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   2242篇
  免费   88篇
  2023年   15篇
  2021年   10篇
  2020年   35篇
  2019年   40篇
  2018年   75篇
  2017年   74篇
  2016年   87篇
  2015年   55篇
  2014年   64篇
  2013年   666篇
  2012年   82篇
  2011年   88篇
  2010年   75篇
  2009年   71篇
  2008年   59篇
  2007年   72篇
  2006年   58篇
  2005年   33篇
  2004年   24篇
  2003年   15篇
  2002年   24篇
  2001年   22篇
  2000年   18篇
  1999年   30篇
  1998年   20篇
  1997年   16篇
  1996年   21篇
  1995年   16篇
  1994年   14篇
  1993年   20篇
  1992年   17篇
  1991年   21篇
  1989年   11篇
  1988年   14篇
  1987年   18篇
  1986年   23篇
  1985年   18篇
  1984年   17篇
  1983年   19篇
  1982年   23篇
  1981年   20篇
  1980年   14篇
  1979年   15篇
  1978年   14篇
  1977年   13篇
  1976年   15篇
  1975年   16篇
  1973年   13篇
  1969年   11篇
  1967年   15篇
排序方式: 共有2330条查询结果,搜索用时 15 毫秒
101.
The paper offers a theory-based evaluation of the ongoing reforms in the Finnish spatial planning regime. The paper argues that Finnish planning is moving in a reactive and market-driven direction. This development is not being brought about solely through a direct decrease in public discretionary powers in planning, but is also unfolding indirectly through a process of rescaling in the spatial planning regime. These processes increase municipal autonomy in relation to other planning scales, despite problems observed in the municipality-centred market-driven planning orientation. The resulting reduction in manoeuvring room in public planning is conceptualized in the paper as expanding vacuums of strategic planning. Building on concepts from the literature on state transformation theory and scale theory, the paper draws together theoretical and empirical conclusions from several case studies conducted in close-to-administration projects.  相似文献   
102.
Portus Ilicitanus (Picola, Alicante) was the main sea harbour of the Roman Colonia Iulia Ilici Augusta and as such played a crucial role in the supply of fundamental commodities to the Iberian Peninsula. Excavations yielded large quantities of glass in fourth‐ and early fifth‐century contexts. Elemental analysis of 60 samples by laser ablation – inductively coupled plasma – mass spectrometry (LA–ICP–MS) confirmed that the glasses were imported from the Eastern Mediterranean. A majority of the glasses correspond to the HIMTa primary production group, which originates from Egypt. The statistical evaluation of published data of 589 HIMT glasses further revealed differential distribution patterns of the HIMTa and HIMTb subtypes between the Eastern and Western Mediterranean, suggesting chronological trends that are linked to wider geopolitical changes. This demonstrates the need for systematic large‐scale approaches to identify supply patterns and possible factors underlying geographical differences and/or chronological developments.  相似文献   
103.
Identifying the origin of marble used in antiquity brings back to light details of the economic, social and political organization of classical societies, and characterizing in depth the chemistry of marble is key to discovering its provenance. Beyond X‐ray diffraction, which could reveal the presence of discriminant secondary crystalline phases and the quantification of accessory minerals combined with a multivariate analysis approach, solid‐state nuclear magnetic resonance (NMR) enables one to recognize the local structure arrangement of both crystalline and amorphous materials by looking at one or more selected atoms. In present paper targets the 13C nuclide, and thus the major component of marble, calcium carbonate. Whatever their geological origin, marbles 13C‐NMR spectra present only one resonance corresponding to the carboxyl function whose intensity and line width vary from one marble to another. If the variation of the NMR signal intensity observed is the result of great T1 variations (from 220 to 5300 s) and is linked to iron content, the line width reflects defects in the calcite crystal in which calcium has been replaced by another element such as magnesium, aluminium or strontium. The specific profile of the NMR signal has been used successfully to help determine the origin of some archaeological items.  相似文献   
104.
In this article by one of the founders of the Georgian school of Oriental Studies, the role of the gholams in Safavid service is highlighted by focusing on the career of Allahverdi Khan and his children. First, it is shown that Allahverdi Khan was not an Armenian, but a Georgian of the noble Undiladze family. Second, the rise of the Georgian slave in the Safavid administration and that of his children is discussed, both their political and cultural roles within the Safavid kingdom as well as their continued relations with Georgia. Finally, the cause of the family's downfall, due to too much success, its continued involvement in the affairs of Georgia, and its rivalry with fellow-Georgian Rostam Khan, is analyzed with emphasis on the use of Georgian sources.  相似文献   
105.
