68 resultados para Robertus, de Sorbona, 1201-1274

em Chinese Academy of Sciences Institutional Repositories Grid Portal


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基于Yamamoto的多孔弹性介质模型,研究了波生底床的稳定性。通过给出的有限深底床下土响应分析解,针对三种土质底床,讨论了主要波参数和土参数对这些底床稳定性的影响。与其他土模型计算结果进行了比较,分析了海洋土内部Coulomb摩擦因素的影响。

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软土地基加固技术是地基工程中一个重要问题,在大量工程实践的基础上,作者采用爆炸法研究了淤泥的排水固结,由于爆炸引起地基的振动加速度与排水关系密切,因此通过实验测量了离爆原近区的加速度,得到加速度随爆炸距离的变化规律;观测分析了爆炸振动过程的加速度波形;通过测定爆炸前后淤泥的工作指标,表明爆炸后短时期内淤泥有含水量有所变化。

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Based on the local properties of a singular field, the displacement pattern of an isoparametric element is improved and a new formulated method of a quasi-compatible finite element is proposed in this paper. This method can be used to solve various engineering problems containing singular distribution, especially, the singular field existing at the tip of cracks. The singular quasi-compatible element (SQCE) is constructed. The characteristics of the elements are analysed from various angles and many examples of calculations are performed. The results show that this method has many significant advantages, by which, the numerical analysis of brittle fracture problems can be solved.

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As an improvement of resolution of observations, more and more radio galaxies with radiojets have been identified and many fine structures in the radio jets yielded. In the presentpaper, the two-dimensional magnetohydrodynamical theory is applied to the analysis of themagnetic field configurations in the radio jefs. Two-dimensional results not only are con-sistent theoretically, but also explain the fine structures of observations. One of the theo-retical models is discussed in detail, and is in good agreement as compared with the observedradio jets of NGC6251. The results of the present paper also show that the magneticfields in the radio jets are mainly longitudinal ones and associate with the double sources ofQSOs if the magnetic field of the central object is stronger; the fields in the radio jets aremainly transverse ones and associate with the double sources of radio galaxies if the fieldof the central object is weaker. The magnetic field has great influence on the morphol-ogy and dynamic process.

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发展了一种求解理查森方程的一般有限元算法.该方法采用积分法处理孔隙水压力对时间的导数项,采用集中质量技术处理有限元方程中质量矩阵来保证数值稳定.所采用的质量守恒迭代方法不须改变迭代方式,采用一般的Picard迭代方法.该方法能求解入渗、地下水位瞬变和排水等范围广泛的饱和-非饱和渗流问题.对3个已公开发表具有详细试验数据的算例的模拟表明,该方法对入渗锋、稳定渗流地下水位和非稳定渗流溢出面都模拟很好.Pieard迭代方法效率很高,且无数值振荡发生.

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We propose a surface planar ion chip which forms a linear radio frequency Paul ion trap. The electrodes reside in the two planes of a chip, and the trap axis is located above the chip surface. Its electric field and potential distribution are similar to the standard linear radio frequency Paul ion trap. This ion trap geometry may be greatly meaningful for quantum information processing.

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将千赫兹高功率全固态Nd:YAG激光器的增益介质当作厚透镜处理,使用矩阵的方法对等效热透镜腔进行分析。采用多条半导体激光列阵侧向紧凑抽运结构设计,提高了增益介质光抽运的均匀性。根据实际抽运功率,通过模拟计算,设计了平凸非稳腔。选择的凸面全反镜的最佳曲率半径有效地补偿了增益介质热透镜效应,激光器实现了动态稳腔运转,激光脉冲能量输出斜度效率大于13%,光束发散角优于1.3mrad。

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Cladding band structure of air-guiding photonic crystal fibers with high air-filling fraction is calculated in terms of fiber shape variation. The fundamental photonic band gap dependence on structure parameters, air-filling fraction and spacing, is also investigated. The numerical results show that the band gap edges shift toward longer wavelength as the air-filling fraction is increased, whereas the relative band gap width increases linearly. For a fixed air-filling fraction, the band gap edges with respect to spacing keep constant. With this method, the simulation results agree well with the reported data. © 2007 Elsevier B.V. All rights reserved.

