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排序方式: 共有221条查询结果,搜索用时 46 毫秒
41.
42.
Takayo Takigawa Hideo Ogawa Masanori Nakamura Katsutoshi Tamura Sachio Murakami 《Fluid Phase Equilibria》1995,110(1-2):267-281
Molar excess enthalpies HmE, isobaric heat capacities CP,mE, volumes VmE and isothermal compressibilities κTE for the 1,3-dioxane(3DX) + cyclohexane mixture were measured at 298.15 K, in order to compare to those of the 1,4-dioxane(4DX) + cyclohexane mixture. HmE is endothermic and the maximum value about 1.5 kJ mol−1 at x ≈ 0.45, and lower than that of the 4DX mixture by about 80 J mol−1. VmE is positive over the whole concentration and the maximum value is about 0.85 cm3 mol−1 at x ≈ 0.45, and lower than that of the 4DX mixture. The above results suggest the energetic unstabilization, resulting in the volume expansion in the mixture. CP,mE shows the characteristic W-shaped concentration dependence, which has maximum at x ≈ 0.45 and two minima at x ≈ 0.1 and 0.9. The maximum CP,mE value for 3DX mixture shifts toward the positive side, compared to that of 4DX mixture. κTE were estimated from speeds of sound, densities, thermal expansion coefficients and isobaric heat capacities of the pure component liquids and the mixtures. The κTE result shows the positive concentration dependence over the whole composition range. The 3DX mixture has the similar thermodynamic properties to the 4DX mixture, despite that 4DX is the nonpolar solvent and 3DX is the dipolar liquid. this means that there exists the local dipolar interaction between 4DX molecules, and the prevalence of “microheterogeneity” in the both mixtures. 相似文献
43.
Masaya Nagai Hiroyuki Yada Takashi Arikawa Koichiro Tanaka 《International Journal of Infrared and Millimeter Waves》2006,27(4):505-515
We demonstrate time-domain attenuated total reflection spectroscopy in terahertz frequency region. Geometry of the reflection
measurement is well optimized to obtain accurate optical constants of water or aqueous biomolecular system. We determine the
dielectric constants of distilled water and sucrose solutions with this technique. This technique will open new aspects in
the research field of biological systems in water. 相似文献
44.
Toshihide Kawashima Katsutoshi Yoshida Yasuo Tohda Masahiro Ariga Yutaka Mori Yoshiteru Sakata Soichi Misumi 《Tetrahedron letters》1984,25(15):1585-1586
A novel derivative of methylviologen, prepared by transannular reaction of [2.2] (3,5) pyridinophane, shows large bathochromic shift in the electronic spectrum and nearly equal redox potential compared with methylviologen. 相似文献
45.
Tatsuya Oshima Akinori Suetsugu Yoshinari Baba Yuka Shikaze Keisuke Ohto Katsutoshi Inoue 《Journal of membrane science》2008
The present study examined the liquid membrane transport of the cationic protein cytochrome c, using the macrocyclic compound calix[6]arene, which is a carboxylic acid derivative, as a carrier. The transport rate was governed by carrier concentration and the pH gradient between the feed and the receiving phases, as well as the salt concentration in the aqueous phases. Transport of cytochrome c was examined using a series of calix[n]arene carboxylic acid derivatives (n = 4, 6 and 8). Cytochrome c successfully permeated membranes in the presence of the calix[6]arene derivative. Liquid membrane separation of cytochrome c from a mixture of cationic proteins was demonstrated under optimal conditions. Cytochrome c was selectively extracted by the calix[6]arene carboxylic acid derivative and 77% of the extracted cytochrome c was recovered into the receiving phase. In this liquid membrane system, which discriminates between the number of lysine residues on the surface of proteins, cationic proteins with similar molecular weights and pIs were separated with macrocyclic compounds. 相似文献
46.
Komaki Shozo Tsukamoto Katsutoshi Okada Minoru Ishida Tomoaki 《Optical and Quantum Electronics》1998,30(11-12):1079-1088
Mobile communication systems such as cellular radio and PHS are rapidly penetrating into our real life, and have gained many subscriber numbers. User demands will be growing to higher data rates that support multimedia mobile computing demands, such as graphics and motion pictures. These demands require more band width and/or spectrum utilization efficiency enhancement, and optically fed communication systems are considered to be one of the most powerful solutions. In this paper, the roles, technologies and application examples of optically fed communication systems are described. In the final part, prospects for systems and requirements for photonic devices are mentioned. 相似文献
47.
