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   1773篇
  免费   14篇
  1787篇
  2023年   7篇
  2020年   21篇
  2019年   26篇
  2018年   40篇
  2017年   37篇
  2016年   51篇
  2015年   48篇
  2014年   32篇
  2013年   597篇
  2012年   56篇
  2011年   55篇
  2010年   75篇
  2009年   60篇
  2008年   39篇
  2007年   77篇
  2006年   71篇
  2005年   20篇
  2004年   34篇
  2003年   24篇
  2002年   19篇
  2001年   19篇
  2000年   10篇
  1999年   16篇
  1998年   15篇
  1997年   8篇
  1996年   10篇
  1995年   20篇
  1994年   12篇
  1993年   9篇
  1992年   14篇
  1991年   9篇
  1990年   10篇
  1989年   13篇
  1988年   14篇
  1987年   18篇
  1986年   13篇
  1985年   14篇
  1984年   14篇
  1983年   10篇
  1982年   11篇
  1981年   15篇
  1980年   14篇
  1979年   7篇
  1978年   8篇
  1977年   8篇
  1976年   8篇
  1975年   9篇
  1972年   10篇
  1971年   7篇
  1970年   9篇
排序方式: 共有1787条查询结果,搜索用时 0 毫秒
101.
    
ABSTRACT

The microstructures of building materials from the archaeological complex of Huaca de la Luna on the northern coast of Peru is assessed for the first time by a multiscale approach. The multiscale microstructural characterization used laboratory techniques including optical microscopy, scanning electron microscopy, X-ray microtomography, and both gas and powder pycnometry. Optical microscopy revealed the presence of organic matter and shell fragments and X-ray microtomography showed differences in the sizes and connectivity of pores. The BET (N2 gas adsorption) specific surface areas showed greater presence of clayey matrix in the mortars. No significant differences among mortars and brick fragments mineralogy were detected by X-ray diffraction, so the larger amount of fine binding matrix in the mortars suggests that they were produced blending raw material with different grain sizes. The aim of this study is to provide data that can be used for a better understanding of the Moche culture, its construction techniques, and to support conservation strategies of the archaeological heritage.  相似文献   
102.
    
One of the most intriguing questions for archaeologists studying clay artefacts concerns technologies employed in their manufacture and whether standardization can be demonstrated through traditional ceramic analysis. Visual comparisons and mechanical measurements have been used to determine correlations and infer standardization. Using a laser multi‐line scanner and software developed to quantify Hausdorff distances between vertices in 3D surfaces, we analysed sample collections of figurines and moulds from Belize, Mexico and Honduras. The results indicated that this procedure was a more precise indicator of common source and standardization in moulded clay artefacts. This method provided data relevant to assessing the scope of ancient trade networks and the nature of social and economic relationships that existed among the ancient inhabitants of Mesoamerica.  相似文献   
103.
104.
The ‘street’ and ‘youth’ have long been issues of social concern and the subject of research both in Brazil and elsewhere. The perception and experiences of youth in relation to the street, however, and the corresponding gender and class relations which permeate these, remain an under-researched topic. Drawing on fieldwork conducted in low- and middle-income neighbourhoods in Recife, this paper shows how the street consists of different spaces and how the youth experience corresponding layers of socio-spatial exclusions and inclusions which vary over time.  相似文献   
105.
In this paper we present data to demonstrate the applicability of laser‐ablation MC–ICP–MS isotope analysis to archaeological artefacts, in this case Roman silver coins. The technique requires no chemical preparation, does minimal damage to the sample and yields external reproducibility that is better than conventional TIMS analysis; 207Pb/206Pb =±0.015% 2σ in comparison with 207Pb/206Pb =±0.04% 2σ, respectively. We show that Pb isotope compositions give isotope fingerprints to mints despite the likely reworking of the metal during coin production.  相似文献   
106.
The study of technology transfer in pottery production to the periphery of the Mycenaean world has been addressed by considering two different areas, southern Italy and central Macedonia. Technological features such as ceramic paste, decoration and firing have been determined for different ceramic groups established according to provenance criteria. The studies of technology and provenance have been performed following an archaeometric approach, using neutron activation analysis, petrographic analysis, X‐ray diffraction and scanning electron microscopy. The results have revealed the existence of two different models. On the one hand, southern Italy seems to exhibit a more organized pottery production, which follows a Mycenaean‐like technology, while in central Macedonia production is probably more varied, being based in part on the technology of the local tradition.  相似文献   
107.
Biogeographers, ecologists, palaeontologists, and conservation managers often deal with checklists in which not all individuals have been identified to a species level, or the accuracy of species identification is questionable. Is it possible and credible to investigate species richness based on such checklists? Studies on macrofauna in the Far Eastern seas, eastern Arctic seas, and adjacent waters of the Pacific and Arctic Oceans suggest that in different habitats and for diverse taxa, species, and higher taxa richness strongly correlate with each other and increase with an expansion in the study area and sample size according to the species–area law. Such an increase is higher in the bottom zone than in the pelagic. Species and higher taxa richness also show a decrease from lower to higher latitudes, which is in line with the Humboldt–Wallace’s law. According to Willis’ law and self-similarity in the organisation of taxonomic levels, species richness can be assessed based on the genus, family, and order richness. In other words, supraspecies richness itself can tell us the same as species richness and therefore certain global patterns revealed at the species level may also be revealed at the supraspecies level. Such a concordance in general trends among richness parameters at different taxonomic levels in practice implies that species richness can be studied based on lists that lack species identifications or lists with doubtful species identification. We suggest bolder use of supraspecies richness in science and practice, discussing the disadvantages and advantages of this approach.  相似文献   
108.
109.
110.
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