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   208篇
  免费   7篇
  2024年   2篇
  2023年   4篇
  2022年   1篇
  2021年   2篇
  2020年   5篇
  2019年   12篇
  2018年   32篇
  2017年   14篇
  2016年   17篇
  2015年   2篇
  2014年   5篇
  2013年   39篇
  2012年   9篇
  2011年   11篇
  2010年   11篇
  2009年   5篇
  2008年   5篇
  2007年   2篇
  2006年   7篇
  2005年   2篇
  2003年   3篇
  2002年   3篇
  2001年   3篇
  2000年   2篇
  1999年   1篇
  1996年   1篇
  1995年   1篇
  1993年   1篇
  1989年   1篇
  1987年   1篇
  1986年   1篇
  1983年   1篇
  1982年   2篇
  1981年   1篇
  1980年   1篇
  1979年   2篇
  1978年   1篇
  1976年   1篇
  1974年   1篇
排序方式: 共有215条查询结果,搜索用时 825 毫秒
51.
52.
Archaeological data reveal two distinctive cultural adaptations on the Pampa and Patagonia of Argentina: terrestrial hunter-gatherers in the former and most of the latter region and maritime hunter-gatherers along the southern extreme. Both adaptations were achieved by the end of the fifth millennium B.C. Thereafter, a stable equilibrium was maintained, with a slow drift toward greater emphasis on resources providing the maximum return for the least effort. The high productivity of the Fuegian environment sustained a population 30 times greater than occupied the Pampa and continental Patagonia prior to Araucanian penetration in the sixteenth century A.D. The long-term stability is attributable to the absence of environmental or demographic pressures or encroachments by neighboring groups, which might have made more intensive exploitation of the environment necessary.  相似文献   
53.
Oil production is an important aspect of ancient Mediterranean economy; therefore, archaeological studies on oil-producing installations using archaeometry and in particular the chemical analysis of absorbed residues is valuable in identifying the substances actually produced and to understand the spatial distribution of the activities carried out at oil mills.Modern contexts may provide a good reference for interpreting the archaeological chemical traces.This study examines the chemical traces in three abandoned oil mills in the Mediterranean: Polveraia (Tuscany, Italy), Martina Franca (Puglia, Italy) and Binibassi (Mallorca, Balearic Islands). To identify the residues released by the production of oil and absorbed by the floors, samples were taken from the floors of these installations and analysed using spot tests aimed at identifying the presence of fatty acids and phosphates. Some of the samples were analysed also with gas chromatography–mass spectrometry. The results of the analyses were plotted in the Geographic Information System (GIS) platform and interpolated with Inverse Distance Weighting (IDW) to determine the spatial distribution of the residues. Overall, the results show a large presence of fats in the analysed floors in all of the installations.  相似文献   
54.
Landscape interpretation is needed for navigating and determining an orientation: with traditional cartography, interpreting 3D topographic information from 2D landform representations to get self-location requires spatial orientation skill. Augmented reality technology allows a new way to interact with 3D landscape representation and thereby facilitate the orientation of oneself in respect to the environment to determine goal location. This paper analyses if AR spatial landform improves the learner’s spatial orientation skill measured with the perspective taking/spatial orientation test by paired sampled t-tests. A workshop was conducted with 123 university students (63 treatment group, 60 control group) in which students had to identify locations and routes based on the interpretation of the relief, represented by AR. Results of the workshop showed an improvement in spatial orientation skill of 20.14 degrees average gain in the treatment group. Students who were not subject to the workshop (control group) did not improve their spatial orientation skill. The possibility of using free AR three-dimensional applications and exploit the potential of tablets and smart phones, which are widespread today, makes it possible to design and implement strategies for the development of spatial skills in formal teaching in the scope of Geography in higher education.  相似文献   
55.
Although the issue of the out-of-plane response of unreinforced masonry structures under earthquake excitation is well known with consensus among the research community, this issue is simultaneously one of the more complex and most neglected areas on the seismic assessment of existing buildings. Nonetheless, its characterization should be found on the solid knowledge of the phenomenon and on the complete understanding of methodologies currently used to describe it. Based on this assumption, this article presents a general framework on the issue of the out-of-plane performance of unreinforced masonry structures, beginning with a brief introduction to the topic, followed by a compact state of art in which the principal methodologies proposed to assess the out-of-plane behavior of unreinforced masonry structures are presented. Different analytical approaches are presented, namely force and displacement-based, complemented with the presentation of existing numerical tools for the purpose presented above. Moreover, the most relevant experimental campaigns carried out in order to reproduce the phenomenon are reviewed and briefly discussed.  相似文献   
56.
The present work aims at elucidating the technology applied in the fabrication of ceramic objects by the ancient ceramists that inhabited the western border of Pantanal, Mato-Grosso do Sul, with the help of a multidisciplinary approach making use of chemical and physical methods of analysis. The potshards under study show the presence of different types of additives, as determined by scanning electron microscopy (SEM) and time of flight secondary ion mass spectrometry (ToF-SIMS). The dispersion of the additives within the ceramic matrix was also addressed by SEM, which shed light on the mounting technique used by the potters to assemble the ceramic vessels. Moreover, the tensile strength conferred to the pottery by the use of a specific type of additive was evaluated by applying a mechanical test. These results were correlated with the firing temperature of the potshards, determined by means of electron paramagnetic resonance (EPR).  相似文献   
57.
58.
This study concerns the moral regulation of the Person in Brazil from the twenties to the end of the forties, from the point of view of the intense academic relationship between anthropology and psychoanalysis. It deals with the conditions under which that dialogue took place: the general crusade for the «civilization» of the country, between the central State initiatives in the promotion of hygiene and education and the medical, intellectual debates about the «African» heritage and the possibility of surmounting cultural «backwardness».  相似文献   
59.
60.
According to the theory of conventions, food value chains (FVCs) involve a complex array of actors who share an agreement about the qualities embodied in their particular foodstuff. Nevertheless, that agreement is continuously challenged by changes in consumer markets. Therefore, I argue that FVCs able to adapt those qualities to new trends will perform better than FVCs whose commitment to certain qualities leads to a misunderstanding between producers and consumers. The organization of the chain itself, the values of national regulatory frameworks, and the goals of the national innovation system are discussed as factors that shape an FVCs' ability to re‐arrange that core agreement. By using professional reports, statistical records and personal interviews, this article focuses on two FVCs that have experienced contrasting trajectories in recent decades in the Spanish market: the wine industry located in the region of Castile and Leon (Spain) and the Norwegian salted cod industry. The growing wine FVC has achieved a successful agreement about a set of qualities linked to nature, tradition, and place, all of them guaranteed by the reputation of the Designation of Origin (DO) system. In contrast, the salted cod FVC is losing its market share because its main actors are failing to properly communicate the key qualities of environmental sustainability and artisanal cod production to concerned Spanish consumers, as well as in the adoption of the place‐related attributes that still shape consumer preferences in Spain.  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