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   1880篇
  免费   45篇
  1925篇
  2024年   3篇
  2023年   18篇
  2022年   7篇
  2021年   3篇
  2020年   24篇
  2019年   30篇
  2018年   325篇
  2017年   243篇
  2016年   273篇
  2015年   48篇
  2014年   52篇
  2013年   127篇
  2012年   62篇
  2011年   178篇
  2010年   190篇
  2009年   56篇
  2008年   87篇
  2007年   82篇
  2006年   6篇
  2005年   34篇
  2004年   14篇
  2003年   9篇
  2002年   4篇
  2001年   7篇
  2000年   5篇
  1999年   4篇
  1998年   2篇
  1997年   2篇
  1996年   5篇
  1995年   2篇
  1994年   1篇
  1993年   4篇
  1992年   1篇
  1990年   1篇
  1989年   2篇
  1988年   1篇
  1987年   1篇
  1986年   1篇
  1985年   2篇
  1984年   1篇
  1982年   1篇
  1981年   2篇
  1973年   1篇
  1957年   1篇
  1952年   1篇
  1950年   2篇
排序方式: 共有1925条查询结果,搜索用时 0 毫秒
71.
Twenty‐six samples from domestic assemblages of 9th–12th century Córdoba were subjected to electron microprobe analysis. The results reveal two main compositional types. The first, encountered in 13 of the samples, seems to result from the combination of plant ashes with high‐impurity sand, and has some contemporary parallels from Syria and Egypt. The second type is a lead–soda–silica glass, encountered in a relatively high proportion of the glasses (11 of the 26 sampled), possibly formed by the addition of lead metal to existing glasses and with very few known parallels. These are among a very small number of results available to date on the chemical composition of glasses from medieval Spain, and the presence of a high proportion of lead–soda–silica glasses is particularly interesting, possibly indicating a technological practice unique to, or originating in, the western Muslim world.  相似文献   
72.
The number of phytolith studies has increased steadily in the last decades in palaeoecological as well as archaeological research, and phytolith analysis is currently recognised as a proper area of expertise within archaeobotany. This has led towards a strengthening in the standardisation of the different steps involved in analysis; e.g. sampling strategies, laboratory extraction or processing of plant material/soils for the creation of reference collections. In spite of this, counting procedures remain one of the areas that could be further developed. The aim of this paper is to assess representativeness of phytolith count size in archaeological samples and specifically to assess whether an increase in total number of individuals counted influences the number or distribution of morphotypes observed. Two statistical tests are performed to evaluate the representativeness of count size: phytolith sum variability analysis (PSVA) and morphotype accumulation curve (MAC). The analyses show the relationship among the number of counted phytoliths, the variability (that is, the number of different morphotypes identified) and the stabilisations of the MACs. Results allow us to support the standard count size in phytolith studies, which ranges from 250 to 300 particles. Together with a quick scan, this strategy should produce a precise and clear phytolith assemblage for archaeological studies.  相似文献   
73.
This article presents a preliminary attempt to characterise Upper Thai-Malay Peninsula prehistoric iron technologies based on assemblages from two recently excavated coastal sites: Khao Sam Kaeo and Phu Khao Thong. These are the earliest known sites involved in the early trans-Asian exchange that connected the eastern Indian Ocean to the South China Sea from the mid-first millennium bc. It is from this period that iron assemblages start appearing at both continental and insular Southeast Asian sites. Three models have been offered confronting an indigenous vs. Chinese or South Asian impetus for the introduction of iron metallurgy in Southeast Asia. These models are discussed in the light of the metallographic and compositional analyses of iron and slag assemblages from these two sites using optical microscopy, scanning electron microscopy with energy dispersive spectrometry, energy dispersive X-ray fluorescence and slag inclusion analysis techniques, together with other production materials from these and other contemporaneous Southeast Asian sites.  相似文献   
74.
The aim of this study was to present classic bone lesions caused by tuberculosis, as seen in a Late Neolithic–Early Copper Age osteoarchaeological sample deriving from the site of Alsónyék‐Bátaszék (the western part of Hungary from the 5th millennium bc ). In one particular case of an adult male skeleton, vertebral bodies' destruction, collapse, ankylosis and marked angulation in the lower thoracic and the upper lumbal region of the vertebral column were observed. The collapse resulted in a severe gibbus formation. The paleopathological analysis was carried out using morphological observation supported by radiological analyses. The results from this study increase our knowledge of the early occurrence of skeletal tuberculosis in past populations. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
75.
76.
77.
The implementation of a 3D Electrical Resistivity Tomography (ERT-3D) survey was carried out in El Pahñú archaeological site, Hidalgo State, Central Mexico. A combination of a new ERT arrays allowed studying the subsoil beneath the Main Pyramid built near the edge of a plateau, along with another important structure (the Tecpan), which was a smaller structure that lodged the governmental council in pre-Hispanic times. The recorded information was acquired through the combination of several electrodic designs: L-Corner (LC), Equatorial (Eq), and Minimum Coupling (MC). For the Main Pyramid, the electrodes were set up around the perimeter of the structure, since they were not permitted to be inserted over the edifice, thus preventing damages to the architectonic elements. The second structure allowed inserting electrodes on selected spots within the architectonic space. The combination of the different arrays made possible the acquisition of 1204 apparent resistivities beneath the Main Pyramid and 2460 resistivity data beneath the Tecpan. The apparent resistivity data were inverted to obtain a three dimensional display of the subsoil electrical resistivity beneath the archaeological structure. The interpreted resistivity model under the Main Pyramid displayed a highly resistive structure towards its northern face that could be associated with infill. Such material was employed by the ancient constructors to level the terrain close to the edge of the cliff. Another interesting anomaly was found towards the central portion of the structure that could be associated to a foundation offer. The interpretation of data beneath the Tecpan identified the structural foundations and other interesting anomalies related to the different occupational times. The investigation supported the archaeological investigation of the site, suggesting areas of potential geological risk and of archaeological interest. For example, the Main Pyramid presents serious stability problems, indicating that the infill has weakened, producing cracks threatening long-term pyramid integrity.  相似文献   
78.
3D surveys of archaeological elements and the construction of virtual models enable us to reconstruct historical sites. They provide useful data to select specific building processes.Photogrammetry and Terrestrial Laser Scanning (TLS) are the most common techniques to obtain synthetically heritage models. These techniques provide massive data which can only be managed by replacing them by primitive shapes, thereby obtaining more simple models and the explicit geometry of the element. Statistical and robust methods are used for this substitution, thereby avoiding the common errors due to measuring. Of these methods, the most widely used are the least-median-of-squares (LMedS) and the RANSAC method.Another computation method consists in recursive processes based on evolutive-type algorithms to adjust the model to the data captured.This paper describes two surface computation methodologies to determine the modelling of a column shaft located in temple G of the archaeological park of Selinunte (Sicily).  相似文献   
79.
80.
This article aims to bridge the gap between media studies and welfare state studies. While media and communications systems are crucial elements in any society, these systems are often not included in studies of the welfare state. Through a discussion of five historical phases in the evolution of Scandinavian societies and media systems, from early democratization in the late 18th century through the ‘golden age’ of the welfare state to the present challenges of globalization, digitization and the fragmentation of social trust, the article discusses the relationships between the two spheres. While Scandinavian communications systems have much in common with those of other Western states, this article argues that they are also products of, and catalysts for, the specific evolution of the Nordic welfare states.  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