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排序方式: 共有1397条查询结果,搜索用时 22 毫秒
121.
Kazuhiro Kobayashi Sunyoung Kim Masakazu Kojima 《Applied Mathematics and Optimization》2008,58(1):69-88
Exploiting sparsity has been a key issue in solving large-scale optimization problems. The most time-consuming part of primal-dual
interior-point methods for linear programs, second-order cone programs, and semidefinite programs is solving the Schur complement
equation at each iteration, usually by the Cholesky factorization. The computational efficiency is greatly affected by the
sparsity of the coefficient matrix of the equation which is determined by the sparsity of an optimization problem (linear
program, semidefinite program or second-order cone program). We show if an optimization problem is correlatively sparse, then the coefficient matrix of the Schur complement equation inherits the sparsity, and a sparse Cholesky factorization
applied to the matrix results in no fill-in.
S. Kim’s research was supported by Kosef R01-2005-000-10271-0 and KRF-2006-312-C00062. 相似文献
122.
We investigated preliminary acute toxicity and primary skin irritation of nine pyrrolidone derivatives which had been previously developed as transdermal penetration enhancers. The acute toxicity was observed at a dose of 500 mg/kg after intraperitoneal administration in mice. Their primary skin irritations were examined with rabbit dorsal skin. 1-Lauryl-2-pyrrolidone induced the most severe irritation among the derivatives. Pyrrolidone derivatives having methyl group and methyloxycarbonyl group caused little irritation. The primary irritation indices of pyrrolidone derivatives were not relative to their accumulations in the skin but to their enhancing effects. In conclusion, 1-hexyl-4-methyloxycarbonyl- and 1-lauryl-4-methyloxycarbonyl-2-pyrrolidone are suggested to be adequate enhancers, judging from the balance of their enhancing activity and irritation. 相似文献
123.
N-Benzyl-D-glucamine dithiocarbamate (BGD), N-p-hydroxymethylbenzyl-D-glucamine dithiocarbamate (HBGD), and N-p-carboxybenzyl-D-glucamine dithiocarbamate (CBGD) were compared for their relative efficacies in the distribution and excretion of cadmium in mice exposed to cadmium. Mice were injected intraperitoneally with 109CdCl2 (1 mg of Cd/kg and 2 microCi of 109Cd/one animal). Three days later, they were injected with chelating agents (400 mumol/kg) every other day for 2 weeks. After injections of BGD and HBGD, cadmium was excreted mainly in the feces through the bile, and the fecal excretion of cadmium by HBGD was significantly higher than that by BGD or CBGD. These chelating agents increased the urinary excretion of cadmium to a small extent. The hepatic cadmium content was decreased only after HBGD injection. Also, the injection of HBGD caused a much greater decrease in renal cadmium content than did BGD or CBGD. These chelating agents did not result in the redistribution of cadmium to the brain, testes, or heart. The growth of mice was only slightly retarded by injections of these chelating agents. The results of this study indicate that the injection of HBGD to mice pretreated with cadmium can remove cadmium from the body, mainly through fecal excretion, without redistribution of cadmium to other tissues such as the brain, testes, and heart, more effectively than BGD or CBGD. 相似文献
124.
Iron mixed-valence complex, (n-C3H7)4N[FeIIFeIII(dto)3] (dto = C2O2S2) shows a new-type of phase transition coupled with spin and charge around 120 K, where the charge transfer between the FeII and FeIII sites occurs reversibly, and shows the ferromagnetic transition at 7 K. To investigate the magnetic structure and its dimensionality of (n-C3H7)4N[FeIIFeIII(dto)3], we have synthesized a mixed crystal system, (n-C3H7)4N[FeII1?xZnIIxFeIII(dto)3], and measured its magnetic properties. In this system, the magnetic moment is reduced with increasing of Zn ratio. Moreover, the ferromagnetic interaction changes to the antiferromagnetic one and the remnant magnetization disappears between x = 0.48 and 0.96, while the charge transfer between the FeII and FeIII sites disappears above x = 0.26. In this paper, we present the magnetic dilution effect on the charge transfer phase transition and the ferromagnetic transition by means of magnetic susceptibility measurement and 57Fe Mössbauer spectroscopy. 相似文献
125.
Noriyuki Kida Masanori Hikita Izuru Kashima Masaya Enomoto Miho Itoi Norimichi Kojima 《Polyhedron》2009,28(9-10):1694-1697
A photo-sensitive organic–inorganic hybrid system (SP)[FeIIFeIII(dto)3] (SP = spiropyran, dto = C2O2S2), has recently been developed, where the photo-isomerization of the intercalated spiropyran in solid state triggers the change of the magnetic properties, including the ferromagnetic transition temperature from 5 to 22 K. We performed 57Fe Mössbauer measurement in order to probe the microscopic states of iron ions in (SP)[FeIIFeIII(dto)3] and have investigated the photo-induced effect on them. The sample without UV-irradiation shows the charge transfer phase transition between 200 and 70 K and the higher and lower temperature phases coexist below 70 K, whereas the UV-irradiated sample does not undergo the charge transfer phase transition and the higher temperature phase is stable between 200 and 6 K. 相似文献
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129.
Takahiro Matsumoto Seikou Nakamura Naoto Kojima Tomohiro Hasei Masayuki Yamashita Tetsushi Watanabe Hisashi Matsuda 《Tetrahedron letters》2017,58(36):3574-3578
From the methanolic extract of the aerial parts of Isodon japonicus, two new ent-kaurane diterpenes, isodonterpenes I and II, were isolated together with 10 known diterpenes. Their chemical structures were elucidated on the basis of chemical and physicochemical evidence. The absolute configuration of isodonterpene I was elucidated by Cu-Kα X-ray crystallographic analysis. Antimutagenic activities of the major diterpenes were evaluated by the Ames test. This study represents the first evaluation of the antimutagenic activities of ent-kaurane diterpenes. 相似文献
130.
A new simplified structural model and its governing equations for beams on elastic foundations with elastic coupling are proposed. This modeling system is simple but appropriate for the initial structural design of large-scale submerged floating-beam structures moored by tension legs spaced at uniform interval along the beam. The model is actually for beam on discrete elastic supports rather than on continuous elastic foundations. Therefore, the governing equations are based on finite difference calculus and solutions for beams on discrete elastic supports with elasticity coupling are also proposed. To clarify the applicability limit of the proposed model, the equivalence between a beam on discrete elastic supports and that on continuous elastic foundation is investigated by comparisons of characteristic solutions. 相似文献