45 resultados para Vico, Giambattista, 1668-1744.


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By the semi-inverse method, a variational principle is obtained for the Lane-Emden equation, which gives much numerical convenience when applying finite element methods or Ritz method.

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The behaviour of gaseous chlorine and alkali metals of three sorts of biomass (Danish straw, Swedish wood, and sewage sludge) in combustion or gasification is investigated by the chemical equilibrium calculating tool. The ranges of temperature, air-to-fuel ratio, and pressure are varied widely in the calculations (T=400-1800 K, gimel=0-1.8, and P=0.1-2.0 MPa). Results show that the air excess coefficient only has less significant influence on the release of gaseous chlorine and potassium or sodium during combustion. However, in biomass gasification, the influence of the air excess coefficient is very significant. Increasing air excess coefficient enhances the release of HCl(g), KOH(g), or NaOH(g) as well as it reduces the formation of KCl(g), NaCl(g), K(g), or Na(g). In biomass combustion or straw and sludge gasification, increasing pressure enhances the release of HCl(g) and reduces the amount of KCI(g), NaCl(g), KCI(g), or NaOH(g) at high temperatures. However, during wood gasification, the pressure enhances the formation of KOH(g) and KCI(g) and reduces the release of K(g) and HCl(g) at high temperatures. During wood and sewage sludge pyrolysis, nitrogen addition enhances the formation of KCN(g) and NaCN(g) and reduces the release of K(g) and Na(g). Kaolin addition in straw combustion may enhance the formation of potassium aluminosilicate in ash and significantly reduces the release of KCl(g) and KOH(g) and increases the formation of HCl(g).

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为解释横向载荷作用下刚性桩的失稳机理,针对桩头自由的刚性桩做了一系列横向加载试验.基础土为粉质粘土,含水量介于9.85%~13.85%之间.由载荷-位移全过程曲线发现,刚性桩在横向载荷达到一定值时会失稳;由试验录像及土体剖面发现,由于土体的软化破坏,在桩后土体内会出现贯穿的局部破坏并形成一楔体,同时在土面伴随一不完全的椭圆形鼓包及一条平行于加载方向的拉伸裂缝,而在桩前土中,由于桩的挤压会形成一条侵彻沟.分析认为,对大位移刚性桩桩后土体的破坏是桩失稳的根本原因.

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A reversible electrochromic effect accompanying domain-inversion during the electrical poling process in LiNbO3: Ru: Fe crystals at room temperature has been observed. In electrode area, both electrochromism and domain-inversion occur alternately, and electrochromism is also reversible during back-switch poling, which is experimentally verified and whose mechanism is briefly explained using a microstructure ferroelectric model. In addition, because of the enhancing elcctrochromic effect, different from the undoped LiNbO3 crystals, the coercive riled (21.0 kV/mm or so) measured in LiNbO3: Ru: Fe is lower than its breakdown field, thus providing a possible new technique for realizing the domain-inversion by constant electric field rather than a pulsed one.

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A nonvolatile recording scheme is proposed using LiNbO3:Ce:Cu crystals and modulated UV light to record gratings simultaneously in two centres and using red light to bleach the grating in the shallow centre to realize persistent photorefractive holographic storage. Compared with the normal UV-sensitized nonvolatile holographic system, the amplitude of refractive-index changes is greatly increased and the recording sensitivity is significantly enhanced by recording with UV light in the LiNbO3:Ce:Cu crystals. Based on jointly solving the two-centre material equations and the coupled-wave equations, temporal evolutions of the photorefractive grating and the diffraction effciency are effectively described and numerically analysed. Roles of doping levels and recording-beam intensity are discussed in detail. Theoretical results confirm and predict experimental results.

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提出了一种新的光刻机像质参数热漂移原位检测技术(TDFM)。详细分析了该技术利用镜像测试标记检测投影物镜最佳焦面热漂移与放大倍率热漂移的基本原理。实验结果表明TDFM技术可同时实现最佳焦面热漂移(FFT)与放大倍率热漂移(MFT)的精确测量。与现有的放大倍率热漂移检测技术相比,该技术有效地解决了放大倍率热漂移技术中放大倍率热漂移受最佳焦面热漂移影响的问题,简化了光刻机像质参数前馈校正的测试过程,测试成本与耗时均减少50%。

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一种抗艾滋病的药物组合物,其中含有抗艾滋病有效量的式(Ⅰ) 化合物β-硝基苯乙烯及可药用载体和/或赋形剂。$上述药物组合物在制备逆转录酶抑制剂药物中的应用;上述药物组合物在制备抗艾滋病药物中的应用.

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本文研究了培养时间、培养基类型、硫酸铵浓度对湖泊沉积物与水中氨氧化细菌(AOB)MPN计数的影响。结果表明,MPN值随培养时间的延长而增大,且趋于稳定。对不同样品而言,培养40d后,MSF培养基均给出稳定的MPN值。在3种不同类型的培养基(XZ-AOB、MSF、SW)中,MSF产生的MPN值最大。此外,培养基中的硫酸铵浓度对MPN计数亦有重要影响,与沉积物AOB相比,湖水AOB对硫酸铵浓度更为敏感。

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无尾类两栖动物的复杂的声行为对其繁殖与物种的识别具有重要的作用,而有尾类除了少数种类可以发出 微弱的“吱吱”声或吠声外,在过去一直被认为是基本不发声的。但是,最近的基于解剖学的证据的研究显示隐腮 鲵科(Cryptobranchidae)可能是一个例外。为了检验这一假说,作者对实验室严格控制的条件下的4只中国大鲵(An- drias davidianus)进行了观察。观察结果不仅表明动物在水下发声,同时也观察到了与之相关联的行为。作者对进 一步在野生条件下开展研究提出了建议。

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根据果蝇ebony基因的序列设计了一系列特异性引物,对1991年发现的一种黑腹果蝇的新的体色突 变(Qian&Zhang,1994)——黑条体突变型的ebony基因进行克隆和序列测定。与野生型W91910的ebony基因 相比,黑条体突变型的ebony基因的编码区无明显的大片段变异,变异仅存在于数个氨基酸位点,且均不位于 该基因产物的关键序列。在黑条体的ebony基因的5’端序列的克隆和序列测定中发现,与野生型W91910及黑檀体 e’的ebony基因相比,黑条体突变型的ebony基因有一个大片段的缺失,