全文获取类型
收费全文 | 2111篇 |
免费 | 94篇 |
专业分类
2205篇 |
出版年
2023年 | 11篇 |
2022年 | 9篇 |
2020年 | 41篇 |
2019年 | 48篇 |
2018年 | 54篇 |
2017年 | 55篇 |
2016年 | 82篇 |
2015年 | 58篇 |
2014年 | 52篇 |
2013年 | 513篇 |
2012年 | 55篇 |
2011年 | 89篇 |
2010年 | 68篇 |
2009年 | 70篇 |
2008年 | 57篇 |
2007年 | 50篇 |
2006年 | 57篇 |
2005年 | 25篇 |
2004年 | 33篇 |
2003年 | 24篇 |
2002年 | 34篇 |
2001年 | 48篇 |
2000年 | 21篇 |
1999年 | 26篇 |
1998年 | 19篇 |
1997年 | 23篇 |
1996年 | 18篇 |
1995年 | 24篇 |
1994年 | 21篇 |
1993年 | 29篇 |
1992年 | 23篇 |
1991年 | 13篇 |
1990年 | 18篇 |
1988年 | 25篇 |
1987年 | 23篇 |
1986年 | 24篇 |
1985年 | 21篇 |
1984年 | 35篇 |
1983年 | 20篇 |
1982年 | 22篇 |
1981年 | 26篇 |
1980年 | 25篇 |
1979年 | 19篇 |
1978年 | 20篇 |
1977年 | 18篇 |
1976年 | 21篇 |
1974年 | 12篇 |
1973年 | 13篇 |
1972年 | 17篇 |
1970年 | 12篇 |
排序方式: 共有2205条查询结果,搜索用时 0 毫秒
41.
42.
A technique for making acetate peels of tools using Triafol is outlined. A series of ‘blind tests’ is described where the suitability of this replica material for reproducing the details of usewear was tested. The advantages and disadvantages of the use of acetate peels are discussed with reference to examination of usewear traces. 相似文献
43.
Lee KS 《Journal of regional science》1984,24(4):509-517
A two-sector dynamic general equilibrium model is developed "to investigate the direction of migration in response to differing demographic and consumption demand behavior, as well as variations in production conditions." The model, which involves a rural sector and an urban sector, incorporates "returns to scale and the natural rate of sectoral population growth as important determinants of the direction of migration, in addition to price and income elasticities, and the sectoral technical change rate with which...previous studies dealt." 相似文献
44.
A multi-regional framework is developed in order to analyze net migration over time to all 10 Canadian provinces within an integrated system of equations. "An extended gravity model is the basis for the equation specification and the use of constrained econometric estimation techniques allows for the provincial interdependence of the migration decision while at the same time ensuring that an important system-wide requirement is respected." The model is estimated using official Canadian data for the 1960s and 1970s. "The results suggest the predominance of the push factor for interprovincial migration for most provinces, although net migration to the Atlantic provinces is also shown to be subject to pull forces from the rest of the country." The effects of wage rate variables, unemployment, and political disturbances in Quebec on inter-provincial migration are noted. 相似文献
45.
46.
47.
Archaeologists, along with other Quaternary researchers, seldom rely upon a single radiocarbon determination to provide an estimate of the age of the phenomenon which is the object of their study. There is an evident need for an explicitly formulated procedure for comparing sets of radiocarbon determinations from the same and from adjacent strata or sites, and for combining these where statistical and archaeological criteria indicate that this combination is warranted. The present contribution provides explicit modelling for a series of recommended procedures, a critique of previous methods, and paradigms for application of the recommended procedures. 相似文献
48.
49.
50.