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1.
杉木维管形成层发生发育的解剖学观察   总被引:2,自引:0,他引:2  
运用细胞生物学手段,初步观察了杉木维管形成层的发生发育。观察结果表明:(1)杉木的顶端分生组织的周围分生组织区细胞分化为原形成层束和皮层;(2) 在初生分生组织区,原形成层呈束状分布,并且具有边分裂边分化的特点;(3) 初生木质部的分化晚于初生韧皮部;(4) 杉木维管形成层于三月初开始活动,4 月中下旬进入活动旺盛期。  相似文献   

2.
作者对刺桐原形成层向维管形成层转化的研究表明,刺桐的维管形成层为叠生形成层,由分散的、排列成环的原形成层束转化而来,其转化过程是渐进的。在初生生长的很早阶段就出现了长、短两类细胞,即原初的纺锤状原始细胞和原初的射线原始细胞。它们分别发育转化为维管形成层中的纺锤状原始细胞和射线原始细胞。在转化过程中,长细胞的端壁由平截转变为尖削,短细胞则由短的长方形转变成近等径的多边形。原初的射线原始细胞和射线原始细胞皆含有淀粉粒,纺锤状原始细胞的叠生状态直到次生生长出现以后才由于连续的径向垂周分裂而获得。在1-4年生枝中,随着年龄的增长,射线高度减小,宽度增加。射线原始细胞可以伸长而转变成纺锤状原始细胞,从而将轴向的高射线隔分成矮射线,纺锤状原始细胞也可以由于横分裂而产生新的射线。纺锤状原始细胞的长度一般为170-290μm;射线原始细胞的长度一般为28-53μm。两种细胞都有多核现象发生。  相似文献   

3.
美洲黑杨维管形成层活动周期可分为休眠期、恢复活动期、活动期和转化期4个时期。休眠期维管形成层区约由3层细胞组成,细胞壁较厚,细胞内具有大量小液泡,其内包含一些电子密度较高的物质;细胞质内充满了游离的核糖核蛋白体,脂粒圆球形,散布在小液泡之间;内质网光滑型,多为短片状,只有近质膜处才呈网格状;线粒体内嵴不清晰,高尔基体数量较少,一般由3~5层扁平囊组成,周围未分泌形成高尔基小泡。恢复活动期维管形成层的细胞壁变薄,细胞内逐渐形成大液泡,内含物降解,细胞质的电子透明度增高。活动期维管形成层区细胞层数可达8~9层,细胞壁非常薄,细胞高度液泡化,细胞质和细胞核贴壁分布,或通过原生质索悬垂在细胞的某一位置,细胞器结构清晰,细胞质膜大量内折,与壁物质的形成有关。转化期维管形成层区细胞停止分裂,细胞壁逐渐增厚,液泡数目增多,体积减小,细胞开始积累淀粉、脂类和蛋白质等类物质。休眠期和活动期细胞超微结构特征相反,而恢复活动期与转化期细胞结构特征相似,互为可逆过程。  相似文献   

4.
刺桐的一年生枝条,在距顶端约180μm处,由顶端分生组织分化出剩余分生组织;在距顶端约240μm处,剩余分生组织分散形成原形成层束。原形成层细胞向外、向内分别衍化出原生木质部和原生韧皮部。由于原形成层细胞横分裂频率的不同,产生长、短两类细胞,短细胞与束间细胞一样,含有淀粉粒。原形成层束间的基本分生组织可以为裂产生新的维管束。  相似文献   

5.
杜仲形成层活动周期及过氧化物酶和酯酶同工酶的变化   总被引:7,自引:0,他引:7  
杜仲(Eucommia ulmoides Oliv.)形成层3月中旬恢复活动,7月下旬形成层细胞停止分解,同时停止产生新的韧皮部细胞,但直到8月中旬才停止产生新的木质部细胞。12月新形成的未成熟韧皮部和木质部组织都继续分化、成熟。形成层活动周期中,过氧化物酶同工酶谱和酶活性在形成层区域和木质部区域中变化最大。POⅠ和POⅡ组同工酶只在春季形成层恢复活动时期的活动状态发生变化。负极端的ESTⅢ ̄Ⅴ组  相似文献   

6.
目的 研究北柴胡茎、叶的个体发育过程.方法 应用常规石蜡切片方法对北柴胡(Bupleu-rum chinense DC.)的茎尖、1年生和2年生茎以及叶进行了横向与纵向解剖观察.结果 北柴胡茎的发育包括原分生组织、初生分生组织、初生结构和次生生长4个阶段.原分生组织由原套和原体组成.其衍生细胞形成初生分生组织.初生分生组织由原表皮、基本分生组织和原形成层组成.初生分生组织的衍生细胞分化形成茎的初生结构,包括表皮、皮层、维管束、髓和髓射线.随着茎的继续发育.维管形成层开始活动,由束中形成层产生次生韧皮部和次生木质部分子,而束间形成层仅产生薄壁细胞形成宽的射线.茎始终未产生周皮,而叶的发育包括原分生组织、初生分生组织和成熟结构3个阶段.北柴胡的叶为典型的异面叶,由叶片和叶柄两部分组成.分泌道在茎中主要分布在皮层和髓中,在叶中分布在维管束的上、下组织中,且这些分泌道均属初生分泌道.结论 北柴胡茎、叶的个体发育过程,类似多年生草本双子叶植物茎、叶的一般发育过程.  相似文献   

7.
白皮松形成层活动周期中过氧化物酶和酯酶同工酶的变化   总被引:10,自引:0,他引:10  
白皮松(PinusbungeanaZucc.)枝条不同组织中过氧化酶(POD)和酯酶(EST)同工酶的酶谱也不同,而且每种组织中这两种酶的同工酶酶谱随形成层活动周期的变化而变化。在休眠期,形成层区域过氧化物酶的同工酶酶带最多,这时周皮和韧皮部中酯酶同工酶谱在正极端出现一些酶带,这可能与抗寒有关。  相似文献   

8.
构树去木质部后,IAA的运输抑制剂TIBA(三碘苯甲酸)可抑制IAA对维管形成层和木栓形成层的再生与活动,以及木质部和韧皮部分化等的促进作用。过氧化物酶和酯酶同工酶的变化与组织的分化过程密切相关。  相似文献   

9.
海棠果插穗扦插生根过程解剖学观察   总被引:8,自引:0,他引:8  
从解剖学角度观察了海棠果插穗不定根的发育过程,结果表明:(1)海棠果2年生插穗茎内无潜伏根原基,不定根由诱生根原基发育形成,诱生根源于初生射线与维管形成层交汇处细胞的分裂分化。大约经15d,不定根原基发育为幼小不定根并伸出周皮之外。(2)愈伤组织内有些细胞分化为具螺纹加厚的厚壁细胞,在愈伤组织内未发现根原基。  相似文献   

10.
木本双子叶植物和裸子植物在生活的整个过程中,根、茎得以不断长粗,是由于维管形成层的产生和周期性地进行分裂,向内形成木质部,向外形成韧皮部的结果。粗大树干和老根外部不断死亡、剥落,而树皮不但没有变薄,而且在不断缓慢增厚,这是除了维管形成层的活动,向外形成韧皮部外,还有木栓形成层的不断产生和活动,年年形成周皮的结果.许  相似文献   

11.
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.  相似文献   

12.
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.  相似文献   

13.
何延凌 《科技信息》2008,(4):258-258
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.  相似文献   

14.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

15.
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。  相似文献   

16.
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.  相似文献   

17.
本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。  相似文献   

18.
19.
The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to  相似文献   

20.
Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with  相似文献   

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