全文获取类型
收费全文 | 15294篇 |
免费 | 465篇 |
专业分类
各国政治 | 930篇 |
工人农民 | 564篇 |
世界政治 | 1194篇 |
外交国际关系 | 610篇 |
法律 | 8822篇 |
中国共产党 | 2篇 |
中国政治 | 171篇 |
政治理论 | 3312篇 |
综合类 | 154篇 |
出版年
2020年 | 190篇 |
2019年 | 234篇 |
2018年 | 336篇 |
2017年 | 345篇 |
2016年 | 359篇 |
2015年 | 289篇 |
2014年 | 301篇 |
2013年 | 1800篇 |
2012年 | 360篇 |
2011年 | 465篇 |
2010年 | 363篇 |
2009年 | 383篇 |
2008年 | 393篇 |
2007年 | 374篇 |
2006年 | 381篇 |
2005年 | 340篇 |
2004年 | 355篇 |
2003年 | 388篇 |
2002年 | 310篇 |
2001年 | 542篇 |
2000年 | 483篇 |
1999年 | 432篇 |
1998年 | 237篇 |
1997年 | 196篇 |
1996年 | 172篇 |
1995年 | 171篇 |
1994年 | 177篇 |
1993年 | 180篇 |
1992年 | 263篇 |
1991年 | 294篇 |
1990年 | 262篇 |
1989年 | 264篇 |
1988年 | 276篇 |
1987年 | 300篇 |
1986年 | 290篇 |
1985年 | 281篇 |
1984年 | 269篇 |
1983年 | 280篇 |
1982年 | 187篇 |
1981年 | 158篇 |
1980年 | 163篇 |
1979年 | 188篇 |
1978年 | 141篇 |
1977年 | 120篇 |
1976年 | 128篇 |
1975年 | 114篇 |
1974年 | 117篇 |
1973年 | 109篇 |
1972年 | 103篇 |
1969年 | 101篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
982.
Leclair B Sgueglia JB Wojtowicz PC Juston AC Frégeau CJ Fourney RM 《Journal of forensic sciences》2003,48(5):1001-1013
Improvements in detection limits/sensitivity and lower sample consumption are potential benefits of reducing PCR reaction volumes used in forensic DNA typing of crime scene samples. This premise was studied first with experimental mixtures and a nine-loci megaplex, which demonstrated stochiometric amplification and accurate detection. Next, adjudicated casework samples were subjected to amplification under 15 different template DNA to PCR reaction volume ratios. Reduction of PCR reaction volume and DNA down to 10 microL and 0.500 ng, respectively, produced identical profiles with the same signal intensity and heterozygous allele peak height ratio (HR). Reduction to 5 microL and 0.063 ng yielded HR values that were slightly affected in one to three STR loci. PCR reaction volume reduction can enhance detection and sensitivity while reducing the consumption of irreplaceable crime scene samples. 相似文献
983.
984.
985.
Brock DW 《Texas law review》2003,81(7):1805-1821
986.
Using Ecological Inference Point Estimates as Dependent Variables in Second-Stage Linear Regressions 总被引:1,自引:0,他引:1
The practice of using point estimates produced by the King ecologicalinference technique as dependent variables in second-stage linearregressions leads to second-stage results that, in general,are inconsistent. This conclusion holds even when all assumptionsbehind King's ecological technique are satisfied. Second-stageinconsistency is a consequence of the fact that King-based pointestimates of disaggregated quantities contain errors correlatedwith the true quantities the estimates measure. Our findingson second-stage inconsistency, as well as a fix that we propose,follow from econometric theory in conjunction with an analysisof simulated and real ecological data sets. 相似文献
987.
This article examines the changing patterns of poverty in Singapore. As Singapore's population ages, the poor increasingly includes the elderly. It appears that ascribed factors, such as gender and race, have significant influence on financial security at old age. As the population ages, the adequacy of existing anti-poverty policy is challenged. 相似文献
988.
989.
990.