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Sakae Uemura Haruo Miyoshi Masaya Okano Isao Morishima Toshiro Inubushi 《Journal of organometallic chemistry》1979,165(1):9-19
Treatment of norbornene, norbornadiene, benzonorbornadiene, and chloro- and methoxy-benzonorbornadiene with thallium(III) acetate in methanol affords only the corresponding cis-exo-acetoxythallation adducts in a sharp contrast to oxymercuration of such strained olefins where methoxymercuration prevails. In the cases of substituted benzonorbornadienes the products are obtained as the regioisomeric mixtures, the isomer ratio being determined by 13C NMR. In the cases of 5-norbornene-2,3-dicarboxylic anhydride, 5-norbornene-2-methyl-2,3-dicarboxylic anhydride, and 5-norbornen-2-endo-carboxylic acid, lactonization occurs to give a trans-oxythallation adduct having a lactone ring, no introduction of either methoxy or acetoxy groups being observed. 1H and/or 13C NMR data for several new oxythallation adducts are provided. The alkaline sodium borohydride reduction of adducts in methanol affords mainly the parent olefin together with 10–16% yields of the corresponding exo-alcohol. 相似文献
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A novel metamaterial multi-span beam with periodic simple supports and local resonators is designed and investigated. The frequency responses of the proposed metamaterial multi-span beam are computed by the spectral element method (SEM). The accuracy and feasibility of the SEM are verified by the finite element method (FEM) and the vibration experiments. The results show that the metamaterial multi-span beam could generate both the local resonance band-gaps in the low-frequency ranges and the Bragg band-gaps in the medium and high frequency regions. By adjusting the natural frequencies of the local resonators, the thickness of the base beam and the length of the unit-cell, the local resonance and the Bragg band-gaps can be controlled, respectively. The coupling effects of these two kinds of band-gaps are investigated by the parametrical design, which broadens the band-gaps and consequently improves the vibration reduction performance. 相似文献
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通过分阶段建立多元线性回归模型,分析了改革开放32年来民航客运量与相关因素之间的关系.结果表明:在不同历史阶段影响民航客运量的因素有所不同,并且从经济学角度对所建立的模型给出了合理的解释. 相似文献
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José M. Sánchez-Ron 《Physics in Perspective (PIP)》2006,8(3):318-343
I provide a tour of Madrid, focusing especially on physical institutions that were created during the 19th and 20th centuries.These
include the Astronomical Observatory close to the Prado Museum, which itself was conceived as a home for the Royal Academy
of Sciences but became instead a world-famous art museum in 1819, leaving the Royal Academy of Sciences without a permanent
home until 1866.The Laboratory of Physical Researches was created in 1910, and under the direction of Blas Cabrera (1878–1945),
who also held a professorship at the Universidad Central, it fostered most of the Spanish research in physics at the time,
in particular the famous spectroscopic researches of Miguel A. Catalán (1894–1957). Nearby were the so-called Transatlantico building and the Students’ Residence where Albert Einstein (1879–1955), for example, lectured in 1923, and which together
continue to serve as a major cultural center in Madrid. Later, the physical laboratory was replaced by the National Institute
of Physics and Chemistry, which was constructed with funds from the Rockefeller Foundation and inaugurated in 1932. A new
University City with its Faculty of Sciences also was constructed on the northwestern outskirts of Madrid, but almost all
of its buildings were totally destroyed during the devastating Spanish Civil War of 1936–1939. It was reconstructed after
the war and became home, for example, to Spain’s first nuclear reactor, which achieved criticality in 1958. 相似文献
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cracy MonthlyD 《大学物理》2006,(8)
ry's CompanionSecretary's CompanionSecretary's CompanionSecretary's CompanionSecretary's CompanionSecretary's CompanionSecretary's CompanionSecretary's CompanionSecretary's CompanionSecretary's CompanionSecretary's CompanionSecretary's CompanionSecretary's CompanionSecretary's CompanionSecretary's CompanionSecretary's CompanionSecretary's CompanionSecretary's C 相似文献
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The experimental results from infrared thermography surveys over two buildings externally exposed walls are presented. Data acquisition was performed on a static configuration by recording direct and indirect solar loading during several days and was processed using advanced signal processing techniques in order to increase signal-to-noise ratio and signature contrast of the elements of interest. It is demonstrated that it is possible to detect the thermal signature of large internal structures as well as surface features under such thermographic scenarios. Results from a long-wave microbolometer compared favorably to those from a mid-wave cooled infrared camera for the detection of large subsurface features from unprocessed images. In both cases, however, advanced signal processing greatly improved contrast of the internal features. 相似文献
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在民用飞机噪声适航合格审定试验中,传声器布置在地面上1.2 m处,测得的噪声包含地面影响。该文提出了一种分析地面对民机噪声适航合格审定试验中有效感觉噪声级影响的方法,并以ARJ21-700飞机噪声适航合格审定试验为例,对地面对飞越噪声的影响进行了计算和分析。在对飞行试验中飞机自由场声压级理论计算方法进行分析的基础上,通过飞越噪声测量点处布置的倒置传声器装置测量结果,计算了该测量点处的自由场声压级。随后,对满足"CCAR-36部"的不同地面声阻抗对噪声的影响进行了计算,分析了地面条件对噪声适航合格审定中有效感觉噪声级的影响。结果表明,地面声阻抗对噪声适航合格审定结果有明显影响,该方法可以为民用飞机噪声适航合格审定试验提供一种分析测量点地面的声学处理对噪声评定结果影响的手段。 相似文献