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1.
光强对曼地亚红豆杉膜代谢及保护系统的影响   总被引:16,自引:0,他引:16  
以不同光强下的3年生曼地亚红豆杉(Taxus cv.Hicksii)为材料,并以自然光作为对照,探讨了光强对曼地亚红豆杉膜代谢及体内保护系统的影响,结果表明:一层遮荫较对照提高了保护酶SOD、POD、CAT活性和抗氧化物质ASA(ascorbic acid抗坏血酸)的含量,降低了O2.-产生速率、MDA(malondialdehyde 丙二醛)含量和细胞膜相对透性,从而使膜脂过氧化维持在一定水平。而二层遮荫下的叶片CAT活性较对照明显增强,但由于SOD、POD酶活性及ASA含量均较对照降低,而使O2.-产生速率、MDA含量上升,细胞膜相对透性有所增加。结果表明,一层遮荫(50.0%的透光率)提高了曼地亚红豆杉清除活性氧的能力,是曼地亚红豆杉在重庆低海拔地区种植的最适宜的光环境。  相似文献   

2.
以不同光照条件下的3年生曼地亚红豆杉为材料,研究了其叶片在自然降温过程中抗寒力的变化及其内源激素的调控,结果表明:不同光照条件下的曼地亚红豆杉抗寒力强弱的顺序为:自然光,1层遮荫,2层遮荫。在自然降温过程中,自然光下植株叶片抗寒力的提高主要与ABA含量增加及ZRs含量下降有关;1层遮荫抗寒力提高主要与ABA含量增加及GA含量下降有关;2层遮荫抗寒力提高主要与IAA含量下降和ABA含量上升有关。其中,ABA含量与抗寒力强弱关系最为密切。  相似文献   

3.
土壤水分胁迫对曼地亚红豆杉光合特性的影响   总被引:18,自引:1,他引:18  
以引种栽培的3年生曼地亚红豆杉为材料,研究了土壤水分胁迫对光合作用的影响。结果表明,水分胁迫使曼地亚红豆杉叶绿素含量下降,叶绿素a的降幅比叶绿素b大;光合速率、光饱和点降低,光补偿点和CO2补偿点升高。土壤含水量维持在田间最大持水量的80%以上,有利于曼地亚红豆杉光合作用的正常进行。  相似文献   

4.
银杏与珊瑚树光合及蒸腾特性研究   总被引:8,自引:0,他引:8  
通过测定相同生境中银杏(Ginkgobiloba)与珊瑚树(Viburnumodoratissimum)的净光合速率、蒸腾速率、气孔导度等生理性指标及其叶绿素含量,研究了两种植物在栽培条件下的光合与蒸腾特性。结果表明:银杏的光补偿点(45μmolm-2s-1)和光饱和点(1236μmolm-2s-1)高于珊瑚树的光补偿点(31μmol·m-2·s-1)和光饱和点(1125μmol·m-2·s-1),前者的光合作用最适温度也高于后者。银杏和珊瑚树的净光合速率日变化都呈现中午降低型,其蒸腾速率日变化也均呈单峰曲线变化。两种植物的气孔导度在午间保持较低值,对光合作用有明显的限制作用。  相似文献   

5.
强光对番茄低温弱光胁迫后不同叶片恢复的影响   总被引:2,自引:0,他引:2  
胡文海 《吉安师专学报》2002,23(5):34-36,49
5℃低温弱光(50μmol·m-2·s-1)处理3d导致番茄叶片Pn、Fv/Fm、ФPSⅡ的下降,但F0并没有变化;强光(800μmol·m-2·s-1),25℃条件恢复5h,番茄成熟叶片Pn、Fv/Fm基本能得到恢复,ФPSⅡ则略有下降;而成长叶片Fv/Fm以及ФPSⅡ却显著下降,F0也明显增加.恢复3d后成熟叶光合作用、叶绿素荧光参数完全得到恢复,而成长叶虽稍有恢复但仍保持较低水平.  相似文献   

6.
5℃低温弱光(60μmol·m-2·s-1)处理3d导致番茄叶片Pn、Fv/Fm、ΦPSⅡ的下降,但F0并没有变化;强光(800μmol·m-2·s-1),25℃条件恢复5h,番茄成熟叶片Pn、Fv/Fm基本能得到恢复,ΦPSⅡ则略有下降;而成长叶片Fv/Fm以及ΦPSⅡ却显著下降,F0也明显增加.恢复3d后成熟叶光合作用、叶绿素荧光参数完全得到恢复,而成长叶虽稍有恢复但仍保持较低水平.  相似文献   

