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排序方式: 共有166条查询结果,搜索用时 31 毫秒
151.
报道采用电晕充电方法,对用高温熔融粘合工艺制备得到的双向拉伸多孔PTFE与PP复合过滤材料进行驻极体改性,并采用热刺激放电和表面电位测量等方法研究了材料的电荷存储稳定性,根据驻极体相关理论,对实验结果进行了解释. 结果表明,电晕充电的多孔PTFE/熔喷或纺粘PP覆膜材料中,既存在空间电荷又存在极化电荷,复合膜的界面是电荷陷阱的主要来源. 从不同面对复合膜材料进行充电时,材料具有完全不同的电荷存储特性. 由于材料体内空间电荷和极化电荷的极性相反、相互补偿,表面电位测定并不能真正反映材料内部电荷的存储状态.
关键词:
驻极体
电晕充电
聚合物复合膜
热刺激放电 相似文献
152.
停流式流动注射催化光度法测定水中痕量亚硝酸根的研究 总被引:7,自引:0,他引:7
亚硝酸盐与人体健康密切相关,是水质分析的重要项目之一。目前测定亚硝酸根的方法以分光光度法为主,但其灵敏度低、选择性欠佳。催化动力学光度法是测定亚硝酸盐的灵敏方法,本文把近几年发展起来的停流式流动注射技术与催化动力学光度法有机地结合起来,建立了高灵敏度、高选择性、简便快速地测定亚硝酸根的新方法,该方法可自动停流、阻断反应,省去了普通催化法所需的终止反应复杂步骤,所以快速、准确、重现性好,测定下限为2.4×1O~(-10)gNO_2~-/mL,除Br~-、I~-、SCN~-外,大多数阳离子和阴离子不干扰NO_2~-的测定,用于水中NO_2~-的测定,结果较为满意。 相似文献
153.
Hui-Ming LiuShi-Yang Chen Pin-Hsuan ChangSuh-Jen Jane Tsai 《Analytica chimica acta》2002,459(1):161-168
Diverse matrix effects on the determination of bismuth, selenium and tellurium (μg g−1) in nickel-based alloys and pure copper by flow-injection hydride generation atomic absorption spectrometry (FIAS-HGAAS) were investigated. Sodium tetrahydroborate was used as the reductant. The separation of analytes from copper matrix was mandatory while the analytes were successfully determined without being separated from the alloy matrix. Hydrochloric acid was effective in the prereduction of bismuth and selenium, however, it did not give any satisfactory result for tellurium in nickel-based alloys. In this work, 5% (w/v) ascorbic acid was proved effective for the prereduction of tellurium.Successful determination of tellurium in copper was achieved when N-nitroso-N-phenylhydroxylamine (cupferron) chelation-extraction was employed for the separation of tellurium from copper matrix. Cupferron chelation-extraction was performed in phosphate buffer (a mixture of 0.2 mol l−1 sodium phosphate and 0.1 mol l−1 citric acid). Lanthanum hydroxide coprecipitation at pH 10.0±0.5 was effective for bismuth and selenium. Standard reference materials of nickel-based alloys and pure copper were analyzed using the proposed methods. The linear range for the calibration curves were 0.30-15 and 0.20-10 ng ml−1 for BiH3 and H2Se, respectively, with a correlation coefficient of 0.9995. For H2Te, the linear range for the calibration curves was 0.50-12 ng ml−1 with the correlation coefficient of 0.9994. Good agreement was obtained between experimental values and certified values. Satisfactory recovery ranged from 91±1 to 106±2% was obtained from five replicate determinations. 相似文献
154.
155.
用巨正则蒙特卡罗分子模拟方法研究了单壁纳米碳管中的微孔即单壁纳米碳管基本孔-内管腔和管间孔对单壁纳米碳管储氢性能的影响.与低温下氮气吸附实验结果的比较发现单壁纳米碳管的内管腔是吸附的主要位置.分析单壁纳米碳管内管腔中吸附势的叠加和利用效率,发现管径为2nm左右时单壁纳米碳管内管腔的储氢容量最高.当单壁纳米碳管阵列的管间距增加时,单壁纳米碳管的管间孔也会成为有效的氢吸附位.
