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   3446篇
  免费   89篇
各国政治   328篇
工人农民   75篇
世界政治   366篇
外交国际关系   257篇
法律   1268篇
中国共产党   1篇
中国政治   24篇
政治理论   1177篇
综合类   39篇
  2023年   10篇
  2022年   14篇
  2021年   33篇
  2020年   61篇
  2019年   59篇
  2018年   99篇
  2017年   118篇
  2016年   120篇
  2015年   77篇
  2014年   94篇
  2013年   599篇
  2012年   87篇
  2011年   103篇
  2010年   86篇
  2009年   125篇
  2008年   152篇
  2007年   140篇
  2006年   101篇
  2005年   110篇
  2004年   106篇
  2003年   87篇
  2002年   95篇
  2001年   71篇
  2000年   64篇
  1999年   69篇
  1998年   61篇
  1997年   55篇
  1996年   46篇
  1995年   57篇
  1994年   47篇
  1993年   45篇
  1992年   29篇
  1991年   49篇
  1990年   27篇
  1989年   41篇
  1988年   32篇
  1987年   36篇
  1986年   51篇
  1985年   15篇
  1984年   25篇
  1983年   30篇
  1982年   31篇
  1981年   19篇
  1980年   27篇
  1979年   17篇
  1978年   22篇
  1977年   16篇
  1976年   16篇
  1974年   20篇
  1973年   8篇
排序方式: 共有3535条查询结果,搜索用时 8 毫秒
871.
There is increasing evidence that tax benefits for college do not affect college enrollment. This may be because prospective students do not know about tax benefits for college or because the design of tax benefits is not conducive to affecting educational outcomes. We focus on changing awareness of tax benefits by providing information to students or prospective students. We sent e‐mails and letters to students that described tax benefits for college, and we tracked college outcomes. For all three of our samples—rising high school seniors, already enrolled students, and students who had previously applied to college but were not currently enrolled—information about tax benefits for college did not affect enrollment or reenrollment. We test whether effects vary according to information frames and found that no treatment arms changed student outcomes. We conclude that awareness is not the primary reason that tax benefits for college do not affect enrollment.  相似文献   
872.
This study aims to shed new light on the petroglyphs found at the site of Aspeberget 12 at the World Heritage site of Tanum, Sweden, from a semiotic perspective. We demonstrate the semiotics of power inherent in the arrangement of the petroglyphs. We start by describing the site in an archaeological way, in order to give an overview of the empirical material used in this case study. Against the backdrop of the overview, we introduce our analytical tools with reference to cartosemiotics, cultural semiotics and, Charles Sanders Peirce’s theory of signs. We suggest, in a tentative conclusion, that Aspeberget 12, as a type of “map”, displays a clear “Ego-culture” and a possible journey. We also suggest that the visual narratives at Aspeberget 12 represent the authority of the Ego-culture and its development. Details of the figurative images such as ships, axes and spears might have been displayed as markers of the high technological standard of the Ego-culture, and thus of power.  相似文献   
873.
The aim of this research note paper is to offer an exploratory review of the extent to which the leading ocean cruise companies are publicly addressing and reporting on their sustainability strategies and achievements and to offer some reflections on sustainability within the cruise industry. The paper begins with an outline of cruising and the cruising industry and a short commentary on the sustainability challenges the industry faces. The information on which the paper is based is drawn from the leading cruise companies' corporate web sites. The findings of the paper reveal a marked variation in the extent to which the leading cruise companies publicly report on their sustainability strategies and achievements. While the two leading cruise companies, namely the Carnival Corporation and Royal Caribbean Cruises, published extensive sustainability reports which covered a number of environmental social and economic issues, the other leading cruise companies published very limited information on sustainability. More critically the authors argued that the cruise companies' commitments to sustainability are driven by the search for efficiency gains and are couched within existing business models centred on continuing growth than on maintaining the viability of natural ecosystems and communities. As such the leading UK retailers are, at best, currently pursuing a ‘weak’ rather than a ‘strong’ model of sustainability. The paper provides an accessible exploratory review of sustainability reporting in the cruise industry, and it will interest professional working in the cruise industry and more generally in the hospitality industry as well as academics and students interested in public relations, business studies and hospitality management. © 2016 John Wiley & Sons, Ltd.  相似文献   
874.
