全文获取类型
收费全文 | 630篇 |
免费 | 12篇 |
专业分类
各国政治 | 40篇 |
工人农民 | 21篇 |
世界政治 | 53篇 |
外交国际关系 | 20篇 |
法律 | 261篇 |
政治理论 | 238篇 |
综合类 | 9篇 |
出版年
2020年 | 7篇 |
2019年 | 9篇 |
2018年 | 14篇 |
2017年 | 9篇 |
2016年 | 19篇 |
2015年 | 7篇 |
2014年 | 25篇 |
2013年 | 94篇 |
2012年 | 10篇 |
2011年 | 15篇 |
2010年 | 8篇 |
2009年 | 9篇 |
2008年 | 14篇 |
2007年 | 22篇 |
2006年 | 10篇 |
2005年 | 11篇 |
2004年 | 16篇 |
2003年 | 11篇 |
2002年 | 17篇 |
2001年 | 15篇 |
2000年 | 12篇 |
1999年 | 14篇 |
1998年 | 12篇 |
1997年 | 12篇 |
1995年 | 8篇 |
1994年 | 11篇 |
1993年 | 12篇 |
1992年 | 11篇 |
1991年 | 10篇 |
1990年 | 10篇 |
1989年 | 11篇 |
1988年 | 14篇 |
1987年 | 11篇 |
1986年 | 11篇 |
1985年 | 7篇 |
1984年 | 10篇 |
1983年 | 8篇 |
1982年 | 13篇 |
1981年 | 12篇 |
1980年 | 8篇 |
1979年 | 11篇 |
1978年 | 5篇 |
1977年 | 13篇 |
1976年 | 5篇 |
1975年 | 4篇 |
1974年 | 6篇 |
1973年 | 5篇 |
1972年 | 6篇 |
1971年 | 5篇 |
1968年 | 5篇 |
排序方式: 共有642条查询结果,搜索用时 15 毫秒
31.
Samyn N De Boeck G Wood M Lamers CT De Waard D Brookhuis KA Verstraete AG Riedel WJ 《Forensic science international》2002,128(1-2):90-97
In a double-blind placebo controlled study on psychomotor skills important for car driving (Study 1), a 75 mg dose of +/- 3,4-methylenedioxymethamphetamine (MDMA) was administered orally to 12 healthy volunteers who were known to be recreational MDMA-users. Toxicokinetic data were gathered by analysis of blood, urine, oral fluid and sweat wipes collected during the first 5h after administration. Resultant plasma concentrations varied from 21 to 295 ng/ml, with an average peak concentration of 178 ng/ml observed between 2 and 4h after administration. MDA concentrations never exceeded 20 ng/ml. Corresponding MDMA concentrations in oral fluid, as measured with a specific LC-MS/MS method (which required only 50 microl of oral fluid), generally exceeded those in plasma and peaked at an average concentration of 1215 ng/ml. A substantial intra- and inter-subject variability was observed with this matrix, and values ranged from 50 to 6982 ng/ml MDMA. Somewhat surprisingly, even 4-5h after ingestion, the MDMA levels in sweat only averaged 25 ng/wipe. In addition to this controlled study, data were collected from 19 MDMA-users who participated in a driving simulator study (Study 2), comparing sober non-drug conditions with MDMA-only and multiple drug use conditions. In this particular study, urine samples were used for general drug screening and oral fluid was collected as an alternative to blood sampling. Analysis of oral fluid samples by LC-MS/MS revealed an average MDMA/MDEA concentration of 1121 ng/ml in the MDMA-only condition, with large inter-subject variability. This was also the case in the multiple drug condition, where generally, significantly higher concentrations of MDMA, MDEA and/or amphetamine were detected in the oral fluid samples. Urine screening revealed the presence of combinations such as MDMA, MDEA, amph, cannabis, cocaine, LSD and psilocine in the multiple-drug condition. 相似文献
32.
33.
Partisan bias refers to an asymmetry in the way party vote share is translated into seats, i.e., a situation where some parties are able to win a given share of seats with a lesser (share of the) vote than is true for other parties. Any districted system is potentially subject to partisan biases. We show that there are three potential sources of partisan bias: (1) differences in the nature of the vote shares of the winning candidates of different parties that give rise to differences in the proportion of each party's votes that come to be ‘wasted’—differences which arise because of the nature of the geographic distribution of partisan support; (2) turnout rate differences across districts that are linked to the partisan vote shares in those districts, such that certain parties are more likely to have ‘cheap seats’ vis-à-vis turnout; and (3) malapportionment. In the context of two-party competition over single-member districts we provide a simple formulation to calculate the independent effect of each of these three factors. We illustrate our analysis with a calculation of the magnitude and direction of effects of the three determinants of partisan bias in elections to the US House and the US Senate in 1984, 1986 and 1988; then we consider how to extend the approach to a system with a mix of single- and multi-member districts or to a weighted voting system such as the US electoral college. We then apply the method to calculate the nature and sources of partisan bias in the 1984 and 1988 US presidential elections. 相似文献
34.
Disentangling the Weight of School Dropout Predictors: A Test on Two Longitudinal Samples 总被引:1,自引:0,他引:1
Janosz Michel LeBlanc Marc Boulerice Bernard Tremblay Richard E. 《Journal of youth and adolescence》1997,26(6):733-762
The aims of this study are to identify the most powerful predictors of school dropout and to determine how stable they are over time. Two generations of White French-speaking boys and girls from 12 to 16 years old (n = 791 in 1974, n = 791 in 1985) completed a self-administered questionnaire on their psychosocial adjustment at least one year before leaving school. As expected, the analyses showed that school, family, behavioral, social, and personality variables could all predict dropping out of school in the two samples. Furthermore, these predictors were quite stable over time. However, statistical improvement measures in logistic regression analyses indicated that school experience variables (i.e., grade retention, school achievement, school commitment) were the best screening variables for potential dropouts. The contribution of other psychosocial variables, even though significant, did not improve very much the capacity to identify who will drop out of school. The discussion highlights the implications of the findings for secondary prevention and screening practices. 相似文献
35.
36.
37.
The switch to prospective payment for hospitals under Medicare is expected to have ramifications in a number of different areas. This paper addresses a select number of those areas: hospital organization and management, other community agencies, and families. Questions are raised as to the capacity to provide adequate care in response to the increased demand for care outside the hospital setting that will result from the new payment system. 相似文献
38.
39.
40.
The position of departmental secretaries has been under debate. There are claims they have been politicised; they have been placed on term appointments. This article examines the careers of departmental secretaries for the last 50 years. It illustrates the changes in their length of tenure, age of departure, mobility and qualifications. The recent profile shows the need for debate about the position and the future of departmental secretaries. 相似文献