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71.
T Oikawa K Hirotani H Ogasawara T Katayama H Ashino-Fuse M Shimamura T Iwaguchi O Nakamura 《Chemical & pharmaceutical bulletin》1990,38(6):1790-1792
The effects of bleomycin (BLM) and its copper complex on embryonic angiogenesis were studied in the chorioallantoic membranes of 4.5-day-old chick embryos. Copper-free BLM inhibited embryonic angiogenesis in a dose-dependent manner, with activity detectable at 1 ng/egg and maximal at 1000 ng/egg. Also, treatment with copper-BLM complex dose-dependently caused inhibition of embryonic angiogenesis in a lower dose range. Since tumor growth is believed to depend on angiogenesis, the present results may indicate that the antiangiogenic activity of BLM is, at least in part, implicated in the antitumor activity of the drug. 相似文献
72.
Naotake Takaishi Yoshiaki Inamoto Koji Aigami Kiyoshi Tsuchihashi Hiroshi Ikeda 《合成通讯》2013,43(4):225-232
Tricyclo[5.3.1.03,8] undecane (II), which would be conveniently refered to by the trivial name 4-homoisotwistane in accordance with Majerski's nomenclature,1 was first prepared by Krantz2 during the stereoselectivity study on intramolecular Diels-Alder reactions of 5-alkenylcyclohexa-1,3-dienes, and recently discovered independently by Schleyer,3 Majerski1 and us4 to be involved as a reasonably stable intermediate in acid-catalyzed isomerization of various tricycloundecane precursors to equilibrium mixtures of 1 and 2-methyladamantanes. 相似文献
73.
Kosuke Makiguchi Seiya Kikuchi Kazuma Yanai Yoshitaka Ogasawara Shin‐ichiro Sato Toshifumi Satoh Toyoji Kakuchi 《Journal of polymer science. Part A, Polymer chemistry》2014,52(7):1047-1054
The ring‐opening polymerizations (ROPs) of ε‐caprolactone (ε‐CL) and L ‐lactide (LLA) have been studied using the organocatalysts of diphenyl phosphate (DPP) and 4‐dimethylaminopyridine (DMAP). The “dual activation” property of DPP and the “bifunctional activation” property of DPP/DMAP were confirmed by the NMR measurement for ε‐CL and its chain‐end model of poly(ε‐caprolactone) and for LLA and its chain‐end model of poly(L ‐lactide) (PLLA), respectively. The molar ratio of DPP/DMAP was optimized as 1/2 for the ROP of LLA leading to the well‐defined PLLA, such as the molecular weight determined from 1H NMR measurement of 19,200 g mol?1 and the narrow polydispersity of 1.10. Additionally, functional initiators were utilized for producing the end‐functionalized PLLAs. The DPP‐catalyzed ROPs of ε‐CL and its analogue cyclic monomers and then the DPP/DMAP‐catalyzed ROP of LLA produced block copolymers. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1047–1054 相似文献
74.
Stepwise application of the Pd-catalyzed S(N)2' reaction and the desilylative S(E)2' reaction to the ambivalent 2-bromo-1-silyl-1,3-dienes provides a novel route to the highly enantioselective construction of tertiary and quaternary propargylic stereogenic centers via axially chiral allenylsilanes. 相似文献
75.
Kireev AS Nadein ON Agustin VJ Bush NE Evidente A Manpadi M Ogasawara MA Rastogi SK Rogelj S Shors ST Kornienko A 《The Journal of organic chemistry》2006,71(15):5694-5707
Pancratistatin is a potent anticancer natural product, whose clinical evaluation is hampered by the limited natural abundance and the stereochemically complex structure undermining practical chemical preparation. Fifteen aromatic analogues of conduritol F, l-chiro-inositol, and dihydroconduritol F that possess four of the six pancratistatin stereocenters have been synthesized and evaluated for anticancer activity. These compounds serve as truncated pancratistatin analogues lacking the lactam ring B, but retaining the crucial C10a-C10b bond with the correct stereochemistry. The lack of activity of these compounds provides further insight into pancratistatin's minimum structural requirements for cytotoxicity, particularly the criticality of the intact phenanthridone skeleton. Significantly, these series provide rare examples of simple aromatic conduritol and inositol analogues and, therefore, this study expands the chemistry and biology of these important classes of compounds. 相似文献
76.
Cavalleri M Näslund LA Edwards DC Wernet P Ogasawara H Myneni S Ojamäe L Odelius M Nilsson A Pettersson LG 《The Journal of chemical physics》2006,124(19):194508
We present a combined x-ray absorption spectroscopy/computational study of water in hydrochloric acid (HCl) solutions of varying concentration to address the structure and bonding of excess protons and their effect on the hydrogen bonding network in liquid water. Intensity variations and energy shifts indicate changes in the hydrogen bonding structure in water as well as the local structure of the protonated complex as a function of the concentration of protons. In particular, in highly acidic solutions we find a dominance of the Eigen form, H(3)O(+), while the proton is less localized to a specific water under less acidic conditions. 相似文献
77.
A novel guanosine derivative with a photoswitching property, 8-styryl-2′-deoxyguanosine was synthesized, and showed very rapid and efficient reversible E-Z photoisomerization upon illumination at specific wavelength. In addition, E-Z photoisomerization can be iteratively performed by alternate illumination with monochroic 254 nm and 370 nm light without any side reactions. 相似文献
78.
79.
T. Sumiyoshi Y. Ninomiya H. Ogasawara M. Obara H. Tanaka 《Applied Physics A: Materials Science & Processing》1994,58(5):475-479
Organic polymer (PES: PolyEther Sulphone and PEEK: PolyEther Ether Ketone) ablation with oscillation-line selected TEA CO2 lasers is successfully demonstrated. With different irradiation conditions the ablative etch-rate slopes were varied, which means that the ablation process is dependent on the ablation conditions such as incident laser intensity and ambient gas. In perforation processing of the PEEK film, the TEA CO2 laser had a higher etch rate of 42 m/pulse at a fluence of 70 J/cm2 in vacuum than the XeCl laser. 相似文献
80.
Cloud points of aqueous solutions of homogeneous poly(oxyethylene)dodecyl ether derivatives (C12(OE)n: n=2–8) and the apparent theta temperatureT
ap
were determined from the abrupt changes in optical transmittance and the temperature dependence of the second virial coefficient obtained by light scattering measurements. It was found that the lower critical solution temperature (LCST) shifts to a lower temperature and lower concentration as the number of oxyethylene units in a molecule decreases. Because of this behavior of LCST, the modified Flory-Schultz plot of phase separation was applied to the present nonionic surfactant-water system, and its theta temperature obtained. The dependence ofT
ap
on the number of oxyethylene units suggests that the polyoxyethylene chain has different effects on the solubility of C12(OE)n in water forn less than or equal to 3 from those forn greater than or equal to 4. 相似文献