首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   12篇
  免费   0篇
  国内免费   6篇
地球物理   3篇
地质学   13篇
自然地理   2篇
  2018年   1篇
  2017年   1篇
  2016年   4篇
  2015年   1篇
  2011年   1篇
  2010年   1篇
  2008年   3篇
  2006年   1篇
  2005年   1篇
  2004年   2篇
  1999年   2篇
排序方式: 共有18条查询结果,搜索用时 15 毫秒
1.
为探究洱海湖滨区环境因子与蜻蜓物种多样性之间的关系,2014年5月至2017年5月对洱海10个样点进行实地调查,记录植物20科46种,共采集蜻蜓11科22属28种1448个体,并对环境因子与蜻蜓多样性进行相关性分析.结果表明蜻蜓成虫多样性与植被丰富度、湿生植被覆盖度、挺水植被覆盖度和沉水植被覆盖度均呈正相关,与浮水植物覆盖度和人为干扰程度呈负相关;稚虫多样性与湖底底质和水体溶解氧呈正相关,并对结果进行了讨论.研究结果给洱海蜻蜓栖息地的保护及湖滨缓冲带生态修复提供了有益的参考和数据支持.  相似文献   
2.
Palaeoperilestes electronicus gen. et sp. nov. is the first perilestid damselfly described from mid-Cretaceous Burmese amber. This new damselfly can be attributed to the family Perilestidae by the midfork being distal of the subnodus and the base of IR2 quite near to the base of RP2, both features found in the extant genera Perilestes and Perissolestes. Palaeoperilestes electronicus gen. et sp. nov. has a strongly zigzagged IR1, however, differing from Perilestes and Perissolestes which have a straight IR1. The discovery not only adds to the diversity of damselflies in Burmese amber, but also puts the origin of Perilestidae back to at least the mid-Cretaceous.  相似文献   
3.
The campterophlebiid new genus and species Ctenogampsophlebia reni is described from the Middle Jurassic of Inner Mongolia, China. It shows close similarities with the Lower to Middle Jurassic genera Gampsophlebia, and Petrophlebia, with closed and short subdiscoidal cells, confirming the attribution of these two other genera to the Campterophlebiidae.  相似文献   
4.
Three new species of fossil dragonflies assigned to Sinokaratawia Nel,Huang and Lin in family Campterophlebildae,i.e.S,daohugouica sp.nov.,S.magica sp.nov.and S.gloriosa sp.nov.,and new materials of male S.prokopi Nel,Huang and Lin,2007 are described from the Middle Jurassic of Daohugou,Inner Mongolia,China.An emended diagnosis of genus Sinokaratawia was proposed.  相似文献   
5.
1INTRODUCTION Manyfactorshavebeenlinkedwithobserved patternsofodonatediversity.Eachhabitatisdifferent andpresentsitsownopportunitiesforexploitationby welladaptedspecies(Krebs,1989).Theyaresensi tiveresponderstonewlycreatedphysicalandtogether withphysiogra…  相似文献   
6.
Environments with higher complexity harbor a greater biodiversity and can directly influence on certain behaviors of aquatic animals. Here, we tested whether habitat complexity predicts odonate larvae emergence and mortality rates by rearing larvae in aquaria with or without artificial complexity. The results show a shorter emergence time in more complex environments, and a higher mortality rate on less complex habitats.  相似文献   
7.
A taxon of the Stenophlebiidae, Yixianstenophlebia magnifica gen. et sp. nov., is described from the Lower Cretaceous Yixian Formation at Liutiaogou, Ningcheng County, Inner Mongolia of China. Its closest relative is the Late Jurassic European genus Stenophlebia. This new discovery is helpful to understand the Jehol Biota assemblage at Liutiaogou Locality. It also confirms that the Stenophlebiidae was a very diverse and widespread family during the Early Cretaceous. The causes of its extinction in the Late Cretaceous remain enigmatic.  相似文献   
8.
The genus Mesosticta Huang, Azar, Cai et Nel, 2015 was established based on the wing bases of two damselflies from mid-Cretaceous Burmese amber. Here we describe a new well-preserved platystictid damselfly, Mesosticta electronica sp. nov., with complete forewings and hindwings. The diagnosis of Mesosticta is revised and augmented in this paper. Mesosticta electronica sp. nov. differs from Mesosticta burmatica Huang, Azar, Cai et Nel, 2015 in having the arculus slightly distal of Ax2, a free subdiscoidal cell, the hindwing AA ending on the middle area of the posterior side of the discoidal cell, and the base of RP2 being three or four cells distal of the subnodus. The new discovery adds to the diversity of damselflies in mid-Cretaceous Burmese amber and puts the origin of Platystictidae to at least the mid-Cretaceous.  相似文献   
9.
辽宁西部九佛堂组昼蜓化石的新发现及其地质意义   总被引:1,自引:0,他引:1  
发现于辽宁省义县早白垩世九佛堂组上段地层中的昼蜓化石(孟氏丽昼蜓Abrohemeroscopus mengi Ren,Liu et Chen,2003)与北京西山卢尚坟组的巴依萨昼蜓(Hemeroscopus baissicus Pritykina,1977)在形态上比较相似,但在演化程度上更为原始,主要体现在后翅臀套较小(仅有6~7个翅室),径增脉(Rspl)缺,后翅CuAa脉弯曲、带有5个明显的后分支,前翅MP脉短、终止于翅后缘近翅结处,翅痣下有一个明显的支脉,后翅CuAa和MP域基部较窄、在三角室下方仅有1排翅室。据此,九佛堂组上段的地质时代定为早白垩世早期(Berriasian-Hauterivian)较为合理。  相似文献   
10.
Mark Harthun 《Limnologica》1999,29(4):449-464
Due to the return of the beaver an increasing number of brooks become restored to a natural condition. It is characterized by an alternation of flowing and standing sectors. In the summer of 1995, different groups of organisms (Odonata, Mollusca, Trichoptera, Ephemeroptera, Diptera) of two brooks in the Spessart mountains (Hesse, Germany) were studied to compare the composition of invertebrates in beaver homeranges and in the non-influenced sectors above. The new living conditions resulted in the disappearance of some species (Drusus anulatus, Trich., Sericostoma personatum, Trich., Radix peregra, Gastr.). Nevertheless the beaver homeranges accommodate a significant higher number of species of dragon flies and damsel flies, molluscs and caddis flies than the brooks above the homeranges. The heterogeneity of natural river systems make a coexistence of running water and silent water organisms possible. The examinations result in a significant higher group dominance of ephemeras (i.p. Cloeon dipterum) in a beaver pond than in lenitic sectors conditioned by the gradient without beaver influence. Here the dominance of chironomids was much higher. High current sectors with their characteristic organisms are also present in the beaver homeranges. The higher number of insects is the basis of nourishment for predatory insects and fishes. The potential effects of beaver ponds on fishes are discussed.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号