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   6111篇
  免费   167篇
  2024年   21篇
  2023年   80篇
  2022年   108篇
  2021年   94篇
  2020年   258篇
  2019年   233篇
  2018年   266篇
  2017年   259篇
  2016年   283篇
  2015年   156篇
  2014年   186篇
  2013年   761篇
  2012年   349篇
  2011年   352篇
  2010年   262篇
  2009年   302篇
  2008年   325篇
  2007年   366篇
  2006年   332篇
  2005年   315篇
  2004年   201篇
  2003年   190篇
  2002年   193篇
  2001年   96篇
  2000年   126篇
  1999年   39篇
  1998年   22篇
  1997年   19篇
  1996年   15篇
  1995年   11篇
  1994年   15篇
  1993年   13篇
  1992年   6篇
  1991年   8篇
  1990年   5篇
  1986年   1篇
  1983年   5篇
  1982年   2篇
  1980年   1篇
  1978年   2篇
排序方式: 共有6278条查询结果,搜索用时 31 毫秒
11.
古人发型是文化界长期关注的一个重要现象。发型不仅是时代的特征与时尚的符号,也是各个族群的辨识标志。从北朝到隋唐的中古社会,"剪头胡雏"的文物图像屡屡出现,一般来说,此类胡人形象是剪发而不是束发,在当时以"高髻为尚"的社会习俗中,"剪头胡雏"发型是有着"阶级感"的存在,是有关底层胡人的直观艺术产物。也说明当时入华胡人还没有彻底"汉化",仍然保留着本族群的发型特征。该发式是胡人与汉人的区别,也是其身份归属的象征。  相似文献   
12.
The site of Kharaib al-Dasht, located on the northern coast of Failaka, is a late Islamic settlement with an extensive fishing infrastructure. It has been excavated since 2013 by the Kuwaiti-Polish Archaeological Mission. The ceramic assemblage collected so far exceeds 18,000 fragments. The sherds underwent technological and typological analyses, which demonstrated a wide diversity of local common kitchen wares, consistent with the needs of households specialised in fishing. A considerable percentage of imported vessels was brought to Failaka from the Arabian Gulf and Persia, though Far Eastern luxury tableware was also attested. This paper demonstrates the socioeconomic role of Kharaib al-Dasht in the context of trade exchange on the microregional (Kuwait) and macroregional (the Gulf, South and Eastern Asia) scales in the eighteenth and nineteenth centuries.  相似文献   
13.
This paper discusses the experiences of Christian Montserratian residents through the 1995-present eruptions of the Soufrière Hills Volcano, highlighting that while the earthly powers of the volcano are fundamentally nonhuman, they are known and understood in a diversity of ways by different actors – and they interfere in politics and the production of knowledge. Montserrat, as a UK Overseas Territory, is a non-sovereign territory with a strong Christian identity that has been enhanced by its geological experience. At the same time, the UK has used the eruption to hold greater legislative control over the island. A final group of stakeholders in the eruption is the volcanologists, mainly from the UK until 2010, whose terminology and knowledge-world has had significant impact on the island, but has also been significantly extended by it. The paper ultimately uses this example to suggest that while there are useful and important insights from the “ontological turn” (incorporating vitalism, materialism, speculative realism) in thinking about the “lively earth”, the enactment of volcanic risk management at the governmental level also constitutes a knowledge-practice that must be approached critically to avoid the pitfalls of modernist science and ensure meaningful political change.  相似文献   
14.
In recent years, bio-energy with carbon capture and storage (BECCS) has been awarded a key role in climate mitigation scenarios explored by integrated assessment models and referenced in reports by the Intergovernmental Panel on Climate Change. Because a majority of scenarios limiting global warming to 2 °C or 1,5 °C include vast deployment of BECCS, a critical discussion has emerged among experts about the moral implications of thus introducing an unproven technology into the policy realm.In this paper, we analyse this discussion as it has played out between 2013 and 2019, with a focus on how expert narratives are constructed in the mass media about the possibilities for decarbonisation within the current political-economic order. We find there are almost no narratives that support massive deployment of BECCS, and that all narratives presuppose limits to decarbonisation imposed by the current political-economic system. The perception of such limits lead some to argue, through deterministic and apolitical narratives, for the necessity of negative emissions technologies, while others argue instead that “degrowth” is the only solution. Thus, there is a distinct lack of positive narratives about how capitalism can bring about decarbonisation.  相似文献   
15.
公共交通是我国老年人出行的主要交通方式之一,公交移动性是衡量老年人生活质量和幸福感的重要指标。从季节和空间双重维度分析老年人公交移动性的影响因素有助于深入理解老年人出行行为机制。利用公交刷卡数据和地理探测器方法分析了季节时空因子对老年人公交移动性的影响。研究发现:①不同季节中空间因子对老年人移动频率、移动半径和移动熵的解释力和显著性存在明显差异,对老年人移动性影响机制的分析应考虑时空变化的双重影响;②不同空间因子之间以及季节与空间因子之间的交互作用可以显著增强对老年人移动性空间分异的解释力,考虑多个因素的协同效应对深入理解老年人行为有一定帮助。研究试图拓宽老年人移动性影响因素的分析思路,为老年宜居城市建设和城市移动性规划提供重要支撑。  相似文献   
16.
