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1.
裂环烯醚萜作为油橄榄叶中的主要成分,具有重要的药用价值及其它实际应用价值.本文对目前国内外油橄榄叶中裂环烯醚萜类化合物的提取分离、化学成分、含量测定及药理作用进行了综述,以期为我国丰富的油橄榄叶资源的开发利用提供借鉴和依据.  相似文献   

2.
污水处理厂废弃污泥已经成为了一种新的污染源.为了实现其资源化利用、减少处置成本,节约土地资源,研究了高附加值观赏植物裂叶喜林芋在不同浓度污泥中的生长情况.结果表明,添加一定比例的废弃污泥不但适合裂叶喜林芋的种植,还能促进其生长.综合考虑植物生长速度、体内叶绿素、Fe及主要重金属含量后,认为添加50%的污泥较为适合裂叶喜林芋种植.  相似文献   

3.
2004年,在对上海佘山地区的植被调查中发现外来入侵物种三裂叶豚草(Ambrosia trifida),当时该物种未形成群落,只为个体的零星分布.但在2006年的追踪调查中,三裂叶豚草已于林缘、路边等形成面积达数十平方米的群落,并完成生长、开花、结实整个生活史,同时有继续蔓延、扩张的趋势,这也是首次在上海发现三裂叶豚草成群落分布.被称作世界性公害植物之一的三裂叶豚草是菊科一年生草本植物,原产于北美加拿大,在世界各国造成了严重的危害,降低农业产量,并威胁到人类的健康.本文通过对三裂叶豚草群落特征的调查,分析其群落组成结构以及生境条件等特征,并对其发展动态变化进行预测,旨在引起相关部门的重视,采取适时措施,对该物种实施监控.  相似文献   

4.
2004年,在对上海佘山地区的植被调查中发现外来入侵物种三裂叶豚草(Ambrosia trifida),当时该物种未形成群落,只为个体的零星分布.但在2006年的追踪调查中,三裂叶豚草已于林缘、路边等形成面积达数十平方米的群落,并完成生长、开花、结实整个生活史,同时有继续蔓延、扩张的趋势,这也是首次在上海发现三裂叶豚草成群落分布.被称作世界性公害植物之一的三裂叶豚草是菊科一年生草本植物,原产于北美加拿大,在世界各国造成了严重的危害,降低农业产量,并威胁到人类的健康.本文通过对三裂叶豚草群落特征的调查,分析其群落组成结构以及生境条件等特征,并对其发展动态变化进行预测,旨在引起相关部门的重视,采取适时措施,对该物种实施监控.  相似文献   

5.
通过试验研究了聚丙烯(PP)膜裂纤维体积率和长度对自密实混凝土力学性能(强度、弹性模量和断裂韧性)的影响,结合扫描电镜微观结构分析、Binham流变理论以及断裂力学基本原理分析了纤维对自密实混凝土的工作性和力学性能的影响机理.当PP膜裂纤维的体积率在0.05%—0.15%之间变化,长度在12—15mm时,结果表明,PP膜裂纤维自密实混凝土抗压强度随纤维体积率增加变化不明显,弯拉强度、劈拉强度、弯拉弹性和断裂韧性随纤维体积率增加而逐步增加,抗压弹性模量随纤维体积率增加而减少;PP膜裂纤维自密实混凝土的轴心抗压强度、弯拉强度以及劈拉强度与立方体抗压强度之比分别在0.70—0.73、0.14—0.17和0.08—0.09范围内,轴心抗压强度与立方体抗压强度比值较普通自密实混凝土对比组略有降低,但弯拉强度、劈拉强度与立方体抗压强度之比分别提高17%—42%和14%—29%.当PP膜裂纤维体积率超过0.15%或长度超过15mm,PP膜裂纤维自密实混凝土的强度、弯拉弹性模量及断裂韧性随纤维体积率增加开始出现不同程度的降低.  相似文献   

