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排序方式: 共有338条查询结果,搜索用时 31 毫秒
101.
Mihoko Maruyama Noriko Shimizu Shigeru Sugiyama Yoshinori Takahashi Hiroaki Adachi Kazufumi Takano Satoshi Murakami Tsuyoshi Inoue Hiroyoshi Matsumura Yusuke Mori 《Journal of Crystal Growth》2010,312(19):2771-2774
Silicone glue (modified silicone polymer) is widely used for both experiments involving inorganic crystal growth and those involving organic materials like proteins. This material is very useful for building a hand-made experiment setup or for fixing protein crystals to specific locations. Though silicone glue is regarded as harmful to proteins, no systematic verification was performed to investigate its impurity effects on protein crystal growth. We focused on and estimated the impurity effects of silicone glue on protein crystal growth. 相似文献
102.
Fujiwara M Terashima S Endo Y Shiokawa K Ohue H 《Chemical communications (Cambridge, England)》2006,(44):4635-4637
A molecular gate attached on the pore outlet of a mesoporous material, which is opened and closed by redox system of thiol groups, effectively switched the progress of a catalytic reaction promoted by the acidic site in the pore void. 相似文献
103.
Hiroyoshi Takamura Takayuki Kishi Yuichi Nakamura Yoshinori Yamamoto 《Tetrahedron》2010,66(29):5329-5344
The convergent total synthesis of brevenal, a non-toxic brevetoxin antagonist, has been achieved. The ABC ring segment and the E ring precursor were connected by the intramolecular allylation followed by ring-closing metathesis to furnish the pentacyclic ether compound. An alternative route to the key synthetic intermediate, a pentacyclic ether core, was also examined. The right- and left-hand side chains were introduced by Wittig and Horner-Wadsworth-Emmons reactions, respectively, to furnish brevenal (1). 相似文献
104.
The C14-C24 fragment of symbiodinolide possessing the 17R/18R/21R absolute configuration, which was obtained as one of the degraded products of symbiodinolide, and its diastereomer possessing the 17R/18S/21R absolute stereochemistry were synthesized stereoselectively from cis-2-butene-1,4-diol, respectively. The detailed comparison of the synthetic products with the degraded product in the spectroscopic data confirmed unambiguously that the stereostructure of the C14-C24 fragment was 17R, 18R, and 21R. 相似文献
105.
A carboxymethyl poly(L ‐histidine) has been synthesized as a new pH‐sensitive polypeptide at endosomal/lysosomal pH. Because of its poor water solubility at physiological pH, an application of poly(L ‐histidine) with a pKa around 6.0 has been limited in spite of the native possession of the pH‐dependent property change at endosomal pH. Although the unmodified poly(L ‐histidine) suddenly precipitates out of the aqueous medium above pH 6.0 as the result of the deprotonation of the imidazole groups, the water solubility of the resulting carboxymethyl poly(L ‐histidine) has been improved at physiological pH. A solution turbidity measurement proved that no significant effect on a rapid aggregate formation or phase separation of serum proteins is induced by carboxymethyl poly(L ‐histidine). Hemolysis assay showed that the carboxymethyl poly(L ‐histidine) enhances membrane disruptive ability at endosomal/lysosomal pH. The cellular uptake of luciferase in the presence of the carboxymethyl poly(L ‐histidine) increases intracellular luciferase activity, which suggests that the carboxymethyl poly(L ‐histidine) makes the luciferase escape from lysosomal degradation. The carboxymethyl poly(L ‐histidine) would be the fundamental compound for designing various drug carriers with the pH sensitivity at endosomal/lysosomal pH. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
106.
