全文获取类型
收费全文 | 1649篇 |
免费 | 65篇 |
专业分类
1714篇 |
出版年
2020年 | 19篇 |
2019年 | 21篇 |
2018年 | 40篇 |
2017年 | 37篇 |
2016年 | 51篇 |
2015年 | 45篇 |
2014年 | 31篇 |
2013年 | 597篇 |
2012年 | 56篇 |
2011年 | 55篇 |
2010年 | 72篇 |
2009年 | 60篇 |
2008年 | 37篇 |
2007年 | 75篇 |
2006年 | 69篇 |
2005年 | 20篇 |
2004年 | 31篇 |
2003年 | 22篇 |
2002年 | 18篇 |
2001年 | 17篇 |
2000年 | 10篇 |
1999年 | 15篇 |
1998年 | 15篇 |
1997年 | 6篇 |
1996年 | 8篇 |
1995年 | 18篇 |
1994年 | 11篇 |
1993年 | 9篇 |
1992年 | 12篇 |
1991年 | 9篇 |
1990年 | 8篇 |
1989年 | 12篇 |
1988年 | 13篇 |
1987年 | 16篇 |
1986年 | 11篇 |
1985年 | 14篇 |
1984年 | 11篇 |
1983年 | 9篇 |
1982年 | 10篇 |
1981年 | 12篇 |
1980年 | 14篇 |
1979年 | 7篇 |
1978年 | 8篇 |
1977年 | 6篇 |
1976年 | 8篇 |
1975年 | 8篇 |
1972年 | 10篇 |
1971年 | 5篇 |
1970年 | 7篇 |
1969年 | 5篇 |
排序方式: 共有1714条查询结果,搜索用时 15 毫秒
81.
Fifty-three copper-based metal fragments, recovered from the Robitaille site in southcentral Ontario, were analysed by neutron activation to establish their chemical make-up and to sort them by their trace elemental chemistries. Three different European copper samples, one brassy copper and 48 brass samples with five different chemistries were found. As few as eight trading actions may account for all of the recovered European metal fragments. 相似文献
82.
Yaroslav V. Kuzmin 《Journal of Archaeological Research》2008,16(2):163-221
This article focuses on the presence of humans in Siberia and the Russian Far East at the coldest time of the Late Pleistocene,
called the Last Glacial Maximum (LGM) and dated to c. 20,000–18,000 rcbp. Reconstruction of the LGM environment of Siberia,
based on the latest models and compilations, provides a background for human existence in this region. Most of Siberia and
the Russian Far East at c. 20,000–18,000 rcbp was covered by tundra and cool steppe, with some forest formations in the river
valleys. Climate was much colder and drier than it is today. Eighteen Upper Paleolithic sites in Siberia are radiocarbon dated
strictly to the LGM, and at least six of them, located in southern parts of western and eastern Siberia and the Russian Far
East, have solid evidence of occupation during that time span. It seems clear that southern Siberia was populated by humans
even at the height of the LGM, and that there was no dramatic decline or complete disappearance of humans in Siberia at that
time. The degree of human adaptation to periglacial landscapes in the mid-Upper Paleolithic of northern Eurasia was quite
high; humans coped with the cold and dry environmental conditions using microblade technology, artificial shelters, tailored
clothes, and megafaunal bones as fuel.
An erratum to this article can be found at 相似文献
83.
J. Buxeda I Garrigs R. E. Jones V. Kilikoglou S. T. Levi Y. Maniatis J. Mitchell L. Vagnetti K. A. Wardle S. Andreou 《Archaeometry》2003,45(2):263-284
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
84.