The British Retail Consortium's Better Retail, Better World initiative launched in 2018 and looks to mobilise the retail industry to make a leading contribution to the United Nations Sustainable Development Goals (SDGs). This short commentary paper outlines the features of this initiative and offers some reflections on some of the challenges British retailers seem likely to face in looking to contribute to the achievement of the SDGs. These challenges include the strategic prioritisation of SDGs, issues of measurement and metrics, communicating the retailers' position on the SDGs to consumers and the stakeholders, the retailers' financial commitment to the SDGs within a difficult trading environment, and fundamental tensions between sustainability and economic growth.  相似文献   
875.
Abstract

The study of policy implementation developed steadily and considerably in the 1970s and 1980s through two generations of research. Since then progress towards a more rigorous scientific “third generation research paradigm”, assumed to be crucial for further theoretical development, has been much slower and more uneven. Comparative studies figure prominently in this respect. On one hand they are strongly encouraged but on the other they are difficult to conduct according to best practice advice in the textbooks. Comparative implementation research is the theme of this special issue. In this Introduction the articles included are presented, focusing on how they deal with some of the issues posed by the norms of a rigorous “third generation” approach. Reasons for the state of affairs in implementation research are discussed. Some inherent dualities and tensions in contemporary comparative implementation research are identified as particular challenges.  相似文献   
876.
The Introduction briefly presents the ideas behind this collection of articles, namely to analyze popular mobilization and the role of civil society, political parties, and regional organizations in relation to the developments in the Middle East and North Africa (MENA) over the last years, and to discuss theoretical approaches and paradigms of relevance for the analysis of these new regional dynamics. The MENA region experienced, in connection with and following the Arab uprisings, a hitherto unseen popular mobilization. Despite the recent highly problematic situation in several Middle Eastern states, the Introduction emphasizes the continued relevance of focusing on a repoliticized MENA reality. The Middle East is still on the move away from the established image of unshakeable authoritarianism attributed to the region, which made the upgrading authoritarianism paradigm seem forever relevant and without any realistic alternative for the decades to come—therefore, the relevance, offered in this collection of articles, of bringing people back in politics.  相似文献   
877.
878.
There are few reported cases of death attributed to retrograde cerebral air embolism from central venous catheter. The pathophysiological mechanism and the necessary conditions are not fully understood, also because of missing experimental data. We performed experimental simulation while working on a possible case of retrograde cerebral air embolism. A hermetic system consisting of two containers connected to each other and to an electric pump by means of rubber hoses was built. In this system, a fluid (water and blood) could continuously flow under conditions similar to those of the common jugular vein. The part of the system representing the jugular vein could be freely positioned at angles between 0 and 90°. A central venous catheter was inserted into this part. After disconnection, the behavior of the air bubbles entering the hose through the tip of the catheter was evaluated at different positions. At angles between 0 and 45°, the air bubbles followed the fluid flow. At angles >45°, the air bubbles showed the tendency to flow upstream; this phenomenon was more evident the more vertically the hose was located. We were able to demonstrate that a retrograde air embolism can be caused by a disconnected catheter and is even more likely if the neck is in a vertical position.  相似文献   
879.
Forensically identifying a suspect's dentition from a bitemark in an open population requires the supposition that every person's dental alignment is different. There have been few studies that have tested this claim. Four hundred and ten lower anterior dentitions from a selected population and 110 lower anterior dentitions from one that was orthodontically treated were measured using geometric morphometric analysis, allowing comparison of arch shape. Dental match rates of 1.46% and 42.7% of individuals were found in the respective populations, given an established measurement error. Orthodontic treatment had a strong effect on match rate suggesting that treated or naturally well-aligned dentitions may be indistinguishable. Sexual dimorphism was found to be only slightly significant. Principal shape variation in both populations was degree of arch curvature. Results of studying these populations show that dental matches can occur, and that statements of certainty concerning individualization in such populations should be approached with caution.  相似文献   
880.
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