M. Karppinen H. Yamauchi H. Suematsu K. Isawa M. Nagano R. Itti O. Fukunaga 《Journal of solid state chemistry》1997,130(2):213-222
The LaCuO3−yperovskite is considered as the first member of the 01(n−1)nseries of “layered cuprates.” Highly oxidized, stoichiometric LaCuO3is stabilized under very high oxygen pressures, and was synthesized in a cubic-anvil-type high-pressure apparatus at 5 GPa and 1400°C using excess amounts of KClO4as an external oxidizing agent. Upon heating under ambient pressure the rhombohedral high-pressure phase loses oxygen yielding tetragonal, monoclinic, and orthorhombic forms of LaCuO3−yas intermediate products before the final decomposition into La2CuO4and CuO or Cu2O around 800°C. All three oxygen-deficient LaCuO3−yphases could be isolated and their stability limits and corresponding oxygen contents conveniently investigated by annealing stoichiometric LaCuO3in a thermobalance of high sensitivity in order toin situdetect the exact amount of oxygen loss. The nominal copper valence values calculated from the oxygen contents are compared and discussed with XPS data as well as with the results evaluated from magnetic susceptibility measurements. 相似文献
107.
Masao Kato Hiroyoshi Kamogawa 《Journal of polymer science. Part A, Polymer chemistry》1968,6(11):2993-3006
Solution polymerizations of allyl(o-vinyl phenyl)ether and allyl(p-vinyl phenyl)ether with cationic and radical initiators were investigated. Soluble polymers were formed in polymerizations with boron trifluoride etherate and with benzoyl peroxide. In polymerization with azobisisobutyronitrile the polymerization in dilute solution gave a soluble polymer, whereas that in concentrated solution gave a crosslinked, insoluble one. For informationon the polymerization behavior some infrared and ultraviolet spectroscopic investigations of the soluble polymers were made. From these results it appears that polymers with pendant allyl groups are formed in polymerization with boron trifluoride etherate at low temperature, and polymers containing pendant vinyl groups and allyl groups are obtained with the two types of radical initiator. Copolymerizations of these monomers with ethyl vinyl ether and styrene with the use of boron trifluoride etherate were sucessfully effected. Such reactions as Claisen rearrangement, crosslinking induced with radical initiators, and epoxidation with perbenzoic acid were examined for the polymers prepared in the polymerization with boron trifluoride etherate. Good results were obtained for the former two reactions. However, the latter was unsuccessful. 相似文献
108.
The polymerization behavior of N-(p-vinyl)phenylacrylamide, synthesized from p-aminostyrene and acryloyl chloride by means of the Schotten-Baumann reaction was studied. Due to a marked difference in electron density between the two double bonds, this monomer provided soluble polymers by both cationic and anionic polymerization procedures, the cationic and anionic polymers mainly carrying, as side chains, the acrylamide and styrene moieties, respectively. The polymerization behavior of the residual double bonds was also investigated for both polymers, leading to crosslinked, insoluble products. 相似文献
109.
Chiaki Hirose Nobuyuki Watanabe Hiroyoshi Yamamoto Akihide Wada Kazunari Domen T. Ohtake Norihisa Mino 《中国化学会会志》1994,41(3):275-278
The vibrational spectroscopy by way of vibrational sum-frequency generation (VSFG) has been made of formic acid adsorbed on MgO(001) surface and of n-alkyltrichlorosilanes chemisorbed on quartz plates. It was revealed that the species on the MgO surface was formate ion (HCOO+) with CH bonds standing vertical to the surface and that the different adsorption sites showed up on repeated cycles of adsorption-desorption processes. The results of chemisorbed films indicated that the g-t and/or g-t-g′ conformational scquences of n-alkyl chains occurred more frequently by the length of alkyl chain and that the surface hydroxyls, which are the sites of chemisorption, are ripped off by pre-exposure of substrate to oxygen plasma. 相似文献
110.
We have developed a new experimental apparatus for performing coincidence measurements of the ions desorbed and projectiles scattered from the surfaces of noble gas solids by slow multiply charged ion impacts at grazing incidence angles. This simultaneously measures the desorbed ions' flight times and the scattered projectiles' charge states. We also conduct experiments on 6 keV Ar6+ impacts onto a solid Ne surface using the device. 相似文献