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11.
Y. Kobayashi S. Tokonami Y. Narazaki W. Zhuo M. Furukawa 《Journal of Radioanalytical and Nuclear Chemistry》2005,266(3):389-396
Summary Radon measurements were carried out in a Japanese wooden house built on granitic geology, where radon-rich well water is used.
Atmospheric radon concentrations were measured over one year with passive integrated radon monitors. The monitors were distributed
at several locations in the house and were replaced every two months. In order to confirm the diurnal variation and heterogeneous
distribution of radon, short-term measurements were carried out accordingly. Radon, its decay products and terrestrial gamma-radiations
were measured in this survey. From the long-term measurement, the radon concentration in the house ranged from 14 to 184 Bq. m-3with an arithmetic mean of 45 Bq. m-3. A radon concentration of 184 Bq. m-3was observed in the bathroom in spring (March-May) though the radon level was normal in the living room and bedroom. In order
to characterize the house, similar measurements were conducted in several surrounding houses. There was a significant difference
in radon concentration between the investigated houses. There was a spatial distribution of the radon concentration and the
highest value was found in the bathroom. Radon and its decay products concentrations varied with time, which increased from
midnight to morning whereas they decreased during daytime. Although the radon concentration in tap water was 1 Bq. l-1, a high level of 353 Bq. l-1was found in the well water.While well water was being used, the indoor radon concentration near the bathroom increased rapidly
with a maximum value of 964 Bq. m-3. It is clear that the use of well water enhanced the radon level around the bathroom. 相似文献
12.
Polymeric micelles based on amphiphilic diblock copolymers methoxy poly(ethylene glycol)-polylactide with various hydrophobic lengths were designed as carriers of poorly water-soluble anticancer drug methotrexate (MTX). Relationship between physicochemical characteristics of micelles and release behavior was explored. The critical micelle concentration was determined by fluorescence spectroscopy using 9-chloromethyl anthracene as fluorescence probe. Core-shell type polymeric micelles were prepared by free-surfactant dialysis technique. The mean size of micelles loaded with MTX was 50-200 nm with narrow polydispersity. Physicochemical properties of drug-loaded micelles were evaluated. In vitro release behavior of MTX was also investigated. MTX was continuously released from micelles and less than 50% MTX was released in 5 days. Release rate was dependent on chemical structures of micelles and enhanced by decreasing polylactide lengths. 相似文献
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15.
二维卷积在动力学分析中的应用 总被引:2,自引:0,他引:2
本文用计算机模拟和二维卷积研究了稀土与间乙酰基偶氮氯膦的显色反应,选择不同的模型参数可描述这类反应的细节,二维卷积则增强对叠合二维谱的分辨。 相似文献
16.
Yiyi Weng Xingxing Ding Joo C. A. Oliveira Xiaobin Xu Nikolaos Kaplaneris Meijie Zhu Hantao Chen Zhuo Chen Lutz Ackermann 《Chemical science》2020,11(34):9290
There is a strong demand for novel native peptide motifs for post-synthetic modifications of peptides without pre-installation and subsequent removal of directing groups. Herein, we report an efficient method for peptide late-stage C(sp3)–H arylations assisted by the unmodified side chain of asparagine (Asn) without any exogenous directing group. Thereby, site-selective arylations of C(sp3)–H bonds at the N-terminus of di-, tri-, and tetrapeptides have been achieved. Likewise, we have constructed a key building block for accessing agouti-related protein (AGRP) active loop analogues in a concise manner.An efficient method for peptide late-stage C(sp3)-H arylations assisted by unmodified side chain of asparagine (Asn) without any exogenous directing group has been reported. 相似文献
17.
Fission fluctuation-dissipation dynamics of heavy nuclei has been studied using Langevin Monte Carlo simulations. The covariant form of the fission transport equation and the coefficients related to it are investigated. To learn about the influence of the dynamics from the ground state to the saddle point on the kinetic energy distributions we have studied various systems and compared the calculations both starting from the ground state and from the saddle point. Both the mean total kinetic energy of the fission fragments and its variances can fit with the experimental values in terms of a finite neck radius as scission condition.This work was supported by the National Natural Science Foundation of China. 相似文献
18.
Arrayed structures are desirable for many applications, but the fabrication of many material arrays remains a significant challenge. As a prominent II-VI semiconductor, large-scale arrayed ZnS structure has not been easily fabricated. Here, we introduce a simple structure conversion route for the synthesis of novel arrayed structures, and large-scale tube-like ZnS structure arrays and cable-like ZnS-ZnO composite arrays were successfully prepared through sulfuration conversion from arrayed rod-like ZnO structure based on a hydrothermal method at low temperature. XRD, EDS, SEM, TEM and PL are used to confirm the formation of the novel arrayed structure and trace the conversion process. The results show that the conversion ratio can be conveniently tailored by the reaction time, and the PL properties of the obtained materials can be adjusted through the conversion ratio. Especially, the cable-like structure holds the PL properties of both ZnO and ZnS structures. This simple solution method can be further extended to the preparation of other semiconductor sulfide and selenide, and can amplify the application field of large-scale arrays of semiconductors. 相似文献
19.
低碳烃芳构化过程中HZSM-5催化剂结炭规律的研究 总被引:3,自引:0,他引:3
用GC、TPO-GC、NH_3-TPD和TEM等方法,测定了丙烷在HZSM-5沸石上芳构化过程中,催化剂的活性、结炭量、结炭C/H比、酸密度等,考察了催化剂的结炭量与其它参数之间的关系。结果表明,在反应温度为873K,进料空速WHSV=5h ̄(-1)时,丙烷在HzSM-5上的结炭首先发生在沸石晶体的外表面的活性中心上(结炭量1.8%之前);结炭量为1.8~3.4%时,主要在孔道交叉点结炭;结炭量在3.4~5.7%时,孔道已有受限或阻塞现象发生,导致一些富氢的结炭物在孔道内生成。 相似文献
20.
[reaction: see text] A series of chiral pyrrolidinylmethanol-based dendritic ligands were synthesized for application in enantioselective aryl transfer reactions to aldehydes with the (ArBO)3/ZnEt2 system in up to 98% ee. 相似文献