首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   7078篇
  免费   167篇
各国政治   358篇
工人农民   300篇
世界政治   543篇
外交国际关系   295篇
法律   4298篇
中国政治   55篇
政治理论   1379篇
综合类   17篇
  2022年   38篇
  2021年   57篇
  2020年   103篇
  2019年   140篇
  2018年   199篇
  2017年   183篇
  2016年   190篇
  2015年   129篇
  2014年   171篇
  2013年   805篇
  2012年   254篇
  2011年   235篇
  2010年   168篇
  2009年   184篇
  2008年   214篇
  2007年   224篇
  2006年   178篇
  2005年   162篇
  2004年   189篇
  2003年   150篇
  2002年   134篇
  2001年   329篇
  2000年   303篇
  1999年   210篇
  1998年   89篇
  1997年   85篇
  1996年   63篇
  1995年   61篇
  1994年   51篇
  1993年   41篇
  1992年   127篇
  1991年   143篇
  1990年   136篇
  1989年   130篇
  1988年   114篇
  1987年   127篇
  1986年   102篇
  1985年   97篇
  1984年   101篇
  1983年   91篇
  1982年   64篇
  1981年   75篇
  1980年   35篇
  1979年   77篇
  1978年   48篇
  1975年   37篇
  1974年   49篇
  1973年   54篇
  1972年   39篇
  1971年   34篇
排序方式: 共有7245条查询结果,搜索用时 15 毫秒
221.
Novel psychoactive substances (NPS) are synthetic drugs that pose serious public health and safety concerns. A multitude of NPS have been identified in the United States, often implicated in forensic investigations. The most common and effective manner for identifying NPS is by use of mass spectrometry and the true utility lies within nontargeted acquisition techniques. During this study, a liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) assay was developed, validated, and implemented for forensic toxicology testing. A SCIEX TripleTOF™ 5600 + with SWATH® acquisition was used. Resulting data were compared against an extensive library database containing more than 800 compounds. The LC-QTOF-MS assay was applied to the reanalysis of biological sample extracts to discover emergent NPS. More than 3,000 sample extracts were analyzed, and more than 20 emerging NPS were detected for the first time. Among these were isopropyl-U-47700, 3,4-methylenedioxy-U-47700, fluorofuranylfentanyl, N-methyl norfentanyl, 2F-deschloroketamine, 3,4-methylenedioxy-alpha-PHP, eutylone, and N-ethyl hexedrone.  相似文献   
222.
223.
Journal of Youth and Adolescence - Adolescence tends to be characterized by a temporary peak in delinquent behavior, and friends in particular play a key role in the initiation and the development...  相似文献   
224.
Journal of Youth and Adolescence - Dual identity (e.g., strong ethnic and national identity) is a psychological resource for minority groups, but how it develops during adolescence is less clear....  相似文献   
225.
This article explores the construction of extremism in media discourse, the factors driving specific constructions and the implications of these constructions for counterterrorism policy. We contend that extremism has predominantly and increasingly been framed as a security issue. This article explores the implications of this practice through the framework of securitisation. We measure the average intensity of security framing in 38,616 articles found in three major US newspapers, New York Times, Wall Street Journal and Los Angeles Times, between 20 January 1993 and 19 January 2017 comprising the Clinton, Bush and Obama presidencies, and look at factors influencing the shift in intensity over time. Through our analysis, we show that it is possible to return to a pre-9/11 discourse but that the confluence of real-world events and the strategic choices of political actors have so far prevented this from fully occurring. We then explore the effect of securitisation on public perceptions of the threat from terrorism, finding that increases in the intensity of security framing artificially increases the public’s worry about becoming a victim of terrorism. We conclude by discussing implications for the communication of counterterrorism policy and the requirements for an after, after 9/11 approach  相似文献   
226.
ABSTRACT

This article analyses how the presence of a dominant group of voters within the electorate affects voter turnout. Theoretically, we argue that its absolute size affects turnout via increased free-riding incentives and reduced social pressure to vote within a larger dominant group. Its relative size compared to other groups within the electorate influences turnout through instrumental and expressive responses – in both the dominant and dominated groups – to the degree of electoral competition between groups. Empirical evidence from a large cross section of German municipalities is in line with these theoretical predictions. The observed effects should be taken into account when redesigning electoral jurisdictions through, for instance, municipal mergers or gerrymandering.  相似文献   
227.
The understanding of positive development across adolescence rests on having a valid and equivalent measure of this construct across the breadth of this period of life. Does the Positive Youth Development (PYD) construct based on the Five Cs model have satisfactory psychometric properties for such longitudinal measurement invariance? Using longitudinal data derived from the 4-H Study of PYD, we assessed 920 youth (61.6% female) from a racially and ethically diverse sample (67.3% European American) who participated in three waves (Grades 8–10) of data collection. Building on prior findings that the Five Cs (i.e., Competence, Confidence, Connection, Character, and Caring) model of PYD was a robust measure that could be assessed comparably during early adolescence, we tested a hierarchy of second-order confirmatory factor analysis models to assess the extent to which PYD can be measured equivalently across middle adolescence. Evidence was found for strict measurement invariance across three measurement occasions, including equivalence of first-order and second-order factor loadings, equality of intercepts of observed variables, and equality of item uniqueness and disturbances of the first-order factors. These results suggest that PYD can be measured in the same way across measurement occasions, a prerequisite for the study of development. Implications for research and application of being able to measure PYD equivalently across adolescence are discussed.  相似文献   
228.
While the financial crisis of 2008 ultimately affected the range of U.S. financial institutions, it began with practices in home ownership finance. The Federal Home Loan Bank (FHLBank) System was the first instrumentality created by the U.S. government, in 1932, to sustain affordable home ownership finance. In this article, the authors ask what role, if any, the FHLBanks played in the subprime lending and securitization practices that precipitated the current crisis. The authors analyze publicly available FHLBank financial data in terms of a framework focused on the System's assets: advances; mortgage loans acquired from members; and investments, particularly in mortgage-backed-securities. They conclude that the FHLBanks did not contribute significantly to problematic practices. Nonetheless, they recommend consideration of three reforms to the FHLBanks to ensure a return to effective regulation and responsible, affordable home ownership finance.  相似文献   
229.
230.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号