Zusammenfassung Der Flussgebietsansatz ist ein zentrales Element der Wasserrahmenrichtlinie (WRRL) und wurde in Deutschland im Zuge der organisatorischen Umsetzung der Richtlinie strukturell implementiert. Die Kooperationsstrukturen auf Flussgebietsebene sollen dabei einen funktionierenden Rahmen auch für die fachliche Umsetzung der Richtlinie bilden. Beim dazu erforderlichen strukturellen Wandel waren insbesondere die in den Flussgebieten bereits vorhandenen Kooperationsstrukturen von Bedeutung. Diese wurden entweder ausgebaut, umstrukturiert oder von neuen Strukturen zur Umsetzung der WRRL überlagert. Die dabei zum Teil entstandenen Doppelstrukturen erh?hen jedoch den Koordinierungsaufwand der Akteure stark, so dass es aktuell zu einer Zusammenführung und Konsolidierungsbewegung kommt. Allerdings wird auch nach der Konsolidierung eine gro?e strukturelle Vielfalt in den Flussgebieten verbleiben, die durch eine enge Zusammenarbeit der Akteure zu bew?ltigen ist. Es bleibt abzuwarten, inwiefern diese Strukturen sich auch eignen, um neuen Herausforderungen, wie beispielsweise den Folgen des Klimawandels, zu begegnen.  相似文献   
106.
107.
108.
The measurement of stable carbon (δ13C) and nitrogen (δ15N) isotopes of caprine bone collagen from the Neolithic sites of Çatalhöyük and Aşıklı Höyük in south-central Anatolia have allowed examination of exploitation and herding practices of sheep and goats. The isotope values from protodomestic caprines at Aşıklı Höyük suggests that these animals were consuming very similar foods to each other and were all confined to the same or similar environments with no access to C4 plants. At Çatalhöyük, the results show how the caprine management strategy develops from the strategy seen at Aşıklı Höyük into a more varied practice at an early stage as the site grows with an increasing dietary contribution obtained from C4 plants. No change in diet is isotopically discernible at Aşıklı Höyük. Interestingly, no distinction could be made between the diets of sheep and goats at either site. Therefore, such studies are a useful method of examining the development of early herding or management strategies of caprines in the Near East.  相似文献   
109.
The paper presents an algorithm for computing the parameters of an ellipse that fits, in a least-squares sense, the surveyed remains of Roman amphitheatre arena walls. The algorithm is validated using ideal data and the near complete remains of the amphitheatre at Sarmizegetusa in Romania. The technique is then applied to the partial remains of the amphitheatre at the Guildhall in the City of London, in the UK, which cover only the Eastern end of the monument. The underlying mathematical model and method of solution is presented. The method was developed with a view to determining firstly whether or not an ellipse is a feasible model for the actual constructed curve geometry, and secondly, where the Western end of the Guildhall amphitheatre might be located. One single ellipse was found to fit the Guildhall remains, with measurement residuals at the level of 30 mm in the eastings and 26 mm in the northings. The ellipse had a semi-major axis of 28.345 m and a semi-minor axis of 22.775 m. The issues of alternative geometries and the practicalities of their use in construction are considered.  相似文献   
110.
The interpretation that a rock has been subjected to cultural utilization is a basic element of hunter-gatherer research. The fracture mechanics of the flaked stone tool production process are well understood and the material residues are routinely identified during fieldwork. Conversely, non-percussion processes such as hot-rock technology, which can result in rock fracture, are less well understood. An experimental study has been developed to examine the fractured gravels observed at a prehistoric site on the Southern Plains (USA). The experiment has sought to determine whether cultural or natural agencies were responsible for the production of the angularly fractured rocks. The positive results of the experiment indicate that not only were humans most likely responsible for the breakages, but also that the fractured rocks often exhibit distinctive morphologies that may be identified during fieldwork. This simple experimental methodology is applicable to other hunter-gatherer sites where the depositional environment is not conducive to the structural preservation of features such as hearths.  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