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   322篇
  免费   19篇
  2024年   2篇
  2023年   8篇
  2022年   2篇
  2021年   1篇
  2020年   12篇
  2019年   16篇
  2018年   33篇
  2017年   36篇
  2016年   28篇
  2015年   13篇
  2014年   20篇
  2013年   85篇
  2012年   6篇
  2011年   5篇
  2010年   11篇
  2009年   9篇
  2008年   9篇
  2007年   4篇
  2006年   2篇
  2005年   1篇
  2004年   1篇
  2001年   2篇
  2000年   2篇
  1999年   1篇
  1998年   6篇
  1997年   1篇
  1996年   4篇
  1995年   3篇
  1993年   2篇
  1992年   2篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1987年   3篇
  1986年   1篇
  1985年   1篇
  1982年   1篇
  1981年   1篇
  1979年   1篇
  1978年   1篇
  1977年   1篇
  1957年   1篇
排序方式: 共有341条查询结果,搜索用时 31 毫秒
91.
A non-invasive procedure for assessing and interpreting the pigments of rock art paintings through computer vision and photogrammetric techniques is presented. The method is designed to document and interpret poorly preserved pigments by making use of advanced techniques of photogrammetry and computational imaging. Two different software solutions that were developed by the authors have been used for this purpose. Finally, two case studies of rock art paintings from Spain have been analysed, which show the reliability of the method.  相似文献   
92.
93.
In the Amazon Basin, within a landscape of infertile soils, fertile Anthrosols of pre-Columbian origin occur (Amazonian Dark Earths or terra preta de Índio). These soils are characterized by high amounts of charred organic matter (black carbon, biochar) and high nutrient stocks. Frequently, they were considered as sign for intensive landscape domestication by way of sedentary agriculture and as sign for large settlements in pre-Columbian Amazonia. Beyond the archaeological interest in Amazonian Dark Earths, they increasingly receive attention because it is assumed that they could serve as a model for sustainable agriculture in the humid tropics (terra preta nova). Both questions lack information about the pre-Columbian practices which were responsible for the genesis of Amazonian Dark Earths. It has often been hypothesized that deposition of faeces could have contributed to the high nutrient stocks in these soils, but no study has focussed on this question yet. We analyzed the biomarkers for faeces 5β-stanols as well as their precursors and their 5α-isomers in Amazonian Dark Earths and reference soils to investigate the input of faeces into Amazonian Dark Earths. Using Amazonian Dark Earths as example, we discuss the application of threshold values for specific stanols to evaluate faeces deposition in archaeological soils and demonstrate an alternative approach which is based on a comparison of the concentration patterns of 5β-stanols with the concentration patterns of their precursors and their 5α-isomers as well as with local backgrounds. The concentration patterns of sterols show that faeces were deposited on Amazonian Dark Earths.  相似文献   
94.
95.
Animal dung is evaluated here as a tool to reconstruct recent societal and environmental changes. Studies completed on the macro- and micro-contents from dung deposited in a mountain cave in Catalonia during the 1970–1980s, preceding the socio-economic changes in the area, was supplemented by the testimony of the last shepherd alive in the area. This information was also compared with evidence from aerial photographs of the area surrounding the cave taken in 1956 and 2009. Although taphonomic distortion of the dung shape precluded its assignment to its producers based on morphology, information from the organic remains reflects the agro-pastoral activities in the mountainous area of the Catalan coast. A lack of calcium phosphate and abundant phytolith and epidermal remains from wild species indicates that the dung was excreted by ovicaprines, who sheltered in the cave during spells of adverse weather. These indicators also signify that the animals fed only on natural vegetation. Insect remains in the dung include fragments of chafers, dung and ground beetles, bees and ants, and whilst the latter may have foraged in the cave, the others may have been accidentally ingested by herbivores. The nannofossils and diatoms found in the dung derive from tertiary crops 4 km away from the cave but within the range of the ovicaprine herd. The lack of cereal and vegetable remains in the dung is consistent with the ethnographic record that shepherds and farmers could not afford to supplement the herds’ diet with fodder crops or grain, a consequence of the low productivity of the local subsistence agriculture. This study further discusses the socio-economic impacts of the introduction of intensive farming, industrialisation and tourism in Catalonia during the latter part of the last century and how they are represented in the dung.  相似文献   
96.
