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991.
Nomura M Nakamura M Soeda R Kikawada Y Fukushima M Oi T 《Isotopes in environmental and health studies》2012,48(3):434-438
Vanadium (V) in the sea squirt (Ciona savignyi) from Onagawa Bay, Miyagi, Japan, was isolated and purified through adsorption on a diamine resin and anion and cation exchanges after the dissolution of sea squirt samples with nitric acid and hydrogen peroxide. The (50)V/(51)V isotope ratio of V thus obtained was mass-spectrometrically determined to be from 2.51×10(-3) to 2.55×10(-3) with the average of 2.53×10(-3) by the thermal ionisation technique. This value agreed with those of vanadyl chloride and vanadyl nitrate both prepared from vanadyl sulphate (Wako Pure Chemical Industries, Ltd., Japan) and of V in coastal seawater (Shimokita Peninsula, Aomori, Japan) within experimental uncertainties (standard deviation of±0.04), which suggested that no appreciable V isotope fractionation occurs accompanying V uptake by the sea squirt from sea water. 相似文献
992.
Zinc isotope separations were studied by displacement chromatography using the chelating properties of malate, citrate and lactate exchange resin and EDTA as ligands. After each chromatographic operation, the heavier zinc isotopes were found to preferentially fractionated into the carboxylate complex solution phase. The separation coefficients (ε) for zinc isotope separation had the largest value and were obtained for the isotopic pairs 68Zn/64Zn (7.16 × 10?4) and 66Zn/64Zn (3.08 × 10?4), respectively, at 298 ± 1 K. The separation coefficient per unit mass differences (ε/ΔM) for the isotopic pair of 68Zn/64Zn was found to range around 1.55 × 10?4. 相似文献
993.
Three new glycosides, 7‐O‐tigloylsecologanol ( 1 ), 7‐O‐tigloylsecologanolic acid ( 2 ), and 3′‐O‐[(2S)‐2‐methylbutanoyl]henryoside ( 3 ), together with seven known ones, were isolated from the leaves of Viburnum plicatum Thunb . var. tomentosum Miq . Their structures were established on the basis of spectral and chemical data. 相似文献
994.
Starting from trimethylsilyl enol ether of 1-acetyl-1,3,5-cycloheptatriene, the title 1,1-dimethyl-, 1,1-diethyl-, and 1,1-dipropyl-1H-azulenium cations 6-8 were synthesized in five steps. The order of pKR+ values of these cations was found to be 7>8>6. A comparison of the values between 1,1-dialkyl- and 1,1-spiroalkylated 1H-azulenium cations with the same number of carbon atoms at the 1-position provided the results of 7>1 and 8<3. The cation 8 shows a relatively lower pKR+ value to those of 3 and 7 probably due to its slightly bulkier propyl groups from which solvation stabilization of 8 under the conditions suffers. An intermolecular charge-transfer interaction between the cations and dibenzo-24-crown-8 was also studied. 相似文献
995.
Mitsuyo Horikawa Toshihiro Hashimoto Shigeru Takaoka Hiroto Kaku Kentaro Yamaguchi Masaki Kawase Masao Sato 《Tetrahedron》2006,62(38):9072-9076
Two novel red pigments, uroleuconaphins A1 (1) and B1 (2) were isolated from the aphid Uroleucon nigrotuberculatum (Olive). The structures and the absolute configurations of 1 and 2 were determined by single-crystal X-ray analysis of their derivatives. These structures were constituted as dimeric compounds of two molecules of quinone A (3), which were linked via a dihydrofuran ring system. 相似文献
996.
997.
998.
Shinya Oda Hiroaki Uchiyama Hiromitsu Kozuka 《Journal of Sol-Gel Science and Technology》2012,61(3):484-493
Optically transparent, ca. 200–800 nm thick TiO2-hydroxypropylcellulose (HPC) hybrid thin films were prepared from Ti(OC3H7i)4–HPC–HCl–H2O–C3H7iOH solutions by the sol–gel method, where the as-deposited films were dried at 120 °C. The effects of the amount of HPC, H2O and HCl in the starting solutions on the refractive index and uncracking critical thickness of the films were studied, where
the effects on the critical thickness was discussed on the basis of in situ stress measurements during heating. The increase
in HPC content increased the critical thickness and lowered the refractive index. The increase in HCl content resulted in
a decrease in critical thickness and an increase in refractive index. Larger H2O contents gave rise to a maximum in critical thickness while the refractive index was unaffected. Such variation in critical
thickness with varying solution compositions was demonstrated to result from the differences in in-plane stress generated
during heating. By optimizing the processing parameters an 810 nm thick TiO2–HPC hybrid film of a refractive index of 1.84 was obtained. 相似文献
999.
1000.