全文获取类型
收费全文 | 8850篇 |
免费 | 333篇 |
出版年
2020年 | 126篇 |
2019年 | 170篇 |
2018年 | 181篇 |
2017年 | 233篇 |
2016年 | 301篇 |
2015年 | 189篇 |
2014年 | 176篇 |
2013年 | 2264篇 |
2012年 | 221篇 |
2011年 | 266篇 |
2010年 | 252篇 |
2009年 | 213篇 |
2008年 | 205篇 |
2007年 | 176篇 |
2006年 | 166篇 |
2005年 | 121篇 |
2004年 | 116篇 |
2003年 | 106篇 |
2002年 | 117篇 |
2001年 | 129篇 |
2000年 | 141篇 |
1999年 | 174篇 |
1998年 | 116篇 |
1997年 | 80篇 |
1996年 | 89篇 |
1995年 | 98篇 |
1994年 | 95篇 |
1993年 | 95篇 |
1992年 | 97篇 |
1991年 | 75篇 |
1990年 | 76篇 |
1989年 | 81篇 |
1988年 | 86篇 |
1987年 | 97篇 |
1986年 | 86篇 |
1985年 | 124篇 |
1984年 | 122篇 |
1983年 | 130篇 |
1982年 | 100篇 |
1981年 | 105篇 |
1980年 | 107篇 |
1979年 | 103篇 |
1978年 | 94篇 |
1977年 | 109篇 |
1976年 | 86篇 |
1975年 | 95篇 |
1974年 | 83篇 |
1973年 | 79篇 |
1972年 | 62篇 |
1971年 | 65篇 |
排序方式: 共有9183条查询结果,搜索用时 15 毫秒
181.
182.
183.
184.
185.
"Malthusians maintain that rapid population growth aggravates poverty, while Marxists contend that social formations determine its nature and extent. Each perspective is incomplete, however, since it ignores the insights of the other. Latin American states, characterized by dependent capitalism formations and dominated by ruling elites, are generally incapable of solving the problems of population and poverty. Since population growth under dependent capitalism weakens labor's bargaining position against capital, reduced population growth is emphasized as a labor empowerment strategy the poor can implement on their own to improve their socioeconomic conditions." 相似文献
186.
A longitudinal approach to migration behavior makes it possible to identify a sufficient condition for positive associations between rates of in-migration and rates of out-migration in the same regions. The longitudinal approach centers on the intervals of time that individuals spend in a region, and these intervals can be analyzed in terms of probability distributions or the equivalent hazard functions or survivor functions. Differences in the distributions of these intervals between subpopulations whose residence in a region begins with in-migration and subpopulations whose residence begins with other events are sufficient for temporal variations in rates of in-migration to produce variations in out-migration rates in subsequent periods of time. Tests for such differences are performed using data from the National Longitudinal Survey of Youth. 相似文献
187.
Johnson JH 《Transactions (Institute of British Geographers : 1965)》1990,15(3):259-276
"A classic case where out-migration interacted with many other geographical phenomena is provided by rural Ireland in the nineteenth century. The apparent turning point was the Great Famine of the 1840s, but the areas with the greatest suffering from starvation did not necessarily show the greatest population decline, suggesting that other forces were active. Considerable economic and social changes were already taking place before the Famine: fertility was being reduced, later marriage was becoming established and considerable emigration was already taking place. Immediately after the Famine those areas which had been hardest hit often reverted to pre-Famine conditions and did not show strong population decline until the 1870s. The Famine was a most serious event, but the modernization of Irish rural life, which linked emigration with changes in family structure, agriculture and population numbers, was more important in bringing about geographical change." 相似文献
188.
189.
190.