918 resultados para Tooth Apex


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淫羊藿系小檗科淫羊藿属植物 ,具有补肾壮阳、强筋骨、祛风湿之功效 .现代药理研究表明 ,它还具有防治骨质疏松和提高免疫功能等作用 .2 0 0 0年版中国药典收载了 5种淫羊藿属植物 ,朝鲜淫羊藿为其中一种 ,是长白山道地中药材之一 .朝鲜淫羊藿中化学成分的研究多集中在黄酮类化合物方面 [1~ 6 ] ,而对其生物碱类化合物的研究较少 [7,8] .本文对朝鲜淫羊藿中生物碱类化合物进行了研究 ,并发现了一种新的生物碱 (6-羟基 -1 1 ,1 2 -二甲氧基 -2 ,2 -二甲基 -1 ,8-二氧 -1 ,3 ,4,8-四氢 -2 H -7-氧杂 -2 -氮 -苯并 [c]菲 ) ,采用核磁共振波谱技术鉴定了该化合物的结构 ,并用电喷雾多级串联质谱对其结构的正确性进行了验证 .1 实验部分1 .1 仪器 APEX FT-ICRMS高分辨质谱仪 (德国 Bruker Daltonnics公司 ) ;FTS-7型红外光谱仪(美国 BIO-RAD公司 ) ;AV40 0核磁共振波谱仪 (德国 Bruker公司 ) ,以 CDCl3作溶剂及内标 ;X-4数字显示显微熔点仪 (北京泰克仪器有限公司 ) ;MSn在 ...

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A novel method for fabrication of nanometer-sized electrodes and tips suitable for scanning electrochemical microscopy (SECM) is reported. A fine etched Pt wire is coated with polyimide, which was produced by polymerization on the Pt surface initiated by heat. This method can prepare electrodes with effective radii varying from a few to hundreds of nanometers. Scanning electron microscopy, cyclic voltammetry, and SECM were used to characterize these electrodes. Well-defined steady-state voltammograms could be obtained in aqueous or in 1,2-dichloroethane solutions. Ibis method produced the nanoelectrodes with exposed Pit on the apex, and they can also be employed as the nanotips for SECM investigations. Different sizes of Pt nanotips made by this method were employed to evaluate the kinetics of the redox reaction of Ru(NH3)6(3+) on the surface of a large Pt electrode by SECM, and the standard rate constant kappa (o) of this system was calculated from the best fit of the SECM approach curve. This result is similar to the values obtained by analysis of the obtained voltammetric data.

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A new species, Axianassa sinica, from the Beibu Gulf (Gulf of Tonkin), northern South China Sea, is described and illustrated. The new species is readily distinguished from A. australis Rodrigues & Shimizu, 1992, by its acute rostrum, merus of pereopod 1 with a tooth distally on lower margin and an elongated telson.

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Two new species of Naticidae (Mollusca, Gastropoda) collected from the coast of China are described: Cryptonaitca huanghaiensis sp. nov. and Sinum. vittatum sp. nov. The morphological characteristics between the new species were described and the related information was provided. The similarities and differenees between the new species and related species were also compared and discussed. The new species Cryptonaitea huanghaiensis differed from Cryptonaitca hirasei and Cryptonaitca andoi in outer shape, operculum and radula. The new species Sinum, vittatum is similar to Sinum, japonicum (Lischke, 1869), but the shell of the former is flat-elliptical in shape, spire very small, slightly convex. While the latter is flat-globular in shape, apex light brown in color, without a brown band on the body whorl. The comparison results revealed that Cryptonaitca huanghaiensis and Sinum vittatum were two new species from the coast of China. Specimens studied were obtained from collections in the Marine Biological Museum, Chinese Academy of Sciences.

