中国特有植物珙桐的生物学特性、濒危原因及保护

珙桐是我国特有的单种属植物，为国家一级濒危保护植物。本文系统综述了珙桐地理分布，分布区自然状况，群落特征，形态解剖，繁殖生长等方面的生物学特性，并分析了其濒危原因，对珙桐的保护提出一和些建议。     

珙桐种群生殖物候及其影响因子研究

珙桐为国家一级重点保护的珍稀濒危植物,本文研究了珙桐种群的生殖周期,生殖时间,生殖物候规律及特征,种群的分布特征及群落学特征等,为探索种群生殖生态和濒危机制提供基础数据。     

珙桐（Davidia involucrata Baill）研究综述

珙桐(Davidia involucrata Baill)作为第三纪古热带孑遗树种,国家一级保护植物,具有特殊的科学研究价值和极高的观赏价值.20世纪80年代以来受到了有关方面及科研工作者的广泛重视.从以下4个方面对珙桐研究现状进行了综述:(1)解剖学与生物学特征及珙桐在系统发育中的归属问题研究;(2)生态学特性与珙桐自然分布区生态条件的研究;(3)珙桐的种群生态学与群落生态学研究;(4)珙桐的繁殖与人工引种研究.     

贵州柏箐喀斯特台原区珙桐群落特征研究

利用群落和种群研究的常规方法，对贵州喀斯特台原区柏箐自然保护区内珙桐群落进行研究，结果表明：珙桐群落主要优势种群为珙桐和五裂槭，重要值分别为142．93和61．79。两种群间呈正联结关系，均为集群分布，但五裂槭聚集强度高于珙桐；五裂槭为进展种群而珙桐种群因幼树缺失为衰退种群；群落灌木层树种稀少，物种多样性低于乔木层。导致珙桐种群幼树缺失和灌木层树种稀少的原因是人为经营活动。因此，必须对珙桐群落实行绝对保护。     

珙桐与光叶珙桐过氧化氢酶活性及酶谱研究

采用铁氢化钾染色法对珙桐和光叶珙桐进行CAT酶谱分析;用碘量法进行CAT酶活性的研究.研究结果表明:珙桐有酶带两条,Rf值分别为0.74和0.90,CAT酶活性为0.40824mg·(g·min)-1;光叶珙桐也有两条酶带,Rf值分别为0.76和0.93,CAT酶活性为1.3608mg·(g·min)-1;表明珙桐和光叶珙桐在遗传特性、生物进化等方面存在差异性;光叶珙桐代谢比珙桐旺盛,先叶珙桐是珙桐的变种,抗逆性更强,为珙桐种质生化分析、植物学分类及品种选育奠定了理论基础.     

珙桐种子的解剖研究

珙桐为濒临灭绝的珍稀观赏树种，为了更好地保护、开发利用，解剖观察了璜桐种子及胚的形态结构，并对胚进行石蜡制作观观察。研究表明：珙桐果核分4－10室，3－5室发育，珙桐的种子为有胚乳子种子，且胚乳较丰富，胚芽、胚轴、子叶等胚的四个部分均发育完全，在此基础上初步探讨了影响珙桐发育的原因。     

珍稀濒危植物攀枝花苏铁的研究现状与展望

攀枝花苏铁是1971年发现的苏铁新种，1981年正式定名，1984年被列入我国第一批珍稀濒危植物名录，属于世界珍稀濒危植物残遗物种．本文从它的地理分布、生殖生物学特性、形态解剖学、化学成分等几个方面的研究进展作简单综述．同时对该植物研究中存在的问题及今后的研究方向做一简单的评论．     

用PO法对星斗山珙桐群落的排序研究

用ＰＯ法对星斗山珙桐群落进行排序。结果显示：由于环境梯度的差异，珙桐群落内有两种基本群丛类型，它们在种类组成、结构、生态特征及外貌等方面存在差别。     

物种生活史策略的研究现状

保护生物学的研究工作近年来发展非常迅速,而植物生殖对策,生活史策略等方面的研究已成为该领域的研究热点之一。章对最近十年来国内外研究对物种生活史策略的研究现状加以综述。     

珙桐群落中珙桐地位及其土壤特征的相关性

为探讨珙桐（Davidia involucrata）在群落中的作用，及其与土壤因子的关系，研究了四川卧龙自然保护区白泥岗地带不同海拔高度的珙桐群落主要物种重要值及其根际土壤性质．结果表明，该地区珙桐重要值最大，是群落优势种，却是一个处于衰退的种群，1500-1700m是该地区最适宜珙桐生长的海拔高度．珙桐根际土壤各指标在三个土层深度间差异显著；整个地区土壤pH值变化范围小；腐殖质层土壤指标1500m、1600m和1700m三个海拔显著高于1800m和1850m两个海拔；沉积层和母质层两层在5个海拔间的变化规律性不强．相关分析表明，珙桐重要值与速效磷和有机质的相关性均不显著；幼树重要值与pH值的相关性随土层的加深而增强而成树重要值与含水量的相关性随土层的加深而增强；A层土壤指标速效氮和速效钾与珙桐重要值相关性最强，它们可能是珙桐生长的限制因子．     

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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