Hirotsugu Minami Masako Yada Tomomi Yoshida Qiangbin Zhang Sadanobu Inoue Ikuo Atsuya 《Analytical sciences》2004,20(3):455-459
A fast and accurate analytical method was established for the simultaneous direct determination of aluminum, calcium and iron in silicon carbide and silicon nitride powders by graphite furnace atomic absorption spectrometry using a slurry sampling technique and a Hitachi Model Z-9000 atomic absorption spectrometer. The slurry samples were prepared by the ultrasonication of silicon carbide or silicon nitride powders with 0.1 M nitric acid. Calibration curves were prepared by using a mixed standard solution containing aluminum, calcium, iron and 0.1 M nitric acid. The analytical results of the proposed method for aluminum, calcium and iron in silicon carbide and silicon nitride reference materials were in good agreement with the reference values. The detection limits for aluminum, calcium and iron were 0.6 microg/g, 0.15 microg/g and 2.5 microg/g, respectively, in solid samples, when 200 mg of powdered samples were suspended in 20 ml of 0.1 M nitric acid and a 10 microl portion of the slurry sample was then measured. The relative standard deviation of the determination of aluminum, calcium and iron was 5 - 33%. 相似文献
48.
Yoshikata Koga Katsutoshi Tamura Sachio Murakami 《Journal of solution chemistry》1995,24(11):1125-1133
Speeds of sound were measured at 25°C in the water-rich region of aqueous 2-butoxyethanol (BE) and 2-butanone (BUT). Density, heat capacity, and thermal expansivity data available in literature were used to calculate isothermal compressibilities,
T
. The composition derivative, N (
T/nB), a third derivative of Gibbs free energy, showed a peak anomaly atx
BE=0.0175 for BE-H2O, and a bend atx
BUT=0.033 for BUT-H2O. nB (nBE or nBUT) is the amount of the solute andx
BE andx
BUT are the respective mole fractions. The location of these anomalies were the same as those of other third derivatives found earlier for the same aqueous solutions. These anomalies were shown earlier to mark the transition point across which the mixing scheme changes in a qualitative fashion. 相似文献
49.
Zhou CJ Shioda S Yada T Inagaki N Pleasure SJ Kikuyama S 《Current protein & peptide science》2002,3(4):423-439
Pituitary adenylate cyclase-activating polypeptide (PACAP) was originally isolated from the ovine brain in 1989 as a novel hypothalamic hormone that potently activates adenylate cyclase to produce cyclic AMP in pituitary cells. This neuropeptide belongs to the secretin/glucagon/vasoactive intestinal peptide (VIP) superfamily, and exists in two amidated forms as PACAP38 (38-amino acid residues) and PACAP27 derived from the same precursor. The primary structure of PACAP has been remarkably conserved throughout evolution among tunicata, ichthyopsida, amphibia and mammalia, and a PACAP-like neuropeptide has also been determined in Drosophila. Both PACAP and its receptors are mainly distributed in the nervous and endocrine systems showing pleiotropic functions with high potency. There are three types of receptors with high PACAP-binding affinity and with different tissue-distribution patterns. All of them belong to G-protein-coupled receptor superfamily with seven transmembrane domains. PAC(1) is the PACAP-specific receptor and exists in at least eight splice variants which couple to different intracellular signal transduction pathways. VPAC(1) and VPAC(2) are the common receptors for both PACAP and VIP, which are coupled to adenylate cyclase. This review article presents and discusses an update on PACAP research and its pleiotropic physiological functions based on multiple receptor-mediated signaling mechanisms in both the central and peripheral nervous system, including the regulation of hypothalamic neurosecretion, homeostatic control of circadian clock and behavioral actions, involvement in learning and memory processes, neuroprotective effects such as anti-apoptosis and response to injury and inflammation, and neural ontogenetic functions on proliferation/differentiation processes from early stages. 相似文献
50.
Katsutoshi Nagai Shuji Machida 《Journal of polymer science. Part A, Polymer chemistry》1981,19(2):571-582
The reaction of 1,3-cycloheptadiene (1,3-CHpD) with acrylonitrile (AN) in the presence of ZnCl2 leads spontaneously to the simultaneous formation of an alternating copolymer and a small amount of cycloadduct. The copolymer has a predominantly cis-1,4-structure. The formation of the charge—transfer complex between 1,3-CHpD and (AN)c (AN coordinated to ZnCl2) in AN was detected by ultraviolet (UV) spectroscopy. The activation energies for the cycloaddition and for the copolymerization under the conditions used were determined to be 17.6 (in the presence of 1,1-diphenyl-2-picrylhydrazyl) and 16.3 kcal/mole, respectively. The rate of copolymerization in AN was found to depend on the 1.5th power of the concentrations of (AN)c and of 1,3-CHpD. Oxygen and UV irradiation causes an acceleration of the copolymerization only. On the basis of these results the mechanism of the spontaneous copolymerization is discussed and its relation to the cycloaddition in systems of 1,3-cyclodienes and AN in the presence of ZnCl2 is mentioned. 相似文献