“拉丁字母”和“罗马字母”

ABCD……这26个字母,既称“拉丁字母”,又称“罗马字母”。两个名称有什么不同?什么时候用“拉丁字母”,什么时候用“罗马字母”,有什么规律?本文从这套字母的发展史谈起,通过考察两个名称在中国及英语国家的使用情况,得出“罗马字母”应该取代“拉丁字母”的结论。     

Cloned pigs derived from somatic cell nuclear transfer embryos cultured in vitro at low oxygen tension

Great progress have been made in animal cloning in China, as evidenced by the live births of cloned cat- tle[1,2], goats[3,4], and sheep[5]. In contrast, pig cloning is still in its infancy though limited fundamental studieshave been conducted[6]. It is g…     

Properties of PbLa（Zr,Sn, Ti）O3 ceramics near ferroelectric-antiferroelectric phase boundary

Shirane found in the middle of the 20th century that the solid solution PZT had a lot of fine characteristics and carried out detailed researches[1]. The critical phase transition field of antiferroelectric decreased by adding titanate. Titanate expands t…     

电磁流量计使用中常见故障诊断

文章将电磁流量计在使用中发生的故障进行归纳分类，并按产生的原因从安装、环境条件和流体特性等方面作了分析。     

银行支付网络操作可靠性增长的研究

银行现代支付系统是电子资金划拨的物质基础，其平稳性的运营有赖于支付网络的可靠性及对支付网络操作的可靠性．将可靠性增长的思想和方法引入银行支付网络操作可靠性的研究，针对实际存在的操作人员的培训与操作实践两个时期的学习模式，用顺序约束模型描述培训时期操作可靠性的分布，导出了培训期末操作失效率的预计模型；用时间函数模型描述操作实践可靠性的增长，给出了支付网络运行时刻操作可靠性的推断方法．     

因子分析模式识别法在乙苯生产调优中的应用

模式识别方法是一种具有独到之处的多元统计处理方法。本文运用因子分析模式识别法,研究乙苯烃化装置的生产调优。自编了相应的计算机程序,建立了数学模式,找到了优化控制条件,获得了十分明显的经济效益。     

固体—气体界面反应动力学公式推导

固体与气体的反应速度和吸附情况有关。本文对五种不同情况下的动力学公式进行了比较详细、严密的推导。     

榆黄蘑发酵液的抗衰老研究

本文以“中央衰老钟”和“自由基”学说为依据,以昆明种十月龄雄性小鼠为实验对象,对榆黄蘑发酵液的抗衰老作用进行了研究.结果表明,榆黄蘑发酵液能抑制脑B型单胺氧化酶(MAO—B)的活性(29.48％);对肝MAO—B活性无显著影响(P>0.05);能降低肝过氧化脂质(LPO)的含量(34.62％);使心肌脂褐素含量下降(40.50％);增高皮肤羟脯氨酸(HYP)的含量(6.41％)以及提高红细胞中超氧化物歧化酶(SOD)的活性(14.10％).据此,可以认为榆黄蘑发酵液具有良好的延缓衰老的作用。     

Forward scattering due to slow-down of the intermediate in the H + HD --> D + H(2) reaction

Quantum dynamical processes near the energy barrier that separates reactants from products influence the detailed mechanism by which elementary chemical reactions occur. In fact, these processes can change the product scattering behaviour from that expected from simple collision considerations, as seen in the two classical reactions F + H(2) --> HF + H and H + H(2) --> H(2) + H and their isotopic variants. In the case of the F + HD reaction, the role of a quantized trapped Feshbach resonance state had been directly determined, confirming previous conclusions that Feshbach resonances cause state-specific forward scattering of product molecules. Forward scattering has also been observed in the H + D(2) --> HD + D reaction and attributed to a time-delayed mechanism. But despite extensive experimental and theoretical investigations, the details of the mechanism remain unclear. Here we present crossed-beam scattering experiments and quantum calculations on the H + HD --> H(2) + D reaction. We find that the motion of the system along the reaction coordinate slows down as it approaches the top of the reaction barrier, thereby allowing vibrations perpendicular to the reaction coordinate and forward scattering. The reaction thus proceeds, as previously suggested, through a well-defined 'quantized bottleneck state' different from the trapped Feshbach resonance states observed before.