7.
遮荫处理的白英光合作用和叶绿素荧光特性研究   总被引:2,自引:0,他引:2  
利用GFS-3000 光合作用仪和MINI-PAM 叶绿素荧光仪测定了遮荫处理(平均光强分别为1 000(对照)、500和250 μmol·m-2·s-1)后白英植株光合作用和叶绿素荧光特性的变化,从而研究了适宜栽培白英的光照条件.结果表明,白英的光系统Ⅱ实际光化学效率和最大光化学效率的日变化比较平稳且维持在一个较高的水平;随着遮光处理的加强,白英叶片的净光合速率,补偿点、光饱和点、CO-2补偿点和CO-2饱和点均呈现出下降的趋势,而光合色素含量均呈现上升的趋势.研究结果证实,白英最适合在866.00 μmol·m-2·s-1光照条件下栽培.  相似文献   

8.
利用点云数据与L-系统规则结合建模的方法,生成精细与高真实感的枇杷果树模型;利用辐射度模型模拟计算了枇杷冠层截获的光合有效辐射(PAR),并从受光面积与光合速率的角度对不同冠形的枇杷冠层光截获效率进行了定量化分析。结果表明:植物冠形对于入射光的响应有明显差异;经过比较,枝叶排列较为开阔且均匀的冠形光截获量与光合速率更优,冠层整体日平均直射PAR与散射PAR分别为154.77 umol·m-2·s-1与47.20 umol·m-2·s-1,日最高光合速率为3.97umol·m-2·s-1。模拟结果与实际情况基本一致,合理可信。研究结果可为农业生产管理以及果树形态设计提供了科学依据与参考。  相似文献   

9.
重庆石灰岩地区十大功劳(Mahonia fortunei) 的光合响应研究   总被引:10,自引:0,他引:10  
运用开放式气体交换CI-310便携式光合作用测定系统,研究了重庆石灰岩地区适生灌木十大功劳(Mahonia fortunei)的光合光响应特性.结果表明十大功劳的净光合速率对光合有效辐射的响应模型为二次曲线方程;蒸腾速率对光的响应模型为一次线性方程;气孔导度对光的响应趋势基本与光合速率一致;胞间CO2浓度的响应趋势与净光合速率恰好相反.净光合速率、蒸腾速率、胞间CO2浓度均与气孔导度有较强的线性关系.十大功劳的光补偿点为61 μmol·m-2·s-1,光饱和点为1 725 μmol·m-2·s-1,为典型的阳性植物,有较高的水分利用效率,但以牺牲光能利用效率为代价.这些光合响应特性是与石灰岩地区的生境相适应的.  相似文献   

10.
]以坛紫菜Z-61品系为研究材料,分析坛紫菜叶状体和丝状体在三种光强(10,50,500 μmol·m-2·s-1)下的应答。发现:1)坛紫菜叶状体和丝状体的光系统 Ⅱ 最大量子产量及叶绿素a和藻红蛋白的含量都随光强增加而降低,但净光合速率、最大光合速率、胞外碳酸酐酶活性和总碳酸酐酶活性则随光强增加而增加。2)当光强从10 μmol·m-2·s-1增加到500 μmol·m-2·s-1时,坛紫菜叶状体的生长速率约增加77%;丝状体的生长速率先增加后降低,在光强500 μmol·m-2·s-1下达到最低,比在10 μmol·m-2·s-1下显著下降了约90%。3)在三种光强下,坛紫菜叶状体的最大光合速率、光系统 Ⅱ 最大量子产量和生长速率都大幅高于丝状体。这些结果表明:坛紫菜的光系统 Ⅱ、光合作用与生长对光强的应答并不完全一致;叶状体比丝状体更适应高光,这可能是长期进化的结果;光强可以改变坛紫菜对无机碳的吸收。  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.
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   

13.
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   

14.
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   

15.
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   

16.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

17.
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.  相似文献   

18.
In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.  相似文献   

19.
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-  相似文献   

20.
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-  相似文献   

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