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1.
通过标本采集和群落调查,发现准格尔黄土丘陵区微生境共有苔藓植物19科、36属、64种(包括变种),其中,天然林区16科、29属、49种,人工林地10科、17属、28种.人工林树干、树干基部和天然林树干、树干基部、岩面分别有苔藓植物27种、13种、12种、21种、34种,共16种群落类型;岩面生群落结构变化最复杂,随着水分条件增加向着顶蒴藓类→顶蒴藓类+苔类+侧蒴藓类→苔类+侧蒴藓类+顶蒴藓类→侧蒴藓类+苔类+顶蒴藓类方向变化;真藓(Bryum argenteum)、土生对齿藓(Didymodon vinealis)、碎米藓(Fabronia ciliaris)、灰藓(Hypnum cupressiforme)等能够适应多种生境类型并具有较宽水分生态幅度,大型苔类和侧蒴藓类如紫背苔(Plagiochasma rupestre)、直叶灰藓(Hypnum vaucheri)、灰藓凹叶变种(Hypnum cupressiforme var.lacunosum)、厚角绢藓(Entodon concinnus)在天然林区树干基部或岩面水分条件最好的微生境凸显优势地位.  相似文献   

2.
植物源昆虫拒食剂的研究与应用前景   总被引:17,自引:1,他引:16  
拒食剂可以定义为能抑制昆虫取食而不直接杀死它们的化合物。昆虫常继续留在经拒食剂处理的植物上并可能因饥饿而死。大部分植物依赖次生代谢物来防御植食性昆虫。各种研究表明协同进化的压力使植物越来越能抵抗昆虫的取食。大部分植物源拒食性次生性化合物可以分为倍半萜烯内酯类、异黄酮类、苦木素类和柠檬苦素类化合物4 大类。虽然到目前为止关于结构与生物活性间关系方面尚未建立确实的规律,但结构与生物活性间关系的研究可以为了解发生在某些昆虫的膜受体水平上的分子过程提供线索,因而可以指导分离或合成高效拒食剂。昆虫感知拒食剂化合物可以通过刺激特定昆虫的特化的拒斥感器或者干扰接收诱食刺激化合物的神经元的正常功能实现。因为植物拒食剂是天然化合物,能在自然环境中很容易地被分解,较少环境污染,因而在IPM 中具有重要的作用。为了开发出无公害新农药,需要进一步进行其作用机制、对环境的影响、结构与生物活性间关系、高效拒食剂的合成及田间试验等方面的研究。  相似文献   

3.
回心草化学成分的研究   总被引:14,自引:0,他引:14  
自云南省大理州产的大叶藓属植物回心草中分离出8个化合物。经鉴定,分别为三十三碳烷、棕榈酸、木栓酮、表木栓醇、菜子甾醇、菜油甾醇、豆甾醇及β-谷甾醇。  相似文献   

4.
广西猫街鸟类自然保护区苔藓植物初步研究   总被引:3,自引:0,他引:3  
通过对采自广西西林县猫街鸟类自然保护区的413份苔藓植物标本整理和鉴定,得到该区苔藓植物33科66属153种(含亚、变种)。其中藓类植物23科53属116种,苔类植物10科13属37种,有65种为广西首次记录。其区系地理成分多样,与其他区系紧密联系。该区以东亚成分为主,占总数的32.03%,温带和热带成分所占比例也较高,反映该地具有南北过渡的特点,与其所处的地理位置相一致;中国特有成分较高,占总数的12.42%,处于我国特有种属分布中心的过渡地带上。在进行的优势科、属分析中,优势科为青藓科Brachytheciaceae、灰藓科Hyp-naceae、丛藓科Pottiaceae、曲尾藓科Dicranaceae、地萼苔科Geocalycaceae、凤尾藓科Fissidentace-ae、叶苔科Jungermanniaceae,占优势的属为凤尾藓属Fissidens、曲柄藓属Campylopus、青藓属Brachythecium、灰藓属Hypnum、叶苔属Jungermannia和异萼苔属Heteroscyphus.该地苔藓植物主要成分以热带、亚热带成分和温带成分为主,处于温带向热带过渡的地段上。  相似文献   

