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61.
Leif Kjr Jrgensen 《Journal of Graph Theory》1989,13(1):75-85
A probabilistic result of Bollobás and Catlin concerning the largest integer p so that a subdivision of Kp is contained in a random graph is generalized to a result concerning the largest integer p so that a subdivision of Ap is contained in a random graph for some sequence A1, A2,… of graphs such that Ai+1 contains a subdivision of Ai. A similar result is proved for subdivisions with odd paths or cycles. The result is applied to disprove a conjecture of Chartrand, Geller, and Hedetniemi. The maximum number of edges in a graph without a subdivision of Kp, p = 4, 5, with odd paths or cycles is determined. 相似文献
62.
Á. Pintér 《Archiv der Mathematik》1993,61(1):64-67
Research supported in part by Grant 4055 from the Hungarian National Foundation for Scientific Research and by Kereskedelmi és Hitelbank Rt. Universitas Foundation. 相似文献
63.
64.
K. Böröczky Jr. 《Geometriae Dedicata》1990,34(1):13-18
An E rc="/content/l848374432616290/xxlarge8834.gif" alt="sub" align="MIDDLE" BORDER="0"> R
2 is r-convex if for every x, y rc="/content/l848374432616290/xxlarge8712.gif" alt="isin" align="MIDDLE" BORDER="0"> E there exists a closed rectangle R such that x, y rc="/content/l848374432616290/xxlarge8712.gif" alt="isin" align="MIDDLE" BORDER="0"> R and R rc="/content/l848374432616290/xxlarge8834.gif" alt="sub" align="MIDDLE" BORDER="0"> E. Several results about r-convexity appeared in [1]. Its authors formulated a conjecture about conditions for a compact, convex set in R
2 to be r-convex. We prove this conjecture in the case of convex domains of constant width. 相似文献
65.
For eachdrc="/content/yjw4751758u4v63u/xxlarge8805.gif" alt="ge" align="MIDDLE" BORDER="0">1 there is a constantc
d>0 such that any finite setXrc="/content/yjw4751758u4v63u/xxlarge8834.gif" alt="sub" align="MIDDLE" BORDER="0">R
d contains a subsetYrc="/content/yjw4751758u4v63u/xxlarge967.gif" alt="chi" align="MIDDLE" BORDER="0">X, |Y|rc="/content/yjw4751758u4v63u/xxlarge8804.gif" alt="le" align="MIDDLE" BORDER="0">[1/4d(d+3)]+1 having the following property: ifErc="/content/yjw4751758u4v63u/xxlarge8835.gif" alt="sup" align="MIDDLE" BORDER="0">Y is an ellipsoid, then |E rc="/content/yjw4751758u4v63u/xxlarge957.gif" alt="ngr" align="BASELINE" BORDER="0"> X|rc="/content/yjw4751758u4v63u/xxlarge8805.gif" alt="ge" align="MIDDLE" BORDER="0">c
d |X|.On leave from the Mathematical Institute of the Hungarian Academy of Sciences, 1364 Budapest, P.O. Box 127, Hungary. Supported by a research fellowship from the Science and Engineering Research Council, U.K., and by Hungarian National Foundation for Scientific Research Grant No. 1812. 相似文献
66.
67.
Shkumbatiuk R Bazel YR Andruch V Török M 《Analytical and bioanalytical chemistry》2005,382(6):1431-1437
A new, simple, rapid, and sensitive spectrophotometric method has been developed for the determination of nitrophenols [picric acid (PA); dinitrophenols (DNP)] in wastewater samples. The method is based on the reaction of nitrophenols with 2-[(E)-2-(4-diethylaminophenyl)-1-ethenyl]-1,3,3-trimethyl-3 H-indolium chloride reagent to form the colored ion associates, which are extracted by organic solvents. The molar absorptivity of the ion associates of PA with the investigated reagent ranges from 8.3×104 to 11.3×104 L mol–1 cm–1, depending on the extractant. Because only PA is extracted in an acidic medium with the investigated reagent, but both PA and DNP are extracted in an alkaline medium, it is possible to determine both substances in a mixture. Appropriate reaction conditions have been established. The absorbance of the colored extracts obeys Beerrc="/content/n912m14u71470217/xxlarge8217.gif" alt="rsquo" align="BASELINE" BORDER="0">s law in the range of 0.04–4.58 mg L–1 PA, 1.0–18.4 mg L–1 2,4-DNP and 1.2–14.7 mg L–1 2,6-DNP, respectively. The limit of detections, calculated from a blank test (n=10; P=0.95), are 0.05 mg L–1 PA, 0.9 mg L–1 (2,4-DNP), and 1.1 mg L–1 (2,6-DNP), respectively. 相似文献
68.
The application of the recently introduced ethylchloroformate derivatization method for the separation and determination of selenomethionine and selenocystein in selenium-enriched yeast and yeast-free tablets by means of a gas chromatography-mass spectrometry (GC-MS) system has been studied. The efficiency of three methods for the extraction of selenomethionine from the tablets were compared. Total selenium content of the same tablets were measured using inductively coupled plasma (ICP)-MS and it was found that in the selenized yeast tablets about 80% of the total selenium is present as selenomethionine. The results were in agreement with the values in the labels and with the literature. The accuracy of the total selenium analysis was controlled by the analysis of a reference material. 相似文献
69.
The present state of a long term program is reviewed. It was started to elaborate a remote controlled automated radiochemical
processing system for the neutron activation analysis of biological materials. The system is based on wet ashing of the sample,
followed by reactive desorption of some volatile components. The distillation residue is passed through a series of columns
filled with selective ion screening materials to remove the matrix activity. The solution is thus “stripped” from the interfering
radioions, and it is processed to single-elements through group separations using ion-exchange chromatographic techniques.
Some special problems concerning this system are treated. (a) General aspects of the construction of a (semi)automated radiochemical
processing system are discussed; (b) Comparison is made between various technical realizations of the same basic concept;
(c) Some problems concerning the “reconstruction” of an already published processing system are outlined. 相似文献
70.
S Çak?r E Co?kunP Naumov E Biçer? Bulut H ?çbudakO Çak?r 《Journal of Molecular Structure》2002,608(1):101-107
Aspartame adduct of copper(II) chloride Cu(Asp)2Cl2·2H2O (Asp=aspartame) is synthesized and characterized by elemental analysis, FT IR, UV/vis, ESR spectroscopies, TG, DTG, DTA measurements and molecular mechanics calculations. Aqueous solution of the green solid absorbs strongly at 774 and 367 nm. According to the FT IR spectra, the aspartame moiety coordinates to the copper(II) ion via its carboxylate ends, whereas the ammonium terminal groups give rise to hydrogen bonding network with the water, the chloride ions or neighboring carboxylate groups. The results suggest tetragonally distorted octahedral environment of the copper ions. 相似文献