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51.
考虑自有平台和第三方平台两种分时租赁方式,将汽车质量划分为性能质量和环境质量,构建销售模式、纯分时租赁模式和混合模式下的产品线策略模型,研究制造商产品线策略与商业模式之间的相互作用。研究发现,同品牌产品间竞争和合并效应是分时租赁模式影响产品线策略的两个关键因素。同品牌产品间竞争的加剧和合并效应的增大都会激励企业选择性能更好的车型而忽略其环境表现。分时租赁模式能同时改进利润与产品环境表现,但存在条件:当消费者价格敏感性较低时,使用成本高且合并效应小是实现同时改进的条件;当消费者价格敏感较高时,使用成本低且合并效应小则是同时改进的条件。 相似文献
52.
The electrochemical and in-situ surface-enhanced Raman spectroscopy (SERS) techniques were used to investigate the electrooxidation behavior of methanol in acidic, neutral and alkaline media at a Pt-Ru nanoparticle modified glassy carbon (Pt-Ru/GC) electrode. The results showed that methanol could be dissociated spontaneously at the Pt-Ru/GC electrode to produce a strongly adsorbed intermediate, CO. It was found that CO could be oxidized more easily in the alkaline medium than in the acidic and neutral media. The peak potential of methanol oxidation was shifted from 0.663 and 0.708 V in the acidic and neutral media to -0.030 V in the alkaline medium, which is due to that the adsorption strength of CO on the Pt surface in the alkaline medium is weaker than that in the acidic and neutral media. The final product of the methanol oxidation is CO2. However, in the alkaline medium, CO2 produced would form CO3^2- and HCO3^- resulting in the decrease in the alkaline concentration and then in the decrease in the performance of DMFC. Therefore, the performance of the alkaline DMFC is not Stable. 相似文献
53.
Lin Jiacheng Li Qianqian Zeng Xiaodong Chen Ziyang Ding Qihang Li Yang Zhou Hui Meng Xianli Chen Deliang Deng Zixin Hong Xuechuan Xiao Yuling 《中国科学:化学(英文版)》2020,63(6):766-770
Osteosarcoma is the most common primary malignant tumor of bone, particularly among children and adolescents. Advances in imaging, surgical techniques, and implants have dramatically reduced the need for amputation in the past three decades.Recently, in vivo fluorescence imaging in the second near-infrared window(NIR-II, 1,000–1,700 nm) shows impressive advantages of deeper tissue penetration and higher spatial resolution, which makes it a promising tool for the early diagnosis and post-operative observation of Osteosarcoma. To the best of our knowledge, this paper is the first time to develop a novel NIR-II fluorescence probe conjugated with an osteosarcoma targeted oligopeptide for molecular tumor imaging in a xenograft orthotopic osteosarcoma mouse model. 相似文献
54.
抗生育植物栀子花化学成分的研究:Ⅱ.栀子花甲酸的结构 总被引:1,自引:0,他引:1
我们已报道从栀子(Gardenia jasminoidesEllis)花的乙酸乙酯提取物中分得一种对大鼠有明显抗早孕作用的新三萜酸——栀子花乙酸(1),本文继续报道从该提取物中分得的另一种新三萜酸——栀子花甲酸(Gardenolicacid A,以下简称甲酸,2)的结构。 2为白色针状结晶,m.p.212~214℃,Liebermann-Burchard试验阳性,[α]_D~(17) 38.3,C_(30)H(46)O_(4),属三萜类。 相似文献
55.
研究了稀土(Ce、Gd和Y)改性丝光沸石用作甲醇胺化催化剂在常压固定床反应器中选择性合成二甲胺的催化性能。结果表明,稀土阳离子交换改性能改善丝光沸石的催化性能。丝光沸石经0.1mol/LCe4+溶液处理,与膨润土成型,再于600℃下焙烧2~3h,这样制得的催化剂在常压400℃时的活性及二甲胺选择性分别达到99.8%和50.3%。此外,详细探讨了不同改性及制备条件对催化剂催化性能及机械强度的影响。 相似文献
56.
《中国化学快报》2022,33(6):2987-2992
A rhodium-catalyzed [4 + 3] cycloaddition reaction between N-methoxybenzamides and gem?difluorocyclopropenes is described. The reaction offers a mild and efficient approach towards the synthesis of fluorinated 2H-azepin-2-ones with broad substrate scope. A consecutive HOAc-assisted CN bond formation and fluorine elimination are involved as key steps for success as illustrated by detailed DFT studies. 相似文献
57.
《The Journal of chemical thermodynamics》2006,38(1):20-33
The apparent molar volumes of l-alanine, dl-serine, dl-threonine, l-histidine, glycine, and glycylglycine in water and in the aqueous solutions of NaCl and DMSO with various concentrations at T = 298.15 K have been measured by the precise vibrating-tube digital densimeter. The calculated partial molar volumes at infinite dilution have been used to obtain corresponding transfer volumes from water to various solutions. The experimental results show that the standard partial molar volumes of the above amino acids and peptide at the dilute DMSO aqueous solutions are very close to those in water. However, the volumes show several types of variations with the increase of the concentrations of DMSO due to different types of side chain of amino acids, which should be discussed specifically. The NaCl changes considerably the infinite dilution standard partial molar volumes of the above amino acids and peptide in the aqueous solutions. The infinite dilution standard partial molar volumes of the each amino acids and peptide increase with the concentrations of NaCl. The experimental results have been rationalized by a cosphere overlap model. 相似文献
58.
Mingzhong Cai Yizheng Huang Rongli Zhang 《Journal of organometallic chemistry》2004,689(15):2436-2440
A silica-supported poly-γ-diphenylarsinopropylsiloxane palladium(0) complex has been prepared from γ-chloropropyltriethoxysilane via immobilization on fumed silica, followed by reacting with potassium diphenylarsenide and palladium chloride, and then the reduction with hydrazine hydrate. The palladium(0) complex has been found to catalyze the allylation of aldehydes via the formation of π-allylpalladium complexes, using allylic chlorides as allylating agent and SnCl2 as reducing agent. This polymeric palladium complex can be recovered and reused. 相似文献
59.
Barium strontium titanate nanoparticles with spherical and rod-like morphologies were synthesized in water/Triton X-100/n-hexanol/cyclohexane quaternary reverse microemulsion solution. The influences of the molar ratio of water to surfactant (ω0) and the concentration of reactants on the morphology and size of barium strontium titanate nanoparticles were studied. The structure, compositions and morphology of the prepared products were characterized by XRD, SAED, ICP, EDS and TEM. The results show that the obtained Ba0.7Sr0.3TiO3 spherical nanoparticles with diameters of 20~100 nm and the Ba0.7Sr0.3TiO3 nanorods with diameters of 70~120 nm and lengths up to 600~800 nm are a single crystal, with a cubic phase. The molar ratio for barium, strontium and titanate in products is about 0.7:0.3:1. 相似文献
60.
Shouzhi Pu Jingkun Xu Liang Shen Qiang Xiao Tianshe Yang Gang Liu 《Tetrahedron letters》2005,46(5):871-875
The photochromic diarylethene, 1,2-bis(2-methyl-5-(2-(1,3-dithiolpentane))-thien-3-yl)perfluorocyclopentene (BMDTP), has been synthesized in high yield and its structure was determined by X-ray crystallographic analysis. The compound undergoes a photochromic reaction both in solution and in the single crystalline phase. In addition, its fluorescence property in solution is discussed. 相似文献