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排序方式: 共有585条查询结果,搜索用时 15 毫秒
61.
Huiling Wu 《Journal of Optimization Theory and Applications》2013,158(3):918-934
This paper considers a non-self-financing mean-variance portfolio selection problem in which the stock price and the stochastic cash flow follow a Markov-modulated Lévy process and a Markov-modulated Brownian motion with drift, respectively. The stochastic cash flow can be explained as the stochastic income or liability of the investors during the investment process. The existence of optimal solutions is analyzed, and the optimal strategy and the efficient frontier are derived in closed-form by the Lagrange multiplier technique and the LQ (Linear Quadratic) technique. 相似文献
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目的 研究组胺作用于腹外侧视前区对大鼠睡眠-觉醒周期的影响。方法 通过脑立体定位、腹外侧视前区微量注射组胺,脑电图仪记录及分析睡眠、觉醒时相。结果 微量注射50μmol/L组胺无明显影响,而100μmol/L组胺显著减少大鼠睡眠,增加觉醒。结论 组胺在腹外侧视前区对大鼠睡眠-觉醒周期发挥重要的调节作用,具有明显的促觉醒作用。 相似文献
64.
Lu Hai Wang Jinlei Li Tao Du Huiling Yi Dawei Fang Jing Hong Bo 《Journal of Solid State Electrochemistry》2018,22(3):953-958
Journal of Solid State Electrochemistry - A novel polyacrylamide/mixed carbon black-coated separator was fabricated for lithium-sulfur batteries. It is demonstrated that the coated separator... 相似文献
65.
本文从刚体作纯滚动时的无滑条件出发,根据静摩擦力的方向与物体相对运动趋势相反的特点,推出了判断纯滚动刚体所受静摩擦力方向的一种新方法。 相似文献
66.
Cheng L Tan H Wu X Hu R Aw C Zhao M Shen HM Lu Y 《Organic & biomolecular chemistry》2008,6(22):4102-4104
Studies on the sensitization, by novel alkynyl luteolin analogues, of TNF-alpha-induced apoptosis in HeLa and HepG2 cells revealed that LA-12 showed better sensitizing effects on TNF-alpha-induced cell death than luteolin, suggesting great potential for alkynyl luteolin analogues in cancer therapy. 相似文献
67.
Xu X Wang X Liu Y Liu B Wu H Yang P 《Rapid communications in mass spectrometry : RCM》2008,22(8):1257-1264
An enzyme-immobilized capillary microreactor for rapid protein digestion and proteomics analysis is reported. The inner surface of the fused-silica capillary was coated with poly(diallyldimethylammonium chloride) (PDDA)-entrapped silica sol-gel matrix, followed by assembly of trypsin onto the PDDA-modified surface via electrostatic adsorption. The immobilization parameters such as PDDA content in the sol-gel matrix, trypsin concentration and pH were investigated in detail. Protein samples including beta-casein, myoglobin and cytochrome c could be effectively digested and electrophoretically separated simultaneously in such a modified capillary. Just 2.26 ng (corresponding to 0.10-0.14 picomole) of sample was sufficient for on-line capillary electrophoresis peptide mapping. The efficiency of the digestion was further demonstrated by digestion of a human liver cytoplasm sample and 253 proteins were identified in one unique run. 相似文献
68.
以三苯胺和苯乙酮为原料,设计合成了一个新的具有D-π-A结构的有机光敏剂(E)-2-氰基-2-((Z)-5-(4-(二苯基氨基)亚苄基)-4-苯基噻唑-2(5H)-亚基)乙酸乙酯(TPAD),并通过核磁1 HNMR,13 CNMR,IR,UV-Vis,XRD和SEM等手段对目标化合物的结构和性质进行表征.制备了复合光催化剂TPAD/Pt(w=0.5%)TiO_2,构建了以TPAD/Pt(w=0.5%)/TiO_2为光催化剂,三乙胺为牺牲剂的产氢体系,系统研究了三乙胺的体积分数、乙腈与水的比例及溶液的pH值等因素对目标光催化剂析氢活性的影响.结果表明:在可见光照射下,当三乙胺的体积分数浓度为5%,pH值为10,乙腈/水的体积比为1∶1时,经3h光照后,体系的析氢量达最大值370μmol,平均析氢速率达25 933.3μmol·h-1·g-1. 相似文献
69.
Singly versus Doubly Reduced Nickel Porphyrins for Proton Reduction: Experimental and Theoretical Evidence for a Homolytic Hydrogen‐Evolution Reaction
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Yongzhen Han Dr. Huayi Fang Huize Jing Huiling Sun Haitao Lei Prof. Dr. Wenzhen Lai Prof. Dr. Rui Cao 《Angewandte Chemie (International ed. in English)》2016,55(18):5457-5462
A nickel(II) porphyrin Ni‐P (P=porphyrin) bearing four meso‐C6F5 groups to improve solubility and activity was used to explore different hydrogen‐evolution‐reaction (HER) mechanisms. Doubly reduced Ni‐P ([ Ni‐P ]2?) was involved in H2 production from acetic acid, whereas a singly reduced species ([ Ni‐P ]?) initiated HER with stronger trifluoroacetic acid (TFA). High activity and stability of Ni‐P were observed in catalysis, with a remarkable ic/ip value of 77 with TFA at a scan rate of 100 mV s?1 and 20 °C. Electrochemical, stopped‐flow, and theoretical studies indicated that a hydride species [H‐ Ni‐P ] is formed by oxidative protonation of [ Ni‐P ]?. Subsequent rapid bimetallic homolysis to give H2 and Ni‐P is probably involved in the catalytic cycle. HER cycling through this one‐electron‐reduction and homolysis mechanism has been proposed previously but rarely validated. The present results could thus have broad implications for the design of new exquisite cycles for H2 generation. 相似文献
70.