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51.
Fukushima S Miyata K Nishiyama N Kanayama N Yamasaki Y Kataoka K 《Journal of the American Chemical Society》2005,127(9):2810-2811
An A-B-C type triblock copolymer, tandemly aligning two types of polycations with different pKa values in a single polymer strand, was developed for the construction of novel polyplex micelles, satisfying a high DNA condensing ability as well as a proton buffering activity directed to elevating gene transfection. The micelle might feature the distinctive three-layered structure, where an inner polyplex layer of condensed pDNA with poly(l-lysine) (pKa approximately 9.4) as the C segment is successively wrapped with an intermediate layer of poly[(3-morpholinopropyl)aspartamide] (B segment) with a comparatively low pKa of approximately 6.2, to provide a buffering effect, and an outer PEG layer (A segment) as a biocompatible palisade. 相似文献
52.
53.
Irradiation of sodium 1-naphthoxide in MeOH gave selectively 1,4-dihydro-4',8-dihydroxy-1,1'-binaphthyl 2. A similar reaction in PhH afforded the regioisomer 5, along with 6, Structural proof is presented for these hitherto unknown dimers. The reaction is completely quenched in the presence of naphthalene, a good electron scavenger. This new type of photodimerization was proved to be initiated by intermolecular electron-transfer from the excited 1-naphthoxide anion to the ground state one to give the oxidation-reduction dimers. 相似文献
54.
Tohru Azumi 《Chemical physics letters》1973,19(4):580-583
The effect of external heavy-atom perturbation is examined for each of the three spin subcomponents of the π,π* triplet state. It is shown that the radiative decay rate from the subcomponent whose spin wavefunction is within the molecular plane is most effectively enhanced. The main perturbing singlet state is the charge-transfer state arising from the excitation of an electron from a π orbital of the molecule to the σ* orbital of the perturber. 相似文献
55.
Miki Murata Hiyoruki Yamasaki Tsukasa Ueta Masayuki Nagata Masanori Ishikura Shinji Watanabe Yuzuru Masuda 《Tetrahedron》2007,63(19):4087-4094
The general and efficient silylation of aryl halides has been developed utilizing triethoxysilane and a rhodium catalyst. The substrate scope is broad and includes ortho-, meta-, and para-substituted electron-rich and -deficient aryl iodides. In addition, the silylation of aryl bromides and fluoroalkanesulfonates proceeded in the presence of tetra-n-butylammonium iodide. 相似文献
56.
Metal-ion-assisted hydrolysis of dipeptides involving a serine residue in a neutral aqueous solution
Yashiro M Sonobe Y Yamamura A Takarada T Komiyama M Fujii Y 《Organic & biomolecular chemistry》2003,1(4):629-632
Dipeptides having a serine residue at the C-terminus, X-Ser, where X is an appropriate amino acid residue, were efficiently hydrolyzed in the presence of ZnCl2 at pH 7.0. The rapid hydrolysis of X-Ser is due to an autocatalysis of the hydroxy group in the serine residue, and is found to be accelerated by a metal ion, in particular by ZnCl2. Roles of the metal ion in the hydrolysis of peptides involving a serine residue, in relation to the recently reported protein cleavages, are discussed. 相似文献
57.
We prove sharp Morawetz estimates — global in time with a singular weight in the spatial variables — for the linear wave, Klein-Gordon, and Schrödinger equations, for which we can characterise the maximisers. We also prove refined inequalities with respect to the angular integrability. 相似文献
58.
Dr. Ji-Rong Huang Dr. Muhammad Sohail Dr. Tohru Taniguchi Prof. Dr. Kenji Monde Prof. Dr. Fujie Tanaka 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(21):5947-5951
Spiro[4,5]decanes and polycyclic compounds bearing spiro[4,5]decane systems are important biofunctional molecules. Described are diastereoselective formal (4+1) cycloaddition reactions to afford oxindole-functionalized spiro[4,5]decanes and organocatalytic enantioselective Michael–Henry cascade reactions of the (4+1) cycloaddition products to generate spirooxindole polycyclic derivatives bearing the spiro[4,5]decane system. Spiro[4,5]decanes bearing oxindoles containing three stereogenic centers and spirooxindole polycycles having seven stereogenic centers, including two all-carbon chiral quaternary centers and one tetrasubstituted chiral carbon center, were obtained with high diastereo- and enantioselectivities. 相似文献
59.
Applications of Clifford’s Geometric Algebra 总被引:1,自引:0,他引:1
We survey the development of Clifford’s geometric algebra and some of its engineering applications during the last 15 years. Several recently developed applications and their merits are discussed in some detail. We thus hope to clearly demonstrate the benefit of developing problem solutions in a unified framework for algebra and geometry with the widest possible scope: from quantum computing and electromagnetism to satellite navigation, from neural computing to camera geometry, image processing, robotics and beyond. 相似文献
60.
Atsushi Sudo Tomoki Yamasaki Takuro Yamashita Dai Ishida 《Journal of polymer science. Part A, Polymer chemistry》2019,57(24):2407-2414
Oligo(spiroketal)s (OSKs) were synthesized from myo‐inositol, a naturally occurring cyclic compound bearing six hydroxyl groups. The successful synthesis of OSKs was achieved using silyl ethers 2 derived from 1,4‐di‐O‐alkylated myo‐inositol 1 as monomers, which underwent polycondensation with 1,4‐cyclohexanedione (CHD) at 0 °C in the presence of trimethylsilyl triflate as a catalyst. Because of the irreversible nature of the condensation reaction of silyl ethers with ketones, the resulting OSKs 7 had higher molecular weights than previously reported OSKs that were obtained by polycondensation of tetraols 1 with CHD, where backward hydrolysis of the ketal functions occurred. In addition, another series of OSKs, 8, were synthesized using silyl ethers 3 derived from 2,5‐di‐O‐alkylated myo‐inositol 6 , which are more symmetric monomers than silyl ethers 2 . Silyl ethers 3 underwent efficient polycondensation with CHD, whereas tetraol 6 did not, demonstrating that the derivation of such tetraols into the corresponding silyl ethers is a powerful strategy to access OSKs. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 2407–2414 相似文献