全文获取类型
收费全文 | 1310篇 |
免费 | 62篇 |
专业分类
1372篇 |
出版年
2023年 | 6篇 |
2022年 | 7篇 |
2020年 | 23篇 |
2019年 | 38篇 |
2018年 | 42篇 |
2017年 | 69篇 |
2016年 | 54篇 |
2015年 | 32篇 |
2014年 | 38篇 |
2013年 | 461篇 |
2012年 | 43篇 |
2011年 | 35篇 |
2010年 | 44篇 |
2009年 | 40篇 |
2008年 | 27篇 |
2007年 | 35篇 |
2006年 | 17篇 |
2005年 | 16篇 |
2004年 | 17篇 |
2003年 | 19篇 |
2002年 | 18篇 |
2001年 | 20篇 |
2000年 | 14篇 |
1999年 | 23篇 |
1998年 | 8篇 |
1997年 | 13篇 |
1996年 | 11篇 |
1995年 | 13篇 |
1994年 | 9篇 |
1993年 | 8篇 |
1992年 | 10篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 8篇 |
1987年 | 6篇 |
1986年 | 7篇 |
1985年 | 8篇 |
1984年 | 9篇 |
1982年 | 5篇 |
1981年 | 11篇 |
1980年 | 9篇 |
1979年 | 14篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1976年 | 7篇 |
1975年 | 6篇 |
1974年 | 9篇 |
1973年 | 11篇 |
1972年 | 4篇 |
1971年 | 5篇 |
排序方式: 共有1372条查询结果,搜索用时 15 毫秒
91.
92.
Troy Sternberg Nicholas Middleton David Thomas 《Transactions (Institute of British Geographers : 1965)》2009,34(3):364-377
The desert-steppe region of southern Mongolia is susceptible to drought and extreme winter weather ( dzud ) that in combination form Mongolia's worst natural hazard. Low precipitation and high climatic variability in this dryland environment impact the landscape and affect pastoralism, the dominant rural lifestyle. Using the Standardised Precipitation Index (SPI), this paper identifies drought occurrence in South Gobi Province, Mongolia. It then examines the relationship of drought with climate factors, interaction with vegetation (derived from Normalised Difference Vegetation Index - NDVI - data), and local human and livestock populations, and the dzuds of 1999–2001. Results show that drought is recurrent in the region, reaching extreme intensity most recently in 2005–2006. In contrast with the prevailing concept of drought impacting dzuds , the study did not find a connection between drought and dzud in South Gobi Province. Though repeated events, these natural hazards occur independently in the region. Climatic variables show increasing temperatures (>1°C), fluctuating precipitation patterns and a decline in vegetation cover. The principal long-term correlation of drought is with human population rather than natural factors, dzud or livestock numbers. 相似文献
93.
94.
95.
Annick Vuissoz Michael Worobey Nancy Odegaard Michael Bunce Carlos A. Machado Niels Lynnerup Elizabeth E. Peacock M. Thomas P. Gilbert 《Journal of archaeological science》2007
We have investigated the survival of PCR-amplifiable mitochondrial and nuclear DNA in a small number of modern and medieval bovine leather samples. The results of this preliminary investigation demonstrate that, while no nuclear DNA can be PCR-amplified from any of the specimens, mitochondrial DNA can be amplified from all samples. To investigate this contrasting pattern of DNA survival further, we have vegetable-tanned cow skin in our own laboratory, and directly assayed the survival of PCR-amplifiable mitochondrial and nuclear DNA at each step of the process. The results indicate that nuclear DNA is reduced to sub-amplifiable levels as a result of the tanning baths, whereas amplifiable mitochondrial DNA survives the complete process. Our results suggest that old and archaeological bovine leather may represent a useful source of genetic information, although this information will most likely be limited to that which can be gained from mitochondrial DNA. 相似文献
96.
97.
Reregulating for Freshwater Enclosure: A State of Exception in Canterbury,Aotearoa New Zealand 下载免费PDF全文
In this paper, we argue that democracy is increasingly indistinguishable from authoritarianism, in a process that is entangled with neoliberalisms. To build this argument, we examine a case study of central government intervention in regional environmental decision making in Aotearoa New Zealand through the lens of Agamben's “state of exception”. The intervention—unprecedented and unconstitutional—squeezed democratic spaces for decision making about freshwater and sought to smooth the way for capital accumulation. The audacity of government actions indicate, we argue, an abandonment of efforts to disguise neoliberal encroachments on democracy, known as the double truth tactic. Yet we also argue that in identifying this as a state of exception, we can examine it as part of a process and therefore demonstrate the possibilities for counter‐hegemonic actions to emerge. 相似文献
98.
99.
Mercedes Murillo-Barroso Thomas Oliver Pryce Bérénice Bellina Marcos Martinón-Torres 《Journal of archaeological science》2010
Recent archaeological investigations at Khao Sam Kaeo, on the Upper Thai-Malay Peninsula, have furnished evidence for a mid/late 1st millennium BCE cultural exchange network stretching from the Indian subcontinent to Taiwan. Typological, compositional and technological study of Khao Sam Kaeo's copper-base artefacts has identified three distinct copper-alloy metallurgical traditions, with reasonable analogies in South Asian, Vietnamese, and Western Han material culture. Furthermore, analyses of technical ceramic and slag suggest that Khao Sam Kaeo metalworkers may have been using a cassiterite cementation process to produce high-tin bronze ingots for export or onsite casting/forging. Not only would this industry constitute the earliest evidence for the exploitation of Peninsula tin resources, but we also offer a speculative argument for the source of Khao Sam Kaeo's copper-base production technology. 相似文献
100.
Gérard Poupeau François-Xavier Le Bourdonnec Tristan Carter Sarah Delerue M. Steven Shackley Jean-Alix Barrat Stéphan Dubernet Philippe Moretto Thomas Calligaro Marina Milić Katsuji Kobayashi 《Journal of archaeological science》2010
In this paper we evaluate the relative analytical capabilities of SEM-EDS, PIXE and EDXRF for characterizing archaeologically significant Anatolian obsidians on the basis of their elemental compositions. The study involves 54 geological samples from various sources, together with an archaeological case study involving 100 artifacts from Neolithic Çatalhöyük (central Anatolia). With each technique the artifacts formed two compositional groups that correlated with the East Göllü Da? and Nenezi Da? sources. The non-destructive capabilities of these methods are emphasized (albeit with certain analytical limitations in the case of SEM-EDS), suggesting important new techniques for Near Eastern obsidian provenance studies. 相似文献