全文获取类型
收费全文 | 1126篇 |
免费 | 28篇 |
出版年
2021年 | 6篇 |
2020年 | 32篇 |
2019年 | 50篇 |
2018年 | 49篇 |
2017年 | 66篇 |
2016年 | 51篇 |
2015年 | 23篇 |
2014年 | 37篇 |
2013年 | 284篇 |
2012年 | 27篇 |
2011年 | 30篇 |
2010年 | 24篇 |
2009年 | 29篇 |
2008年 | 24篇 |
2007年 | 29篇 |
2006年 | 28篇 |
2005年 | 21篇 |
2004年 | 22篇 |
2003年 | 20篇 |
2002年 | 12篇 |
2001年 | 22篇 |
2000年 | 8篇 |
1999年 | 14篇 |
1998年 | 5篇 |
1997年 | 8篇 |
1996年 | 8篇 |
1995年 | 10篇 |
1994年 | 11篇 |
1993年 | 8篇 |
1992年 | 6篇 |
1990年 | 8篇 |
1989年 | 7篇 |
1987年 | 9篇 |
1986年 | 9篇 |
1985年 | 10篇 |
1984年 | 9篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 8篇 |
1980年 | 9篇 |
1979年 | 11篇 |
1978年 | 11篇 |
1977年 | 5篇 |
1976年 | 9篇 |
1975年 | 9篇 |
1974年 | 4篇 |
1973年 | 7篇 |
1972年 | 9篇 |
1970年 | 6篇 |
1969年 | 4篇 |
排序方式: 共有1154条查询结果,搜索用时 15 毫秒
81.
82.
Melissa Shaffer-O’Connell 《The American review of Canadian studies》2017,47(1):89-100
Federalism often creates additional decisions for interest groups in determining how best to advocate for their policy recommendations in the legislative process. Should they focus their advocacy at the local, state, or national level of government? This article examines interest group behaviors in water quality policy in the Great Lakes region from 1960 to 2000. I evaluate the reasons for interest group decisions about which level of government to target, using historical analysis of Great Lakes water quality policy in the United States and Canada. The results of this analysis show that in many cases groups are influenced in their decision-making based on the level of government that has the greatest jurisdiction over the policy, supporting a neoinstitutional argument. 相似文献
83.
A Rock‐Magnetic Quest for Possible Ore Sources for the Ancient Iron‐Smelting Industry in the Olkhon Region (Lake Baikal,Siberia)
下载免费PDF全文
![点击此处可从《Archaeometry》网站下载免费的PDF全文](/ch/ext_images/free.gif)
G. G. Matasova A. Yu. Kazansky N. O. Kozhevnikov S. V. Snpokov A. V. Kharinsky 《Archaeometry》2017,59(3):511-527
Rock‐magnetic techniques were used to examine the topsoil layer of Kurma archaeological site (in the Olkhon region, on the north‐western coast of Lake Baikal, Siberia) in an effort to determine the possible sources of iron ores for iron‐smelting centres (at about the bc /ad boundary). Measurements have shown a magnetic enhancement of the topsoil due to magnetite grains resulting from weathering of strongly magnetic crystalline rocks. They have also revealed a preliminary picture of the distribution of strongly magnetic topsoils around the ancient iron‐smelting centres. Perhaps, in addition to traditional sources of raw materials, the ancient metallurgists used black sand talus as an ore deposit. 相似文献
84.
85.
Robert Van de Noort Brian Cumby Lucy Blue Anthony Harding Linda Hurcombe Tom Monrad Hansen Andy Wetherelt Jenny Wittamore Andy Wyke 《International Journal of Nautical Archaeology》2014,43(2):292-313
This paper reports on the construction of a full‐scale Bronze Age‐type sewn‐plank boat based on the Ferriby boats. The boat, which was named Morgawr, was constructed in the National Maritime Museum Cornwall in Falmouth, England, during 2012 and the first months of 2013, as part of a larger exhibition in the museum. This paper provides the background and context of the project, describes the process of building the craft, and reflects in particular on differences between Morgawr and the ‘hypothetical reconstruction of a complete sewn‐plank boat’ published in 1990 by Ted Wright and John Coates which formed the basis for this project. 相似文献
86.
87.
Tom Astley 《Journal of Latin American Cultural Studies (Travesia)》2014,23(1):65-86
This paper takes several examples from the work of one Cuban punk band – Porno Para Ricardo – to assess the use of memory as a tool for reflecting fragments of a national identity which is both quotidian and contemporary. This singular case study is chosen not for their pertinence within Cuban culture, or even within Cuban alternative music, but rather as an exemplar of the assertion that popular music, rather than changing identities, often reflects aspects of identity and how they manifest in the everyday. Porno Para Ricardo are one such point of reflection. However, their remembrances often stray into areas too traumatic or politically admonished to be ‘remembered’ as part of a more rigid revolutionary history. By remembering the cultural (and thus, vicariously, the political) legacy of the Soviet Union within Cuba, and by re-personalising (or personifying) the traumas of mass generational exodus experiences in the early 90s, Porno Para Ricardo both augment the space of collective Cuban memory, and thus identity, but also attempt to reconnect the slabs of Cuban history often cleaved into evental epochs after which a ‘new way of being’ is constructed, as a means to better make sense of, and better reflect, contemporary Cuban identity. 相似文献
88.
A simple mathematical expression is proposed to estimate spectra reduction damping factors for seismic design of systems with viscous dampers. The expression is obtained from the ratios between ordinates of uniform hazard spectra associated with two different return intervals (50 and 125 years), corresponding to sites with different types of soil within the Valley of Mexico. The expression proposed depends on the dominant period of the soil, and on both the vibration period and damping ratio of the structural system. Values of the damping factors proposed here are comparable to those recommended by different authors and seismic design building codes. 相似文献
89.
Thermal–hydrological–mechanical coupling processes suggest that fault permeability should undergo dynamic change as a result of seismic slip. In igneous rocks, a fault's slip surface may have much higher permeability than the surrounding rock matrix and therefore operate as a conduit for fluids. We conducted laboratory experiments to investigate changes in fracture permeability (or transmissivity) of a fault in granite due to shear slip and cyclic heating and cooling. Our experiments showed that high initial fracture transmissivity (>10?18 m3) was associated with a high friction coefficient and that transmissivity decreased during slip. We propose that this reduction in transmissivity reflects the presence of gouge in fracture voids, increasing the area of contact in the fault plane and reducing the hydraulic aperture. In contrast, when initial fracture transmissivity was low (<10?18 m3), we observed that friction was lower and transmissivity increased during slip. The high transmissivity and high friction may be explained by large areas of bare rock being in contact on the slip surface. Slip velocity had little influence on the evolution of permeability, probably because gouge produced at different slip velocities had similar grain size distributions, or because gouge leaked from the slip surface. Transmissivity decreased with increasing temperature in heating tests, probably due to thermal expansion increasing normal stress on the fracture. Frictional heating did not influence transmissivity during the shearing tests. 相似文献
90.