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151.
A. Sakaguchi M. Yamamoto M. Hoshi K. N. Apsalikov B. I. Gusev 《Journal of Radioanalytical and Nuclear Chemistry》2004,260(3):543-555
Recent controversies concerning the radiation doses for populations living in the village of Dolon due to the nuclear explosions
carried out at the Semipalatinsk Nuclear Test Site (SNTS) have encouraged us to evaluate in more detail the levels and distributions
of residual long-lived radionuclides137Cs and Pu isotopes (238Pu,239,240Pu) in soils within the village. Soil core samples up to a depth of about 30 cm and/or 100 cm were collected at 25 sites and
subjected to analysis of 137Cs and Pu isotopes. The inventories of 137Cs and 239,240Pu were found to be in the wide range of 790-10,310 and 530-14,320 Bq/m2, respectively. Sequential leaching of Pu from the soil showed that more than ca. 80% of the 239,240Pu was not leached by hot digestion with conc. HNO3 + H2O2, indicating the presence of Pu associated with fused silicates. Further, the presence of hot-particles from the Pu contaminants
by a-track radiography technique using CR-39 polycarbonate was confirmed in the soil, even at present, after about 50 years
from the first nuclear weapon testing.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
152.
A direct preparative route to benzoyltrimethylsilane has been found by the reaction of benzoyl chloride with hexamethyldisilane in the presence of a specified palladium(II) complex as catalyst. 相似文献
153.
154.
155.
The synthetic procedures for spilanthol and trail-following pheromone for a southern subterranean termite were described. The syntheses heavily depend on the new diene synthesis using titanium reagent. 相似文献
156.
Synthesis and characterization of 6-O-acyl-2-O-alpha-D-glucopyranosyl-L-ascorbic acids with a branched-acyl chain 总被引:3,自引:0,他引:3
We previously reported the chemical synthesis of a series of novel monoacylated vitamin C derivatives, 6-O-acyl-2-O-alpha-D-glucopyranosyl-L-ascorbic acids (6-Acyl-AA-2G) possessing a straight-acyl chain of varying length from C(4) to C(18), as effective skin antioxidants. In this paper, we describe branched type of 6-Acyl-AA-2G derivatives (6-bAcyl-AA-2G) synthesized by use of a 2-branched-chain fatty acid anhydride as an acyl donor. The stability of 6-bAcyl-AA-2G in neutral solution was much higher than that of 6-Acyl-AA-2G, while they were susceptible to enzymatic hydrolysis for exerting vitamin C effect. These branched derivatives as well as 6-Acyl-AA-2G increased the radical scavenging activity against 1, 1-diphenyl-2-picrylhydrazyl and the lipophilicity in octanol/water-partitioning systems with increasing length of their acyl group. In addition, the 6-bAcyl-AA-2G derivative with an acyl chain of C(12), 6-bDode-AA-2G had the excellent solubility to various solvents, suggesting easy handling in cosmetic use. These characteristics of 6-bAcyl-AA-2G may be available for skin care application as an effective antioxidant. 相似文献
157.
Nagao S Hirai Y Suzuki A Yamamoto Y 《Journal of the American Chemical Society》2005,127(12):4146-4147
A 19F NMR study on the acid-alkaline transition in sperm whale myoglobin reconstituted with a perfluoromethyl heme, 13,17-bis(2-carboxylatoethyl)-3,8-diethyl-2,12,18-trimethyl-7-trifluoromethylporphyrinatoiron(III), demonstrated that the thermodynamics of the transition is predominantly controlled by the stability of acidic form. 相似文献
158.
Masayoshi Nakasako Masamitsu Wada Satoru Tokutomi Kotaro T. Yamamoto Jun Sakai Mikio Kataoka Fumio Tokunaga † Masaki Furuya 《Photochemistry and photobiology》1990,52(1):3-12
Abstract— The quaternary structure of pea phytochrome type I (PI) dimer in the red-light-absorbing form was studied by small-angle X-ray scattering (SAXS) technique and rotary-shadowing electron microscopy. Structural parameters for PI 114 kDa chromopeptide dimer and its tryptically digested N-terminal 59 kDa chromopeptide monomer, such as average electron density, molecular volume and the second moment of electron density distribution, were determined in terms of SAXS using the contrast variation method. Furthermore, by means of model simulation for the scattering profiles of the chromopeptides, most plausible structural models for both peptides were constructed. The distance between the chromophoric domains was estimated to be about 70 A in the resultant model for 114 kDa chromopeptide dimer. Furthermore, the model was consistent with the electron-micrographic images of both the intact PI dimer and the PI 114 kDa chromopeptide dimer, so that the N-terminal 7 kDa fragment did not significantly contribute the low-resolution images of the dimer. 相似文献
159.
The selective generation of three different silver-BINAP catalysts has been achieved via the proper combination of metal/ligand ratio and/or choice of silver salt. Indeed, the X-ray crystallographic study has been used to gain insight into the structure of the catalyst. After the evaluation of each species, 1:1 (AgX.(R)-BINAP) complex was found to be the real active species in the O-selective nitroso aldol reaction. On the other hand, a systematic survey of solvent has shown that the optimal 2:1 (AgX.(R)-BINAP) complex is the effective catalyst in the N-selective pathway. Thus, a new method of generation of the silver-BINAP catalyst and the synthetic transformations provide not only new insights into the developing area of catalytic enantioselective nitroso aldol synthesis but also clear guidance for the design of an effective catalyst. 相似文献
160.
Electrophoretic mobilities of red blood cells (RBCs) were measured in microgravity using a home-made capillary electrophoresis unit, which consisted of two small reservoirs of 0.6 mL and a fused-silica capillary tubing with 2 cm in length and 50 num in inner diameter. Migration of RBCs was observed by a microscope at 1000 times magnification and recorded on a videotape. The experiments were performed during stays in microgravity (about 0.01 G), which lasted 20 s and were attained by parabolic flights of an aircraft. On average, the electrophoretic mobilities of RBCs determined in microgravity were about 30% higher than those measured at 1-G condition irrespectively whether the cells were suspended in saline or serum during measurements. This difference might be explained as being mainly due to the cell floating in microgravity. Morphological changes of RBCs may contribute partly to the difference, while the variation in viscosity of the medium under microgravity could play only a minor role. 相似文献