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   11964篇
  免费   549篇
  2020年   177篇
  2019年   245篇
  2018年   332篇
  2017年   334篇
  2016年   394篇
  2015年   263篇
  2014年   228篇
  2013年   3308篇
  2012年   313篇
  2011年   346篇
  2010年   341篇
  2009年   342篇
  2008年   306篇
  2007年   291篇
  2006年   252篇
  2005年   177篇
  2004年   158篇
  2003年   163篇
  2002年   171篇
  2001年   193篇
  2000年   167篇
  1999年   192篇
  1998年   146篇
  1997年   127篇
  1996年   136篇
  1995年   125篇
  1994年   108篇
  1993年   125篇
  1992年   119篇
  1991年   90篇
  1990年   91篇
  1989年   106篇
  1988年   97篇
  1987年   110篇
  1986年   107篇
  1985年   139篇
  1984年   165篇
  1983年   166篇
  1982年   131篇
  1981年   129篇
  1980年   144篇
  1979年   130篇
  1978年   137篇
  1977年   122篇
  1976年   127篇
  1975年   141篇
  1974年   84篇
  1973年   77篇
  1972年   71篇
  1971年   66篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
941.
Despite phytoliths having been used to understand past human use of plants and palaeoenvironment in Middle Paleolithic sites, little is known on this aspect in the well-documented central region of Mediterranean Iberia. This paper presents the first phytolith and mineralogical study conducted at Abrigo de la Quebrada (Chelva, Valencia). Forty-one samples were analyzed through phytoliths and Fourier transform infrared spectroscopy (FTIR) from different areas, stratigraphic levels, and archeological contexts (hearth, hearth-related, and non-hearth-related sediments) of the shelter. The results obtained point towards a different pattern of preservation in the site depending firstly on the stratigraphy and secondly on the area where the samples were collected. Postdepositional processes that may have chemically affected phytolith preservation are discussed. Grasses are the main plant component identified in all the samples while woody plants are scarce. The abundance of grasses in the non-hearth-related sediments might be related, at least partially, to the dispersion of ashes from hearths, as indicated by the FTIR results. The results are indicative of an occupation of the site during the spring-autumn season. At this time, the area would be dominated by a semi-open environment with supramediterranean vegetation.  相似文献   
942.
A holistic landscape approach to cultural resource analysis of a set of archaeological sites in the central Penobscot Valley led to inferences regarding the Holocene physical and biological environmental context. Targeted environmental studies include (1) examination of forest and wetland changes through time and (2) lake-level studies as a key to paleohydrology. These studies were combined with broad-scale geomorphic investigations and detailed stratigraphic analyses, and studies of archaeological sites and their artifact assemblages. Together, these studies provide a picture of dramatic changes to the physical and vegetational landscape. These included reestablishment of a major river following deglaciation, evolution of extensive lakes to uplands and peatlands, and a shifting mosaic of open and closed forest composed of a variety of hardwood and softwood species. Inferences based on buried soils exposed in archaeological excavations supported climatic interpretations based on vegetation and paleohydrology. As a result, this work allowed evaluation of (1) site formation and preservation processes and (2) occupational patterns. Site formation and preservation of Early Holocene sites can be linked to sedimentation by hydraulic damming upstream of rapids at the mouths of tributary streams. Shifting human land use reflected by changes in occupation patterns appears to correspond to changes in forest composition as well as wetland and stream evolution through time.  相似文献   
943.
Achieving an accurate perception of time and context remains a major challenge in archaeology. This paper highlights the potential benefits of microstratigraphic study to address this goal, drawing on case studies from Lower, Middle, and Upper Paleolithic, Neolithic, and Iron Age archaeological sites. First, we discuss the importance of site formation reconstruction and the ways in which current field methods approach the sedimentary record. Then, we focus on both field identification and high-resolution study of stratigraphic contacts, which are ubiquitous in archaeological deposits. Examples are presented to highlight the role of microstratigraphy in characterizing the nature of contacts and their significance for archaeological interpretation. A microstratigraphic approach is especially useful for distinguishing between contacts that originate from changes in depositional processes and contacts that form as a result of post-depositional processes such as pedogenesis, diagenesis, or burning. Further examples show how “invisible” anthropogenic surfaces and different kinds of occupation deposits can come to light at a microscopic scale of observation. Finally, we illustrate cases in which what appeared to be sterile layers in the field yielded anthropogenic elements. In the end, we discuss how archaeological projects might incorporate microstratigraphic analyses and their results within broader research frameworks that prioritize site formation process reconstruction.  相似文献   
944.