关键词:
Monte Carlo方法
单壁纳米碳管
储氢
微孔 相似文献
156.
This paper considers an epidemic model of a vector-borne disease which has direct mode of transmission in addition to the vector-mediated transmission. The incidence term is assumed to be of the bilinear mass-action form. We include both a baseline ODE version of the model, and, a differential-delay model with a discrete time delay. The ODE model shows that the dynamics is completely determined by the basic reproduction number R0. If R0?1, the disease-free equilibrium is globally stable and the disease dies out. If R0>1, a unique endemic equilibrium exists and is locally asymptotically stable in the interior of the feasible region. The delay in the differential-delay model accounts for the incubation time the vectors need to become infectious. We study the effect of that delay on the stability of the equilibria. We show that the introduction of a time delay in the host-to-vector transmission term can destabilize the system and periodic solutions can arise through Hopf bifurcation. 相似文献
157.
Capillary electrophoresis using immobilized whole cells with overexpressed endothelin receptor for specific ligand screening 总被引:1,自引:0,他引:1
A new capillary electrophoresis method using immobilized cells as the stationary phase has been developed. The power of this method is demonstrated by the separation and identification of endothelin antagonists on a capillary column coated by the transfected Chinese hamster ovary (CHO) cells with overexpressing endothelin receptors. The screening results are validated by functional assays suppressing the increase of intracellular calcium concentration induced by endothelin-1. Instead of making efforts in isolating protein receptors, the easily prepared whole-cell capillary column provides a superior tool on the basis of ligand/receptor affinity for a rapid screening of potent drug candidates from compound libraries. 相似文献
158.
Evidence of intermittent fluctuation of target fragments in ^84Kr-AgBr interactions at 1.7 A GeV
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Intermittency and fractal behaviour have been studied of emission spectra of target associated fragments from ^84Kr-AgBr interactions at 1.7 A GeV in emission angle space and azimuthal angle space separately. The intermittent behaviour is observed in the two spaces separately. Prom the intermittency exponent, the anomalous fractal dimension dq is calculated and the variation of dq with the order q is investigated. It is found that the anomalous dimensions are found to increase with the order of moments q, thereby indicating the relation of multifractality to production mechanism of target associated fragments. 相似文献
159.
Xiang-Dong Kang Ping Wang Lai-Peng Ma Hui-Ming Cheng 《Applied Physics A: Materials Science & Processing》2007,89(4):963-966
LiBH4 possesses a high hydrogen content, and though it is highly stable, its restoration from LiH+B+H2 can only be accomplished under unacceptable high temperature and pressure conditions (650 °C and 15 MPa). Recently, it has
been reported that destabilizing LiBH4 by, i.e., MgH2, transition metal oxides and chlorides presents a promising approach to exert its potential for hydrogen storage. In the
present study, we find that simple mechanical milling with Al in a mole ratio of 2:1, markedly improves the reversible dehydrogenation
performance of LiBH4. The system possesses a theoretical capacity of 8.5 wt. % and could be reversibly operated at 400–450 °C. The combined property
and phase examinations suggest that the observed property improvement should be associated with the formation of AlB2 in the dehydriding process. Further cyclic examination found that the system suffered from a serious capacity loss in the
dehydriding/rehydriding cycles. A better understanding of the degradation mechanism may provide a means for further material
property improvement.
PACS 81.05.Zx; 84.60.Ve; 82.30.-b; 82.33.Pt; 82.65.+r 相似文献
160.
The interaction potential for spherical-deformed reaction partners is calculated. The shape, separation and orientation dependence of the interaction potential and fusion cross section of the system ^32S+^154Sm are investigated within the double-folding model of the deformed nuclei. The effective nucleon-nucleon interaction is taken to be the M3Y-Reid potential. The density is considered for three terms of the expansion using the truncated multipole expansion method, which is a deformed Fermi shape With quadrupole and hexadecapole for the density distribution of ^154Sm. It is found for the interaction potential that the height and the position of barrier strongly depend on the deformations, the orientation angle of the deformed nucleus, and hence produce great effects on fusion cross section. The integrated fusion cross section is in good agreement with the experimental data. 相似文献