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1.
采用国际统一鉴定及描述车轮虫的方法对重庆部分地区的3种淡水车轮虫,即:杜氏车轮虫(Trichodina domerguei Wallengren,1897),显著车轮虫(Trichodina nobillis Chen,1963)及异齿车轮虫(Trichodina heterodentata Duncan,1977)进行了较为详细的再描述。其中异齿车轮虫为中国新纪录种。对大量感染异齿车轮虫的鲫鱼鳃作了鳃组织的病理学研究表明,异齿车轮虫对鲫鱼的寄生虽未引起寄主明显的组织增生反应,但从患病鱼观察,可见粘液大量分泌,鳃小片愈合。粘液的异常分泌和鳃丝的缺损,不可避免地导致寄主鱼呼吸缺陷,从而影响了鳃组织的正常气体交换, 严重时会导致寄主鱼窒息死亡。  相似文献   

2.
采用国际统一鉴定及描述车轮虫的方法对重庆部分地区的3种淡水车轮虫,即:杜氏车轮虫(Trichodina domerguei Wallengren,1897),显著车轮虫(Trichodina nobillis Chen,1963)及异齿车轮虫(Trichodina heterodentata Duncan,1977)进行了较为详细的再描述。其中异齿车轮虫为中国新纪录种。对大量感染异齿车轮虫的鲫鱼鳃作了鳃组织的病理学研究表明,异齿车轮虫对鲫鱼的寄生虽未引起寄主明显的组织增生反应,但从患病鱼观察,可见粘液大量分泌,鳃小片愈合。粘液的异常分泌和鳃丝的缺损,不可避免地导致寄主鱼呼吸缺陷,从而影响了鳃组织的正常气体交换,严重时会导致寄主鱼窒息死亡。  相似文献   

3.
雅鲁藏布江中上游鱼类区系和资源状况初步调查   总被引:5,自引:0,他引:5  
根据2006年~2007年4次调查结果,雅鲁藏布江中上游共分布25种鱼类.其中土著鱼类16种,由裂腹鱼亚科、条鳅亚科及鮡科3个类群组成,属典型的高原鱼类区系.高原裸鲤、兰格湖裸鲤和黄斑褶鮡为雅鲁藏布江中上游干支流新纪录种.渔获物主要是由拉萨裸裂尻鱼、双须叶须鱼、异齿裂腹鱼、拉萨裂腹鱼、巨须裂腹鱼等组成,构成鱼类产量的9...  相似文献   

4.
黄河上游玛曲段极边扁咽齿鱼的资源现状与保护措施   总被引:1,自引:0,他引:1  
极边扁咽齿鱼主要分布在黄河上游地区,是我国的特有种.资源调查发现:①黄河上游饵料资源丰富,极边扁咽齿鱼肠充塞度大多为4、5级.②极边扁咽齿鱼种群体长与体重的关系为W=0.009×L^3.0289(R^2=0.9741),表明极边扁咽齿鱼总体生长基本符合均速生长型.③在种群中,雌性个体数量占优,其中9龄以上个体全部为雌性,正金字塔型的种群年龄结构已经被破坏,低龄鱼仅占35%,表明极边扁咽齿鱼资源量呈下降趋势,年龄结构呈现一定程度的老龄化.文中对极边扁咽齿鱼的保护提出了建议.  相似文献   

5.
报道寄生于细尾异齿YanOreoglanis delacouri(Pellegrin)鳃丝上的一种异齿Yan新施分虫新种。  相似文献   

6.
初始巢湖裂齿鱼(Chaohuperleidus primus)产自安徽省巢湖市马家山采石场南陵湖组上段地层(早三叠世奥伦尼克期斯帕斯亚期), 由于模式材料保存很差, 其骨骼学特征未被完整地记述。依据模式材料及同一层位发现的 3 件保存完整的新材料, 补充描述初始巢湖裂齿鱼的骨骼解剖信息, 修正其属征, 复原其头骨的骨骼模式。修正后的巢湖裂齿鱼属征支持以往的分类学结论, “顶骨与膜质翼耳骨愈合形成的骨块具有发育的前、中、后凹线, 鳃盖骨与下鳃盖骨高度近等, 下鳃盖骨具大的圆形前背突”是该属可能的近裔性状。巢湖裂齿鱼属与裂齿鱼属(Perleidus)的形态特征最相似, 除可能的近裔性状外, 与后者不同之处是次眶骨、鳃条骨和轴上鳍条的数量更多。依据巢湖裂齿鱼属头骨的骨骼特征, 与以往错误地归入裂齿鱼目的早三叠世类群及裂齿鱼目内最相近的类群进行解剖学比较和讨论, 为新鳍鱼类干群的谱系分析提供新的解剖学依据。  相似文献   

7.
目的:了解异长齿黄芪的化学成分。方法:通过硅胶柱层析对异长齿黄芪乙酸乙酯部位进行分离,采用现代波谱技术进行化合物的结构鉴定。结果:从异长齿黄芪乙酸乙酯部位中分离了6个单体化合物,分别鉴定为甘油三亚油酸酯(1)、羽扇豆醇(2)、3-甲氧基-4-羟基-反式苯丙烯酸正十八醇酯(3)、二十四碳酸(4)、β-谷甾醇(5)、异甘草素(6)。结论:化合物1~6均为首次从该种植物中分离得到。  相似文献   

8.
<正> 本文记述(鱼句)亚科鱼类11属20种,鲅亚科鱼类2属2种,现将对其咽骨咽齿的比较研究结果予以报导。(鱼句)亚科Gobioninae,咽骨的长宽度常有变异。体长为骨长的12.0一27.0倍,骨长为骨宽的2.5~7.0倍。前肢略长于或等于后肢。前后角圆钝或后角不明显。咽齿1~3列,内列5齿,中列2一3齿,外列1齿,各齿光滑无锯齿。  相似文献   

9.
本文对广东北江(鱼句)亚科鱼类的咽骨咽齿进行比较研究,研究的结果表明,其咽骨的形态和咽齿结构的特点与食性相适应和与其演化的关系。  相似文献   

10.
正中科院古脊椎动物与古人类研究所徐光辉研究团队在贵州发现了2.44亿年前的一种大型肉食性基干新鳍鱼类,并将其命名为"盘州暴鱼"。盘州暴鱼的发现揭示了疣齿鱼科生态适应多样性,更新了人们对三叠纪海洋生态系统复苏的认识。  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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