全文获取类型
收费全文 | 20690篇 |
免费 | 701篇 |
专业分类
各国政治 | 951篇 |
工人农民 | 1396篇 |
世界政治 | 1227篇 |
外交国际关系 | 931篇 |
法律 | 11758篇 |
中国政治 | 82篇 |
政治理论 | 4940篇 |
综合类 | 106篇 |
出版年
2023年 | 70篇 |
2021年 | 85篇 |
2020年 | 248篇 |
2019年 | 309篇 |
2018年 | 1542篇 |
2017年 | 1534篇 |
2016年 | 1366篇 |
2015年 | 360篇 |
2014年 | 350篇 |
2013年 | 1743篇 |
2012年 | 480篇 |
2011年 | 1204篇 |
2010年 | 1318篇 |
2009年 | 933篇 |
2008年 | 1009篇 |
2007年 | 1015篇 |
2006年 | 350篇 |
2005年 | 433篇 |
2004年 | 557篇 |
2003年 | 494篇 |
2002年 | 377篇 |
2001年 | 426篇 |
2000年 | 364篇 |
1999年 | 321篇 |
1998年 | 195篇 |
1997年 | 162篇 |
1996年 | 171篇 |
1995年 | 194篇 |
1994年 | 197篇 |
1993年 | 164篇 |
1992年 | 232篇 |
1991年 | 240篇 |
1990年 | 204篇 |
1989年 | 219篇 |
1988年 | 186篇 |
1987年 | 200篇 |
1986年 | 189篇 |
1985年 | 194篇 |
1984年 | 159篇 |
1983年 | 181篇 |
1982年 | 130篇 |
1981年 | 129篇 |
1980年 | 91篇 |
1979年 | 147篇 |
1978年 | 106篇 |
1977年 | 96篇 |
1976年 | 80篇 |
1975年 | 58篇 |
1974年 | 68篇 |
1973年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
82.
The enzyme activity of phosphoglucomutase (PGM) has been investigated in red cell haemolysates from 142 individuals and compared to the sub-type as determined by isoelectric focusing. The 10 phenotypes showed significant differences in PGM-activity which indicates that there is a correlation between the level of activity and the isolelectric point of homozygotes. No indication of silent alleles or alleles with reduced activity was found in this collective. 相似文献
83.
84.
Bone fragments were stored in water for 2 years at room temperature and investigated serologically using the following methods: Absorption-elution, extraction of blood group substances and immunohistochemistry (PAP). All 3 methods gave essentially specific results for fresh bone tissue but with putrid bone tissue unspecific reactions were found predominantly with the absorption-elution and PAP techniques. In contrast, more specific reactions were obtained from the extracts although they were much weaker. From this it can be concluded that pure physical binding plays a substantial role in the unspecific reaction between antibodies and bone material. It is suggested that the relevant physical properties are altered by putrification. 相似文献
85.
86.
87.
88.
89.
90.
David Brady Yunus Kaya Jason Beckfield 《Studies in Comparative International Development (SCID)》2007,42(1-2):1-35
Development debates have been greatly influenced by the growth consensus: the conventional wisdom that economic growth should be the primary priority for less-developed countries (LDCs) because it most effectively improves the well-being of the world’s poor. We compare the impact of growth to other independent variables in an unbalanced panel analysis of up to 109 LDCs and 580 observations across six time points (1980, 1985, 1990, 1995, 2000, and 2003). Our dependent variables include caloric consumption, infant survival probability, one-to-five year survival probability, female life expectancy, and male life expectancy. First, we find that gross domestic product (GDP) has significant positive effects on caloric consumption, female life expectancy, and male life expectancy. Second, GDP does not have robust effects on infant and one-to-five survival probabilities. Third, fertility, urbanization, and secondary school enrollment have larger effects than GDP in the majority of models. The more powerful effects of fertility, urbanization, and secondary schooling cannot simply be attributed to an indirect effect of GDP. Fourth, we find that dependency variables do not have robust significant effects. Fifth, over time, GDP has become much less effective at improving caloric consumption and infant and one-to-five survival. We infer that there are serious limitations to concentrating exclusively on economic growth to improve well-being in LDCs. 相似文献