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   122篇
  免费   2篇
  2023年   1篇
  2022年   1篇
  2021年   1篇
  2020年   4篇
  2019年   6篇
  2018年   10篇
  2017年   6篇
  2016年   10篇
  2015年   1篇
  2014年   3篇
  2013年   31篇
  2012年   7篇
  2011年   7篇
  2010年   9篇
  2009年   2篇
  2008年   2篇
  2007年   1篇
  2006年   6篇
  2005年   2篇
  2003年   2篇
  2002年   2篇
  2000年   2篇
  1999年   1篇
  1996年   1篇
  1993年   1篇
  1987年   1篇
  1983年   1篇
  1982年   1篇
  1980年   1篇
  1979年   1篇
排序方式: 共有124条查询结果,搜索用时 15 毫秒
61.
62.
A collection of 54 bronze artefacts recovered from the inland settlement of Castro dos Ratinhos (Portugal) and belonging mainly to the 9th–8th centuries BC, was studied by the use of non-invasive and micro analytical techniques. EDXRF, Micro-EDXRF, SEM-EDS and Optical Microscopy were used to determine the alloy composition and to identify the different thermo mechanical operations applied in the production of the artefacts. Results show that the collection is entirely composed of good quality binary bronzes (with an average tin content of 10.1 ± 2.5%). Alloys with higher tin contents were kept in as-cast condition and used in the making of ornaments, while tools were often finished with forging and annealing operations. Despite the existence of some Orientalising features in the Castro dos Ratinhos, e.g. rectangular habitat structures, wheel-turned ware and amphorae, the exclusive use of binary alloys with a narrow range of tin content seems to be associated with an indigenous metallurgical tradition inherited from the Late Bronze Age. This may indicate that the Phoenician interaction within the inland indigenous communities was a slow and selective process, probably dependant on the social-economic and cultural development of local communities.  相似文献   
63.
64.
65.
Certain trace elements may accumulate in bone in relation to dietary habits, so some of them are of interest in paleodietary analysis. This is the case with strontium (Sr) and barium (Ba), whose potential value as paleodietary indicators is enhanced by their relatively inert metabolic behaviour. The presence of carious lesions may indicate consumption of sugar and vegetables, whereas the etiology of dental calculus deposition is multifactorial, although some authors consider this as an indicator of protein consumption. Based on these facts we analysed (1) Ba, Sr, and calcium (Ca) content of inner cortical bone obtained from the ramus mandibularis, by atomic absorption spectrophotometry, (2) presence of teeth with carious lesions, and (3) presence of teeth with calculus deposition in 62 mandibles. All samples were obtained from the church La Concepción, an 18th century burial place in Tenerife. Gender was assessed by analysing genetic expression of amelogenin in some cases (14), and by inspection of pelvic bones when available (41 cases). We found (1) Carious lesions in 32 cases, and dental calculus, in 39; no association was observed between sex and presence of dental caries or calculus deposition, nor between the sex and the proportion of carious teeth nor the proportion of teeth with calculus deposition; (2) people buried near the altar (priests and individuals of the highest social class) showed a significantly higher proportion of teeth with dental calculus deposition (χ2 = 5.36, p = 0.021); (3) bone Sr and bone Ba were significantly higher than the values observed in a control group of 10 modern omnivorous individuals; the lowest Sr values were observed among people buried near the altar; and (4) the Ba/Sr ratio was directly related with the proportion of teeth with carious lesions. These data suggest that there were differences in dietary pattern among the individuals belonging to different social classes; overall, consumption of vegetables was widespread, as shown by the high proportion of carious lesions, in relation with raised Ba/Sr ratio, whereas consumption of marine products was scarce.  相似文献   
66.
