现行画法几何学教科书中关于直线、平面的分类方法如下;在三投影面体系中,除去一般位置直线外,都是特殊位置直线。特殊位置直线根据其对投影面的相对位置不同,可以分为两类:平行于一个投影面的直线;垂直于一个投影面的直线。……平行于...现行画法几何学教科书中关于直线、平面的分类方法如下;在三投影面体系中,除去一般位置直线外,都是特殊位置直线。特殊位置直线根据其对投影面的相对位置不同,可以分为两类:平行于一个投影面的直线;垂直于一个投影面的直线。……平行于一个投影面的直线,统称为投影面平行线。平行于 H 面的直线,称为水平线。……垂直于投影面的直线,统称为投影面垂直线。垂直于一个投影面的直线必同时平行于另两个投影面,垂直于 H 面的直线,称为铅垂线;……以铅垂线为例,按定义它垂直于 H 面,同时必平行于 V 面和 W 面,它是正平线和侧平线的特例。展开更多
During the Late Miocene,numerous medium to large-sized herbivores,that resemble the living Ovibos in skeletal morphology,dispersed throughout the Holarctic realm and comprised eleven genera:Lantiantragus,Shaanxispira,...During the Late Miocene,numerous medium to large-sized herbivores,that resemble the living Ovibos in skeletal morphology,dispersed throughout the Holarctic realm and comprised eleven genera:Lantiantragus,Shaanxispira,Tsaidamotherium,Criotherium,Mesembriacerus,Hezhengia,Urmiatherium,Parurmiatherium,Plesiaddax,Sinotragus,and Prosinotragus.These genera are primarily found in eastern Asia,in which nine genera are found in northern China,as well as in countries in eastern Europe and western Asia.They are distinguished by unique characteristics,including a perpendicular braincase,specialized horn cores,and a robust basioccipital.Previous studies have often classified these‘ovibovin’bovids as part of the conventional subfamily/tribe Ovibovinae/Ovibovini,along with extant Ovibos.Nevertheless,an increasing number of studies do not support the monophyly of the subfamily/tribe Ovibovinae/Ovibovini,nor is a close relationship likely between these Late Miocene‘ovibovin’bovids and extant Ovibos.Among the eleven genera of‘ovibovin’bovids,Plesiaddax,Hezhengia,and Urmiatherium are often considered to have a very close relationship and conventionally form the tribe Urmiatheriini.However,previous phylogenetic analyses do not support the monophyly of Urmiatheriini.This paper presents a summary of the transmutation of the terms Ovibovidae/Ovibovinae/Ovibovini/Ovibovina,the temporal and spatial distribution of the Late Miocene‘ovibovin’bovids in Eurasia,the principal characteristics of these taxa,and the previous phylogenetic analyses.展开更多
文摘现行画法几何学教科书中关于直线、平面的分类方法如下;在三投影面体系中,除去一般位置直线外,都是特殊位置直线。特殊位置直线根据其对投影面的相对位置不同,可以分为两类:平行于一个投影面的直线;垂直于一个投影面的直线。……平行于一个投影面的直线,统称为投影面平行线。平行于 H 面的直线,称为水平线。……垂直于投影面的直线,统称为投影面垂直线。垂直于一个投影面的直线必同时平行于另两个投影面,垂直于 H 面的直线,称为铅垂线;……以铅垂线为例,按定义它垂直于 H 面,同时必平行于 V 面和 W 面,它是正平线和侧平线的特例。
文摘During the Late Miocene,numerous medium to large-sized herbivores,that resemble the living Ovibos in skeletal morphology,dispersed throughout the Holarctic realm and comprised eleven genera:Lantiantragus,Shaanxispira,Tsaidamotherium,Criotherium,Mesembriacerus,Hezhengia,Urmiatherium,Parurmiatherium,Plesiaddax,Sinotragus,and Prosinotragus.These genera are primarily found in eastern Asia,in which nine genera are found in northern China,as well as in countries in eastern Europe and western Asia.They are distinguished by unique characteristics,including a perpendicular braincase,specialized horn cores,and a robust basioccipital.Previous studies have often classified these‘ovibovin’bovids as part of the conventional subfamily/tribe Ovibovinae/Ovibovini,along with extant Ovibos.Nevertheless,an increasing number of studies do not support the monophyly of the subfamily/tribe Ovibovinae/Ovibovini,nor is a close relationship likely between these Late Miocene‘ovibovin’bovids and extant Ovibos.Among the eleven genera of‘ovibovin’bovids,Plesiaddax,Hezhengia,and Urmiatherium are often considered to have a very close relationship and conventionally form the tribe Urmiatheriini.However,previous phylogenetic analyses do not support the monophyly of Urmiatheriini.This paper presents a summary of the transmutation of the terms Ovibovidae/Ovibovinae/Ovibovini/Ovibovina,the temporal and spatial distribution of the Late Miocene‘ovibovin’bovids in Eurasia,the principal characteristics of these taxa,and the previous phylogenetic analyses.