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碳纳米管的小直径、高纵横比、高强度和高弹性、优良的耐磨损性能以及独特的电学和化学特性,使其成为高分辨率原子力显微镜的理想探针针尖。本文根据制作工艺的特点,综述现有碳纳米管探针的代表性研究和制作方法:组装式和生长式。组装式是通过手工、电场或磁场的方式将制备好的碳纳米管粘附到常规硅探针的末端;而生长式是在常规硅探针末端或悬臂梁上定点催化生长出一定直径和长度的CNT。最后指出这些方法目前存在的主要问题。

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A number of proxy records of paleoenvironment using stable isotopes could show the history of past environmental changes. These archives include peat and lake sediments, loess-paleosot sequence, fossil mammals and stalagmite, and so on. The stable isotopic composition of carbonate and organic matter and frequency magnetic susceptibility from Tianshuigou and Yuanlei loess-palesol sequence can be used to give estimates of the paleoenvironmental history of Dali, and even of the whole Chinese Loess Plateau during the last 250ka. Features of the High Temperature and Large Precipitation Event in the Tibet Plateau and its adjacent area during 40~30kaBP had been studied by Professor Shi Y. In this dissertation, its impact on Chinese Loess Plateau has been discussed again. Carbon and oxygen isotopic ratios, magnetic susceptibility and frequency magnetic susceptibility in Tianshuigou and Yuanlei profiles show that the Event in this area is not so stronger as the Tibet Plateau. The carbon isotopic composition of organic matter in Tianshuigou, Yuanlei, dingcun and Jingcun loess-palesol sequences are indicative of major changes in the paleovagetation between terrace and plain of the Chinese Loess Plateau. Water is one of the most important factors adjusting the relative biomass of C4 plant in terrestrial ecosystems. Stable carbon isotope ratio of vertebrate tooth enamel is used increasingly to reconstruct environmental and ecological information modern and ancient ecosystems. The SI3C value of tooth enamel bioapatites can distinguish between browsers and grazers. Data from typical grassland of Inter Mongolia, the Alpine meadow of Qinghai-Tibet Plateau and the Yaluzangbu Great Canyon indicate that diets of mammals could record the relative biomass of C4 plant only in the C4 dominated ecosystem. In a C3 dominated ecosystem, diet of mammals would include more C3 plants than vegetation. According to Professor Cerling, proxy records from North and South America, Africa and Pakistan show that at the end of the Miocene (between 8Ma to 6 Ma) there was a global expansion of CA biomass, probably when atmospheric CO2 levels declined. Thus, "C4 world" and "CO2 starvation" are put forward. In this dissertation, carbon isotopes of fossil tooth such as Equus sanmeniensis and Hipparion chiai from Linxia, China reveal that there is a C3 dominated ecosystem in the late Miocene. Diets of ancient mammals in Linxia are not evidence of global expansion of C4 biomass.

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The carbon isotope compositions of plants in Xilinguole, Haibei and Jilong and the tooth enamel of animals in Jilong have been analyzed. The study of carbon isotope discrimination of plants along altitude gradient among the three areas has found decreased discrimination.The eolian deposits of Heyeping can be used to reconstruct Holocene climate variability in the region. Some proxies indicates that the 8. 2 ka event can be found in north China, and it is warm and arid in the 4900~6800(or 6900) cal. a BP.

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In my research, I have performed an extensive experimental investigation of harmonic-drive properties such as stiffness, friction, and kinematic error. From my experimental results, I have found that these properties can be sharply non-linear and highly dependent on operating conditions. Due to the complex interaction of these poorly behaved transmission properties, dynamic response measurements showed surprisingly agitated behavior, especially around system resonance. Theoretical models developed to mimic the observed response illustrated that non-linear frictional effects cannot be ignored in any accurate harmonic-drive representation. Additionally, if behavior around system resonance must be replicated, kinematic error and transmission compliance as well as frictional dissipation from gear-tooth rubbing must all be incorporated into the model.

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Tese de Doutoramento apresentada à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Doutor em em Biotecnologia e Saúde, Epidemiologia e Saúde Pública.

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Monografia apresentada à Universidade Fernando Pessoa para obtenção do grau de Licenciada em Medicina Dentária.

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Monografia apresentada à Universidade Fernando Pessoa para obtenção do grau de Licenciada em Medicina Dentária

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Monografia apresentada à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Licenciada em Medicina Dentária

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Trabalho apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária.

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Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Ciências Farmacêuticas

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Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária