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991.
本文根据中国香料香精企业的现状,从几个方面分析了入世后对中国这个行业的影响,提出了一些应对策略,包括提高企业竞争力、创新能力和投资海外、走战略联盟等,并预测了中国香料香精行业的未来发展前景。  相似文献   
992.
Well-crystallized bismuth tungstate (Bi2WO6) powders with different morphologies were successfully synthesized via a low-temperature molten salt method. The powders were characterized by X-ray diffraction, transmission electron microscopy, and UV-Vis, respectively. It was found that the variation of morphology of the obtained Bi2WO6 powder mainly depends on the different reaction temperatures and the weight ratio of LiNO3–NaNO3 salt to precursor. In addition, the UV-Visible absorption spectra showed that the synthesized powders had strong light absorption properties not only in the ultraviolet light but also in the visible light region.  相似文献   
993.
Jun Fan  Xiaodong Wu  Lei Yang  Duan Weng   《Catalysis Today》2007,126(3-4):303-312
CeO2–ZrO2–La2O3 (CZL) mixed oxides were prepared by citric acid sol–gel method. The as-received gel was calcined at 500, 700, 900 and 1050 °C to obtain the so-called C5, C7, C9 and CK, respectively. The C5, C7 and C9 powders were impregnated with H2PtCl6 and then calcined at 500 °C to prepare P5C5, P5C7 and P5C9, respectively. The impregnated CK powders were calcined at 500, 700 and 900 °C to prepare P5CK, P7CK and P9CK, respectively. The XRD and XPS analyses show that the surface distribution of Pt is evidently influenced by the structural and textural properties of the support. The CO adsorption followed by FTIR reveals that the dispersion and the chemisorption sites of Pt are reduced as the calcination temperature of CZL support increases. The chemisorption ability of the CK samples is even completely deactivated. The encapsulation mechanism, which has been applied to explain the so-called strong metal–support interaction (SMSI) after reductive treatment, is introduced here to demonstrate the abnormal observations though the samples were prepared in oxidative atmosphere. The HRTEM results also confirm this explanation. The effects of oxygen vacancies, the chemisorption sites on the Pt surface and Pt/Ce interfacial sites on the three-way catalytic activities are discussed.  相似文献   
994.
A quantum identity authentication scheme based on ping-pong technique without entanglements is proposed. It can verify the legitimate user’s identity and update the initial authentication key for reuse. The security of the proposed scheme is extensively analyzed and accordingly confirmed in the case of general individual attacks. The present scheme owns high efficiency due to the use of single-particle states in a two-way quantum channel. Moreover, the scheme is economical and feasible with present-day technique.  相似文献   
995.
The present paper studies the integrated size and topology optimization of skeletal structures under natural frequency constraints. It is found that, unlike the conventional compliance-oriented topology optimization problems, the considered problem may be strongly singular in the sense that the corresponding feasible domain may be disconnected and the global optimal solutions are often located at the tips of some separated low dimensional sub-domains when the cross-sectional areas of the structural components are used as design variables. As in the case of stress-constrained topology optimization, this unpleasant behavior may prevent the gradient-based numerical optimization algorithms from finding the true optimal topologies. To overcome the difficulties posed by the strongly singular optima, some particular forms of area/moment of inertia-density interpolation schemes, which can restore the connectedness of the feasible domain, are proposed. Based on the proposed optimization model, the probability of finding the strongly singular optimum with gradient-based algorithms can be increased. Numerical examples demonstrate the effectiveness of the proposed approach.  相似文献   
996.
Graft copolymerization of acrylonitrile (AN) and methyl methacrylate (MMA) onto polychloroprene (CR) was carried out using benzoyl peroxide as initiator. The effects of mole ratio of AN to MMA, reaction temperature, reaction time, solvent, and initiator concentration on the graft copolymerization were examined. It was found that the thermal stability and weatherability of the AN—CR—MMA graft copolymer (ACM) were considerably better than those of CR.  相似文献   
997.
塑料注射成型新技术——微孔发泡技术的应用   总被引:5,自引:0,他引:5  
主要介绍微孔发泡技术的工艺过程、应用特性及加工条件、气体条件对微孔发泡过程的影响  相似文献   
998.
氨氮废水降解技术进展   总被引:19,自引:0,他引:19  
介绍了氨氮废水的主要来源,论述了氨氮废水降解的各种技术及其工艺过程,重点论述了生物处理技术及工艺、物理化学处理技术及工艺以及它们在工业中的应用和特点,并探讨了氨氮废水降解机制,综述了目前国内外研究进展状况。  相似文献   
999.
曹军  赵慧丽  陈英新 《辽宁化工》2002,31(3):129-130
建立了异辛酸合成过程中异辛醇、异辛酸和酯的气相色谱分析方法。以 10 %改性聚乙二醇 2 0M为固定液 ,苯乙酮为内标物 ,氢火焰离子化检测器 ,内标法定量分析异辛酸。实验结果表明 ,该方法准确可靠 ,测得异辛酸的相对重量校正因子 1.30 5 ,相对误差小于 2 .0 %。同时通过与化学法对照结果显示 ,合成液用内标法测定较好 ,而精产品用带校正因子的归一化法测定较好。  相似文献   
1000.
以紫胶桐酸为原料,经三步反应合成了地老虎性信息素类似物E-7-十五碳稀-1-醇乙酸酯。关键步骤是16-羟基-9E-十六碳烯酸(2)在DBU作用下的脱羧反应。  相似文献   
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