全文获取类型
收费全文 | 781篇 |
免费 | 52篇 |
出版年
2023年 | 11篇 |
2021年 | 6篇 |
2020年 | 20篇 |
2019年 | 40篇 |
2018年 | 41篇 |
2017年 | 59篇 |
2016年 | 49篇 |
2015年 | 25篇 |
2014年 | 39篇 |
2013年 | 209篇 |
2012年 | 25篇 |
2011年 | 23篇 |
2010年 | 30篇 |
2009年 | 15篇 |
2008年 | 20篇 |
2007年 | 23篇 |
2006年 | 11篇 |
2005年 | 8篇 |
2004年 | 10篇 |
2003年 | 12篇 |
2002年 | 16篇 |
2001年 | 5篇 |
1999年 | 11篇 |
1998年 | 6篇 |
1997年 | 9篇 |
1996年 | 4篇 |
1995年 | 10篇 |
1994年 | 6篇 |
1993年 | 2篇 |
1992年 | 6篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 7篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 8篇 |
1984年 | 3篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1974年 | 4篇 |
1973年 | 4篇 |
1970年 | 2篇 |
1969年 | 2篇 |
排序方式: 共有833条查询结果,搜索用时 15 毫秒
781.
782.
Canada’s climate change strategy faces an uncertain future since the country’s withdrawal from the Kyoto Protocol in 2011, making domestic public debate and awareness critical in the search for effective mitigation policies. This article presents a spatio-temporal analysis of newspaper reporting across Canada on climate change and carbon reduction approaches, ranging from renewable energies (solar, wind, hydro power) to carbon management (e.g., carbon capture and storage [CCS]) and economic approaches (e.g., carbon trade, ecological fiscal reform). The findings of a news article keyword analysis show that the overall growth of the Canadian news coverage during this time period was significantly fragmented into isolated peaks of activity rather than continuous growth of the topic of climate change. Furthermore, the study finds a strong news emphasis on technology- and growth-oriented solutions as opposed to a comprehensive ecological modernization that would encourage a deeper structural discussion about Canada’s much-criticized carbon-intensive energy economy. 相似文献
783.
784.
785.
Daniel Alan DeGroff 《European Review of History》2012,19(2):229-248
Artur Hazelius (1833–1901), founder of the Nordiska Museet and the Skansen Open-Air Museum, was a pioneering figure in the practice of ethnographic display in Europe. Hazelius achieved Europe-wide recognition following his presentation of Swedish and Scandinavian peasant ethnography at the Paris Universal Exposition of 1878, where his displays were reviewed positively in the international press. This paper argues that the significance of the Hazelian ethnographic project was embedded in overlapping contextual frames with centres in Stockholm and Paris. If the displays most readily spoke to a general concern with the decline of traditional life as rooted in the countryside, they arguably took on other, different and occasionally conflicting meanings as they were moved from one exhibitionary context to another. Whereas in Stockholm the ethnographic displays were inscribed in the conciliatory rhetoric of Scandinavism, the exhibitionary setting of the exposition universelle imposed an interpretative frame defined by the logic of a competitive nationalism. For Nordic audiences, the scenes reflected the positive historical significance of the peasantry in the unfolding narrative of Scandinavian political modernity; for the French audience, however, those same scenes were either applauded for their life-likeness or seen as reflective of the ethnographic richness of the ‘kingdom of Sweden’. 相似文献
786.
787.
