探索原子核新极限——记新核素222Np的合成

质子和中子是组成原子核的两种基本粒子,具有不同质子和中子数目的原子核构成了不同的核素.人们以质子数目和中子数目分别为纵轴和横轴,以每个核素对应位置作为标记的图被称为核素图.因此,每一种原子核都是核素图中的基本单元. 在自然界中,能够被发现的原子核只有大约300多种,这其中稳定存在的原子核仅有254种,其他都是长寿命的放...     

Q：世界上的元素真的就像元素周期表上那样是有限的吗？

A：从目前的情况看是这样的。元素是由原子核中的质子和中子数目决定的，这两种粒子要聚拢在一起形成原子核，就必须有力量将它们“捆绑”在一起。不过，都带正电的质子彼此之间存在有斥力，也就是说它们只会互相推搡。好在，质子和中子（最强）、中子和中子、质子和质子间存在强力，这种力就将质子和中子粘在了一起。但是，强力的有效作用距离非常有限，同时，质子之间斥力的“电磁力”的有效作用距离则很长。这样就造成，     

元素立体周期律初探

通过中子数与质子数的差值研究元素周期律，探讨发展“元素立体周期律”。     

粒子加速器

一、引言1911年,法国物理学家芦瑟福提出了原子的核式结构论。这种理论认为,一切元素的原子都是由一个原子核和围绕原子核而旋转着的电子所组成,原子核带正电荷,电子带负电荷。后来,由于中子的发现,人们确定原子核乃是由中子和质子所构成,中子不带电性,质子带正电荷,质子和中子统称为核子,在原子核里,核子紧密地结合在一起,使原子核成为一个稳定的结构,形成这种稳定结构的力,称为核子力,这种核子力,即不是两个物体之间相互作用的万有引力,也不可能是两个带电体间相互作用的电     

关于重子一介子族的质量差问题

早在1932年,海森堡(Heisenberg)就曾提出〔1〕:质子和中子本是同一种粒子,只是它们的带电状态不同罢了.这一观点并为大家所公认.但从实质上讲,这一点是不正确的,因为,它在解释重子一介子族的质量差问题上遇到了困难. 大家知道,重子族的同族粒子有一个质量差规律,这就是中性粒子的质量大于带正电粒子的质量,带负电粒子的质量又大于中性粒子的质量.中子的质量较质子的质量大1.3Mev.就是其中最引人注意的一例.按照海森堡的观点,质子既然较中子多了带电     

原子核壳层結構与同质異能素

“只要自然科学思惟着,那么它底发展形式总是假设。”(恩格斯)。实验事实指出,处在基态或低激发态的原子核底性质具有周期的变化。正象原子底化学性质随着电子数目(原子序数)底增加而发生周期变化一样,原子核底性质随着它所包含的中子或质子(统称核子)数目底增加而发生周期的变化。例如结合能环绕着平均曲线发生着有规律的周期偏差,以及同位素底分布和慢中子俘获截面等一系列实验都指出某些原子核具有特殊的稔定性,这些原子核所包含的中子数或质子数等于下列被称为“幻数”之一:2,8,20,50,82,126.除了“幼数”底存在以外,周期性还表现在,例如,电四极     

核子磁矩和质量的半经典讨论

对质子和中子提出了一个半经典模型，并对其电磁质量和磁矩进行了计算，从而解释了质子和中子质量和磁矩的“反常”，并设计了质子和中子电磁质量的实验测量方法。     

三联数字与元素周期表

当我们展开门氏的元素周期表时,它明白的告诉我们:因核电荷(Z)的递增而有不同性质的原子核,这与原子核是由质子和中子构成的理论相一致。现代元素周期表只列到109号元素,就整个元素周期表而言是不完整的,那完整的元素周期表(不包括同位素)应该有多少种元素呢?本文从三联数字的角度来探讨一下这个问题。     

中能重离子反应中中子-质子有效质量劈裂的研究

利用同位旋相关的量子分子动力学模型,研究了~(112)Sn+~(112)Sn,~(124)Sn+~(124)Sn和~(132)Sn+~(132)Sn在能量为50,100,200MeV/u的反应系统中,不同中子-质子有效质量劈裂对原子核阻止和中子、质子发射数的影响.结果表明:中子-质子有效质量劈裂对原子核阻止和中子、质子发射数有很明显影响,且原子核阻止和中子、质子发射数随着有效质量劈裂的增加而递减.可以通过实验测定的原子核阻止和中子、质子发射数来确定中子-质子有效质量劈裂的值.     

中子辐照对锆合金氧化性能的影响

综述了由中子辐照引起的锆合金微观结构的变化对锆合金氧化性能的影响。阐述了中子辐照导致锆合金及氧化膜内缺陷的形成和锆合金合金元素分布变化的现象，较全面地总结了缺陷数目和合金元素分布对锆合金氧化性能的影响，较系统地提出了中子辐照下锆合金氧化性能变化的机制，概述了提高中子辐照条件下锆合金抗腐蚀能力的方法，并就该方向的进一步研究提出了看法。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with