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91.
Masahito Segi Katsuhiko Tanno Masumi Kojima Mitsunori Honda Tadashi Nakajima 《Tetrahedron letters》2007,48(13):2303-2306
1,3-Dipolar cycloaddition between aromatic selenoaldehydes, generated by thermal retro Diels-Alder reaction of anthracene cycloadducts, and nitrile oxides or nitrile imines proceeded efficiently to give the corresponding [3+2] cycloadducts as a single isomer in good yields, being 1,4,2-oxaselenazoles or 1,3,4-selenadiazoles, respectively. 相似文献
92.
Summary Selective and sensitive procedures are described for the direct differential pulse polarographic determination of antimony(III), indium(III) and cadmium(II) in propylene carbonate. This method was based on the salting-out extraction of their halide complexes into the solvent from acidic aqueous media. The extracted Sb(III), In(III) and Cd(II) complexes exhibit sharp differential pulse polarographic peaks at –0.21 V, –0.63 V and –0.72 V vs. SCE in salted-out propylene carbonate phases respectively. The lower limits of determination are 5.0g for Sb(III), 0.6g for In(III), and 0.2g for Cd(II) in 10 ml of the organic phase. A number of foreign ions are eliminated through both processes of solvent extraction and polarography using propylene carbonate.
Propylencarbonat als Lösungsmittel für die Fällungs-Extraktion und die nachfolgende Differential-Puls-Polarographie
Zusammenfassung Selektive und empfindliche Verfahren für die direkte Bestimmung von Sb(III), In(III) und Cd(II) in Propylencarbonat mit Hilfe der Differential-Puls-Polarographie wurden beschrieben. Die vorliegende Methode beruht auf der Fällungs-Extraktion der Halogenid-Komplexe aus wäßrig-saurem Medium in das Lösungsmittel. Die extrahierten Komplexe des Sb(III), In(III) und Cd(II) ergeben scharfe Peaks bei –0,21 V, –0,63 V und –0,72 V gegen die Kalomelelektrode in den betreffenden Propylencarbonat-Phasen. Die unteren Grenzen der Bestimmungen liegen bei 5,0g Sb, 0,6g In bzw. 0,2g Cd in 10 ml organischer Phase. Eine Anzahl Fremdionen wird durch die beiden Prozesse der Extraktion und der Polarographie in Propylencarbonat ausgeschaltet.相似文献
93.
Chetsumon Aparat Umeda Fusako Maeda Isamu Yagi Kiyohito Mizoguchi Tadashi Miura Yoshiharu 《Applied biochemistry and biotechnology》1998,(1):249-256
A photobioreactor was constructed using anchored polyurethane foam strips (1 x 1 x 40 cm) fixed onto a stainless-steel ring
to prevent flotation, as a biomass support material (BSM). This type of reactor was named a seaweed-type bioreactor. A filamentous
cyanobacterium, Scytonema sp. TISTR 8208, which produces a novel cyclic dodecapeptide antibiotic, was immobilized in seaweed-type
photobioreactor and cultivated with air containing 5% CO2 sparged at a gas flow rate of 250 mL/min under illumination at a light intensity of 200 μmol photon m-2s-1. The antibiotic produced in the seaweed-type photobioreactor was purified by HPLC and examined regarding its spectrum and
mode of action. The antibiotic effectively inhibited the growth of Gram-positive bacteria, pathogenic yeasts, and filamentous
fungi, but it had only a weak effect on Gram-negative bacteria. Scanning electron micrograph analysis showed that the most
characteristic change was swelling of the cells after exposure to the antibiotic. The antibiotic seems to alter the conformation
of the microbial cell membrane, thereby changing its permeability, leading to osmotic shock. 相似文献
94.
Itaru Yamashita Youhei Kawabata Tadashi Kato Masakatsu Hato Hiroyuki Minamikawa 《Colloids and surfaces. A, Physicochemical and engineering aspects》2004,250(1-3):485-490
Small angle X-ray scattering (SAXS) is measured for the lamellar phase in aqueous systems of 1-o-β-3,7-dimethyoctyl-D-glucopyranoside (β-Glc(Ger)), which has recently been prepared by us, 1-o-β-decyl-D-glucopyranoside (β-GlcC10), and 1-o-β-octyl-D-glucopyranoside (β-GlcC8). The repeat distance d obtained from the position of the diffraction peak does not follow the swelling law d = 2δhc/hc, where δhc and hc are the thickness and the volume fraction of the hydrophobic layer, respectively. This may result from the fact that δhc increases and, equivalently, the surface area per surfactant molecule (as) decreases with increasing concentration. So we calculate δhc and as from the observed d value at each concentration using the above swelling law. The half-thickness δhc increases in the order β-GlcC8 < β-Glc(Ger) < β-GlcC10 at a fixed concentration. On the other hand, the data on as for β-GlcC10 and β-GlcC8 lie on the same line and the data for β-Glc(Ger) lies above this line. These results suggest that the cross-sectional area of the geranyl chain is larger than that of the glucose headgroup. Existence of water filled defects in bilayer sheets is also discussed based on the SAXS pattern and the concentration dependence of d. 相似文献
95.
