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   60篇
  免费   3篇
  2019年   1篇
  2018年   5篇
  2017年   1篇
  2016年   9篇
  2015年   5篇
  2014年   8篇
  2013年   11篇
  2012年   4篇
  2011年   2篇
  2010年   2篇
  2008年   2篇
  2007年   1篇
  2005年   3篇
  2003年   1篇
  2002年   3篇
  2001年   2篇
  2000年   2篇
  1999年   1篇
排序方式: 共有63条查询结果,搜索用时 62 毫秒
21.
The aim of this work was to detect imprints on soil properties from former Islamic land use (9th to 11th century) using a multi-method, soil-chemical approach. Four soil profiles (with buried horizons) found in the vicinities of former Islamic settlements in Sicily were analysed for phosphorus (total, organic and inorganic), nitrogen (total, NO3 and NH4+), carbon compounds (δ13C, lipids, polycyclic aromatic hydrocarbons (PAH) and functional groups), physical and chemical C-fractions and the state of soil weathering. Two soil profiles contained ceramic sherds from the Islamic period. Inorganic nitrogen forms, phosphorous and the PAH content indicated strong impacts from traditional agriculture and/or burning. Radiocarbon dating of soil organic carbon (SOC) fractions from buried horizons showed that distinct changes must have occurred during the Islamic epoch. The isotopic composition of SOC indicated that land use was probably different in earlier times. C4 plant cultivation was expected but surprisingly lipid analyses did not confirm this. A high amount of aliphates and low C/N ratio indicated a good, long-term SOC stabilisation under the native conditions combined with Islamic land use. The irrigation of the soils probably increased the production of weakly-crystalline Fe forms that helped to stabilise SOC.  相似文献   
22.
The type (and only known) specimen of Melbournopterus crossotus Caster & Kjellesvig-Waering, an enigmatic late Silurian fossil that was initially assigned to the eurypterid family Stylonuridae, is critically examined for the first time in 60 years. It is reinterpreted as most likely the dorsal valve of a craniate brachiopod, with prominent paired adductor muscle scars (described originally as ‘lateral eyes’) situated anteromedially, a short hingeline and a spinose anterior margin.

James C. Lamsdell [lamsdell@ku.edu], Department of Geology and Paleontological Institute, University of Kansas, 1475 Jayhawk Boulevard, Lawrence, KS 66045, USA; Ian G. Percival [ian.percival@industry.nsw.gov.au], Geological Survey of New South Wales, W.B. Clarke Geoscience Centre, 947–953 Londonderry Road, Londonderry NSW 2753, Australia; Markus Poschmann [markus.poschmann@gdke.rlp.de], Generaldirektion Kulturelles Erbe RLP, Direktion Landesarchäologie, Referat Erdgeschichte, Große Langgasse 29, D-55116 Mainz, Germany. Received 12.10.2012; revised 13.12.2012; accepted 26.12.2012.  相似文献   
23.
24.
Today pilgrimage is experiencing an increasing interest, although motives are notable changing. Sites along pilgrim routes normally profit in an economically way. But until today regional economic effects of even very small pilgrimage sites are underexplored. Therefore economic impulses of the pilgrimage site in Biberbach (Bavaria) were identified using interviews and calculations. According to that the 10,000 visitors per year generate nearly 30,000 € gross turnover and 0.5 jobs. So even small pilgrimage sites can obviously produce a notable increase of local EVA.  相似文献   
25.
This article summarizes the evolution of consumption in Germany in the last decades with special focus on the intricacy of demand. The authors discuss some established approaches of marketing and compare it with the actual impact of basic meta trends. Further, the impact of consumption on establish retail locations and new areas to supply is discussed.  相似文献   
26.
This study explores the relationship between dietary patterns and social structure in a pre-industrial mining community in Salberget, Sweden c. 1470 to 1600 A.D. using a combination of different research approaches and tools, including archaeology, osteology, bone chemistry and history. The correlation between demographic criteria (sex and age) and archaeological variables (burial type and burial location) shows that Salberget was a highly stratified community. Group diets were investigated through analyses of stable isotopes (carbon, δ 13C, and nitrogen, δ 15N) of bone collagen from a sub-sample of individuals buried at the site (n = 67), interpreted alongside data from human dental lesions and deficiencies, animal bone waste and information on eating habits extracted from the extensive historical documents regarding mining activities at Salberget. These integrated analyses provide a clear association between social status and diet and confirm that social status, and to a lesser extent sex, gender and age, likely governed food choice and opportunity in this diverse community.  相似文献   
27.
The aim of this article is to examine conceptually and empirically how innovative firms combine knowledge (1) provided by different sources, (2) accessed at different spatial scales and (3) acquired through different channels. We add to the conceptual debate by contrasting and synthesising the perspectives offered on these issues by four key concepts, namely the local buzz and global pipelines argument, the knowledge-base approach, the notions of Science–Technology–Innovation and Doing–Using–Interacting modes of innovation as well as the regional innovation systems concept. The empirical part of the article contains an analysis of knowledge-sourcing activities employed by 181 firms belonging to the Austrian automotive supplier industry. Our findings reveal that it is, indeed, combinations of knowledge sourced from different partners located at different spatial scales and acquired through different channels that are relevant. However, it is particular combinations that dominate while others are negligible. Austrian automotive supplier firms combine knowledge provided by customers with knowledge inputs from a variety of other sources. Most of the combinations involve the European or global levels combined with the regional and/or national level. Finally, firms combine spillovers with a variety of other channels to acquire innovation-relevant knowledge.  相似文献   
28.
29.
Abstract. There are many disagreements among the three main paradigms of the nationalism literature. Yet most modernists, ethno‐symbolists and constructivists agree that elites play a key role in inventing and re‐inventing nations. Notwithstanding this insight, none of these schools of thought has generated a compelling answer to the question of why the inventors of a certain nation build, out of an infinite number of possibilities, a particular nationness. Analysing the case of twentieth century Irish identity, this article seeks to shed light on this question by inquiring into the process through which elites come to imagine the nation that they seek to build. I argue that epistemic understandings of the world delineate which kinds of national identity are conceivable for, and plausible to, nation‐building elites.  相似文献   
30.
The knowledge base concept in the past was often applied in its “pure form”, i.e. it was assumed that there are dominant knowledge bases in particular sectors and firms shaping knowledge and innovation processes and related networks. For “analytical sectors” such as biotech, it has been argued that codified knowledge generated by universities and R&D organizations is the key for innovation, whereas “synthetic sectors” such as machinery innovate more incrementally by recombining existing knowledge often drawn from suppliers or service firms. Empirical literature has partly confirmed these patters, but also shown more complex knowledge processes. More recently it has been argued that combinations of different knowledge bases might enhance the innovation performance of firms. For example in “analytical sectors”, firms might benefit not just from new and basic knowledge generated by research, but also from recombining existing and applied knowledge or by drawing on symbolic knowledge. Combinatorial knowledge bases might also be relevant for “synthetic” and “symbolic sectors”, but in different forms. This study investigates for the ICT sector in regions of Austria if the reliance on combinatorial knowledge leads to a better innovation performance than the use of more narrow knowledge bases.  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