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961.
T. Nakamura Atsushi Ogata Takahiro Hoshi Retsu Oiwa 《Analytical and bioanalytical chemistry》1998,362(3):254-257
In quantitative XPS, the preparation of reference samples is difficult or impossible, and the correction factor method has been employed. Therefore, a convenient and practical procedure to get correction factors to estimate atomic ratios is proposed, in which it is assumed that the XPS intensity distribution corresponds to the distribution of the photoionization cross section. This procedure can be applied to some instruments and various samples without the previous collection, preparation of reference sample groups, and determination of sensitivity factors for each element. 相似文献
962.
Yasuo Saegusa Minoru Kuriki Akihiro Kawai Shigeo Nakamura 《Journal of polymer science. Part A, Polymer chemistry》1994,32(1):57-63
A series of fluorine-containing aromatic homopolyformal and copolyformals with a wide range of unit ratio were synthesized by the solution polycondensation of 2,2-bis (4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane (Bisphenol AF) and/or 2,2-bis (4-hydroxyphenyl)propane (Bisphenol A) with dichloromethane, and the effect of the fluorine substitution on the preparation and properties of these polymers was investigated by comparing with those of Bisphenol-A-based homopolyformal without fluorine. Irrespective of the ratio of Bisphenol AF, high-molecular-weight, fluorine-containing polyformals with reduced viscosities of 1.4–5.3 dL/g were obtained in high yields by using dichloromethane as both comonomer and solvent, potassium hydroxide as a base, and N-methyl-2-pyrrolidone as a comedium at 75°C for 4 h. Their solubility increased markedly by the introduction of fluorine atom. Colorless, transparent, and tough films were cast from chloroform solution irrespective of fluorine content. These films had good mechanical properties comparable to that of Bisphenol-A-based homopolyformal. The contact angles by water were larger than 90°, regardless of their fluorine contents, at 25°C. The glass transition temperature and thermal stability increased monotonically with increasing fluorine content. © 1994 John Wiley & Sons, Inc. 相似文献
963.
Yo Nakamura Takashi Norisuye Akio Teramoto 《Journal of Polymer Science.Polymer Physics》1991,29(2):153-159
Second virial coefficients A2 and third virial coefficients A3 for benzene solutions of ten polystyrene fractions ranging in weight-average molecular weight Mw from 104 to 2 × 107 at 25°C were determined by light scattering. The third coefficient is represented approximately by A3 = 8.0 × 10?6 M mol g?3 cm6 for Mw above 105. In this molecular weight region, the factor g defined by A3/AMw/ This trend of g is consistent with predictions of early two-parameter theories but not with those of renormalization group theories. In particular, quantitative agreement is observed between the present experiments (for Mw ? 2 × 105) and the mean-field two-parameter theory of Stockmayer and Casassa. 相似文献
964.
Toshio Ito Nobuya Tomiyoshi Koki Nakamura Shizuo Azuma Makoto Izawa Fumio Maruyama Mitsutoshi Yanagiya Haruhisa Shirahama Takeshi Matsumoto 《Tetrahedron》1984,40(1):241-255
The total synthesis of dl-coriolin has been achieved in a stereoselective way. The key tricyclic intermediate was synthesized from dicyclopentadiene through a route which involved an SN2 reaction at a neopentylic position. 相似文献
965.
Tatsuya Morozumi Takashi Kimura Tomomi Ujiie Hiroaki Yonemura Taku Matsuo Hiroshi Nakamura 《Journal of inclusion phenomena and macrocyclic chemistry》2004,50(1-2):105-110
The complexation behavior of a series of electron donor–accepter (D–A) covalently linked compounds with cyclodextrins (CyDs) has been reviewed. The structure of these complexes showed rotaxane type conformations, which were investigated by means of 1 H NMR spectrometry. The complex formations induced a fixation of a conformation of guest D–A molecules, and D–A distances were enlarged. Thus, accurate photo-induced charge transfer behaviors can be discussed. 相似文献
966.
