不同发育时期紫竹梅雄蕊花丝毛细胞间胞间连丝超微结构的变化

紫竹梅雄蕊花丝毛细胞间的胞间连丝随着细胞的生长、发育、衰老而呈现动态开放过程。花蕾和开放花的雄蕊花丝毛细胞间的胞间连丝，具备胞间连丝的一般结构，直径约５０ｎｍ。衰老花的雄蕊花丝毛细胞间的胞间连丝拓宽，并且，随着细胞的进一步衰老，胞间连丝内的链管逐步降解，降解物撤离，呈开放式通道，直径约１００－１５０ｎｍ。     

胞间通道的演变与信息大分子的交通

综述比较了高等植物和低等植物胞胞间连丝的发生和次生变化，由于酶的作用，胞间连丝向胞间通道转化形成了约１００－１０００ｍｍ的开放性通道，胞间通道通过交换信息大分子调控基因表达和器官的分化形成。     

沙田柚花粉管在花柱中的生长途径及其识别

应用辣根过氧化物酶酶标ConA电镀细胞化学方法观察了沙田柚不同发育时期1／2花柱通道细胞的结构与功能,结果表明,四分体至双核期,是壁物质,胞间质和糖蛋白合成期,双核至开花期,通道细胞分化成熟,壁物质降解,角质层下腔形成并贮存胞间质,糖蛋白呈颗粒状定位于质膜与壁之间电子透明层中,授粉后1－3d,通道细胞逐步衰老,糖蛋白定位地纤维外壁,未见胞间隙形成,花粉管是从几个相邻通道细胞角隅处的角质层下腔和纤维外壁之间生长通过,自交花粉管因胼胝质在壁上添加而停止生长,花粉管生长道路决定于引导组织细胞壁的厚薄及角质层破裂时间,此外,讨论了纤维外壁上的糖蛋白对花粉管与花柱的识别作用。     

胞间连丝与胞间通道

利用电子显微镜技术、通过超薄切片获得一些胞间连丝和胞间通道的横切和纵切的结果，表明胞间连丝是由质膜形成外壁，内质网压缩形成内壁，内外壁之间的空胞是物质运输的通道，而压缩内质网消失后的胞间连丝，即胞间通道，结构简单，但运输能力增大     

胞间通道的超微结构及其调控物质运输的机理

通过对胞间连丝的起源，形成、分布、结构及其调控物质运输机理的讨论，说明胞间连丝是物质运输和信息传递的重要通道。对一系列不同观点进行了分析和综合，旨在从超微结构上认识胞间连丝的调控机制。     

甜菊不同叶龄叶片细胞ATPase活性的定位

在甜菊幼叶细胞中,ATPase活性定位于质膜、液泡、胞间连丝、细胞间隙及细胞壁的某些部位上。成熟叶细胞的液泡ATPase活性增强,而质膜ATPase活性减弱。当叶片接近衰老时,除叶绿体片层膜上表现较弱的ATPase活性外,其它部位的ATPase活性丧失。     

病原体胁迫下植物细胞壁的变化

植物细胞壁是阻止病原体侵入的第一道结构屏障.植物在受病原体胁迫时,细胞壁的结构和组分变化是一种早期的防御反应,这种变化往往伴随胼胝质、富含羟脯氨酸糖蛋白和木质素的合成.植物受病原体感染时,胼胝质于乳突和胞间连丝等处大量积累.胁迫信号通过影响胼胝质合成酶和β-1,3-葡聚糖酶基因的转录表达,最终调节细胞壁中胼胝质的量.另外,病原体胁迫可诱导植物细胞内抗病性相关的木质素合成酶活性增强和细胞壁木质化.木质素和胼胝质在细胞壁的积累,加强了细胞壁的机械强度和堵塞病原体在细胞间扩散的通道,从而限制病原体进一步侵入原生质和在组织中的繁衍.植物细胞壁中富含羟脯氨酸糖蛋白(HRGP)的积累也可由病原体和一些非病原体激发子诱导,并作为结构屏障和凝集素起到抗病作用.     

烟草植株各器官中可溶性过氧化物酶的分布

用化学发光法测量了烟草植株各器官中可溶性过氧化物酶的活性,发现各个器官中的过氧化物酶,以花器官(特别是花萼和花冠)中的活性为最高,年幼组织活性最低,当器官或组织成熟衰老时,酶活性也随着增高,在过氧化物酶活性增高的同时,出现过氧化氢酶活性降低。过氧化物酶活性的增加与衰老之间的关系,可能与分解由于过氧化氢酶活力下降而积累的过氧化氢有关。它代表植物一种适应性保护机制,用以延缓衰老过程。     

烟草植株各器官中可溶性过氧化物酶的分布

用化学发光法测量了烟草植株各器官中可溶性过氧化物酶的活性,发现各个器官中的过氧化物酶,以花器官(特别是花萼和花冠)中的活性为最高,年幼组织活性最低,当器官或组织成熟衰老时,酶活性也随着增高,在过氧化物酶活性增高的同时,出现过氧化氢酶活性降低.过氧化物酶活性的增加与衰老之间的关系,可能与分解由于过氧化氢酶活力下降而积累的过氧化氢有关.它代表植物一种适应性保护机制,用以延缓衰老过程.     

木霉菌的几丁质酶与植病生防

木霉菌的几丁质酶是其防治植物真菌性病原菌的主要机制之一，它能降解真菌的细胞壁。木霉菌的几丁质酶具有结构和编码基因多样性。已经纯化的木霉菌几丁质酶有内切和外切几丁质酶，壳二糖酶和N—乙酰—β—D—葡萄糖胺酶。已经克隆的有编码33和42—KDa内切几丁质酶和编码73—KDa的N—乙酰—β—D—葡萄糖胺酶基因。42—KDa内切几丁质酶是目前研究最多的，已经用于转基因植物的培育；对它的表达和调控也有部分了解。     

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.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

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.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

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