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   16篇
  免费   0篇
  2019年   1篇
  2017年   1篇
  2016年   1篇
  2013年   2篇
  2012年   3篇
  2010年   3篇
  2002年   2篇
  1999年   1篇
  1991年   1篇
  1959年   1篇
排序方式: 共有16条查询结果,搜索用时 31 毫秒
1.
2.
3.
4.
Artificial cranial modification (ACM) involves the alteration of cranial vault shape by cultural means, and is performed during infancy while the cranial bones remain soft and malleable. The direction of normal cranial growth is altered through the application of external forces. In this study, three types of ACM from north‐central Peru (posterior flattening, bilobed and circumferential) were analysed using standard craniometric techniques. The aim was to determine the effects of these forms of ACM on craniofacial morphology, and the extent to which different types of ACM could be distinguished from one another and unmodified crania on the basis of these measurements. Significant differences between artificially modified and unmodified crania, and between different types of ACM, were demonstrated in cranial vault shape for all types. Significant differences in facial morphology were found only in the bilobed group compared with the unmodified crania. Canonical variates analysis (discriminant analysis) confirmed that major differences between modification types and unmodified crania were in measurements and angles of the cranial vault. While the results show some similarities to previous studies, they add to the variability in the patterns and extent of differences documented to date. It is suggested, based on these results and visual observations, that interpopulation variation in ACM within major modification categories may explain some of the variability in results between studies, an explanation which has previously received insufficient recognition but which remains to be tested since varied methodology between studies may also be a contributory factor. While previous studies have often sought to generalise about the effects of ACM, the examination of the differences between populations even within major ACM categories may offer new insight into cultural variation in modification techniques between populations and the nature of craniofacial development. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   
5.
This paper investigates evidence for subsistence and settlement activities in the Levantine Middle Epipalaeolithic through the application of stable isotope analysis to human and non-human remains from the site of 'Uyun al-Hammam, northern Jordan. In general, bone from the site suffers a high degree of diagenesis and collagen could not be extracted for analysis here. Carbon and oxygen isotopic values from human tooth enamel samples were variable, but within expected values for the Middle Epipalaeolithic, whereas animal carbon and oxygen isotopic values varied widely, most likely due to hydrological and climatological factors. Carbon and isotopic values for the human samples indicated a predominantly C3 plant dietary input, while animal samples appeared to have varying amounts of C4 inputs into their diet. This is the first isotopic analysis conducted on material from the Middle Epipalaeolithic of the southern Levant and, as such, even results constrained by temporal and climatological variants within the region contribute to the overall knowledge of settlement and subsistence strategies during this cultural period.  相似文献   
6.
This article focuses on philhellenic travellers' perceptions and experiences of Greece in the early nineteenth century, especially during the War of Independence in the 1820s. The central argument is that philhellenes – that is to say, supporters of Greek independence from the Ottoman Empire – understand Greece as a ‘real-and-imagined’ space. Greece is an ‘imagined’ location in the sense that philhellenic conception of it is shaped by certain rhetorical assumptions and priorities. But, evidently, it is also a ‘real’ space, not simply in the obvious sense that the landscape has a tangible existence, but also in that those rhetorical constructions have concrete consequences and expressions. These expressions are especially significant because philhellenic travellers conceive the region as both a literal and conceptual borderland on the edges of Europe. They consider Greece fundamental to European history, culture and self-definition, but because it is ruled by the Ottoman Empire, it is also an unfamiliar space at the margins of Europe. In other words, Greece is both within and outside European space, and its liminal position represents wider uncertainties about the conception of Europe in the early nineteenth century.  相似文献   
7.
Gi?ka, W., Zakrzewska, M., Baranov, V., Wang, B. &; Stebner, F., May 2016. The first fossil record of Nandeva Wiedenbrug, Reiss &; Fittkau (Diptera: Chironomidae) in early Eocene Fushun amber from China. Alcheringa 40, xxx–xxx. ISSN 0311-5518

The first fossil representative of the extant chironomid genus Nandeva Wiedenbrug, Reiss &; Fittkau, 1998 Wiedenbrug, S., Reiss, F. &; Fittkau, E.J., 1998. Nandeva, gen. nov., a new genus of Chironomini (Insecta, Diptera, Chironomidae). Spixiana 21, 5968. [Google Scholar] is described based on a specimen found in early Eocene (50–53 Ma) Fushun amber from China. The adult male of Nandeva pudens sp. nov. has the long RM vein as a continuation of M and R4+5, the bare squama, the strongly reduced anal area of the wing and hypopygial characters typical of extant species of the genus. Following the systematic concept based on adult male morphology and characters examinable in fossil specimens, we present N. pudens as a possible member of the Tanytarsini, arguing that Nandeva is part of this tribe or a possible sister group to the tribe. This is the first record of Nandeva from the Palaearctic region.

Wojciech Gi?ka [] University of Gdańsk, Department of Invertebrate Zoology and Parasitology, Wita Stwosza 59, 80-308 Gdańsk, Poland; Marta Zakrzewska [] University of Gdańsk, Department of Invertebrate Zoology and Parasitology, Wita Stwosza 59, 80-308 Gdańsk, Poland; Viktor Baranov* [] Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, 12587 Berlin, Germany; Bo Wang? [] Chinese Academy of Sciences, Nanjing Institute of Geology and Palaeontology, State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing 210008, PR China; Frauke Stebner [] University of Bonn, Steinmann-Institute, Section Palaeontology, Nussallee 8, 53115, Bonn, Germany. *Also affiliated with Humboldt University of Berlin, Faculty of Mathematics and Natural Sciences, Geography Department, Rudower Chaussee 16, 12489 Berlin, Germany. ?Also affiliated with Chinese Academy of Sciences, Institute of Zoology, Key Laboratory of Zoological Systematics and Evolution, Beijing 100101, PR China.  相似文献   
8.