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本研究应用数字地球技术,基于1950年~1980年的全国958个气象站的基本气象数据(包括气象站的经纬度,海拔,月均温,月降水,年均温, 年降水,日照时数,日照百分率,风速等),比较了四个不同的根据水、热平衡原理设计的气候一植被关系模型(Penman模型、Holdridge生命地带系统、和Kira方法Thomthwaite模型)在中国应用的一致性和适用性。结果表明:(1) Penman模型在温带草原区和青藏高原地区的一致性指数超过50%,在青藏高原最出色,最有发展潜力。(2) Thornthwaite模型在热带雨林、季雨林区达到39. 72%,可以弥补Holdridg模型在热带地区分类精度的不足。(3) Holdridg生命地带系统在不同地带间适用性最广;只在热带地区,例如西部季雨林、雨林区域(52)、西部草原亚区域(63)和青藏高原温性荒漠地带(86)以及青藏高原温性草原地带(84)不理想。(4)吉良(Kira)方法在亚热带常绿阔叶林区可与Holdridg模型相媲美;在低海拔和湿润、半湿润地区效果尚可,但在温带荒漠区与青藏高原区的模拟效果与实际相差较远。 这四个传统的分类方法在中国植被区划一级分类上是适用的,Holdridge生命地带系统KAPPA -致性指数达到0.57模拟效果优于其它三者,但在特定地区,如青藏高原,所有模型均需改进优化或启用新的模型因子才能很好地区分植被亚地带。本研究还指出,数字地球技术的应用有助于推动气候一植被关系的研究,尤其在气候一植被指标(气候参数和模型参数)的大范围实时动态监测、气候一植被关系数据的海量信息高效、有序基础管理和功能型模型库支撑框架体系方面。

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采用PCR 方法从4 个灵长目物种中获得了泌乳刺激素(Prolactin, PRL)基因的第2~5 外显子的序 列, 结合GenBank 中已有的序列, 计算了PRL 基因在灵长目中的氨基酸替换速率. 对异义替换速率和 同义替换速率进行比较的结果显示, 在灵长目进化的过程中未发现任何一个枝系有正选择作用的迹象. 此外, 用最大似然(Maximum-Likelihood, ML)法没有检验到任何一个受到正选择作用的位点; 在快速 进化时期内发生的所有32 个氨基酸替换中, 只有2 个位点包含在功能重要的40 个氨基酸之内, 提示所 发生的氨基酸替换主要集中在功能上并不是很重要的位点上. 此外, 在PRL 基因的快速进化过程中, PRL 的部分功能被胎盘泌乳刺激素(placental lactogen, PL)所替代. 基于以上原因, 推测发生在灵长目 PRL 基因的快速进化很可能是选择压力的放松, 而不是正选择作用的结果.

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Aim: To study the pharmacokinetics of sifuvirtide, a novel anti-human immunodeficiency virus (HIV) peptide, in monkeys and to compare the inhibitory concentrations of sifuvirtide and enfuvirtide on HIV-1-infected-cell fusion. Methods: Monkeys received 1.2 mg/kg iv or sc of sifuvirtide. An on-line solid-phase extraction procedure combined with liquid chromatography tandem mass spectrometry (SPELC/MS/MS) was established and applied to determine the concentration of sifuvirtide in monkey plasma. A four-I-127 iodinated peptide was used as an internal standard. Fifty percent inhibitory concentration (IC50) of sifuvirtide on cell fusion was determined by co-cultivation assay. Results: The assay was validated with good precision and accuracy. The calibration curve for sifuvirtide in plasma was linear over a range of 4.88-5000 mu g/L, with correlation coefficients above 0.9923. After iv or sc administration, the observed peak concentrations of sifuvirtide were 10626 +/- 2886 mu g/L and 528 +/- 191 mu g/L, and the terminal elimination half-lives (T,12) were 6.3 +/- 0.9 h and 5.5 +/- 1.0 h, respectively. After sc, T-max was 0.25-2 h, and the absolute bioavailability was 49% +/- 13%. Sifuvirtide inhibited the syncytium formation between HIV-1 chronically infected cells and uninfected cells with an IC50 of 0.33 mu g/L. Conclusion: An on-line SPE-LC/MS/MS approach was established for peptide pharmacokinetic studies. Sifuvirtide was rapidly absorbed subcutaneously into the blood circulation. The T-1/2 of sifuvirtide was remarkably longer than that of its analog, enfuvirtide, reported in healthy monkeys and it conferred a long-term plasma concentration level which was higher than its IC50 in vitro.