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   352篇
  免费   20篇
  2024年   3篇
  2023年   11篇
  2022年   1篇
  2021年   4篇
  2020年   14篇
  2019年   15篇
  2018年   37篇
  2017年   39篇
  2016年   27篇
  2015年   16篇
  2014年   22篇
  2013年   99篇
  2012年   5篇
  2011年   11篇
  2010年   8篇
  2009年   6篇
  2008年   10篇
  2007年   4篇
  2006年   1篇
  2004年   2篇
  2003年   2篇
  2002年   1篇
  2001年   4篇
  2000年   3篇
  1999年   2篇
  1998年   3篇
  1997年   2篇
  1996年   2篇
  1995年   1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
  1979年   1篇
  1978年   1篇
  1977年   1篇
  1957年   1篇
排序方式: 共有372条查询结果,搜索用时 15 毫秒
341.
Graphic and metric archaeological documentation is an activity that requires the capture of information from different sources, accurate processing and comprehensive analysis. If monitoring of the state of conservation is required, this task has to be performed before intervention, during and after the completion of the works in a repetitive way.This paper presents the use of terrestrial laser scanning (TLS) in order to effectively produce, prior to intervention, accurate and high-resolution 3D models of a cave with engravings dating back to the Upper Palaeolithic era. The processing of the TLS data is discussed in detail in order to create digital surface models. The complexity of the cave required the integration of two techniques, TLS and close range photogrammetry to yield not only traditional drawings such as sections and elevations, but also photo-realistic perspective views and visual navigation worlds fully operational in 3D environments. This paper demonstrates the potential of integrating TLS and close range photogrammetry to provide both accurate digital surface models and photo-realistic outputs. This processed data can be used to systematically improve archaeological understanding of complex caves and relief panels of prehistoric art with tiny engravings.  相似文献   
342.
The exploitation of ungulates in the Cantabrian region during the Upper Palaeolithic is characterized by the appearance of progressively specialized hunting strategies, especially during the Magdalenian. This specialization focused on either Iberian ibex or red deer, depending on environmental or topographic features. Red deer, for instance, was hunted mostly on the plains while ibex and/or chamois was hunted in rocky and mountainous areas. Here we present new zooarchaeological and taphonomic evidence from Coímbre cave (northern Spain), a site located in the rugged region between the Picos de Europa and Sierra del Cuera (Asturias) which has evidence for specialized ibex hunting. We discuss the possible reasons for such a selective hunting pattern. While the predominance of mountain species such as Iberian ibex or chamois in the Magdalenian levels suggests prey selection based on topographic or environmental criteria, the predominance of large bovids in the Gravettian level could imply that other alternatives were available. We also provide evidence of a pattern of rabbit exploitation which is unusual by comparison with other Upper Palaeolithic sites of northern Spain, and which taphonomic evidence suggests was due to human activity.  相似文献   
343.
344.
345.
ABSTRACT

The 2010 Maule Chile earthquake (Mw 8.8) caused extensive structural damage to the built heritage. In particular, the poor seismic performance of a set of unreinforced masonry (URM) churches highlighted the need to implement protective and safety strategies in order to preserve these buildings which exhibit unique constructive and typological features, as a result of a combination of Chilean and European construction cultures.

The peculiarity of this heritage and the high seismic hazard of Chilean territory have motivated the present study which aims to apply systematic procedures to assess the seismic vulnerability of these buildings. This article is of archival nature and presents a complete database generated from the geometrical, constructive, and structural characteristics of a representative stock of 106 churches located in central Chile, with the goal of proposing fragility curves to be used in seismic risk assessment. Considering variables related with geometrical, architectonic, and stylistic features, as well as damage levels for the 2010 Maule earthquake, this church sample is classified into three homogenous groups: colonial, neo-classic, and neo-gothic. Moreover, a preliminary qualitative assessment of the seismic capacity of these structures is provided using a survey and analysis of geometric indices for each of the three selected groups.  相似文献   
346.
Damage generated by large and small carnivores is common in many Middle Pleistocene sites. However, identifying the predator that produces the faunal accumulations is often a difficult task. In order to recognize the main type of carnivore that acts on a faunal assemblage, a combination of several characteristics should be taken into account: taxonomic and skeletal element representation, age profiles, carnivore damage (location, frequencies and dimensions of tooth-marks, bone breakage and digested bones), degree of fragmentation and frequencies of coprolites. But, adding environmental characteristics and the ethology of non-human predators/scavengers is also important. All these aspects are applied to the faunal assemblage from the TD8 level of the Gran Dolina site (Sierra de Atapuerca, Burgos, Spain). Paleomagnetic data combined with ESR and U-series place the TD8 level at the beginning of the Middle Pleistocene, specifically circa 700 kyr ago. The TD8 level contains a large faunal accumulation primarily composed of ungulate skeletal elements, and to a lesser extent carnivore remains. This assemblage is characterized by an overrepresentation of fallow deer (Dama vallonetensis), a skeletal profile biased towards cranial remains and limb bones, diversity of ages at death, a high proportion of carnivore damage and tooth-marks of large size, and an absence of human activity. According to these data, the accumulation seems to have been produced primarily by large carnivores, possibly hyenas. This observation does not rule out the possible occasional activity by other carnivores. Nevertheless, the characteristics of the TD8 assemblage do not correlate entirely with those traditionally used to define carnivore dens. In TD8, there are (1) no immature carnivore remains (remains of just one young Mosbach wolf); (2) scarce traces related to the end stages of consumption and some anatomical connexions; (3) few coprolites; (4) high proportion of adult ungulates and; (5) high quantities of whole bones and epiphyses. From this perspective, the TD8 faunal assemblage seems to correspond to a succession of carnivore occupations that allows the development of a suite of features to identify the activities of several species of predators that may have used the cave in different ways and durations. This study aims to emphasize the importance of these analyzes in order to know the behaviour of different non-human predators/scavengers in the European Middle Pleistocene sites.  相似文献   
347.
348.
349.
Zheng, D., Nel, A., Jarzembowski, E.A., Chang, S.-C., Zhang, H. & Wang, B., May 2018. Exceptionally well-preserved dragonflies (Insecta: Odonata) in Mexican amber. Alcheringa xxx, xxx–xxx.

Dragonflies (odonatans) are comparatively rare as amber inclusions, and most are not well preserved on account of their size. Here, we report a single piece of Mexican amber with one complete dragonfly and two damselflies. The dragonfly is attributed to the extant gomphid Erpetogomphus Selys Longchamps, and the damselflies belong to the extant coenagrionid Argia Rambur. Both genera are nowadays distributed widely in Mexico. The new discovery dates the origins of these two genera to the Miocene at least.

Daran Zheng [], Edmund A. Jarzembowski* [] Haichun Zhang [] and Bo Wang? [] State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, 39 East Beijing Road, Nanjing 210008, PR China; André Nel [] Institut de Systématique, Évolution, Biodiversité, ISYEB-UMR 7205-CNRS, MNHN, UPMC, EPHE, Muséum national d’Histoire naturelle, Sorbonne Universités, 57 rue Cuvier, CP 50, Entomologie, F-75005, Paris, France; Daran Zheng, Su-Chin Chang [] Department of Earth Sciences, The University of Hong Kong, Hong Kong Special Administrative Region, PR China. *Also affiliated with Department of Earth Sciences, The Natural History Museum, London SW7 5BD, UK. ?Also affiliated with Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, PR China. Received 23.1.2018; revised 6.3.2018; accepted 20.3.2018.  相似文献   

350.
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