The superposition of anthropogenic remains usually results in archaeological palimpsests, hindering an accurate characterization of the behavior underlying such remains. Aimed at facing this methodological constraint in the study of Palaeolithic contexts, we present a contextual approach to Neanderthal settlement dynamics based on an understanding of lithic assemblage formation processes. We focused on a set of lithic artifacts from the Middle Palaeolithic site of El Salt. With the goal of isolating temporally constrained units of behavioral analysis, we analyzed the spatial distribution of lithic, faunal and combustion remains. Then, the lithic records from each of the resulting units were analyzed from a genetic and technical perspective. This goal was achieved by identifying lithic Raw Material Units (RMU) through observations on reduction processes, refits and their spatial distribution. Our results suggest that El Salt SU X lithic remains represent several diachronic human occupation episodes and different site functions. This study illustrates the benefit of investigating lithic assemblage formation processes to alleviate the palimpsest problem in Palaeolithic contexts.  相似文献   
945.
This study examines the diet consumed by the population at the neighborhood center of Teopancazco, Teotihuacan, in the basin of Mexico. We used stable isotope analysis of δ13C and δ15N of the dentine collagen as well as the δ13C from enamel bioapatite from teeth (M2 and M3) of 39 of excavated burials. The results show that the diet consumed by the majority of the population during childhood and adolescence had high 13C enriched values in both dietary components: δ13C enamel_bioapatite = ?2.0 ‰ ± 1.5 for the whole diet and δ13C dentine_collagen = ? 9.4 ‰ ± 2.1 for the protein component. According to the bi-variable and multivariable models, some individuals consumed higher amounts of C4/CAM resources than those specified in cluster #2 (70 % C4 diet; ≥50 % C4/CAM protein). An inter-tissue adjustment of 2.3 ‰ was used to relate the enamel bioapatite data to the bone bioapatite of the models. Average δ15Ndentine_collagen was 10.2 ‰ ± 2.8 with high variability especially for four individuals, three of which belong to special burials, suggesting different access to meat or marine products due to their social or migration status and/or to pathological conditions. The data suggest that maize was the staple crop of the population not only at Teopancazco but for Teotihuacan as a whole, in the form of tortillas, tamales, atole, and protein from maize-fed animals with the inclusion of other CAM, C4, and C3 resources probably from the bountiful ecosystem of the basin of Mexico or from the wide trade system that Teotihuacan had with Mesoamerica.  相似文献   
946.
According to Shi?i tradition, the seminary (?awza) in Najaf, Iraq is 1,000 years old. The origins of the ?awza are closely associated with the famous scholar Shaykh al-?ūsī (385/995?459/1067). This paper addresses the question of whether or not there is sufficient historical evidence to support the tradition that the ?awza of Najaf is indeed 1,000 years old. On the basis of Arabic sources, the article argues that although Shi?i educational institutions in Najaf were incepted a millennium ago, Najaf was rarely the locus of Shi?i education prior to the thirteenth/nineteenth century. Based on statistical and historical analysis of Shi?i scholars in Najaf, this paper outlines a short history of scholarly activity in one of the oldest college towns in the world. In addition to developing a working definition of the term ?awza, the paper situates the rise of Shi?i educational systems in the broader context of the evolution of Islamic scholarly institutions, including colleges (madrasas).  相似文献   
947.
948.
949.
950.
26 sites with Pre‐Columbian (Taíno) rock art are known in Jamaica, most with petroglyphs only, but there are four with painted images, and three of these are discussed: Mountain River Cave, Potoo Hole, and Spot Valley Cave. In addition, an account is given of the Warminster rock shelter, which has petroglyphs described as among the best remaining in Jamaica. Spot Valley Cave was newly surveyed in 2005, with the help of the Jamaican Caves Organization, and in the same year a rescue operation to restore the Warminster petroglyphs was carried out, in cooperation with Dr Johannes Loubser. Comparisons are made, where appropriate, to Taíno artefacts in different materials, and also to Pre‐Columbian images on other islands in the Caribbean, notably Puerto Rico. The interpretation of the Taíno images, in Jamaica and elsewhere, relies to a considerable extent on the “Account of the Antiquities of the Indians”, compiled by Fray Ramón Pané in 1494–1498, on the express instructions of Columbus. Whatever the shortcomings of a narrative compiled by an outsider, we would be much worse off without it.  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