Genetics and African Cattle Domestication   总被引:1,自引:0,他引:1  
Whether cattle domestication occurred independently on the African continent is among the most controversial questions in the Holocene archaeology of northern Africa. One long-established scenario, based upon early archaeological evidence, suggested that Africa’s earliest cattle derived from several introductions from Southwest Asia through the Nile Valley, or via the Horn of Africa. Based upon archaeofaunal remains retrieved in the late twentieth century, other archaeologists argued that an independent domestication of the African aurochs gave rise to Africa’s earliest domestic cattle. Up to now, the genetic data have also been controversial. This paper reviews the archaeological evidence and the scope of debate, and then focuses on the recent contributions of genetic research to clarifying these issues.  相似文献   
9.
In a spatial context, flexible substitution patterns play an important role when modeling individual choice behavior. Issues of correlation may arise if two or more alternatives of a selected choice set share characteristics that cannot be observed by a modeler. Multivariate extreme value (MEV) models provide the possibility to relax the property of constant substitution imposed by the multinomial logit (MNL) model through its independence of irrelevant alternatives (IIA) property. Existing approaches in school network planning often do not account for substitution patterns, nor do they take free school choice into consideration. In this article, we briefly operationalize a closed‐form discrete choice model (generalized nested logit [GNL] model) from utility maximization to account for spatial correlation. Moreover, we show that very simple and restrictive models are usually not adequate in a spatial choice context. In contrast, the GNL is still computationally convenient and obtains a very flexible structure of substitution patterns among choice alternatives. Roughly speaking, this flexibility is achieved by allocating alternatives that are located close to each other into nests. A given alternative may belong to several nests. Therefore, we specify a more general discrete choice model. Furthermore, the data and the model specification for the school choice problem are presented. The analysis of free school choice in the city of Dresden, Germany, confirms the influence of most of the exogenous variables reported in the literature. The estimation results generally indicate the applicability of MEV models in a spatial context and the importance of spatial correlation in school choice modeling. Therefore, we suggest the use of more flexible and complex models than standard logit models in particular. En un contexto espacial, los patrones sustitución flexible juegan un papel importante en el modelamiento del comportamiento de las decisiones individuales. Varios problemas de correlación pueden presentarse si dos o más alternativas de elección comparten características no observables por el modelador. Los modelos de valor extremo (multivariate extreme value‐MEV) ofrecen la posibilidad de relajar la propiedad de sustitución constante (constant substitution) presente en los modelos logit multinomiales (multinomial logit‐MNL), a través de su propiedad de independencia de alternativas irrelevantes (Independence of irrelevant alternatives property ‐IIA). A menudo, los enfoques existentes en la planificación de redes escolares no toman en consideración los patrones de sustitución y de libre elección de escuela. En este artículo, los autores presentan brevemente el funcionamiento de un modelo de elección discreta (discrete choice model) para la maximización de utilidad o modelo logit anidado generalizado (generalized nested logit model‐GNL) para dar cuenta de la autocorrelación espacial. Los autores sostienen que modelos demasiado simples y restrictivos no suelen ser adecuados en un contexto de elección espacial. En contraste el modelo GNL es conveniente en términos de su computación y obtiene una estructura muy flexible de los patrones de sustitución entre las alternativas de elección. En términos generales, esta flexibilidad se logra mediante la asignación (o anidación) de las alternativas cercanas en el espacio (una alternativa puede pertenecer a varios nidos). Por lo tanto, los autores presentan un modelo de elección discreta más general. El estudio presenta además datos y la especificación del modelo para un caso de elección de escuela concreto: el análisis de libre elección de escuela en la ciudad de Dresden, Alemania. El análisis confirma la influencia de la mayoría de las variables exógenas presentes en la literatura. Los resultados de la estimación demuestran en términos generales la aplicabilidad de los modelos MEV en un contexto espacial y la importancia de la autocorrelación espacial en el modelado de elección de escuela. Los autores concluyen sugiriendo el uso de modelos más flexibles y complejos que los modelos utilizados habitualmente, en particular los modelos logit estándar. 从空间视角看,灵活的替代模式在个人行为选择建模中发挥着重要作用。当存在两个或两个以上备选方案集具有共性且无法被建模者观察到时,就可能出现相关性问题。多元极值模型(MEV)通过不相关的替代属性(IIA)实现了对多元logit模型(MNL)中常数限制的松弛替代。现有校园网络规划方法通常无法解释替代模式,而且没有考虑到自由择校因素。本文简要地建立一个封闭离散选择模型(广义嵌套(GNL)模型),从效用最大化角度来解释空间相关性。此外分析还表明,非常简单的约束模型通常不具有足够的空间选择情境。相比之下,GNL模型计算便捷,且可以在各选择方案中获得非常灵活的替代模式。大致而言,这种灵活性大体是通过与住处位置距离上彼此靠近的替代选择分配而获得,一个给定的选择可能属于不同的住处。因此,我们给出了一个更一般的离散选择模型。此外,还给出了针对择校问题的数据和模型设定。基于德国德累斯顿市自由择校分析,证实了已有研究中多数外生变量的影响。估计结果证实了MEV模型在空间分析中的适用性以及择校模型中空间相关的重要性,并建议使用更加灵活和复杂的模型而不是标准的logit模型。  相似文献   
10.
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