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   135篇
  免费   8篇
  2020年   2篇
  2019年   4篇
  2017年   2篇
  2016年   2篇
  2015年   4篇
  2014年   3篇
  2013年   18篇
  2012年   5篇
  2011年   11篇
  2010年   12篇
  2009年   11篇
  2008年   10篇
  2007年   10篇
  2006年   6篇
  2004年   5篇
  2003年   2篇
  2002年   1篇
  2001年   2篇
  2000年   1篇
  1999年   1篇
  1998年   1篇
  1997年   3篇
  1996年   4篇
  1995年   3篇
  1994年   1篇
  1993年   3篇
  1992年   1篇
  1991年   3篇
  1990年   1篇
  1985年   1篇
  1982年   2篇
  1981年   1篇
  1976年   2篇
  1975年   1篇
  1974年   1篇
  1973年   1篇
  1972年   2篇
排序方式: 共有143条查询结果,搜索用时 804 毫秒
11.
One hundred and twenty‐five new lead isotopic analyses on galena, mainly from the Los Pedroches – Alcudia Valley area of southern Iberia, are presented. These data allow us to define four compositional groups in the 207Pb/206Pb versus 208Pb/206Pb and 207Pb/206Pb versus 206Pb/204Pb diagrams. Group I compositions are intermediate between those previously reported for southeastern and southwestern Iberian ore mineral locations. The compositions of Group II, the largest group, overlap with ore data from southwestern Spain. Groups III and IV have compositions that have never before been identified in this region and are comparable to those from the Sardinian Cu ores, which might explain the previously assumed exotic origin for local Bronze Age artefacts.  相似文献   
12.
Historians study the living and the dead. If we can identify the rights of the living and their responsibilities to the dead, we may be able to formulate a solid ethical infrastructure for historians. A short and generally accepted answer to the question of what the rights of the living are can be found in the Universal Declaration of Human Rights. The central idea of human rights is that the living possess dignity and therefore deserve respect. In addition, the living believe that the dead also have dignity and thus deserve respect too. When human beings die, I argue, some human traces survive and mark the dead with symbolic value. The dead are less than human beings, but still reminiscent of them, and they are more than bodies or objects. This invites us to speak about the dead in a language of posthumous dignity and respect, and about the living, therefore, as having some definable core responsibilities to the dead. I argue further that these responsibilities are universal. In a Declaration of the Responsibilities of Present Generations toward Past Generations, then, I attempt to cover the whole area. I identify and comment on four body‐ and property‐related responsibilities (body, funeral, burial, and will), three personality‐related responsibilities (identity, image, and speech), one general responsibility (heritage), and two consequential rights (memory and history). I then discuss modalities of non‐compliance, identifying more than forty types of failures to fulfill responsibilities toward past generations. I conclude that the cardinal principle of any code of ethics for historians should be to respect the dignity of the living and the dead whom they study.  相似文献   
13.
14.
To help improve the well‐being of the local people, a joint Vietnamese‐UK team set out to establish a way of estimating soil and nutrient losses under different land management scenarios, using field data extrapolated through remote sensing and GIS, to obtain catchment‐wide estimates of the impact of land cover change. Immigration from remote provinces to the Dong Phu District of Binh Phuóc Province, about 120 km north of Ho Chi Minh City, has led to disruption of soil surface stability on easily eroded clayey sandstones, creating rapid nutrient depletion that affects crop yields and siltation in the channel of the Rach Rat river downstream. The poor farmers of the areas see crop yields drop dramatically after two or three years of cultivation due to the fertility decline. Soil loss varies dramatically between wet season and dry season and with ground cover. Erosion bridge measurements showed a mean loss of 85.2 t ha?1 y?1 under cassava saplings with cashew nuts, 43.3 t ha?1 y?1 on uncultivated land and 41.7 t ha?1 y?1 under mature cassava. The rates of erosion were higher than those reported in many other parts of Vietnam, reflecting the high erodibility of the friable sandy soils on the steep side‐slopes of the Rach Rat catchment. However, although the actual measurements provide better soil loss data than estimates based on the parameters of soil loss equations, a large number of measurement sites is needed to provide adequate coverage of the crop and slope combinations in this dissected terrain for good prediction using GIS and remote sensing.  相似文献   
15.
16.
Although much is known about broad trends in Australian Indigenous geographies, particular aspects of Indigenous spatiality continue to be rendered invisible by standard statistical measures. The national census, for example, only registers moves at one and five year intervals. Any mobilities enacted within these timeframes are not measured. Yet these statistically ‘un‐captured’ mobility processes are often integral to Indigenous lived experiences and have a significant dialectical relationship to government service delivery processes. Understanding these population dynamics is therefore a critical, though underdeveloped, consideration within geographic enquiry and contemporary debates about State and Federal Indigenous policy directions and initiatives. This paper presents qualitative research findings regarding local experiences and perceptions of Indigenous spatiality in Yamatji country, Western Australia. Within this grounded framework, the paper builds on existing literature by drawing out some of the common spatial, temporal and demographic characteristics, or dimensions, of statistically un‐captured Indigenous mobility processes. With this discursive, albeit generalised and malleable, typology established, the analysis turns to a reflection on some of the methodological and conceptual complexities of measurement, interpretation, and translation of these mobility processes across the policy‐research nexus.  相似文献   
17.
This paper makes the case for advancing sustainability science partnerships (SSPs) both within universities and through innovative means of integrating universities with external public‐private and civil sectors. It links the basic principles of sustainable development with an emerging science of cooperative learning that connects researchers to a wide range of partners. SSPs are specifically designed to be transformational through becoming active agents for societal change. Universities play a special role here because they can act both as communication networks and as laboratories for developing the capability to design and manage SSPs in the creative transition to sustainability. It is gratifying to note that these ideas are beginning to emerge in a number of universities, with European examples being highlighted in this paper. Further steps towards introducing full‐blooded SSPs across the university spectrum are suggested.  相似文献   
18.
19.
The employment of synchrotron techniques complemented by conventional laboratory systems has allowed us to deepen and improve our knowledge of Roman wall painting procedures. The palette identified in wall paintings from Pompeii and Herculaneum from the second century bc includes goethite, hematite, cinnabar, glauconite, Egyptian blue, and other components such as calcite and aragonite. Proof of the use of organic binders is provided by FTIR and PY–GC/MS. Therefore, the possibility of the use of ‘a secco’ techniques cannot be ruled out. Pigments in wall paintings are usually found in small percentages and conventional X‐ray diffractometers do not detect them. Synchrotron radiation – high‐resolution X‐ray powder diffraction has allowed identification with only a few micrograms of sample.  相似文献   
20.
We investigated the major and trace element composition and Pb and Sr isotope characteristics of a series of about 20 colourless glass objects from a single high‐status Roman burial from the Netherlands (Bocholtz). The major elements show a relatively homogeneous group, with one outlier. This is corroborated by the Sr isotopes. Based on the Sb and Pb content, three major groups can be discerned, with two other outliers. This grouping is corroborated by the contents of the trace elements Bi, Sn, Ag, As and Mo, and by variations in lead isotopic ratios. On the basis of these results, we conclude that the glass of all objects was probably made with sand and lime from the same source. The variation in trace elements and lead isotope composition is most likely the result of variations in the composition of the sulphidic antimony ore(s) that were used to decolourize the glass. The composition of the Bocholtz glass is compared with that of other Roman glass, and implications for production models, trade and use of colourless glass objects are discussed. On the basis of isotopic and major element variation, we conclude that the antimony ore presumably originated from different mines.  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