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   1973篇
  免费   57篇
  2023年   9篇
  2020年   40篇
  2019年   58篇
  2018年   49篇
  2017年   77篇
  2016年   78篇
  2015年   26篇
  2014年   49篇
  2013年   584篇
  2012年   49篇
  2011年   59篇
  2010年   47篇
  2009年   61篇
  2008年   50篇
  2007年   47篇
  2006年   41篇
  2005年   36篇
  2004年   43篇
  2003年   25篇
  2002年   30篇
  2001年   27篇
  2000年   16篇
  1999年   35篇
  1998年   16篇
  1997年   18篇
  1996年   16篇
  1995年   21篇
  1994年   20篇
  1993年   11篇
  1992年   12篇
  1991年   13篇
  1990年   16篇
  1989年   13篇
  1987年   11篇
  1986年   17篇
  1985年   20篇
  1984年   20篇
  1983年   23篇
  1982年   19篇
  1981年   10篇
  1980年   16篇
  1979年   27篇
  1978年   26篇
  1977年   9篇
  1976年   19篇
  1975年   18篇
  1974年   10篇
  1973年   12篇
  1972年   12篇
  1970年   11篇
排序方式: 共有2030条查询结果,搜索用时 15 毫秒
991.
992.
This article investigates how expansive new security projects have gained both legitimacy and immediacy as part of the 'global war on terror' by analysing the process that led to the fencing and securitising of the border between India and Bangladesh. The framing of the 'enemy other' in the global war on terror relies on two crucial shifts from previous geopolitical boundary narratives. First, the enemy other is described as not only being violent but also as outside the boundaries of modernity. Second, the enemy other is represented as posing a global and interconnected threat that is no longer limited by geography. These two shifts are used to justify the new preventative responses of pre-emptive military action abroad and the securitisation of the borders of the state. This article argues that in India the good and evil framing of the global war on terror was mapped onto longstanding communal distinctions between Hindus and Muslims. In the process, Pakistan, Bangladesh and increasingly Muslims generally are described as violent, irrational and a threat to the security of the Indian state. These changes led to a profound shift in the borderlands of the Indian state of West Bengal, where fencing and securitising the border with Bangladesh was previously resisted, but now is deemed essential. The article concludes that the framing of the war on terror as a global and interconnected problem has allowed sovereign states to consolidate power and move substantially closer to the territorial ideal of a closed and bounded container of an orderly population by attempting to lock down political borders.  相似文献   
993.
ABSTRACT Spatial heterogeneity at the city level is crucial for explaining local inequality. This heterogeneity will continue from a cultural perspective, an age profile perspective, and a productivity perspective. The process of catching up to the technological leader is influenced by geographic proximity and local input–output linkages, particularly to upstream industries. Heterogeneity of urbanization patterns and spatial linkages affect foreign direct investment flows. The relative power of the economic agglomerating and spreading forces are not scale neutral but heterogeneous, more specifically: spatial linkages are found to be more important at higher levels of aggregation.  相似文献   
994.
995.
In this article, we trace the evolution of punctuated equilibrium theories of the policy process to the development of a full theory of government information processing. Noting that punctuated equilibrium is one realization of a larger theory of government information processing, we outline a research agenda for the study of agenda setting, policy dynamics, and information flows in the policy process. In doing so, we relate the study of government information processing to such important features of American government as inter-institutional dynamics and delegation in the policy process.  相似文献   
996.
We argue that the treatment of trans-subsystem change, and particularly the role of public opinion in fostering such change, within the Advocacy Coalition Framework (ACF) has been underspecified. We propose a model of "policy topography" that combines the concepts of public opinion, clusters of linked subsystems, and policy issue venues. While the ACF has characterized subsystems as relatively self-contained, we argue that they are more usefully understood as operating in a relatively permeable fashion among evolving clusters of subsystems linked together by networked relations, strategically overlapping policy considerations, and public opinion disruptions. The "policy topography" model offers opportunities to assess the relationships across policy subsystems, and to better specify the critical relationship between public policy and mass opinions. We offer examples, and suggest hypotheses along with avenues for appropriate empirical analysis.  相似文献   
997.
