study the bifurcation problems, and give the sufficient condition of d-determination of bifurcation problems with respect to C 0 contact equivalence. The special cases of the main result in this paper are the results of Sun Weizhi and Zou Jiancheng. 相似文献
45.
We compute the entropyh
A
(
U
) in the sense of Connes, Narnhofer and Thirring of Bogoliubov automorphisms
U
of the CAR-algebra with respect to invariant quasifree states
A
with 0A1 having pure point spectrum.Supported in part by a grant from the National Science Foundation 相似文献
46.
DongJunWANG QunLUO DanDanJIA XiaoDongLI XinQiouWANG YongHuang ZhenZHEN XinHouLIU 《中国化学快报》2003,14(12):1306-1308
The hydrolysis of tetraethoxysilane (TEOS) occurred on the surface of poly(methyl methacrylate) (PMMA) microshperes immediately after these microshperes were prepared in TEOS. Micron-sized hollow SiO2 spheres were obtained by calcination of the coated PMMA microshperes. It was found that the final hollow spheres were constituted by small SiO2 particles. 相似文献
47.
48.
Angelica pubescens and Angelica sinensis belong to the Umbelliferae family and both are used as traditional Chinese medicines. In the present study, headspace solid-phase microextraction (HS-SPME) with gas chromatography-mass spectrometry (GC-MS) was used for the analysis of the volatile constituents present in their roots. Eighty-seven compounds in Angelica pubescens and thirty-six compounds in Angelica sinensis were identified by GC-MS. Their relative contents were calculated by the peak area ratio. HS-SPME was compared to steam distillation (SD) by analyzing the volatile constituents of Angelica sinensis root. A good agreement between results obtained with both techniques was found. As a conclusion, HS-SPME is a powerful tool for determining the volatile constituents present in the TCMs. 相似文献
49.
Two layered amine-templated cobalt squarates, [C6N2H14]2[Co2(C4O4)3(H2O)4], I, and [C3N2H5]2[Co2(C4O4)3(H2O)4], II, have been prepared under hydrothermal conditions. Both I and II contain chains formed by dimers comprising two cobalt atoms bound to the squarate units, the chains being connected through hydrogen bond interactions. An amine-templated cobalt squarate of the formula [C4N2H12][Co(C4O4)2(H2O)4][H2O]2, III, as well as its Ni, Zn and Cd analogues have been prepared by room temperature reactions. III has a layered architecture wherein the cobalt-squarate monomers are linked by the amine molecules. Co and Zn analogues of [Ni(C4O4)(H2O)2(C3N2H4)] with ligating imidazole units have also been prepared and characterized. 相似文献
50.
TONG Hua-Nan ZHANG Hao CHENG Wen-Dan WU Dong-Sheng GONG Ya-Jing ZHU Jing HUANG Shu-Ping ZHAO Dan 《结构化学》2007,26(3)
The single crystal and crystallized powder of triphosphate CeP3O9 have been synthesized, and the space group of CeP3O9 has been determined to be C2221 with the cell parameters ofa = 8.6059, b = 11.2437, c = 7.3518 (A), V= 711.4(3) (A)3, Z= 4, Dc = 3.520 g/cm3, F(000) = 700,R = 0.0377 and wR = 0.0930. The absorption and emission spectra have been measured, for which the strongest absorption and emission peaks are located at 280 and 320 nm, respectively. The density of state (DOS) and dielectric function have been calculated by the DFT method. The crystal is transparent provided the wavelength is larger than 341 nm, and the observed ultraviolet cut-off edge is at about 350 nm for a polycrystalline power sample. It is possible that the triphosphate CeP3O9 will become an ultraviolet emission material. 相似文献