聚醋酸乙烯酯(PVAc)乳液是常见的彩绘类文物保护材料。采用激光粒度仪、热重/差热分析、红外光谱、X-射线衍射、扫描电镜、透射电镜等表征了PVAc乳液的粒径以及胶膜的热稳定性、结构和形貌;采用粘度计、表面张力仪、pH计、电导率仪等研究了乳液浓度与其粘度、表面张力、pH、电导率的关系;通过冻融、室温-高温放置、离心分离研究了乳液的稳定性;同时用PVAc乳液对模拟起甲和酥碱的壁画进行了修复。结果表明,PVAc乳液粒径呈双峰分布,小粒子的平均粒径为380 nm,大粒子的平均粒径为5.85μm;乳液胶膜为非结晶物质,胶膜热重的最终质量残留为1.54%,335℃出现放热峰。PVAc乳液的电导率随浓度的增大而增大,pH随浓度的增大而下降;相同温度下表面张力随浓度的增大而基本呈现低浓度下降,高浓度上升的趋势。相同浓度下,表面张力随温度升高而无显著变化,表明PVAc乳液的表面张力受温度变化影响不大。相同温度下,乳液粘度随浓度的增大而增大;相同浓度下,乳液的粘度随温度的升高而降低。冻融、离心分离和不同温度下静置发现,该乳液出现分层。用该乳液对模拟起甲和酥碱壁画修复后,再分别老化20个循环和12个循环,发现颜料层再次空鼓、起甲。综合分析,说明实验中所使用的该种PVAc稳定性和抗老化能力较弱,在修复彩绘类文物中应慎重选择PVAc的种类,综合考虑PVAc的使用浓度、环境因素对其性能的影响,以达到最佳使用效果。  相似文献   
17.
慈利白公城遗址历史悠久,具有重要的考古价值。该遗址出土了大量木质井壁及少量其他木质文物,为了解这些木材的特点,以及为木材保护提供相关的参考,通过徒手切片,并利用光学显微镜对该遗址出土的10件木质样品进行鉴定。结果表明其中1件为无患子(Sapindus. mukorossi Gaertn.),1件为冷杉(Abies fabri(Mast.)Craib),2件为湖南杨桐(Adinandra. acutifolia Hand.-Mazz.),2件为香椿(Toona sinensis A. Juss.),4件为润楠(Machilus pingii Cheng ex Yang)。通过实验结果,初步推测井壁的制作在当时是比较重要的工作,此时已经在选择性地使用木质井壁原料。从树种适宜生长的环境上看,同时期该遗址附近可能是以阔叶材为主的针阔叶混交林,气候温暖湿润。  相似文献   
18.
Critical physical geography (CPG) calls for integrative research on material landscapes and the socio-political dynamics of scientific knowledge production. Network analysis, a rich tradition of tools and approaches for analyzing relational information, has seen little use in the CPG literature to date. This represents a fruitful opportunity, as many of CPG's core interests—knowledge politics, histories of scientific concepts, and ecosocial relations—can be effectively analyzed using network techniques. In this article, I argue for adapting network approaches to CPG. First, I provide an overview of various network concepts, approaches, and their origins. I then discuss bibliometric network techniques for “science mapping” including co-word, co-authorship, and citation analyses. Next, I describe discourse network analysis, a recent mixed-method approach from political science. Finally, I discuss overlaps with emerging approaches from qualitative and visual network analysis. In each section, I provide existing and hypothetical examples, as well as software and visualization techniques, that demonstrate how network approaches could add new insights to CPG and related scholarship. Linking CPG with the diverse traditions of network analysis has the potential to produce new empirical understandings and bring the field into conversation with a growing body of research that spans the social sciences, natural sciences, and humanities.  相似文献   
19.
In this review essay, I examine the arguments made by Marnie Hughes-Warrington, with Anne Martin, in Big and Little Histories: Sizing Up Ethics in Historiography. While I find much to praise in this history, I also ask critical questions about the impact of non-Western ethics on historical writing, the role of ethics in historical writing generally, the need to further investigate the everyday lifeworlds of history makers in order to fully understand their ethical dispositions, and the relationship between the ethics of history making and engaged forms of historical writing. I conclude this review essay by offering some reflections on the interrelationship between history and memory and the ethics involved in both.  相似文献   
20.
In this paper, we develop a three-region economic geography model with workers of heterogeneous skills and mobility rates to consider how first-nature, regional differences impact both inter- and intraregional inequality. In our model, the skill premium within a region summarizes both the degree of intraregional inequality between mobile, skilled workers and immobile, unskilled workers and the interregional inequality through differences in the welfare of unskilled workers across regions. Regions with the highest skill premium have the greatest degree of intraregional inequality and provide the lowest level of welfare to unskilled workers, relative to other regions. We find that the skill premium will be higher in regions with a greater supply of unskilled labor, lower supply of housing, or are more remote. An increase in a region's housing supply or centrality will lower intraregional inequality and raise the welfare of the local, unskilled workforce. However, the magnitude of these changes are declining in the initial number of skilled workers in the region. The model is extended to consider imperfectly elastic housing supply. The larger the price elasticity of housing, the larger the range of values, such that more populated regions will host a disproportionate share of skilled workers, have lower levels of intraregional inequality, and provide higher levels of welfare for unskilled workers.  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