This study uses data of about 9,000 apartment sales in Stockholm, Sweden, to assess the impact of crime on property prices. The study employs hedonic pricing modelling to estimate the impact of crime controlling for other factors (property and neighbourhood characteristics). Geographic Information System (GIS) is used to combine apartment sales by coordinates with offences, land use characteristics and demographic data of the population. The novelty of this research is threefold. First, it explores a set of land use attributes created by spatial techniques in GIS in combination with detailed geographical data in hedonic pricing modelling. Second, the effect of crime in neighbouring zones at one place can be measured by incorporating spatial lagged variables of offence rates into the model. Third, the study provides evidence of the impact of crime on housing prices in a capital city of a traditional welfare state, information otherwise lacking in the international literature. Our results indicate that apartment prices in a specific area are strongly affected by crime in its neighbouring zones, regardless of crime type. When offences were broken down by types, residential burglary, theft, vandalism, assault and robbery individually had a significant negative effect on property values. However, for residential burglary such an effect is not homogenous across space, and apartment prices in central areas are often less discounted by being exposed to crime than those in the city's outskirts. 相似文献
85.
The results of the lead isotope analysis (LIA) of 15 copper‐base artefacts from the Bronze Age site of al‐Midamman, Yemen, are reported. The LIA data suggest the existence of an indigenous Bronze Age metal production and exchange system centred on the southern Red Sea region, distinct from those in neighbouring regions of Arabia and the Levant. These preliminary results are highly significant for the archaeology of the region, suggesting that local prehistoric copper extraction sites have thus far gone unrecorded, and highlighting the need for systematic archaeometallurgical fieldwork programmes in the countries surrounding the southern Red Sea. 相似文献
86.
Igor V. Volvenko Andrey V. Gebruk Oleg N. Katugin Georgy M. Vinogradov Alexei M. Orlov 《Geographical Research》2023,61(4):503-511
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
87.
88.
Véronique Favre-Bonte Elodie Gardet Catherine Thevenard-Puthod 《European Planning Studies》2019,27(5):1035-1057
As there is little research on the link between territories and interorganisational networks, this paper examines how the nature of a territory influences the characteristics of innovation networks. It compares the innovation network forms of two types of territories (high-altitude and medium-altitude mountain resorts) regarding four characteristics of networks widely debated in the literature: the nature of the relationships between members, the mode of regulation used, the architecture, and the geographical proximity of members. This research makes a significant contribution to both the spatial development and innovation management literature: indeed, our results show that according to the nature of the territory, innovation networks differ in terms of partners, geographical proximity, and regulation mode. However, the nature of the territory does not seem to influence the architecture of the innovation network since those networks need a hub organization that orchestrates the partners’ actions. These results, by providing a better understanding of the characteristics of innovation networks, help tourist territories to better attract customers. 相似文献
89.
V. Flores‐Als F. J. Alejandre F. J. Blasco‐Lpez M. Torres‐Gonzlez C. Núez 《Archaeometry》2019,61(5):1097-1110
The Royal Artillery Factory of Seville in Spain originated from pre‐existing private bronze foundries dating from the 16th century. The paper analyses the stratigraphy of wall cladding in the areas traditionally known as the ‘Old Foundry’ and the ‘New Foundry’, through its characterization by optical microscopy, scanning electron microscopy with energy‐dispersive X‐ray spectrometry (SEM‐EDX), micro‐X‐ray fluorescence (μ‐XRF) and micro‐X‐ray diffraction (μ‐XRD), in order to analyse the metal deposits that have accumulated since the 17th century. The data obtained allowed the verification of the available historiographical information and the location of the original bronze smelting furnaces. The analysis of patinas deposited on the overlapping layers of lime also confirmed that neither the raw materials nor the composition of the alloys used presented any substantial changes. 相似文献
90.
Voltammetry of microparticles using a paraffin‐impregnated graphite electrode (VMP/PIGE) was applied as a very local and non‐invasive analytical technique in order to investigate the presence of remains of metallic plating on two ferrous and one cuprous artefact from the medieval period. The analyses have been performed locally and selectively on regions presenting particular features, such as texture, cohesion and colour differences. The results confirm local differences in chemical composition, leading to conclusions about the presence of metallic plating on these artefacts. 相似文献