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   4829篇
  免费   132篇
  2024年   15篇
  2023年   64篇
  2022年   91篇
  2021年   85篇
  2020年   175篇
  2019年   161篇
  2018年   177篇
  2017年   174篇
  2016年   193篇
  2015年   119篇
  2014年   140篇
  2013年   477篇
  2012年   297篇
  2011年   272篇
  2010年   210篇
  2009年   262篇
  2008年   277篇
  2007年   321篇
  2006年   281篇
  2005年   282篇
  2004年   188篇
  2003年   167篇
  2002年   186篇
  2001年   81篇
  2000年   111篇
  1999年   34篇
  1998年   16篇
  1997年   16篇
  1996年   11篇
  1995年   10篇
  1994年   14篇
  1993年   14篇
  1992年   6篇
  1991年   8篇
  1990年   6篇
  1986年   1篇
  1985年   2篇
  1984年   1篇
  1983年   5篇
  1982年   4篇
  1981年   2篇
  1980年   2篇
  1979年   1篇
  1978年   2篇
排序方式: 共有4961条查询结果,搜索用时 15 毫秒
71.
The long established distinction between civic nationalism and ethnonationalism is useful heuristically to understand different dimensions of nationalism and perhaps track a movement from ethnic forms to civic allegiances, though some have challenged its empirical veracity and others question the normative implications of such a distinction. This paper demonstrates the ways in which the two are elided in everyday discourses about migrants in Australia. We argue suspicion of cultural difference, identified more than three decades ago as the new racism, has given way to talk of the need for migrants to ‘follow the law’. This serves rhetorically to reinforce the notion that migrants, often implied to overlap with the category ‘Muslims’, are insisting on breaking the law and/or changing it and are therefore culturally incompatible with a modern liberal democracy. We argue that since ethnic nationalism, like racism, is out of favour normatively, ethnic nationalist arguments are now superficially concealed beneath the acceptable language of civic nationalism. The manner in which this occurs is mapped discursively using data from a corpus of twenty seven focus groups conducted around Australia.  相似文献   
72.
CO2 injected into rock formations for deep geological storage must not leak to surface, since this would be economically and environmentally unfavourable, and could present a human health hazard. In Italy natural CO2 degassing to the surface via seeps is widespread, providing an insight into the various styles of subsurface ‘plumbing’ as well as surface expression of CO2 fluids. Here we investigate surface controls on the distribution of CO2 seep characteristics (type, flux and temperature) using a large geographical and historical data set. When the locations of documented seeps are compared to a synthetic statistically random data set, we find that the nature of the CO2 seeps is most strongly governed by the flow properties of the outcropping rocks, and local topography. Where low‐permeability rocks outcrop, numerous dry seeps occur and have a range of fluxes. Aqueous fluid flow will be limited in these low‐permeability rocks, and so relative permeability effects may enable preferential CO2 flow. CO2 vents typically occur along faults in rocks that are located above the water table or are low permeability. Diffuse seeps develop where CO2 (laterally supplied by these faults) emerges from the vadose zone and where CO2 degassing from groundwater follows a different flow path due to flow differences for water and CO2 gas. Bubbling water seeps (characterized by water bubbling with CO2) arise where CO2 supply enters the phreatic zone or an aquifer. CO2‐rich springs often emerge where valleys erode into CO2 aquifers, and these are typically high flux seeps. Seep type is known to influence human health risk at CO2 seeps in Italy, as well as the topography surrounding the seep which affects the rate of gas dispersion by wind. Identifying the physical controls on potential seep locations and seep type above engineered CO2 storage operations is therefore crucial to targeted site monitoring strategy and risk assessment. The surface geology and topography above a CO2 store must therefore be characterized in order to design the most effective monitoring strategy.  相似文献   
73.
