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   547篇
  免费   17篇
  2024年   4篇
  2023年   5篇
  2022年   10篇
  2021年   7篇
  2020年   17篇
  2019年   9篇
  2018年   27篇
  2017年   8篇
  2016年   11篇
  2015年   22篇
  2014年   13篇
  2013年   35篇
  2012年   31篇
  2011年   37篇
  2010年   42篇
  2009年   54篇
  2008年   38篇
  2007年   44篇
  2006年   31篇
  2005年   31篇
  2004年   6篇
  2003年   20篇
  2002年   17篇
  2001年   11篇
  2000年   6篇
  1999年   8篇
  1998年   5篇
  1997年   4篇
  1996年   5篇
  1995年   2篇
  1994年   2篇
  1992年   1篇
  1990年   1篇
排序方式: 共有564条查询结果,搜索用时 15 毫秒
1.
According to tradition, King Richard I of England visited Dubrovnik (Ragusa) in 1192. Much of the evidence for this visit comes from a dispute at the end of the sixteenth century concerning the rights of the abbot of Lokrum. Medieval evidence can also be taken into contribution, notably the comments of the English chronicles of the early thirteenth century and the surviving documentation for the career of a Ragusan archbishop who later became bishop of Carlisle. The author concludes that King Richard's visit was a reality.  相似文献   
2.
史前漆膜的分析鉴定技术研究   总被引:5,自引:0,他引:5  
研究了漆膜分析的三种主要方法:裂解质谱,红外光谱,裂解色谱。通过大量实验比较了各种方法的适应性和可靠性,建立了以裂解色谱/富里叶红外光谱联用技术来鉴定漆膜,并对影响裂解反应的因素及色借条件进行了深入的研究,获得了可以重复,具有特征性的漆膜高分辨裂解色谱图,同时对裂解色谱图中主要组分作了定性鉴定,提高了裂解色谱法分析漆膜的可靠性。该方法具有灵敏度高,样品用量小,共存杂质影响小,操作简便等优点。应用核分析技术对河姆渡,良诸庙前遗址出土的二件红色涂料样品进行了鉴定。分析结果证实了河姆渡出土的红色涂料木碗上的涂料是我国至今发现的最早的生漆漆膜。  相似文献   
3.
This study takes a valuation perspective to study how and where products and innovations are gaining ‘economic significance’ in the contemporary economy. Building on a recent research stream in economic geography and urban and regional studies, it highlights that the economic value of many products is not formed within production systems alone, but relies on co-constructed connections between production and consumption systems, playing out across multiple geographies. It distinguishes between three types of economic valuation pathways – namely technical, experiential and identity-based – which although analytically distinct may actually build and reinforce one another. This approach is empirically illustrated with the case of the surf-related economy in the city of San Sebastian (Basque Country, Spain), which is used to make a broader point about the growing relevance of a valuation approach to understand competitive advantage and economic renewal in localized production systems.  相似文献   
4.
Shear walls are important lateral force-resistant components of tall buildings. Hence, a reliable numerical model that can accurately represent the mechanical characteristics and large deformations of shear walls is critical for realistic collapse simulation of tall buildings. Based on the theory of generalized conforming element, a high-performance quadrilateral flat shell element, NLDKGQ, accounting for the large deformation using the updated Lagrangian formulation, is proposed herein and implemented in OpenSees. The reliability of NLDKGQ is validated using classical benchmark problems and reinforced concrete specimens. In addition, its capability in simulating the collapse of a tall building is also demonstrated.  相似文献   
5.
The concept of providing a fuse in a structural system has been both developed and investigated over the past few years (e.g., the use of replaceable links in eccentrically braced frames or the use of replaceable links in the new San Francisco-Oakland Bay Bridge). This paper presents a new coupling beam with a creative fuse installed in the mid-span of a steel-concrete composite beam via an end plate and high-strength bolts. First, a practical design methodology of a replaceable coupling beam is presented. Next, the seismic behavior of the proposed fuse is tested and evaluated, and two structural wall specimens with or without a fuse are designed and fabricated according to the proposed design methods. The two specimens possess similar shear capacities under large-scale cyclic loading, and the walls of the two specimens show similar failure modes; however, the new walls exhibit slightly lower levels of damage than the conventional walls. In particular, the inelastic deformation and damage of replaceable coupling beams are mainly concentrated in the fuse, whereas the non-yield segment and the beam-wall pier interfaces remain nearly intact and produce only slight damage, which is beneficial regarding the replacement of the fuse in post-earthquake events.  相似文献   
6.
Pan, Z., Zhu, M., Zhu, Y. &; Jia, L., August 2017. A new antiarch placoderm from the Emsian (Early Devonian) of Wuding, Yunnan, China. Alcheringa 42, 10–21. ISSN 0311-5518.

