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71.
We determine the Nomura algebras of the type-II matrices belonging to the Bose-Mesner algebra of a conference graph. 相似文献
72.
73.
Kazuaki Kuwata Rie Fujita Kengo Hanaya Shuhei Higashibayashi Takeshi Sugai 《Tetrahedron》2018,74(7):740-745
A formal total synthesis of (?)-hamigeran B was achieved in 17 steps from commercially available ethyl 2-oxocyclopentanecarboxylate. Carbonyl reductase-catalyzed asymmetric reduction and the subsequent chemical transformations furnished an enantiomerically pure synthetic intermediate, (R)-5-formyl-2-isopropyl-5-methylcyclopent-1-en-1-yl trifluoromethylsulfonate. Suzuki-Miyaura coupling with Gao's arylboronate [2-(2-formyl-3-methoxy-5-methylphenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane], under PdCl2(dppf)?CH2Cl2 catalysis, and the subsequent cyclization by way of intramolecular reductive SmI2-mediated 1,2-diol formation provided a tricyclic skeleton with a tetrasubstituted double bond between C-1 and C-9b. Upon hydrogenation of this double bond, the proper stereochemistry of the remaining chiral centers was established. Exclusive addition of the hydrogen atom from the β-face occurred, owing to the shielding of the α-face with a bulky TBS protective group on the C-4 alcohol. The hydrogenation products were transformed into Clive's synthetic precursor for (?)-hamigeran B. 相似文献
74.
Rie Makiura 《Research on Chemical Intermediates》2018,44(8):4775-4782
The influence of synthetic conditions on the shape and size of SrTiO3 (STO) nanocubes was studied. These were synthesized in aqueous solution using Sr(OH)2 as the Sr2+ source and titanium(IV) bis(ammonium lactate)dihydroxide (TALH) as the TiIV source in the presence of oleic acid and hydrazine. A large excess of OH? at a pH of the precursor solution higher than 12 is necessary for the formation of STO nanocubes without the need for any calcination. Performing the synthesis in a N2 atmosphere additionally prevents the formation of SrCO3 impurity, leading to the creation of uniformly sized STO nanocubes in a reproducible manner. Such size-regulated STO nanocubes are found to align over a large area. 相似文献
75.
The notion of an observable and a state on a D-poset have been introduced. In the present paper the independence of a sequence of observables is defined and the strong law of large numbers is proved. 相似文献
76.
Treatment of Mn(CO)5SiTolp2H (2) with an excess of LiAlH4, NaBH4, or NaBH3(CN) in THF at room temperature gave hydrosilane H---SiTolp2H in high yield together with Mn2(CO)10. No reduction of CO ligands was observed. On the other hand, treatment of 2 with an excess of Red-Al (=Na[(CH3OCH2CH2O)2AlH2]) in toluene and subsequent addition of aqueous acidic solution afforded alkylsilanols (CH3)SiTolp2(OH) and (C2H5)SiTolp2(OH). Treatment of the reaction mixture of 2 and Red-Al with LiAlH4 in diethyl ether instead of hydrolysis gave alkylhydrosilanes (CH3)SiTolp2H and (C2H5)SiTolp2H. The methyl and ethyl groups on silicon originate from the CO ligands in 2. These products clearly demonstrate that not only the Si---C coupling, but also C---C coupling occurs efficiently in this reaction. 相似文献
77.
A synthesis of an advanced ABCDE ring system (24c) having characteristic substituents in both benzene rings of ecteinascidin marine natural products is described based on our model studies. 相似文献
78.
Yaoita Y Yoshihara Y Kakuda R Machida K Kikuchi M 《Chemical & pharmaceutical bulletin》2002,50(4):551-553
Two edible mushrooms, Pleurotus eryngii and Panellus serotinus, have been investigated chemically. Two new sterols, 5alpha,9alpha-epidioxy-8alpha,14alpha-epoxy-(22E)-ergosta-6,22-dien-3beta-ol (1) and 3beta,5alpha-dihydroxyergost-7-en-6-one (2), have been isolated from P. eryngii, together with six known ones (3-8). Compound 1 was also isolated from P. serotinus. The structures of the new compounds were elucidated on the basis of their spectral data. 相似文献
79.
Sergio Di Nuzzo Menno A. de Rie Chris M. van der Loos Jan D. Bos Marcel B. M. Teunissen 《Photochemistry and photobiology》1996,64(6):988-993
Abstract— The proportion and composition of the human cutaneous CD3+ T lymphocyte population was determined in situ following a single exposure to physiological, erythema-inducing doses of simulated solar radiation, mainly consisting of UV radiation. Biopsies were taken 1, 2 and 7 days after local irradiation of normal volunteers with 1,2 and 4 MED by a xenonarc lamp and immunohistochemistry was performed on cryostat sections. Ultraviolet radiation caused an initial decrease of intraepidermal CD3+ T-cell numbers or even could lead to T-cell depletion 24 and 48 h postirradiation, and this was followed by an infiltration of T cells in the epidermis as determined 1 week after UV exposure. The number of dermal CD3+ T ceDs was increased 24 h after irradiation, reached a maximum at 48 h and subsequently declined at day 7, though remained significantly higher than the unirradiated control Double staining demonstrated that the CD3+ T cells, which immigrated into the (epi)dermis upon UV exposure, coexpressed CD4 but not CD8. Therefore the CD4/CD8 ratio in skin was markedly increased during the first week upon UV exposure. Our time course study shows that UV radiation affects die T-cell population within human skin by depleting the majority of epidermal T cells and initiating a selective influx of CD4+ T cells. 相似文献
80.
Single crystals of the strontium copper tellurium oxochloride SrCu2(TeO3)2Cl2 were synthesized via solid-gas reactions in sealed evacuated silica tubes. The compound crystallizes in the monoclinic system, space group P21, a=7.215(2), b=7.2759(15), c=8.239(2) Å, β=96.56(4)°, Z=2. The building units are [SrO6Cl2] irregular polyhedra, [CuO4] and [CuO3Cl] square planes, [TeO3E] tetrahedra and [TeO3+1E] trigonal bipyramids; E being the 5s2 lone pair of Te(IV). The Cu atoms can be regarded as forming a chain of weakly connected dimers. The magnetic susceptibility of the compound shows a broad maximum typical for antiferromagnetic spin fluctuations with a non-magnetic ground state. A Heisenberg spin model with coupled s=1/2 dimers leads to a satisfactory fitting of the experimental data. 相似文献