5.
大花旋覆花中的新倍半萜内酯   总被引:1,自引:0,他引:1  
从大花旋覆花(InulabritannicaL.var.chinensis)中分离得到了3个新倍半萜内酯化合物,应用波谱技术和化学方法确定了其结构。其中二乙酰基大花旋覆花内酯(1,6—O,O—diacetylbritannilactone)显示有细胞毒活性。同时,从该植物中还得到了蒲公英醇、蒲公英醇乙酸酯、胡萝卜甙、肉豆蔻酸、棕榈酸和硬脂酸甘油酯。  相似文献   

6.
余治锦  姜山 《贵州科学》2012,30(2):52-61
苔藓植物是没有维管束的陆生植物,分为藓纲、苔纲和角苔纲3类。近年来的研究表明,苔藓植物能产生萜类、黄酮类及联苄类等生物活性物质,其中许多对病原真菌和细菌具有良好的抑制作用,是天然抗菌药物的重要来源。本文主要介绍苔藓植物的化学组成及其抑菌作用的研究情况。  相似文献   

7.
采用硅胶柱层析、ODS 反相柱层析、Sephadex LH-20 凝胶柱层析、半制备高效液相 HPLC等色谱分离方法对薜荔(Ficus pumila)叶80%乙醇提取物进行分离纯化,得到7个化合物。 根据化合物的理化性质和核磁共振波谱数据比对文献,分别鉴定为:3-hydroxy-damascone (1),月 桂酸乙酯(2),马桑酸(3),13-hydroxy-(9Z,11E,15E)-octadecatrienoic acid (4),乙基-β-D-吡喃 葡萄糖苷(5),苄醇-β-D-葡萄糖苷(6)和2-[4-(3-hydroxypropyl)-2-methoxyphenoxy]-propane- 1,3-diol (7)。其中化合物7为首次从该属植物中分离得到,化合物1为首次从该植物中分离得到。 抗肿瘤活性测试结果表明,化合物 1 对 A549 细胞显示出一定的抑制活性,IC50值为 32.21 µg/mL。 抗菌活性测试结果表明,所有化合物对测试的4株人体致病菌和2株弧菌均无明显抗菌活性。  相似文献   

8.
香精配方5则     
根据本所馆藏文献整理出香精配方5则,供读者参考:一、牙青香精(质量份)留兰香油500薄荷素油150薄荷脑200茴香脑40丁香油30柳酸甲酯50麝香草酚30/1000二、膏霜香精(质量份)白兰花油1橡苔净油10依兰依兰油20树兰花浸膏10墨红净油1茉莉香基32苯乙醇75十一烯醛4Evernyl3柳酸异戊酯10柳酸己酯40柳酸苄酯45异甲基紫罗兰酮60玫瑰醇20玉簪素40叶醇1Irival2酮麝香30佳乐麝香20香豆素20甲基柏木酮60二缩丙二醇216/1000三、汽水香精白柠檬香基600柠檬香基5…  相似文献   

9.
具有抗肿瘤活性的天然萜类化合物   总被引:4,自引:0,他引:4  
萜类化合物是广泛分布于植物、昆虫、微生物和海洋生物体内的一大类有机化合物,其中很多具有一定的抗肿瘤生物活性。这些抗肿瘤天然萜类化合物中分布较多的为倍半萜类的二萜类,它们分子结构中的订生物活性基团为α-亚甲基-γ-丁内酯,该文着重阐述了近年来在这一领域中的研究进展。  相似文献   

10.
从植物中录找农药活性物质(Ⅲ):紫茎泽兰化学成分…   总被引:2,自引:0,他引:2  
从菊科泽兰属植物紫茎泽兰茎中分到5个化合物,通过IR、MS、^1HNMR,^13CNMR,^13CNMR-DEPT、元素分析等手段,单体分别鉴定为表木栓醇(1),豆甾醇(2),正二十八烷酸(3),β-胡罗卜甙(4),2-异丙烯基-5-乙酰基-6-羟基苯骈呋喃的乙酰化物(5),邻羟基桂皮酸(6),除豆甾醇外,其余的化合物都是首次在紫茎泽兰中发现。  相似文献   

11.
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   

12.
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   

13.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

14.
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   

15.
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   

16.
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   

17.
18.
The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.  相似文献   

19.
R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).  相似文献   

20.
The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.  相似文献   

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