6.
合金热裂的凝固力学判据   总被引:1,自引:0,他引:1  
对当前已提出的有关热裂判据进行了分析,基于实验结果及力学强度理论揭示了传统热裂应变理论的不足,提出了热裂为本质塑性断裂及热裂势的概念,并建立了其凝固力学判据。  相似文献   

7.
通过对钢纤维混凝土轴拉试验结果的分析 ,研究了钢纤维体积率、混凝土强度等级对钢纤维混凝土轴拉初裂强度的影响。结果表明 :混凝土轴拉初裂强度分别随钢纤维体积率的增大和混凝土强度等级的提高而增大。最后 ,按照断裂力学理论建立了钢纤维混凝土轴拉初裂强度的计算模型 ,提出了钢纤维混凝土轴拉初裂强度的计算公式 ,供修订我国的《钢纤维混凝土设计与施工规程》以及工程设计与施工参考  相似文献   

8.
入侵植物三裂叶蟛蜞菊叶片叶绿素荧光对温度的响应   总被引:2,自引:0,他引:2  
选取入侵植物三裂叶蟛蜞菊(Wedelia trilobata)及其本地近缘种蟛蜞菊(Wedelia chinensis)为实验材料,以叶绿素荧光影像仪研究整株植物在零上低温(10℃)和室温(25℃)条件下,强光(1700μmo1·m^-2·s^-1)诱导叶片的叶绿素荧光的特性,探讨入侵种三裂叶蟛蜞菊对强光及温度的响应特性和生态适应性.结果表明,室温强光处理5h后三裂叶蟛蜞菊PSⅡ最大光能转化效率(■/R)、PSⅡ实际光化学量子产量(趾埘)、表观光合电子传递速率(ETR)的下降幅度均显著小于本地种蟛蜞菊,而在低温强光处理5h后三裂叶蟛蜞菊的Fv/Fm、Yield、ETR降低幅度显著高于本地种蟛蜞菊.研究结果初步表明,三裂叶蟛蜞菊对室温强光适应性强,而对低温强光则较敏感.这一结果暗示外来入侵种三裂叶蟛蜞菊可能较适应我国南方热带亚热带地区的高温强光气候,而向北方地区进一步扩散有可能受到低温等环境因子的限制.  相似文献   

9.
司晓磊 《科学技术与工程》2012,12(11):2626-2630,2636
利用ANSYS软件,研究了整体加筋翼梁结构止裂筋位置和截面不同时的应力强度因子和裂纹扩展特性,为了便于比较,并对无止裂筋梁进行了分析。给出了不同止裂筋位置和截面宽厚比下的应力强度因子曲线,分析了止裂筋断裂后对整体加筋翼梁的影响。最后,在给定止裂筋重量条件下讨论了最优止裂性能筋条的宽厚比。  相似文献   

10.
选取入侵植物三裂叶蟛蜞菊(Wedelia trilobata)及其本地近缘种蟛蜞菊(Wedelia chinensis)为实验材料,以叶绿素荧光影像仪研究整株植物在零上低温(10℃)和室温(25℃)条件下,强光(1700molm-2s-1)诱导叶片的叶绿素荧光的特性,探讨入侵种三裂叶蟛蜞菊对强光及温度的响应特性和生态适应性.结果表明,室温强光处理5 h后三裂叶蟛蜞菊PSⅡ最大光能转化效率(Fv/Fm)、PSⅡ实际光化学量子产量(Yield)、表观光合电子传递速率(ETR)的下降幅度均显著小于本地种蟛蜞菊,而在低温强光处理5 h后三裂叶蟛蜞菊的Fv/Fm、Yield、ETR降低幅度显著高于本地种蟛蜞菊.本文结果初步表明,三裂叶蟛蜞菊对室温强光适应性强,而对低温强光则较敏感.这一结果暗示外来入侵种三裂叶蟛蜞菊可能较适应我国南方热带亚热带地区的高温强光气候,而向北方地区进一步扩散有可能受到低温等环境因子的限制.  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.
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   

19.
20.
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   

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