A Nakamura S Nagai T Ueda J Sakakibara Y Hotta K Takeya 《Chemical & pharmaceutical bulletin》1989,37(9):2330-2333
A technique to assay Na+ ions in cells is presented. Intracellular and extracellular Na+ ions in a suspension of guinea pig erythrocytes were conveniently determined by using sodium-23 nuclear magnetic resonance (23Na-NMR), in combination with two anionic shift reagents: Dy(TTHA)3- and Dy(PPPi)2(7-). Monensin (1), monensylalanine (2b), monensylserine (2c), and monensylphenylalanine (2d) induced large increases of intracellular Na+ ion concentration ([Nain]), while monensylglycine (2a), monensyltyrosine (2e), monensylaspartic acid (2f), and monensylglutamic acid (2g) showed slight increases. The values of initial increasing rate (Vi) of 2a-g were much smaller than that of 1. This fact was probably due to the lower lipophilicity of 2a-g than 1, because a good correlation was observed between Vi and Rm50 values of 1 and 2a-g. This lower lipophilicity is a consequence of conformational differences between 1 and 2a-g. 相似文献
967.
Saito T Sunaga T Sakai N Nakamura Y Yamamoto S Iriuchijima D Yoza K 《Inorganic chemistry》2005,44(12):4427-4432
A trinuclear rhenium sulfide cluster complex, [(Ph(3)P)(2)N][Re(3)(mu(3)-S)(mu-S)(3)Cl(6)(PMe(2)Ph)(3)], synthesized from Re(3)S(7)Cl(7), dimethylphenylphosphine, and [(Ph(3)P)(2)N]Cl is readily converted to a bridging SO(2) complex, [(Ph(3)P)(2)N][Re(3)(mu(3)-S)(mu-S)(2)(mu-SO(2))Cl(6)(PMe(2)Ph)(3)], by reaction with O(2). The oxygen atoms on the SO(2) ligand react with phosphines or phosphites to form phosphine oxides or phosphates, and the original cluster complex is recovered. The reaction course has been monitored by (31)P NMR as well as by UV-vis spectroscopy. The catalytic oxygenation of PMePh(2) in the presence of the SO(2) complex shows that turnovers are 8 per hour at 23 degrees C in CDCl(3). The X-ray structures of the cluster complexes are described. 相似文献
968.
Soil-to-plant transfer factors of 31 stable elements were determined by neutron activation analysis. The transfer factor is
one of the important parameters used to estimate the internal radiation dose from radionuclides through food ingestion. In
the present study, 12 species of agricultural plants such as root crops, fruit vegetables, green vegetables and pasture grasses,
and their soils were collected from 150 farm fields in Aomori prefecture, Japan. The elements described are those that could
be detected by this method, which include both essential and nonessential elements for plant growth. The concentrations of
individual elements in the cultivated soil samples for each plant were similar in values and their standard deviations were
within one order of magnitude, because of the relatively narrow geographic sampling area. The elements were classified into
two groups, each having different transfer factor characteristics. In the first group of elements there was an inverse correlation
between the transfer factors and the concentrations of elements in the soil, especially for Cl, K and Ca. In the second group,
especially Sc and Co, however, the transfer factors were independent of the concentrations of elements in the soil. 相似文献
969.
We have developed a theoretical model of photoinduced reactions on metal surfaces initiated by the substrate/indirect excitation mechanism using the nonequilibrium Green's function approach. We focus on electron transfer, which consists of (1) electron-hole pair creation, (2) transport of created hot electrons, and (3) tunneling of hot electrons to form an anion resonance. We assume that steps (1), (2), and (3) are separable. By this assumption, the electron dynamics might be restated as a tunneling problem of an open system. Combining the Keldysh time-independent formalism with the simple transport theory introduced by Berglund and Spicer, we present a practical scheme for first-principle calculation of the reaction probability as a function of incident photon energy. The method is illustrated by application to the photoinduced desorption/dissociation of O2 on a Ag(110) surface by adopting density functional theory. 相似文献
970.
The fluorimetric determination of secondary amines based on conversion with sodium hypochlorite to primary amines and the o-phthalaldehydemercaptoethanol (OPA) reagent is discussed. Interference by excess hypochlorite (e.g., oxidation of OPA or conversion of primary amines to chloramines) were suppressed by 2,2′-thiodiethanol. Two spectrophotofluorimetric method are reported, one for aromatic and the other for aliphatic secondary amines. These methods permitted determinations at nanomolar levels; relative standard deviations were 4% for 5 nmol of N-methylaniline and 13% for 5 nmol of sarcosine. 相似文献