ABSTRACT In this paper, we analyze the isotopic niche and resource use of the guanaco (Lama guanicoe), pampas deer (Ozotoceros bezoarticus) and marsh deer (Blastocerus dichotomus) on the temperate plain of the northern Pampa region in the southeast of South America. The measured stable isotope compositions in bone tissue are δ13C, δ15N and δ18O. All the analyzed samples were recovered from different archaeological sites from the late Holocene. According to the results, the guanaco was strictly confined to the Pampa plain environment, developing a broad niche based on C3 plants and a variable contribution of C4 grasses within a grazing trend. The pampas deer preferentially used the Pampa plain, but also the prairies on the borders of the wetland, showing eurioic characteristics and a narrower niche based on C3 plants. In turn, the marsh deer was strictly confined to wetland environments, developing a C3 diet–base, within a narrow isotopic niche and stenoic characteristics. The three mammals showed a wide range of intraspecific variability, which was a key factor in their adaptability to spatial and temporal changes in the vegetation coverage. In fact, the temporal trends of their isotopic values were concurrent with the major climatic variations of the Holocene. Differences in the correlations between the values of both carbon sources in both deer species compared with the guanaco suggest a distinct chemical composition of their diet and/or differences in the allocation of nutrients. The isotopic values of nitrogen and spacing of the carbon sources in guanaco (pseudoruminant) and both deer species (ruminants) show no significant differences between them, thus establishing the values for local large herbivores. Significant correlations between δ13C and δ15N were found in the guanaco and marsh deer. The regional and extra–regional variability in the guanaco's δ13Ccollagen and δ15N probably reflect the clinal variations in the vegetation coverage and the amount of rainfall. The collagen isotope values in the guanaco throughout the entire Holocene show that the humid Pampa would have shifted between being a more recurrent mesic and temperate plain with minor phases of dry–mesic conditions like during the Little Ice Age, and a humid and warm one at the peaks of the Holocene Thermal Maximum and the Medieval Climatic Anomaly. The guanaco and the pampas deer adapted to all the climatic changes that happened on the humid Pampa until the biological invasions of large European mammals changed the herbivores’ guild composition of this vast plain, pushing them into peripheral habitats due to competition. The within–species variability in isotopic signals through time and space make it necessary to carry out adequate sampling before reconstructing the diets of local past populations. 相似文献
788.
Daniel Boyd 《Interdisciplinary science reviews : ISR》2020,45(1):71-94
ABSTRACTThe existence of biological information systems is generally taken as given in discussions of their function. However, any theory of such systems must be considered incomplete unless it can also explain how the system comes to exist. This article describes the ways in which complex functional systems in general can be created through design, self-assembly and evolution. The differences and relationship between physical and informational entities, organization, processes and dimensionality are also discussed. Through comparison with information technologies, whose origins we understand, conclusions are drawn concerning the creation of functional biological neural networks: specifically, that this involves the self-assembly of information entities into a number of strongly emergent levels of organization. Finally, potential approaches are considered to overcome the hurdles to scientific investigation of emergent information-based systems and the processes by which they are created. 相似文献
789.
Claudia I. Montalvo Pedro O. Tallade Fernando J. Fernández Germán J. Moreira Daniel J. Rafuse Luciano J.M. De Santis 《Journal of archaeological science》2011,38(12):3541-3548
The following paper presents the results of the analysis of the avian prey bones found in uneaten remains of crested caracara (Caracara plancus, Aves, Falconiformes) from La Pampa province, Argentina. Anatomical parts representation and taphonomic modifications were evaluated and compared to results of the evaluation of bone remains recovered from crested caracara’s pellets and to previous studies of other diurnal birds of prey. The results suggest a preferential consumption of some body parts of avian prey, as evidenced in the high frequency of wing elements in the uneaten prey remains. This analysis helps to support interpretative data concerning the origins of avian remains in the zooarchaeological and paleontological record, and contributes to the knowledge of a common predator found throughout diverse environments in South America. 相似文献
790.
Daniel Weidner 《Political Theology》2020,21(1-2):71-88
ABSTRACTThe paper discusses Paul Tillich’s changing conception of a “prophetic critique” of contemporary culture and society through the notion of a “kairos”, the moment of fullfilled time. It shows how Tillich refers both to a specific notion of prophecy (developed in Max Weber’s reflections on charisma) and to a concept of eschatological time (developed in Karl Barth’s dialectical theology). In different texts from the 1920ies and the 1950ies, Tillich uses the idea of “kairos” for a critique of the “idols” of bourgeois culture that is both radical and urgent. However, read in their historic sequence, these texts also reveal the difficulty of upholding the urgency of such a critique over time – as a result, Tillich’s notion of “kairos” becomes more and more reflexive and self critical as the possibility of prophetic critique is concerned. 相似文献