全文获取类型
收费全文 | 894篇 |
免费 | 63篇 |
出版年
2023年 | 6篇 |
2022年 | 3篇 |
2021年 | 4篇 |
2020年 | 20篇 |
2019年 | 35篇 |
2018年 | 39篇 |
2017年 | 54篇 |
2016年 | 50篇 |
2015年 | 35篇 |
2014年 | 26篇 |
2013年 | 200篇 |
2012年 | 27篇 |
2011年 | 36篇 |
2010年 | 34篇 |
2009年 | 30篇 |
2008年 | 36篇 |
2007年 | 24篇 |
2006年 | 17篇 |
2005年 | 15篇 |
2004年 | 17篇 |
2003年 | 17篇 |
2002年 | 26篇 |
2001年 | 18篇 |
2000年 | 14篇 |
1999年 | 10篇 |
1998年 | 13篇 |
1997年 | 14篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1993年 | 10篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 9篇 |
1989年 | 4篇 |
1988年 | 10篇 |
1987年 | 9篇 |
1986年 | 2篇 |
1985年 | 9篇 |
1984年 | 5篇 |
1983年 | 8篇 |
1982年 | 8篇 |
1981年 | 3篇 |
1980年 | 7篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1970年 | 2篇 |
排序方式: 共有957条查询结果,搜索用时 15 毫秒
51.
52.
This study examines preservation of microfossils identified as introduced Ipomoea batatas in soils from northern New Zealand. Starch grains and xylem cells showed highly variable preservation, from good to extremely poor. For starch grains, the latter included brown-staining, expansion and distortion of the grain and vacuole, loss of the Maltese cross, pitting, cracking, fragmentation and disintegration. Degraded xylem showed similar brown-staining, occasional cracking, cross-wise fragmentation, with wall pits becoming progressively less visible or showing distortion, expansion and coalescence. 相似文献
53.
54.
55.
Mark W. Hauser Christopher R. DeCorse 《International Journal of Historical Archaeology》2003,7(1):67-98
Local earthenware associated with enslaved African populations in the Americas, variously called Colono-Ware, Afro-Caribbean Ware. Yabbas, and Criollo ware, has received considerable attention from researchers. What unifies this disparate group of ceramics is not method of manufacture, design and decoration, or even form and function but the association or potential association with African diaspora populations. The ceramics incorporate some skills and techniques possibly brought by African potters to the Americas, as well as skills reflecting European and Native American traditions, and local adaptations in form, function, and manufacture. Analogies linking African ceramic traditions to American industries have at times been employed uncritically and have relied on generalized characteristics to infer overly specific meanings. With particular reference to low-fired earthenwares from Jamaica, this paper examines the historical and cultural context of these ceramics and the methodological and theoretical problems faced in their interpretation. 相似文献
56.
57.
RESIDENTIAL SORTING AND ENVIRONMENTAL EXTERNALITIES: THE CASE OF NONLINEARITIES AND STIGMA IN AVIATION NOISE VALUES 下载免费PDF全文
This paper explores the sorting process in response to differing levels of aviation noise exposure in a housing market. Spatiotemporal hedonic pricing (HP) and stated choice (SC) results reflect nonlinearities and stigma. The HP models reveal nonlinear noise depreciation increasing from 0.40 to 2.38 percent per decibel as noise increases, while the SC noise values are lower in an area with high long‐term noise exposure. These nonlinearities are attributed to the spatial sorting of noise tolerant individuals. HP results from the same “noisy” area show a “stigma” from noise during the first year after the complete removal of aviation noise. 相似文献
58.
THE URBAN–RURAL GAP IN UNIVERSITY ATTENDANCE: DETERMINANTS OF UNIVERSITY PARTICIPATION AMONG CANADIAN YOUTH 下载免费PDF全文
Based on existing work, there are clear differences in the incidence of degree holders across the urban–rural hierarchy in favor of large urban areas. In large part, this gradient can be traced to the higher probability of obtaining a degree among residents of larger urban centers. Utilizing data from the Youth in Transition Survey (YITS), this paper explores factors that may account for university participation among Canadian youth. It asks whether this difference is due to local access to universities, family characteristics (e.g., parental income, education, and immigrant status), and local labor market characteristics that may increase the incentive for urban youth to attend university. 相似文献
59.
60.
“Blue Ribbon” Commissions,Interest Groups,and the Formulation of Policy in the American States 下载免费PDF全文
Despite the prevalence of state‐level commissions convened to make policy recommendations, research to date has not systematically investigated the ways in which these bodies impact policy or degree to which state‐level interest groups can use these institutions in that process. We argue that less powerful groups will favor these mechanisms and use them to get issues onto the institutional agenda and to increase the likelihood of legislative success. We also suggest that traditionally powerful groups will oppose the creation of reform‐minded task forces, but will likely use them to hinder policy change once they are formed. We test this assertion in an analysis of the creation and recommendations of task forces convened to study autism insurance mandates, as well as the eventual adoption of such mandates, in the American states between 2001 and 2010. The results suggest that public and industry groups influence the formation and recommendations of task forces, but that the latter appears to have a relatively larger impact. They also suggest that a task force recommendation has a large impact on the likelihood of adopting an autism insurance mandate and that neither the insurance industry nor autism advocacy groups have a direct influence on adoption after controlling for the presence of a recommendation. 相似文献