Wufengshania magniforaminis, a new genus and species of the Euantiarcha (Placodermi: Antiarcha), is described from the late Emsian (Early Devonian) of Wuding, Yunnan, southwestern China. The referred specimens were three-dimensionally preserved in black shales, allowing a high-resolution computed tomography reconstruction of anatomical details. The new euantiarch is characterized by a large orbital fenestra, an arched exoskeletal band around the orbital fenestra and a developed obtected nuchal area of the skull roof. Maximum parsimony analysis, using a revised data-set of antiarchs with 44 taxa and 66 characters, resolves Wufengshania gen. nov. as a member of the Bothriolepididae, which is characterized by the presence of the infraorbital sensory canal diverging on the lateral plate, and the nuchal plate with orbital facets. New analysis supports a sister group relationship between Dianolepis and the Bothriolepididae. Luquanolepis, a coeval euantiarch from the neighboring site of the new form, is referred to the Asterolepidoidei and represents the basalmost and earliest member of the Asterolepidoidei.

Zhaohui Pan* [], Min Zhu* [], You’an Zhu? [] and Liantao Jia [] Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, PO Box 643, Beijing 100044, PR China. *Also affiliated with University of Chinese Academy of Sciences, Beijing, 100049, PR China. ?Also affiliated with Uppsala University, PO Box 256, 751 05 Uppsala, Sweden.  相似文献   
7.
This paper deals with the cultural and educational relations between the United States and Portugal during the Cold War. It is built upon the premise that cultural policies and cultural relations between states are a fundamental part of international relations. History of International Relations, therefore, should overcome an analysis based only upon political and diplomatic dimensions to address what can also be referred to as ‘cultural diplomacy’. The Cold War period, because of its historical features, is particularly relevant to the study of processes of cultural diplomacy and some authors even consider it as the ‘golden age’ of cultural diplomacy.11. William Glade, ‘Issues in the Genesis and Organization of Cultural Diplomacy: A Brief Critical History’ in The Journal of Arts Management, Law, and Society (Winter 2010), vol. 39, issue 4, 242. For cultural diplomacy during the Cold War see Jessica Gienow-Hecht, ‘Culture and the Cold War in Europe’ in Leffler, Melvyn & Westad, Odd Arne, The Cambridge History of the Cold War Vol. i, (Cambridge University Press, 2010), 398–419; Akira Iriye, ‘Culture and International History’ in Michael J. Hogan and Thomas G. Paterson (ed), Explaining the History of American Foreign Relations, 2nd ed. (Cambridge: Cambridge University Press, 2004); Richard T. Arndt, The First Resort Of Kings: American Cultural Diplomacy In The Twentieth Century (Virgínia: Potomac Books, 2005).View all notes  相似文献   
8.
王璐 《东南文化》2018,(2):6-12
"原状"认识来源于西方经典保护理论,历经启蒙运动、法国大革命和反修复等社会运动。至19世纪,其思想内涵不断发生变化,从单纯地强调"原物""原状"发展到将历史真实的"原状"观念扩大到历史时间和"环境"等更大的对象范畴。20世纪以来,经典保护理论走向成熟,"原状"也真正从追求"原物真实"走向了传递其蕴含的"价值意义"。"不改变原状"是我国文物古迹保护的核心原则,经历了"初建时的原状""整旧如旧"、对于"原状"的多元释义、"体现价值的状态"等四个阶段。文化遗产的保护要从原物、原信息、原地点、原场所精神、原用途五个方面综合考虑"原状",才能真正保护好遗产的价值。  相似文献   
9.
A reference sample of dental and oral nonmetric traits should represent its biological population from which it stems. The presence of individuals born at different times, different regions, and separate countries in the Coimbra-identified cranial collections provides the test of whether this sample reflects the biological continuity of this Portuguese sample among the late modern (early industrialization, nineteenth century) to early contemporary (early demographic transition, first half of the twentieth century) population of this region of central Portugal. The Coimbra collections were scored for 61 traits using methodology by Hauser and De Stefano (1989), Turner et al. (1991), Scott and Turner (1997), Irish (1998), and Marado and Silva (2016). The 600 individuals in the sample were divided by generation, region, and nationality. Their phenetic diversity was tested with principal component analysis and with the mean measure of divergence statistic. The proximity between the subsamples was generalized, and it mimicked previous genetic marker results. Some small subsamples hindered conclusions; nevertheless, this Coimbra sample is considered a reliable dental reference sample for the Portuguese late modern/early contemporary population.  相似文献   
10.
As the criterion used by archaeologists for determining early white porcelain is quite ambiguous, the origin of Chinese white porcelain remains a point of disagreement. In this study, we systematically investigate 61 typical Xing porcelains of the late Northern dynasties to the early Sui dynasty (550–600 CE) using spectrophotometer, X-ray fluorescence (XRF), scanning electron microscopy (SEM), and X-ray powder diffraction (XRD), and analyze the differences between early white porcelain and celadon of Xing kiln in terms of their whiteness and raw materials characteristic. The results show that early white porcelain is a new type of ware that differs from celadon, which can be distinguished by whiteness, with a whiteness greater than 8% being early white porcelain and a whiteness less than 8% being celadon. It is assumed that the ancient potters created the whiter wares based on celadon by improving the glaze and selecting new raw materials for the body, but the production of this type of ware was short lived and subsequently refined in the Sui dynasty (581–618 CE) owing to the limited improvement in whiteness.  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