In the fourth millennium BP, there were major environmental and cultural changes on the Andean altiplano of South America, but the chronology remains vague. A recent synthesis describes a slow, gradual transition from hunting and gathering to agropastoralism. This proposal is tested by refining the date of the onset of more humid and stable conditions, around 3550 cal BP, based on a Bayesian model of 26 dates from Lake Wiñaymarka and an updated calculation of the lacustrine offset. This is compared to Bayesian models of 191 dates from 20 archaeological sites, which incorporate a number of recently processed radiocarbon dates. A synthesis is presented of 15 full coverage surveys, a summed probability distribution, and a Bayesian model of the transition to ceramics, which together support a scenario of a very rapid demographic increase. Fourteen models from archaeological sites are cross-referenced in a composite model, which identifies a brief, altiplano-wide emergence of agropastoralism with starting and ending boundaries of 3540 and 3120 cal BP, respectively. This starting boundary correlates strongly with the onset of improving environmental conditions, indicating synchronous cultural and environmental change. The suite of accelerating cultural changes included a marked reduction in mobility, a demographic surge, increased subsistence diversity, the adoption of ceramics, farming and the integration of camelid herding into a remarkably resilient economic strategy still in use today. This is a highly relevant but yet to be used comparative case study for the variable tempos of ‘big histories’, and ecocultural interactions that generate rapid, emergent episodes of wide-spread and enduring cultural change.  相似文献   
74.
宋广波 《安徽史学》2015,(6):163-168
本文考证了胡适致任鸿隽、胡近仁两封信的写作时间,纠正了以往的误判。将信件的内容置于广阔的历史背景下加以考察,并与相关史料参考互证,不仅有助于考察信件的写作时间,且有助于理解信函的真实含义。  相似文献   
75.
徐俊嵩 《安徽史学》2015,(2):120-124
宗祧承继是宗族研究的一个重要内容,学界对明清宗族继承问题研究已久,也取得了丰硕的成果,对于越继和降继,则甚少涉及。先贤们对徽州宗族社会有诸多理想性的描述,然而这些描述在很大程度上只是一种表象,现实的徽州社会要复杂得多,越继和降继就是其表现之一。探讨这两种承继方式,对于更好地解读宗祧承继和剖析明清时期徽州宗族社会的发展脉络,都有一定的积极意义。  相似文献   
76.
Siraf is well‐known archaeologically and historically as an ancient port in the Persian Gulf that prospered during the medieval period. Siraf played a leading role in facilitating maritime and terrestrial trade, connecting long‐distance Indian Ocean and China routes with those in the Gulf region. Despite its history, no previous research has been dedicated to the maritime infrastructure of Siraf. Through the ‘2012 Siraf pilot project’ a preliminary survey of the underwater and shoreline remains of this ancient port city was conducted. The site's location is unique in many respects to trade routes and logistical considerations; however, its maritime infrastructure is difficult to assess in light of the extensive threats to the site.  相似文献   
77.
This article looks into what happened to the children of Dutch Nazi collaborators after the liberation of the Netherlands in May 1945. The author first outlines the historical context in which these children lived and the manner in which they recounted and recorded their memories much later. In combination with new archival research on social-welfare policy and ‘re-education’ of former National Socialist youth, this puts the discourse that dominated the Dutch debate, that is, the discourse of the ‘innocent child’ harshly punished by society, in a different light. The framework of the innocent child being punished by a cruel society obscured our view of experiences that did not fit this mould. Furthermore, it made the values and norms that were current during the reconstruction period disappear from the picture: the bad memories of children of collaborators partly originate in policy that was considered normal in those days. This, however, should not obscure the impact of the vulnerable social position which these children experienced after the war.  相似文献   
78.
Abstract

Engaging communities in the protection of heritage means that the communities living around the heritage sites are involved in the process of identifying issues that affect the conservation of these sites and can propose ways by which they can be addressed. In Ghana, the Elmina Castle project shows close collaboration between the communities living around these slave forts and castles, the legal custodians, and other stakeholders. This case study unpicks the process to show how the existing traditional systems were approached and involved. The result of this participatory collaboration is a strategic document which will be implemented to ensure proper protection of these sites in the wake of development and modernization.  相似文献   
79.
80.
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