This article examines separation movements in Britain’s Australasian colonies during the first decade of responsible government, 1856–65. Separation movements sought to carve new colonies from the territory of existing ones or, in the case of a number of New Zealand movements, to create new provinces within that colony’s quasi-federal system. Their demands rested upon assertions that a colonial or provincial government neglected large and prosperous hinterlands from which considerable revenue was collected. Only one colonial separation movement achieved its goal, but four provinces succeeded. I argue that responsible government played a major role in the success or failure of these movements. Responsibility concentrated authority in a remote capital; colonial separatists desired to exercise this privilege within a smaller new colony that they controlled, but its operation within the larger existing colony provided London with justification to reject most appeals. Further, it allowed New Zealand’s parliament to frame a mechanism that enabled discontented regions to become provinces without referral to local or imperial legislatures. Thus, I provide new insights into the formation of colonial polities and the influence of responsible government on settler political campaigns.  相似文献   
97.
The military is an important factor for the success or failure of democratisation processes. Portugal and Spain provide two paradigmatic cases. Despite their socio-economic, political and cultural similarities, these countries developed very different civil-military relations which significantly impacted their transitions. After having handed power over to a civilian dictator, Salazar, the Portuguese military eventually caused the downfall of his authoritarian Estado Novo regime and steered the transition to democracy. In contrast, the Spanish military, which had helped Franco defeat the Second Republic, remained loyal to the dictator’s principles and, after his death, obstructed the democratisation process. Drawing on primary and secondary sources, this interdisciplinary article contrasts the challenges posed by the military and the policies implemented by the Iberian governments to depoliticise and control it. It shows that the failed coups d’état in these countries helped tighten civilian control and paved the way for democratic consolidation. Using a policy instruments comparative framework, this paper demonstrates that not only the attitudes of the military but also the tools used to keep them under control were substantially different in Portugal and Spain. Historical legacies from the Spanish Civil War, Second World War and Colonial conflicts, as well as contextual factors, serve to explain this variation.  相似文献   
98.
99.
As the largest part of military usage of the territory depends on a thorough analysis of its morphology, spatial analysis with Geographic Information Systems (GIS) software reveals a great potential as a way for studying battlefields and/or other military buildings and scenarios from the past, while supporting interpretations of territorial occupation and related organization of military forces through event simulation. This paper presents a GIS-based method to model and assess the permeability of historical defensive systems from the period that preceded the mechanization of warfare of the late nineteenth century, i.e., based on artillery installed in fortifications. The method was applied to analyze the permeability of the Lines of Torres Vedras (LTV) defensive system, a multi-line fortification complex which was operational during the Peninsular War in the beginning of the nineteenth century and located north of Lisbon, Portugal. The structures of the LTV and local terrain were modelled in GIS using a set of proposed parameters that support territorial analysis, combined with the capability of contemporary weaponry. A methodical quantification and combination of these parameters enabled a better understanding of the systemic design of the defensive lines in terms of its permeability, contributing to a discussion of the LTV particular military setting based on the interpretation of these indicators. Global and sectorial analyses of the permeability of the LTV defensive system were conducted.  相似文献   
100.
The term “millets” is used to identify several genera of grasses (Poaceae), most of which belong to the subfamily Panicoideae. Millets are one of the major food sources in arid and semi-arid areas of the world and they have been important crops in the prehistory of Africa and Eurasia. In this paper, we discuss phytoliths and starch grains from two of the less studied major millets (Pennisetum glaucum and Sorghum bicolor) as well as from some small millet species that are not normally considered of much importance (so-called forgotten millets: Digitaria ciliaris, Echinochloa colona, Echinochloa frumentacea, Brachiaria ramosa, Setaria pumila and Setaria verticillata). The preliminary results of this study on phytolith morphology, both at single and joined (silica skeletons) morphotypes, and starch grains show great potentials for the identification of different genus or species on the basis of microremains.  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