长在深山人未识——记北京的杓兰

世界上的兰科植物大约有3万种之多。日常生活中,人们通常将它们统称为兰花。许多兰科植物是非常重要的观赏、药用或香料植物,并已在世界各地广为栽培。中国原产的兰科植物大约有1200多种,从种的绝对数量上来看并不算很多,但其生物多样性却极为丰富,从热带到温带、从附生兰到腐生兰,各种类型均有分布。     

铁皮石斛生理生化性质的研究

对兰科植物铁皮石斛的生理生化特性进行了研究,并将其与典型的C3 植物大豆、C4 植物玉米、景天酸代谢(CAM)植物仙人掌进行了对比实验 从实验结果来看,铁皮石斛的叶绿素a/b值较低,pH变化与仙人掌非常相似:白天都是从低到高,夜里都是从高到低 有机酸含量有昼夜波动 磷酸烯醇式丙酮酸羧化酶(PEPCase)活性较大豆略高     

植物乳杆菌素plantaricin Q7在牛乳贮藏保鲜中的应用

植物乳杆菌素plantaricin Q7是由植物乳杆菌Lactobacillus plantarum Q7产生的,其具有广谱抑菌活性的细菌素,有安全、高效、稳定性好等优点.将效价为533 AU?mL-1的植物乳杆菌素Q7添加到牛乳中,探究其在牛乳贮藏过程中的保鲜效果.结果表明:植物乳杆菌素Q7维持了牛乳良好感官,牛乳贮...     

微波谐振腔微扰法测量植物叶片介电常数

采用微波谐振腔微扰法测量植物叶片介电常数。实验采用三种不同植物的叶片,并分早、午、晚不同时间测量。通过对数据处理与分析得出叶片介电常数与矿物质的含量与种类有关,且植物叶片在不同的时间由于生理活动的不同,其介电常数也存在差异,从而影响到植物叶片在交变电场中行为的差异。     

植物原生质体对逆境反应的研究 Ⅰ.葱、小麦、莜麦原生质体对低温的反应及其与抗寒性的关系

从膜的结构、成分和功能等方面研究植物对低温的反应和抗低温的关系,已有不少的报导。而且有很多的工作已深入到分子水平。但长期以来作为简而易行的植物抗寒生理指标,一直未能得到很好解决。本文以不同抗寒力植物的原生质体为材料,观察到在不同低温的情况下,其成活率的多少与抗寒力之间有一定的相关性。这种关系可以期望作为植物抗     

RNAi技术在植物抗病领域的应用研究进展

RNAi是一种内源的基因沉默现象.由于其简便、高效及特异性,RNAi技术在各种模式和非模式生物系统中得到了广泛的应用.植物基因工程的宗旨是将动物、植物或微生物中分离到的目的基因,通过各种手段整合到植物基因组上,使其稳定遗传并赋予植物新的优良性状.RNAi技术在植物基因工程领域得到了广泛的应用,目前已经成功培育出了抗病毒、抗细菌、抗真菌、抗线虫转基因植物.2007年,美国Monsanto公司及中国科学院研究人员利用RNAi技术分别获得了抗虫转基因玉米和棉花,为农业害虫的防控提供了新的思路和方法.本文重点探讨RNAi技术的发展史及通过RNAi技术培育抗虫转基因植物的原理和途径.     

微波谐振腔微扰法测量植物叶片介电常数

采用微波谐振腔微扰法测量植物叶片介电常数.实验采用三种不同植物的叶片,并分早、午、晚不同时间测量.通过对数据处理与分析得出叶片介电常数与矿物质的含量与种类有关,且植物叶片在不同的时间由于生理活动的不同,其介电常数也存在差异,从而影响到植物叶片在交变电场中行为的差异.     

怀山药与同属植物甾体成分差异性比较研究

采用HPLC、GC-MS等技术手段,对怀山药块茎甾体成分进行了分析.结果在怀山药中未检测到薯蓣皂苷及其苷元,而检测到大量的植物甾醇;同时对薯蓣属植物进化次序与甾体成分差异之间的关系进行了分析,指出甾体皂苷是一类原始成分,植物甾醇是一类进步成分,其差异性主要由参与生物合成的关键酶的差异所致.研究结果为山药的开发利用及薯蓣属植物的分类提供了参考.     

闽南九龙江河口高等植物的分布

本文研究了九龙江河口高等植物分布规律。九龙江河口共有高等植物183种,隶属141属,58科。其中非喜盐植物有155种,随机分布于两岸低盐坡面喜盐植物28种,沿上游至可口滩坡分布,种类递增。按分布界限,喜盐植物可分为河口低盐、中高盐、高盐和河口广盐四个生态类群。从垂直分布看,从沿岸到低潮带种类递减,其组成差异也较大。这些研究结果可为今后河口滩坡区域利用提供参考。     

生理过程模糊神经推理的虚拟植物

提出一种基于模糊神经生理过程推理系统的植物生长模型。该模型基于机器学习理论,从测量的数据中自动学习拟合植物器官生长函数,提取植物生长规律。在植物生长发育过程中,源库器官根据其生长函数响应虚拟环境,并进行生产、分配、利用同化物。同时器官功能部分的变化反馈到结构部分,对表示植物结构信息的L文法字符串进行修改。当生长环境变化时,模型自动调整生长函数的参数和L文法,在环境中进行优化选择,最终形成适应当前虚拟环境的植物。基于辣椒实验仿真表明,该方法能够准确提取植物生长函数和结构规律,逼真地展现植物对生长环境的响应和适应。     

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

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