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171.
杨萍 《福建师范大学学报(自然科学版)》1998,14(3):112-118
追溯现代技术革命的源泉,90%的应用成果来自基础性研究,事实表明,基础研究正以惊人的速度呼唤出巨大的自然力,然而国家对基础研究提出控制规模的资助方针,使其成果完全为实现国家目标服务,作为地方基础性研究,如何为地方经济建设服务,突出地方特色,是地方基金工作的重点。 相似文献
172.
阐述了高耸柔性结构振动主动控制的必要性、基本概念及其关键技术,综述了其研究现状及存在的问题,并指出高耸柔性结构机敏化/智能化是确保结构安全性与耐久性的重要途径。 相似文献
173.
探讨海洋科技成果管理与转化之间的关系,建议建立起一种跨行业跨部门的管理体系,多方位促进成果应用,加快科技兴海计划实施步伐. 相似文献
174.
简要介绍了国家“八五”重点教育科研课题“建立中国教育文献数据库”的子课题“建立全国高教研究期刊及论文数据库”中对数据库及其管理系统软件的设计思想及其实现技术。 相似文献
175.
176.
Anna B. DenisovaVyacheslav Ya. Sosnovskikh Wim Dehaen Suzanne ToppetLuc Van Meervelt Vasiliy A. Bakulev 《Journal of fluorine chemistry》2002,115(2):183-192
Reaction of 2-hydrazinothiazoles 1 with 1-thienyl- and 1-furyl-1,3-butanediones 2a,b in methanol in the presence of hydrochloric acid mainly leads to a mixture of pyrazoles 3 and pyrazolines 4 or pyrazoles 3 and 5 in strong acidic conditions. Isomeric hydrazones 6 and pyrazolines 4 were formed and isolated in these reactions in the absence of hydrochloric acid. It has been shown that the regioselectivity in the reaction of diketones 2 with hydrazine 1 is governed by both the concentration of acid and the nature of substituents in the 1,3-diketones 2. Cyclization of hydrazones 6 is shown to occur under milder conditions than dehydration for pyrazolines 4. The new heterocyclic compounds were prepared and fully characterized by NMR spectra and by X-ray analysis for 3c. 相似文献
177.
Masaaki?HanedaEmail author Isao?Nakamura Tadahiro?Fujitani Hideaki?Hamada 《Catalysis Surveys from Asia》2005,9(4):207-215
Comprehensive studies combining surface science and real catalyst were performed to get further insight into catalytic active
site and reaction mechanism for NO decomposition over supported palladium and cobalt oxide-based catalysts. On palladium single-crystal
model catalysts, adsorption, dissociation and desorption behavior of NO was found to be closely related to the surface structures,
the stepped surface palladium being active for dissociation of NO. In accordance with this result, the activity of powder
Pd/Al2O3 catalysts for NO decomposition was directly related to the number of step sites exposed on the surface, suggesting that the
step sites act as the catalytic active site for NO decomposition on Pd/Al2O3. NO decomposition over cobalt oxide was found to be significantly promoted by addition of alkali metals. Surface science
study and catalyst characterization led to the same conclusion that the interface between the alkali metal and Co3O4 serves as the catalytic active site. From the results of in situ Fourier transform infrared (FT-IR) spectroscopy and isotopic transient kinetic analysis, a reaction mechanism was proposed
in which the reaction is initiated by NO adsorption onto alkali metals to form NO2− species and then NO2− species react with the adsorbed NO species to form N2 over the interface between the alkali metal and Co3O4. 相似文献
178.
A class of extended 2,5‐disubstituted‐1,3,4‐oxadiazoles R1‐C6H4‐{OC2N2}‐C6H4‐R2 (R1=R2=C10H21O 1 a , p‐C10H21O‐C6H4‐C?C 3 a , p‐CH3O‐C6H4‐C?C 3 b ; R1=C10H21O, R2=CH3O 1 b , (CH3)2N 1 c ; F 1 d ; R1=C10H21O‐C6H4‐C?C, R2=C10H21O 2 a , CH3O 2 b , (CH3)2N 2 c , F 2 d ) were prepared, and their liquid‐crystalline properties were examined. In CH2Cl2 solution, these compounds displayed a room‐temperature emission with λmax at 340–471 nm and quantum yields of 0.73–0.97. Compounds 1 d , 2 a – 2 d , and 3 a exhibited various thermotropic mesophases (monotropic, enantiotropic nematic/smectic), which were examined by polarized‐light optical microscopy and differential scanning calorimetry. Structure determination by a direct‐space approach using simulated annealing or parallel tempering of the powder X‐ray diffraction data revealed distinctive crystal‐packing arrangements for mesogenic molecules 2 b and 3 a , leading to different nematic mesophase behavior, with 2 b being monotropic and 3 a enantiotropic in the narrow temperature range of 200–210 °C. The structural transitions associated with these crystalline solids and their mesophases were studied by variable‐temperature X‐ray diffractometry. Nondestructive phase transitions (crystal‐to‐crystal, crystal‐to‐mesophase, mesophase‐to‐liquid) were observed in the diffractograms of 1 b, 1 d , 2 b, 2 d , and 3 a measured at 25–200 °C. Powder X‐ray diffraction and small‐angle X‐ray scattering data revealed that the structure of the annealed solid residue 2 b reverted to its original crystal/molecular packing when the isotropic liquid was cooled to room temperature. Structure–property relationships within these mesomorphic solids are discussed in the context of their molecular structures and intermolecular interactions. 相似文献
179.
180.