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   25010篇
  免费   518篇
各国政治   931篇
工人农民   1618篇
世界政治   1630篇
外交国际关系   858篇
法律   14706篇
中国共产党   2篇
中国政治   77篇
政治理论   5531篇
综合类   175篇
  2020年   213篇
  2019年   256篇
  2018年   1542篇
  2017年   1510篇
  2016年   1377篇
  2015年   343篇
  2014年   348篇
  2013年   1731篇
  2012年   578篇
  2011年   1286篇
  2010年   1288篇
  2009年   915篇
  2008年   1130篇
  2007年   1112篇
  2006年   457篇
  2005年   452篇
  2004年   558篇
  2003年   560篇
  2002年   410篇
  2001年   680篇
  2000年   628篇
  1999年   508篇
  1998年   297篇
  1997年   254篇
  1996年   223篇
  1995年   231篇
  1994年   269篇
  1993年   222篇
  1992年   342篇
  1991年   371篇
  1990年   333篇
  1989年   349篇
  1988年   316篇
  1987年   336篇
  1986年   340篇
  1985年   344篇
  1984年   297篇
  1983年   329篇
  1982年   265篇
  1981年   242篇
  1980年   181篇
  1979年   254篇
  1978年   172篇
  1977年   157篇
  1976年   132篇
  1975年   122篇
  1974年   138篇
  1973年   124篇
  1972年   114篇
  1971年   94篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
861.
Using data from the Michigan Panel Study of Income Dynamics, this article estimates the impact of the Earned Income Tax Credit (EITC) on economic risk. Risk is measured through the variance of full income (income holding labor supply constant). The results show that the EITC significantly reduces economic risk, but its effects are weaker dollar for dollar than traditional means-tested programs like Food Stamps. The difference is not statistically significant, however. Moreover, for many middle-class people, the risk-reduction benefits of the EITC exceed the tax burden it imposes. This is less true of means-tested transfers. These results are significant for the politics of antipoverty policy. They show that a real-world antipoverty program can generate enough middle-class economic security to build for itself a solid base of political support.  相似文献   
862.
Schools across the country are ending the practice of grouping students based on ability, in part, because of research indicating that tracking hurts low-ability students without helping students of other ability levels. Using a nationally representative survey conducted by the National Center for Education Statistics, (NCES) we reexamine the impact of tracking on high school student achievement through the estimation of a standard education production function. This approach allows us to control for the possibility that track is correlated with factors such as class size and teacher education. In addition, we address the possibility that there are unobserved student or school characteristics that affect both achievement and track placement. Our results indicate that abolishing tracking in America's schools would have a large positive impact on achievement for students currently in the lower tracks, but that this increase in achievement would come at the expense of students in upper-track classes.  相似文献   
863.
Journal of Youth and Adolescence - Adolescents are spending considerable time on social media, yet it is unclear whether motivations for social media use drive different forms of social media...  相似文献   
864.
Brian Masshardt 《East Asia》2007,24(3):319-335
Prime Minister Koizumi’s six consecutive annual visits to Yasukuni shrine played a key role in initiating a new phase of domestic citizen political mobilization not seen since the early 1970s. This paper is based on field research during the Koizumi years (2001–2006) centering on domestic groups that conduct activities in “protection” of or “opposition” to Yasukuni shrine. As a study of street-based politics, this paper seeks to uncover the processes, strategies, and outcomes of citizen responses to elite political action at Yasukuni Shrine as well as explore meaning of their actions within the context of Japan’s democratic polity.
Brian MasshardtEmail:

Brian Masshardt   is Lecturer, Musashi University, and a Ph.D. Candidate, University of Hawaii-Manoa, whose research addresses the political aspects of Yasukuni in the context of domestic politics and citizen’s movements. His doctoral dissertation, entitled ‘Democracy and Yasukuni: Citizen Reaction to political action at Yasukuni Shrine, 2001–2006’ has served as the basis for conference presentations on Yasukuni and its attendant controversies.  相似文献   
865.
高等教育创新的新机遇   总被引:1,自引:0,他引:1  
人口结构的变化、科学技术的变革以及经济全球化,都对高等教育产生了很大影响,提供了很多新的机遇。这些机遇不仅可以提高我们的效率,同时也可以带来新的创造知识和传播知识的方式方法。  相似文献   
866.
Journal of Youth and Adolescence - Parent–adolescent conflict can be intense, yet parents and adolescents do not always agree on the intensity of conflict. Conflict intensity tends to change...  相似文献   
867.
Microbial communities have potential evidential utility for forensic applications. However, bioinformatic analysis of high-throughput sequencing data varies widely among laboratories. These differences can potentially affect microbial community composition and downstream analyses. To illustrate the importance of standardizing methodology, we compared analyses of postmortem microbiome samples using several bioinformatic pipelines, varying minimum library size or minimum number of sequences per sample, and sample size. Using the same input sequence data, we found that three open-source bioinformatic pipelines, MG-RAST, mothur, and QIIME2, had significant differences in relative abundance, alpha-diversity, and beta-diversity, despite the same input data. Increasing minimum library size and sample size increased the number of low-abundant and infrequent taxa detected. Our results show that bioinformatic pipeline and parameter choice affect results in important ways. Given the growing potential application of forensic microbiology to the criminal justice system, continued research on standardizing computational methodology will be important for downstream applications.  相似文献   
868.
This study presents a number of pseudo-operational trials on plastic bags investigating the double- and co-fuming process of a one-step fluorescent cyanoacrylate (LumicyanoTM) in comparisons with the two-step process with basic yellow 40 (BY40) staining for the detection of latent fingermarks. The results demonstrate that both Lumicyano solution and dye contribute to the increased detection of latent fingermarks during the double-fuming process (trial 1). Co-fuming the Lumicyano solution and dye separately (at a concentration of 8%) but simultaneously was less effective than 8% Lumicyano (trial 2). Co-fuming Lumicyano 8% and an additional 8% Lumicyano dye by weight was more effective than Lumicyano 8% (trial 3), possibly due to increased fluorescent material deposition during co-fuming allowing for better visualization. The use of BY40 after Lumicyano resulted in a considerable increase in detected fingermarks.  相似文献   
869.
870.
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   
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