This report presents the results of using NASA/JPL airborne synthetic aperture radar data (AIRSAR) to detect ancient Maya settlements beneath jungle canopy in Guatemala. AIRSAR stands out from previous applications of radar remote sensing in the Maya lowlands because of its canopy-penetrating capabilities. The authors offer an overview of the AIRSAR technology, followed by a case study in which the AIRSAR data receive testing in the field. Reconnaissance in the region around the Maya site of El Zotz led to the discovery of two new sites, including the medium-sized settlement of La Avispa. AIRSAR also aided archaeologists in detecting zones of residential settlement around the site core of El Zotz. This research will serve as a guide for future applications of radar remote sensing in Maya archaeology.  相似文献   
67.
This paper presents the results of an experimental study into the usefulness of X-ray florescence (XRF) in identifying the composition of metal artifacts found at aboriginal sites in northwestern Ohio. In the late 1990s, we subjected 96 samples to XRF and documented our results. We then compared our data to that collected by more precise spectrographic methods to assess the effectiveness of the XRF method for this application. While not precise enough to source native coppers, we conclude that XRF is a cheap, nondestructive method for differentiating native copper from its European counterparts at sixteenth- and seventeenth-century Late Woodland sites.  相似文献   
68.
Teen employment is a very important socioeconomic phenomenon because of its consequences on human capital formation. We assess the relation between teen employment and poverty, education, and unemployment in the city of Rosario, using information from the 2010 Argentina Census disaggregated at census block level. We use two different spatial models: The spatial lag model (SLM) and a linear regression model with the spatial component filtered (filtering model, FM). Given the nature of the variables employed, multicollinearity is an issue. One of the techniques proposed in the literature to deal with multicollinearity problems is principal component regression (PCR). We develop an adaptation of such methodology to be used in the SLM. Both models are estimated using their traditional methodologies (instrumental variables for the SLM and OLS for the FM) and using PCR. Although results are similar between the two models, depending on the methodology used in the estimations they differ greatly. Under traditional methodologies estimations show high variability, instability, and contradictory outcomes, but under PCR, results behave according to the literature.  相似文献   
69.
This article aims to highlight the main arguments that sought to justify the incorporation and legitimization of Urban Regeneration in the urban policy agenda in Brazil. It shows how the convergence between different and even conflicting propositions related to urban development provided ideological support to the construction of discourses in which urban regeneration is portrayed as beneficial to society as a whole, and how recent international ideas on urban development were incorporated in urban policies of contemporary Brazil, considering our local socio-economic and political environment, planning tradition and regulatory frameworks. The focus will be on Rio de Janeiro and particularly São Paulo given the key role these two cities play in defining urban policy paradigms, guiding government agendas and exporting regulatory models to other parts of Brazil.  相似文献   
70.
Vallone, E.R., Vezzosi, R.I. & Cione, A.L. February 2017. First fossil fish (Teleostei, Siluriformes) from the Late Pleistocene of Santa Fe Province, Argentina. Alcheringa 00, 000–000. ISSN 0311-5518.

The record of fossil fish from the Pleistocene of Argentina is poor. Here we describe the first ichthyofauna from Late Pleistocene riverbank beds in the Salado River of Santa Fe Province, Argentina. The material consists of isolated pectoral and dorsal fin spines, together with skull fragments. Four species-level taxa referable to three families can be identified: Pterodoras granulosus (Doradidae), Pimelodus cf. maculatus and Pimelodus cf. albicans (Pimelodidae) and cf. Hypostomus sp. (Loricariidae). Specimens attributed to Pterodoras granulosus and Pimelodus maculatus represent a minimum age for origin of these taxa. The Salado River assemblage includes the richest record of Pleistocene catfishes yet documented from southern South America.

Evelyn Romina Vallone [] and Raúl Ignacio Vezzosi [], Laboratorio de Paleontología de Vertebrados, CICYTTP-CONICET, Materi y España, (3105) Diamante, Entre Ríos, Argentina; Alberto Luis Cione [], División Paleontología de Vertebrados. Museo de La Plata. Paseo del Bosque s/n, (1900) La Plata, Argentina.  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