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   2996篇
  免费   121篇
  2020年   47篇
  2019年   62篇
  2018年   92篇
  2017年   92篇
  2016年   94篇
  2015年   63篇
  2014年   69篇
  2013年   986篇
  2012年   60篇
  2011年   86篇
  2010年   63篇
  2009年   61篇
  2008年   56篇
  2007年   57篇
  2006年   39篇
  2005年   28篇
  2004年   30篇
  2003年   25篇
  2002年   31篇
  2001年   32篇
  2000年   44篇
  1999年   43篇
  1998年   29篇
  1997年   29篇
  1996年   31篇
  1995年   29篇
  1993年   19篇
  1992年   18篇
  1991年   28篇
  1990年   19篇
  1989年   30篇
  1988年   24篇
  1987年   25篇
  1986年   30篇
  1985年   39篇
  1984年   28篇
  1983年   35篇
  1982年   24篇
  1981年   37篇
  1980年   35篇
  1979年   34篇
  1978年   36篇
  1977年   26篇
  1976年   33篇
  1975年   24篇
  1974年   19篇
  1973年   27篇
  1972年   22篇
  1971年   18篇
  1969年   22篇
排序方式: 共有3117条查询结果,搜索用时 15 毫秒
991.
The study of the fish bones from the Neolithic shell midden of Suwayh 1, excavated in the 2000s, identified a total of 1060 identifiable fish bones, from 23 families, 33 genera and 28 different species. Radiocarbon dating demonstrates that the sites date to the early 6th to mid 5th millennium BC. The results follow an eight-phase chronology highlighted by an earlier malacological study. The most important taxa were the Carcharhinidae (requiem shark), Rhinopteridae (cownose rays), Sparoidea (Sparidae and Lethrinidae: sea breams and emperors) and Ariidae (sea catfishes). The results of the fish study show that the Suwayh lagoon must have gradually opened up to the sea and been populated with mangroves. The unique presence of so many sharks at this site seems to indicate that the inhabitants had a special interest in shark fishing and that their location was ideal for this specialised activity. Two types of fishing nets and hooks have been discovered, which require the use of different fishing techniques.  相似文献   
992.
This paper considers the epistemic career of visual media in ethology in the mid-20th century. Above all, ethologists claimed close contact with research animals and drew scientific evidence from these human-animal communities, particularly in public relations. However, if we look into the toolboxes of comparative behavioral biologists, it becomes evident that scientifically valid research results were primarily obtained by experimenting with model images. These visual specimens tell a technical story of the methodological requirements in behavioral science necessary to bridge everyday observations between the laboratory and the field. By neutralizing individual traces of animal bodies as well as their observers, they prompted the abstraction of ethological hypotheses. The case study of East-German biologist Günter Tembrock (1918–2011), who maintained his own collection of newspaper clippings, drawings, photographs, and films, offers a new perspective on the methodological development of this field. Furthermore, this article contributes to a scholarly discussion geared toward expanding the spaces of ethological research. My analysis of the image collections of the Forschungsstätte für Tierpsychologie presents the archive as a relevant site of study in the history of ethology.  相似文献   
993.
As the largest part of military usage of the territory depends on a thorough analysis of its morphology, spatial analysis with Geographic Information Systems (GIS) software reveals a great potential as a way for studying battlefields and/or other military buildings and scenarios from the past, while supporting interpretations of territorial occupation and related organization of military forces through event simulation. This paper presents a GIS-based method to model and assess the permeability of historical defensive systems from the period that preceded the mechanization of warfare of the late nineteenth century, i.e., based on artillery installed in fortifications. The method was applied to analyze the permeability of the Lines of Torres Vedras (LTV) defensive system, a multi-line fortification complex which was operational during the Peninsular War in the beginning of the nineteenth century and located north of Lisbon, Portugal. The structures of the LTV and local terrain were modelled in GIS using a set of proposed parameters that support territorial analysis, combined with the capability of contemporary weaponry. A methodical quantification and combination of these parameters enabled a better understanding of the systemic design of the defensive lines in terms of its permeability, contributing to a discussion of the LTV particular military setting based on the interpretation of these indicators. Global and sectorial analyses of the permeability of the LTV defensive system were conducted.  相似文献   
994.
Abstract

The history of both the Red Cross and the Japanese Red Cross is based on a teleological and eurocentric narrative which is strongly shaped by national histories and focused on persons. To assume 1863 as the founding date of the Red Cross is highly debatable, considering that most national relief organisations were renamed ‘Red Cross Societies’ only in the 1880s. In this Japan is no exception, since first a Haku-Ai-Sha (Philanthropic Society) was founded in 1877 and then turned into the Japanese Red Cross Society in 1887. Japanese actors must be regarded as intrinsically motivated and active participants in the Red Cross movement who saw an ideal and a model in the Euro-American ‘way of civilisation’ and humanity. It has taken about 30 years to turn the Haku-Ai-Sha in Japan into a humanitarian society which is accepted both at home and abroad and, with its 728,507 members in 1900, which constituted the largest Red Cross Society in the world.  相似文献   
995.
996.
The EU has recently launched several initiatives that aim to foster the idea of a common European cultural heritage. The notion of a European cultural heritage in EU policy discourse is extremely abstract, referring to various ideas and values detached from physical locations or places. Nevertheless the EU initiatives put the abstract policy discourse into practice and concretize its notions about a European cultural heritage. A common strategy in this practice is ‘placing heritage’ – affixing the idea of a European cultural heritage to certain places in order to turn them into specific European heritage sites. The materialisation of a European cultural heritage and the production of physical European heritage sites are crucial elements in the policy through which the EU seeks to govern both the actors and the meanings of heritage. On the basis of a qualitative content analysis of diverse policy documents and informational and promotional material, this article presents five strategies of ‘placing heritage’ used in the EU initiatives. In addition, the article presents a theoretical model of circulation of the tangible and intangible dimensions of heritage in the EU heritage policy discourse and discusses the EU’s political intents included in the practices of ‘placing heritage’.  相似文献   
997.
The Ruhr area has advanced to the largest university region in Germany – often unnoticed within and outside. At the same time scientific institutions have become a major economic factor. Because of the higher and extra-university research institutions about 2.5 billion euros are effective as a demand potential in the region. 1.7 billion euros of this amount are directly associated with investments and operating expenditures of the scientific institutions as well as consumptions of employees and students. Additional 770 million euros result in revenues of many branches such as trade, housing, gastronomy sector, handcraft industry etc. It should not be underestimated that higher and extra-university research institutions generate with their research activities particular funding from the European Union or the rest of Germany for benefit of the region. Each euro spent by the state government for basic funding creates 39 cents third-party funding. These regional-economic effects result in noticeable employment impacts within the region. Around 25,000 people are directly employed in higher and extra-university research institutes or student unions (Studierendenwerke), about 22,000 jobs in other economic sectors are ensured or created by the induced demand. Science has thus become an important economic factor and represents an essential counterbalance to employment decline in shrinking industries of the region. The specific inclusion of science in a regional development strategy and targeted relining with appropriate measures to strengthen the science creates therefore an effective starting point for the design of structural change.  相似文献   
998.
999.
1000.
This article reports on the artefacts and environment of marine ballast and pottery sites identified through inter‐tidal and underwater survey around Kilwa, Tanzania, one of the most important medieval sultanates along the east African coast. An inter‐tidal site on the limestone fringing reef on the approaches to Kilwa Kisiwani Harbour and an underwater site within the harbour have been dated from associated pottery to c.8th–10th century and the 13th–16th century respectively. The presence of exotic basalt ballast is discussed as an indicator of wreck‐sites.  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