全文获取类型
收费全文 | 16245篇 |
免费 | 546篇 |
国内免费 | 5篇 |
专业分类
各国政治 | 653篇 |
工人农民 | 719篇 |
世界政治 | 1067篇 |
外交国际关系 | 534篇 |
法律 | 10527篇 |
中国共产党 | 6篇 |
中国政治 | 153篇 |
政治理论 | 2967篇 |
综合类 | 170篇 |
出版年
2020年 | 220篇 |
2019年 | 268篇 |
2018年 | 331篇 |
2017年 | 386篇 |
2016年 | 392篇 |
2015年 | 291篇 |
2014年 | 299篇 |
2013年 | 1464篇 |
2012年 | 444篇 |
2011年 | 474篇 |
2010年 | 390篇 |
2009年 | 408篇 |
2008年 | 494篇 |
2007年 | 533篇 |
2006年 | 513篇 |
2005年 | 463篇 |
2004年 | 453篇 |
2003年 | 484篇 |
2002年 | 417篇 |
2001年 | 663篇 |
2000年 | 538篇 |
1999年 | 475篇 |
1998年 | 242篇 |
1997年 | 165篇 |
1996年 | 200篇 |
1995年 | 170篇 |
1994年 | 196篇 |
1993年 | 194篇 |
1992年 | 321篇 |
1991年 | 353篇 |
1990年 | 338篇 |
1989年 | 281篇 |
1988年 | 319篇 |
1987年 | 270篇 |
1986年 | 317篇 |
1985年 | 280篇 |
1984年 | 229篇 |
1983年 | 218篇 |
1982年 | 175篇 |
1981年 | 190篇 |
1980年 | 127篇 |
1979年 | 171篇 |
1978年 | 122篇 |
1977年 | 106篇 |
1976年 | 96篇 |
1975年 | 123篇 |
1974年 | 132篇 |
1973年 | 103篇 |
1972年 | 100篇 |
1969年 | 98篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
331.
332.
Simmons AB 《Estudios demográficos y urbanos》1991,6(1):5-31, 215
The author presents the case that the study of migration over the past century has become too diverse. He reviews works by writers from the several disciplines covering the topic, then cites the need to develop a consistent classification of the types of migration and their origins using standardized terminology. (SUMMARY IN ENG) 相似文献
333.
334.
335.
336.
337.
338.
339.
Rizk IA Stokes CS Nelson MR 《Studies in Comparative International Development (SCID)》1982,17(2):74-86
Child mortality was analyzed in relation to 3 dimensions of reproductive behavior: birth intervals, additional children desired, and contraceptive use. Study data were drawn from a 1978 survey conducted in 2 predominantly rural governorates, Beheira and Kafr El-Sheikh, in lower Egypt. Within each governorate, 2 districts were selected on the basis of their distance from the capital of the governorate, agricultural output by major crops, percent of the population urban, infant mortality rate, and crude birthrate. Within each of the 4 districts, villages were randomly drawn from 3 strata: villages lacking any governmental services; villages with limited services (health center or primary school); and villages served by a combined unit center providing integrated services. A random sample of household heads was selected from household registration records of the provision office of each district. 1200 interviews were obtained from 685 households. Restriction of the sample to women with 1 or more live births, and the elimination of 13 cases with incomplete or inaccurate information, yielded 1010 cases for analysis. The basic measure of actual fertility was birth intervals. For the total sample and within each age category, cumulative fertility is higher the greater the number of child deaths. The data demonstrate a strong relationship between child mortality experience and cumulative fertility. The problem lies in interpreting such results. With some exceptions, birth intervals increased as expected with increasing parity. Women without child death experience displayed longer birth intervals than women who had not lost a child. With the single exception of the 7th parity women, all differences were statistically significant. The data fail to eliminate potential biological influences on subsequent fertility. With biological influences adequately controlled, no behavioral differences remained. Women who experienced child mortality desired greater numbers of additional children than women without child death experience. 19% of respondents were ever users of contraception, with women of low parity the least likely ever to have used contraception. 相似文献
340.