H Harada K Iizuka T Kamijo K Akahane R Yamamoto Y Nakano A Tsubaki T Kubota I Shimaoka H Umeyama 《Chemical & pharmaceutical bulletin》1990,38(11):3042-3047
The experimental details for the synthesis of human renin inhibitors are described. In order to avoid metabolic degradation of the Phe-His (P3-P2) amide bond in transition-state analogs, structurally modified acyl residues (P4-P3) were incorporated into the inhibitors. Compound 1a, which contained 2-(1-naphthylmethyl)-3-(N-phenethylcarbamoyl)propionyl residue (P4-P3) with a retro-inverso amide bond, L-histidine, and norstatine isoamylamide residue (P1-P1) as a transition-state mimic, had potent human renin inhibitory activity, and it lowered blood pressure when administered orally to common marmosets. 相似文献
96.
Reversed-phase high-performance liquid chromatography (HPLC) was used to determine the levels of nucleosides, bases and their metabolites in perchloric acid extracts of gastrointestinal mucosa. By comparing the levels of these compounds in the normal portion with the neoplastic portion of mucosa resected from malignant cancer patients, it was found that there was significant elevation of the uracil level in the neoplastic mucosa of all eight patients with colorectal cancer (2.7-fold in normal mucosa), but only in the neoplastic mucosa of one out of four patients with gastric cancer. The levels of hypoxanthine and uridine in the colorectal cancer mucosa samples and the inosine in gastric cancer samples were also significantly higher than those in normal mucosa. The urinary modified nucleosides were prefractionated with a boronate affinity gel column, and their levels were determined by the same HPLC method. There was no significant difference in the concentrations of pseudouridine, 1-methylguanosine N2-methylguanosine and N2,N2-dimethylguanosine between urine samples taken before and after surgery from eight patients with malignant colorectal cancer. Contrary to other reports, no significant differences in modified nucleoside levels were observed between urine samples from patients with colorectal cancer and those from normal subjects. 相似文献
97.
Letk be a positive integer, and letG be a graph of ordern withn 4k – 5,kn even and minimum degree at leastk. We prove that if the degree sum of each pair of nonadjacent vertices is at leastn, thenG has ak-factor. 相似文献
98.
A new type of chiral receptor (R,R)- or (S,S)-1b with C(2) symmetry was synthesized. An induced-fit type of binding behavior of 1b for diamines was revealed by CD spectroscopy. NMR studies demonstrated that 1b can function as a highly sensitive chiral shift reagent for the determination of the enantiomeric purity of chiral diamines, aziridine, and isoxazoline at the microgram level. [structure: see text] 相似文献
99.
Lin Wang Shinji Takeoka Eishun Tsuchida Satoru Tokuyama Takahiro Mashiko Tadashi Satoh 《先进技术聚合物》1992,3(1):17-21
The carbonyl hemoglobin (CO-Hb), which was used to prevent denaturation (metHb) during the preparation of samples, was encapsulated into lipid vesicles constituted from unsaturated phospholipid, cholesterol and unsaturated fatty acid. Unsaturated components were polymerized by γ-irradiation to enhance the stability of bilayer membrane. An aqueous dispersion of resulting Hb vesicles was freeze-dried in the presence of saccharides (50–200 mM) to obtain a dehydrated powder of Hb vesicles. Change in the vesicle size, the leakage of encapsulated Hb and the oxidation of Hb to metHb were not observed. Therefore, the long-term storage of Hb vesicles can be realized as a dry powder. 相似文献
100.
The asymmetric hydroformylation of 2‐ and 3‐vinylfurans ( 2a and 2b , resp.) was investigated by using [Rh{(R,S)‐binaphos}] complexes as catalysts ((R,S)‐binaphos = (11bS)‐4‐{[1R)‐2′‐phosphino[1,1′‐binaphthalen]‐2‐yl]oxy}dinaphtho[2,1‐d:1′,2′‐f][1,3,2]dioxaphosphepin; 1 ). Hydroformylation of 2 gave isoaldehydes 3 in high regio‐ and enantioselectivities (Scheme 2 and Table). Reduction of the aldehydes 3 with NaBH4 successfully afforded the corresponding alcohols 5 without loss of enantiomeric purity (Scheme 3). 相似文献