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   162篇
  免费   8篇
  2024年   1篇
  2023年   3篇
  2022年   4篇
  2021年   4篇
  2020年   8篇
  2019年   13篇
  2018年   12篇
  2017年   14篇
  2016年   9篇
  2015年   6篇
  2014年   6篇
  2013年   24篇
  2012年   9篇
  2011年   4篇
  2010年   6篇
  2009年   7篇
  2008年   6篇
  2007年   2篇
  2006年   4篇
  2005年   3篇
  2004年   2篇
  2003年   1篇
  2002年   1篇
  2001年   3篇
  2000年   4篇
  1999年   2篇
  1997年   2篇
  1996年   1篇
  1994年   2篇
  1992年   2篇
  1991年   1篇
  1990年   1篇
  1983年   1篇
  1982年   1篇
  1977年   1篇
排序方式: 共有170条查询结果,搜索用时 15 毫秒
71.
This study tests the precision and accuracy of laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) for measuring strontium isotope ratios (87Sr/86Sr) in fossil teeth from Swartkrans and Sterkfontein in South Africa, and explores the extent of diagenesis in these specimens. Compared to solution MC-ICP-MS or thermal ionization mass spectrometry (TIMS) methods, LA-MC-ICP-MS can be faster and less expensive, but has lower precision and accuracy. We found that 87Sr/86Sr ratios in fossil rodent teeth measured by LA-MC-ICP-MS were offset from solution values by a mean of 0.0005 ± 0.0010 (2σ). Because of the very wide spread of biologically available 87Sr/86Sr ratios (∼0.710 to ∼0.790) in the region, LA-MC-ICP-MS is more than sufficient for assessing the geographic origins of the fossil rodents. The concentration of strontium in modern and fossil enamel from the area is statistically indistinguishable, as is the range of 87Sr/86Sr ratios in modern rodents and fossil rodents from Swartkrans. Thus, there is little evidence of diagenetic Sr in the fossil enamel. In contrast, the fossil dentine may contain up to ∼50% diagenetic strontium, although many dentine 87Sr/86Sr ratios are still far removed from the background cave value of 0.729. We propose that LA-MC-ICP-MS will also be of use for investigating the geographic origins of other, non-rodent fossil teeth from the Sterkfontein and Swartkrans collections, and may prove of similar utility at other suitable sites.  相似文献   
72.
73.
74.
The aim of this study was to define a strategy for a correct selection of bone samples by employing inductively coupled plasma optical emission spectroscopy (ICP-OES) for reconstructing the biological mineral content in bones through the determination of major elements, trace elements and Rare Earth Elements (REE, lanthanides) in skeletal cremains of ancient Iberians (III–II B.C), discovered in the Necropolis of Corral de Saus (Moixent, Valencia) between 1972 and 1979. The biological mineral content was determined taking into account diagenetic factors. A control method for a better reading of results was applied. To explore large geochemical datasets and to reduce the number of variables, Principal Component Analysis (PCA) was used, thus, providing a deeper insight into the structure of the variance of the dataset. PCA shows that the elemental profiles of bone and soil samples are clearly different. Bone samples obtained from the outer bone layer were shown to have a different elemental composition; more similar to soil samples than samples of the inner bone layer. PCA scores and loadings plots were preferred to dendrograms obtained using Cluster Analysis, due to the limits of the latter one to appreciate the spatial ordering of samples. Partial least squares discriminant analysis (PLS-DA), a frequently used supervised classification method, was applied to differentiate between degradation states of bone samples. PLS-DA results obtained in this study confirmed that changes derived from different burning conditions were associated with transformations in the mineral part of the bones. Accordingly, carbonized bones can be differentiated from cremated bones. Class assignment of bone samples with uncertain thermal conditions in dependence on their elemental composition has shown to be feasible. Consequently, for biochemical-archaeological studies the analysis and statistical classification of carbonized and cremated archaeological bones, as well as those exposed to unknown thermal conditions together with experiments in modern bones, are recommended.  相似文献   
75.
The archaeological record of Eastern Hungary indicates that settlement patterns, subsistence strategies, ceramic style, trade patterns and mortuary customs changed from the Late Neolithic to the Copper Age (5000–2700 cal BC). Despite a rich archaeological tradition, questions remain regarding the management and use of domesticated animals and the role animal husbandry played in social change during this transition. Some researchers have hypothesized that these changes reflect a shift towards an economy that intensified its focus on primary and perhaps secondary animal products. Here we synthesize isotope data from human and animal remains and residue analysis from pottery sherds from Neolithic and Copper Age assemblages. Results indicate that the consumption and use of animal protein and fat was relatively high for both periods, with an increase in animal fats in ceramic vessels during the Middle Copper Age; however, milk products do not appear to have played an important dietary role. We conclude that livestock management remained small-scale during the Neolithic and Copper Age and that dairy use was minimal. It is proposed that the cultural changes that occurred at this time were associated with the emergence of smaller, independent farmsteads and perhaps the innovative use of secondary products like manure.  相似文献   
76.
77.
This article investigates the housing experiences of international students in comparison to other newcomers in the mid-sized Canadian city of St. John's, Newfoundland and Labrador, with a focus on how they navigate housing crises. Drawing on recent literature on housing justice, a quantitative survey of 188 participants, and 30 qualitative interviews, the findings reveal that international students and other newcomers are at different stages of their housing careers, have different needs and goals, and are experiencing the affordability crisis differently. Housing discrimination is a pressing concern, especially for international students who are subjected to intersectional prejudice, exploitation by landlords, and amplified challenges due to the COVID-19 pandemic. The article argues for inclusive housing and immigration policies that acknowledge international students as part of the Canadian housing market and ensure their rights to housing.  相似文献   
78.
79.
80.
In Darwin in the Northern Territory of Australia, Aboriginal men made up more than half of the domestic servant population by 1938. They replaced the Chinese and Malay male servants who had worked for British colonists in the early colonial period. Much of the historical work on male domestic servants in colonial situations plots the construction of the ‘houseboy’ as emasculated, feminised and submissive. In contrast, colonial constructions of Aboriginal men as ‘houseboys’ in Darwin emphasise the masculinity of the Aboriginal hunter. Aboriginal men were characterised as requiring constant discipline and training, and this paternalistic discourse led to a corresponding denial of manhood or adulthood for Aboriginal men. While male domestic servants in other colonial settings were allowed some privileges of masculinity in relation to female workers, amongst Aboriginal domestic workers, it was so‐called ‘half‐caste’ women who, in acknowledgment of their ‘white blood’, received nominally higher wages and privileges for domestic work. Aboriginal men were denied what was referred to as a ‘breadwinning’ wage; an Australian wage awarded to white men with families. Despite this, their role as husbands was encouraged by the administration as a method of controlling sexual relations between white men and Aboriginal women. These sometimes contradictory images can be understood as manifestations of the racialised construction of gender in Australia.  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