The Middle Son valley in north-central India preserves extensive Quaternary alluvial deposits. A long history of archaeological and geological research in the valley has resulted in the discovery of lithic assemblages ranging from Lower Palaeolithic to microlithic, a rich corpus of fossilised faunal remains, and ash deposits from the 74,000 year-old Toba supereruption. This paper reviews the chronology and stratigraphy of the valley’s Quaternary sediments, and presents a model that hypothesizes the temporal sequence of important lithic assemblages from excavated and surface contexts. Artefacts in these assemblages are analysed and changes in lithic technology through time are described; this evidence is used to propose shifts in hominin behaviour and demographic structure in this region during the Upper Pleistocene. Recognising gaps in our understanding of the Middle Son record, future avenues of research are recommended that will build upon previous research and address questions of palaeoanthropological significance. The Middle Son valley preserves a long and rich record of hominin occupation from all periods of the Palaeolithic that is rarely paralleled by other sites in India.  相似文献   
998.
Variations in the 13C/12C ratios of wheat grain at different spatial and temporal scales are examined by analysis of modern samples, including harvests of einkorn and durum wheat from Greece, and serve as a guide to interpreting data for Bronze Age grains from Assiros Toumba. The normal distribution and low variability of δ13C values of einkorn from 24 containers in the Assiros storerooms are consistent with pooling of local harvests, but less likely to represent the harvest of several years or include grain imported from further afield. Correlation between emmer and spelt δ13C values provides strong support for other evidence that these were grown together as a maslin crop. 13C discrimination (Δ) for the Bronze Age samples is estimated to be 2.5‰ larger than at present, and would be consistent with an intensive, horticultural regime of cereal cultivation, possibly involving some watering.  相似文献   
999.
It is sixteen years since the first detection of Mycobacterium tuberculosis DNA in archaeological specimens, yet the validity of findings continues to be questioned. Rigorous scientific scrutiny and debate is valuable and has led to a coalescence of procedures and precautions amongst those actively engaged in this work. It is disappointing that these good practices are not recognised by certain scientists whose primary expertise is in the related fields of archaeology, palaeopathology, and eukaryote ancient DNA. There is a danger that by constant repetition, disputable and inadequately justified concerns will assume the status of self-perpetuating myths and misunderstandings. We discuss these issues with reference to a recent article in this journal, in which clear peer-reviewed scientific data were specifically targeted as part of a general critique of the field of the palaeomicrobiology of tuberculosis. We believe we have given sufficient evidence and cogent argument to persuade the unbiased reader that the views in the critique by Wilbur et al. are unjustified.  相似文献   
1000.
A combined near surface geophysical survey conducted in San Miguel Tocuila show that geophysical methods offer the possibility to characterize and reconstruct the geometry of subsurface structures without destroying the deposits, providing a way to find solutions to the questions of archaeological or engineering significance. The survey consisted of the application magnetometry, seismic refraction tomography (SRT) and ground penetrating radar (GPR) within a depth range of 10 m. Before Spanier conquest San Miguel Tocuila was a very prominent suburb of the main Aztec ceremonial complex located on the eastern margin of Lake Texcoco, central Mexico, where several mounds known as Tlateles in Nahuatl language have been identified. Nowadays, the rapid expansion of Mexico City's metropolitan area within the last four decades has strongly influenced Tocuila's environment and has compromised several of its archaeological and ancient human settlements. This study shows how the high resolution imagining of non-invasive geophysical methodologies in addition with surface archaeological studies [Parsons, J.R., 1971. Prehistoric Settlement Patterns in the Texcoco Region, Mexico. Memoirs of the Museum of Anthropology, University of Michigan, Number 3] provide different kinds of information that characterize the subsoil and a buried structure. Based on the history of the ancient settlements in the zone and considering the characteristics of shape and height of the structure, we interpreted that the subsurface images obtained depict a buried Tlatel which corresponds to a ceremonial–civic center of Late Aztec times.  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