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91.
大埋深粘土三轴高压卸载变形与强度特征 总被引:1,自引:0,他引:1
以取自山东巨野矿区埋深近 4 30~ 6 0 0m的深部粘土样为例 ,分析测试了土的常规物理力学性质参数。考虑该埋深土的天然应力水平及其在煤矿建井开挖中的卸载应力变化 ,在三轴伺服仪上 ,进行三向等压分别达 11MPa、12MPa、14MPa下的卸除围压、保持轴压的三轴高压卸载试验 ,分析了深部粘土三轴高压卸载变形和强度特点 ,得到了相关力学参数。成果丰富了土的高压卸载力学性研究 ,并为巨野矿区煤矿立井建设提供了工程地质基础参数 相似文献
92.
Solid phase extraction with electrospun nanofibers for determination of retinol and α-tocopherol in plasma 总被引:1,自引:0,他引:1
A novel packed-fiber solid phase extraction procedure based on electrospun nanofibers for simultaneous determination of vitamins A (retinol) and E (α-tocopherol) in human plasma has been developed. Parameters affecting extraction efficiency were investigated in detail. The limit of detection is 0.01 μg mL?1 for retinol, and 0.3 μg mL?1 for α-tocopherol. The linear range is from 0.05 to 2.0 μg mL?1 for retinol, and from 0.5 to 30 μg mL?1 for α-tocopherol. The precision (RSD) is <6%, and the relative recovery >90%. The method was applied to analysis of retinol and α-tocopherol in human plasma with satisfactory results. 相似文献
93.
Lu Wen Zhiyong Guo Qing Li Dezhi Zhang Zhigang She L. L. P. Vrijmoed 《Chemistry of Natural Compounds》2010,46(3):363-365
A new griseofulvin derivative, 7-chloro-2',5,6-trimethoxy-6'-methylspiro(benzofuran-2(3H),1'-(2) cyclohexene)3,4'-dione (1),
together with the known 2-acetyl-7-methoxybenzofuran (2), was isolated from the marine-derived mangrove endophytic fungus
Sporothrix sp. (No. 4335). The structure of new compound 1 was elucidated by analysis of spectroscopic data. 相似文献
94.
95.
Zhiyong Yang Linlin Zhang Gang Li Qingjiang Wang Pingang He Yuzhi Fang 《Chromatographia》2010,71(5-6):439-445
A composite electrode was fabricated from Cu2O powder, carboxyl-functionalized multi-wall carbon nanotubes (MWCNT-COOH), and paraffin oil in the proportions 51:17:32 (w/w). This composite electrode was used for amperometric detection (CZE–AD) in simultaneous capillary zone electrophoretic analysis of chlorogenic acid, rutin, sucrose, glucose, mannose, and fructose in tobacco samples. Under the optimum conditions, the six analytes could be separated in 100 mmol L?1 NaOH buffer within 30 min. Good linearity was achieved in the range 1 × 10?7–1 × 10?4 mol L?1 for the two polyphenols and 5 × 10?6–1 × 10?3 mol L?1 for the four sugars. The detection limits (S/N = 3) for the polyphenols and sugars were as low as 10?8 mol L?1 and 10?6 mol L?1, respectively. 相似文献
96.
Two kinds of spinel LiMn2O4 thin film for lithium ion micro-batteries were successfully prepared on polycrystal Pt substrates by spin coating methods, which were carried out under ultrasonic irradiation (USG) and magnetic stirring (MSG), respectively. The microstructures and electrochemical performance of LiMn2O4 thin films were characterized by thermogravimetry analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), and galvanostatic charge-discharge measurements. It was found that the crystalline structure of USG samples grew better than that of the MSG samples. At the same time, higher discharge capacity and better cycle stability were obtained for the LiMn2O4 thin films of USG at the current density of 50 μAh/cm2 between 3.0 and 4.3 V. The 1st discharge capacity was 57.8 μAh/cm2-μm for USG thin films and 51.7 μAh/cm2-μm for MSG thin films. After 50 cycles, 91.4% and 69% of discharge capacity could be retained respectively, indicating that ultrasonic irradiation condition during spin coating was more suitable for preparing spinel LiMn2O4 thin films with better electrode performance for lithium ion micro-batteries. 相似文献
97.
98.
In this paper, we study a kind of system of second order quasilinear parabolic partial differential equation combined with algebra equations. Introducing a family of coupled forward–backward stochastic differential equations, and by virtue of some delicate analysis techniques, we give a probabilistic interpretation for it in the viscosity sense. 相似文献
99.
Zhiyong Li Jonathan Crook Galina Andreeva 《The Journal of the Operational Research Society》2014,65(3):466-479
Bankruptcy prediction is a key part in corporate credit risk management. Traditional bankruptcy prediction models employ financial ratios or market prices to predict bankruptcy or financial distress prior to its occurrence. We investigate the predictive accuracy of corporate efficiency measures along with standard financial ratios in predicting corporate distress in Chinese companies. Data Envelopment Analysis (DEA) is used to measure corporate efficiency. In contrast to previous applications of DEA in credit risk modelling where it was used to generate a single efficiency—Technical Efficiency (TE), we assume Variable Returns to Scale, and decompose TE into Pure Technical Efficiency and Scale Efficiency. These measures are introduced into Logistic Regression to predict the probability of distress, along with the level of Returns to Scale. Effects of efficiency variables are allowed to vary across industries through the use of interaction terms, while the financial ratios are assumed to have the same effects across all sectors. The results show that the predictive power of the model is improved by this corporate efficiency information. 相似文献
100.
Zhiyong Gong Qingwen Liu Pengchong Xue Kechang Li Zhiguang Song Zaiqun Liu Yinghua Jin 《应用有机金属化学》2012,26(3):121-129
Several novel chiral thiazoline primary and tertiary alcohols were easily synthesized from commercially available l ‐cysteine in three steps and with high yield. These ligands were subsequently applied to the asymmetric addition of diethylzinc (Et2Zn) to various aldehydes. Products with S configuration were obtained when thiazoline‐containing tertiary alcohol ligands were used as catalysts. The primary alcohol induced corresponding products with R configuration in 68% enantiomeric excess, which was a higher value relative to other N―O ligands possessing a primary alcohol unit in the literature. Furthermore, a plausible transition state model was proposed to explain the observed enantioselectivities. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献