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   168篇
  免费   9篇
  2024年   1篇
  2023年   2篇
  2022年   1篇
  2021年   2篇
  2020年   2篇
  2019年   10篇
  2018年   16篇
  2017年   11篇
  2016年   17篇
  2015年   8篇
  2014年   11篇
  2013年   34篇
  2012年   11篇
  2011年   8篇
  2010年   7篇
  2009年   9篇
  2008年   6篇
  2007年   4篇
  2005年   1篇
  2004年   1篇
  2003年   1篇
  2002年   1篇
  2001年   1篇
  2000年   1篇
  1999年   2篇
  1998年   3篇
  1997年   1篇
  1996年   2篇
  1993年   1篇
  1978年   1篇
  1975年   1篇
排序方式: 共有177条查询结果,搜索用时 15 毫秒
41.
42.
Our study explores research avenues that can help policymakers to assess regional capabilities for ‘green’ economic restructuring. After reviewing the relevant literature, and envisioning research paths which consider both market transactions and externalities, we propose possible ways to translate past research findings into novel statistical tools. Our point of departure is the ‘skill relatedness’ among economic sectors in Norway, as inferred from intersectoral labour flows (years 2008–2014). Then, on the basis of the industrial composition in each of the 161 Norwegian labour market areas, candidate regions that could benefit the most from a ‘green’ restructuring policy, aimed at photovoltaics in our empirical example, are brought forward.  相似文献   
43.
Technological progress has widely been acknowledged as a key driver in the achievement of environmental sustainability, and a new concern has recently arisen for assessing the role of differences in regional innovation performances with respect to the pursuit of pollution targets. We investigate the impact of innovative activities on environmental efficiency at the regional level, adopting a spatial panel data approach to account for dependence between geographical observations and to get deeper insights into spatial knowledge spillovers arising from agglomeration economies. The spatial panel analysis covers 103 Italian provinces (equivalent to NUTS3 regions) on four major air pollutants (i.e., CO2, CH4, NMVOC, CO) over the 1995–2010 period. Our findings show that the state of local technology development, proxied by patents, has a positive impact on GDP emission efficiency and that its magnitude is higher for more localized pollutants as a result of larger spillover effects. Finally, to analyze the Italian North-South dualism of emission levels of pollutants, we offer a spillover effect study to emphasize the remarkable difference among effects in the territory. This calls for closer attention to the local relevance of the pollution damage when environmental impact of innovation strategies is to be evaluated.  相似文献   
44.
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   
45.
Several authors agree that stone surface consolidation works should not significantly alter original mechanical and hygrometric properties of the stones in order to avoid differential stress between the consolidated and non-consolidated parts. Specific limitedly destructive methodologies have been developed for assessing the variation in both mechanical and hygrometric properties, but they require preliminary calibration procedures that are very costly to adopt in terms of both time and money. This research study describes an analytical and experimental procedure aimed at obtaining the necessary hygrometric and mechanical characterization of natural and/or artificial stone, before and after consolidation works, by simply assessing the variation in the distribution of the porous structure.  相似文献   
46.
Hagia Sophia is one of the oldest and most complex existing monuments. Many unanswered questions are still open on the historical and constructive evolution of this monument. The boundaries between the different construction phases and the details of the masonry and materials used in the various phases are still not defined with precision.

The thermographic survey, carried out inside the monument, made ??it possible to answer some of these questions by specifying the exact location of the past interventions and the variability of the materials employed allowing a better understanding of the constructive history of the monument. The technique was applied at a great distance and in normal environmental conditions, taking advantage of the high thermal sensitivity of the instrumentation. The results achieved confirm the validity of the technique in the study of ancient buildings.  相似文献   
47.
48.
Abstract

Surpassing the national perspective usually adopted, the authors confirmed the existence of a pattern of population distribution common to the whole Iberian Peninsula in the long run. This pattern is clearly associated with geographical factors. These variables seem to have more weight in explaining changes between 1877/78 and 1940 than in the period from 1940 to 2001. The observation of the cross-border region has shown that proximity to the frontier has not generated any distinct pattern of population density on either side of the boundary line. The spatial coherence of the observed phenomena throughout the Peninsula and of its evolution, independent of the border between states, reinforces the importance of geographic factors in their explanation. At the same time, this verification opens up new issues related to the effect of national political and economic policies.  相似文献   
49.
Current knowledge about the Mesolithic–Neolithic transition in the Central and Western Mediterranean European regions is deeply limited by the paucity of Late Mesolithic human osteological data and the presence of chronological gaps covering several centuries between the last foragers and the first archaeological evidence of farming peoples. In this work, we present new data to fill these gaps. We provide direct AMS radiocarbon dating and carbon (δ13C) and nitrogen (δ15N) stable isotope analysis were carried out on bone collagen samples of two single burials from the recently discovered open-air Late Mesolithic site of Casa Corona (Villena, Spain). The results shed new light on the chronology and subsistence patterns of the last Mesolithic communities in the Central Mediterranean region of the Iberian Peninsula. Radiocarbon results date the human remains and funerary activity of the site to 6059–5849 cal BC, statistically different from other Late Mesolithic sites and the earliest Neolithic contexts, and bridging the 500 yrs chronological gap of the Mesolithic–Neolithic transition from the area. Isotopic evidence shows that diet was based on terrestrial resources despite the proximity to the site of lagoon and marine ecosystems. This and previous isotope studies from the region suggest a lower reliance upon marine resources than for Atlantic and Cantabrian sites, although intra-regional patterns of neighbouring Mesolithic populations exhibit both fully terrestrial diets and diets with significant amounts of aquatic resources in them. We hypothesize that in the Central Mediterranean region of Spain the Late Mesolithic dietary adaptations imposed structural limits on demographic growth of the last foragers and favoured rapid assimilation by the earliest Neolithic populations.  相似文献   
50.
An archaeometric study was carried out on 40 gold leaf tesserae from mosaics in Italy dated 1st to the 9th century AD. Glass layers and gold leaf were both analysed by X-ray microanalysis. The main aim was the identification of the composition of the glass and of the gold leaf, in order to assess the variations in composition and nature of the tesserae in the examined period.  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