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41.
Given a pair of start and target configurations, each consisting of n pairwise disjoint disks in the plane, what is the minimum number of moves that suffice for transforming the start configuration into the target configuration? In one move a disk is lifted from the plane and placed back in the plane at another location, without intersecting any other disk. We discuss efficient algorithms for this task and estimate their number of moves under different assumptions on disk radii. We then extend our results for arbitrary disks to systems of pseudodisks, in particular to sets of homothetic copies of a convex object. 相似文献
42.
Propylene polymerization on TiCl4/donor/MgCl2 (donor = ethyl benzoate, dibutyl phthalate, diisobutyl phthalate, diethyl 2,3-diisopropylsuccinate) supported catalysts is considered. The states of the donors in the catalysts have been investigated by diffuse reflectance IR spectroscopy. Data characterizing the distribution of the donors and the active component (TiCl4) on the support surface have been obtained. Molecular weight distribution data for polypropylene are presented. The molecular weight distribution of polypropylene depends on the location of the donor and TiCl4 molecules. 相似文献
43.
Study of the viscoelastoplastic deformation of an element of a body with a three-branch loading path
Yu. N. Shevchenko R. G. Terekhov N. S. Braikovskaya S. M. Zakharov 《International Applied Mechanics》1991,27(12):1162-1167
Institute of Mechanics, Academy of Sciences of the Ukraine, Kiev. Translated from Prikladnaya Mekhanika, Vol. 27, No. 12, pp. 26–33, December, 1991. 相似文献
44.
Sergey V. Avgustinovich Olof Heden Faina I. Solov’eva 《Designs, Codes and Cryptography》2006,39(3):317-322
The main result is that to any even integer q in the interval 0 ≤ q ≤ 2n+1-2log(n+1), there are two perfect codes C1 and C2 of length n = 2m − 1, m ≥ 4, such that |C1 ∩ C2| = q. 相似文献
45.
Alexander I. Roshchin Sergey M. Kelchevski Nikolai A. Bumagin 《Journal of organometallic chemistry》1998,560(1-2)
Substituted 2-methylbenzofurans were obtained from 2-allylphenols via Pd2+-catalyzed oxidative cyclization using Cu(OAc)2–LiCl as a reoxidant and wet DMF as a solvent. 相似文献
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N. S. Prostakov Keti Sudzhi N. M. Mikhailova L. A. Murugova V. F. Zakharov 《Chemistry of Heterocyclic Compounds》1981,17(10):1038-1042
1-Methyl-1H-indeno[1,2-b]pyridine and 1-methyl-1H-5-(, -dicarbomethoxyvinyl)-(formyl, acetyl)indeno[3,2-b]pyridines were obtained by treatment of N-methyl-4-azafluorenium iodide, as well as mixtures of it with acetylenedicarboxylic ester, dimethylformamide (DMF), and phosphorus oxychloride or acetic anhydride, with bases. 4-Azafluoronenone was used to synthesize 9-(p-methoxyphenyl)-4-azafluoren-9-ol, which was reduced to 9-(p-methoxyphenyl)-4-azafluorene, and 1-methyl-1H-5-(p-methoxyphenyl)indeno[3,2-b]pyridine was obtained from the methiodide of the latter.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1382–1386, October, 1981. 相似文献
50.
F. M. Stoyanovich E. P. Zakharov O. V. Lysenko V. N. Yarovenko M. M. Krayushkin 《Russian Chemical Bulletin》1991,40(1):225-227
Preparative syntheses have been developed for 2-amino-5-cyano-1,3,4-oxadiazole from the semicarbazone of methyl glyoxylate and some of its transformations were studied. This product is an important intermediate in the preparation of its derivatives.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1. 243–246, January, 1991. 相似文献