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31.
正Objective Symphyta,as an ancestral and paraphyletic group,are mainly phytophagous lineages.In order to truly elucidate their natural history and the development trends,we need to cover more species,including the extinct and extant species.In general,fossils sometimes appear to be necessary since extinct species usually have the so-called transitional states,which play important roles in their early evolution.It is well known that the Early Cretaceous  相似文献   
32.
New Mesozoic Mesopsychidae(Mecoptera)from Northeastern China   总被引:2,自引:2,他引:0  
<正>The Mesozoic family Mesopsychidae Tillyard,1917 presently consists of seven described genera and 13 species from the mid-Triassic to the Early Cretaceous of Australia,South Africa and Eurasia.In the present paper one new genus and three new species of fossil mesopsychids are described that add significant distributional and stratigraphic extensions to the family.This finding documents the first formal record of fossil Mesopsychidae in China.Both Lichnomesopsyche gloriae gen.et sp.nov.and L.daohugouensis gen.et sp.nov. were found from the Middle Jurassic Jiulongshan Formation of Inner Mongolia,whereas Vitimopsyche kozlovi sp. nov.,of mid Early Cretaceous age,was collected from the Jehol Biota of northern Hebei Province.This new,well-preserved material from China reveals complete and previously unknown body features,including head, antennae,mouthparts,legs and abdomen.The delicate and long proboscides of these new taxa indicate that they were feeding on externally exposed,nutrient-rich fluids of gymnospermous ovulate fructifications,and incapable of piercing surface epidermis-attributable principally to the absence of stylets.These proboscides originated, perhaps multiply,among basal Mecoptera and are functionally and structurally convergent with equivalent mouthparts borne by fossil and extant Diptera,Lepidoptera,Neuroptera and Coleoptera.  相似文献   
33.
Studies of the breaking criteria for solitary waves on a slope are presented in this paper. The boundary element method is used to model the processes of shoaling and breaking of solitary waves on various slopes. Empirical formulae that can be used to characterize the breaking of solitary waves are presented. These include the breaking index, the wave height, the water depth, and the maximum particle velocity at the point of breaking. Comparisons with the results of other researches are given.  相似文献   
34.
中国地震活动的某些特征   总被引:21,自引:0,他引:21       下载免费PDF全文
我国是一个多地震的国家,有较丰富的历史地震资料。公元前1831年即有地震记述。自宋、元以来(约十二世纪),地方志逐渐盛行,特别是明代以后(公元1368年),地震记载较为普遍与详细,不仅记有强震破坏,而且对远震波及与当地的弱震情况都有所描述,甚至一些抗震经验也有所涉及。 解放后,为了我国社会主义建设中抗震设计的需要,中国科学院组织了各方面人员查阅了各种文史书籍八千余种,以不到两年的时间,基本上完成了资料的搜集和整理工作,  相似文献   
35.
1932年昌马地震破裂带及其形成原因的初步探讨   总被引:1,自引:0,他引:1       下载免费PDF全文
1932年12月25日,我国甘肃省西部玉门镇以南的昌马地区发生了7.6级地震。震中区产生了规模较大的地面破裂带,其中有张性、压性和剪切等多种型式裂缝。本文根据分析各种自然破坏现象的形成条件,结合极震区地质构造特征,对震源区的应力作用和地震成因提出初步看法。 对地震破裂带的分析结果表明,这次地震起主要作用的是南北向的水平挤压作用,并与自白垩纪以来控制着本区构造断裂的区域应力场是一致的。地震破裂带出现的部位与长期活动的昌马构造断裂带一致。因此,我们认为昌马地震的发生是昌马构造断裂带继承性活动的结果。  相似文献   
36.
Ⅰ作者在本论文的第一报里(气象杂志第十三卷第709页),曾经以天气的晴雨为例,提出一个检视交替事象持续性有无的方法,并就南京自1928年至1936年的天气晴雨纪录,应用上述的理论,得到了天气晴雨有连续至十日左右的持续性的结论。那时是这样规定持续性  相似文献   
37.
Three new species of the extinct genus of Eoptychopterina from the Eoptychopteridae family, Eoptychopterina antica sp. nov., Eoptychopterina adnexa sp. nov., and Eoptychopterina mediata sp. nov., are described and illustrated. These three new species are established based on fossil specimens with bodies and complete wings. All were collected from the Middle Jurassic Jiulongshan Formation of Daohugou in eastern Inner Mongolia, China. Based on the new materials, the name of two species in Eoptychopterina from China--Eoptychopterina elenae Ren and Krzeminski and Eoptychopterina gigantea Zhang--is sysnonymum junius.  相似文献   
38.
Since Holcorpa maculosa was first described in 1878, it has attracted lots of attention due to its extremely elongate abdominal segments from the sixth to the eighth. Fossil records of family Holcorpidae are very rare, comprising two species in one genus represented by three fossil specimens, resulting in limited knowledge on the structure and function of holcorpid’s unique male organ, as well as its evolutionary relationship with other scorpionflies. Herein we describe a new genus with a new species, Conicholcorpa stigmosa gen. et sp. nov., of the Holcorpidae from the Middle Jurassic Jiulongshan Formation near Daohugou Village, Inner Mongolia, China. This is the first holcorpid documented from the Daohugou locality, albeit two previously reported species with extremely elongate male organs but deemed as Family Incertae sedis. C. stigmosa gen. et sp. nov. is the earliest holcorpid hitherto, extending its existence from the Early Eocene to the Middle Jurassic by 114 million years and providing one more early case of presenting exaggerated male body parts for sexual display and/or selection. Our analysis supports the sister relationship between Holcorpidae and Orthophlebiidae. Our results not only enhance our knowledge of the morphology of Holcorpidae but also elucidate the relationship of known species of this family.  相似文献   
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