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   6181篇
  免费   201篇
  国内免费   60篇
管理学   286篇
民族学   71篇
人口学   31篇
丛书文集   689篇
理论方法论   301篇
综合类   3984篇
社会学   358篇
统计学   722篇
  2024年   15篇
  2023年   47篇
  2022年   47篇
  2021年   69篇
  2020年   89篇
  2019年   119篇
  2018年   138篇
  2017年   133篇
  2016年   131篇
  2015年   148篇
  2014年   337篇
  2013年   553篇
  2012年   414篇
  2011年   401篇
  2010年   373篇
  2009年   370篇
  2008年   365篇
  2007年   437篇
  2006年   414篇
  2005年   407篇
  2004年   337篇
  2003年   300篇
  2002年   245篇
  2001年   193篇
  2000年   115篇
  1999年   36篇
  1998年   21篇
  1997年   27篇
  1996年   31篇
  1995年   25篇
  1994年   23篇
  1993年   14篇
  1992年   10篇
  1991年   8篇
  1990年   10篇
  1989年   11篇
  1988年   6篇
  1987年   3篇
  1986年   1篇
  1985年   3篇
  1984年   6篇
  1983年   4篇
  1982年   1篇
  1981年   2篇
  1979年   1篇
  1977年   1篇
  1975年   1篇
排序方式: 共有6442条查询结果,搜索用时 31 毫秒
91.
Response‐adaptive randomisation (RAR) can considerably improve the chances of a successful treatment outcome for patients in a clinical trial by skewing the allocation probability towards better performing treatments as data accumulates. There is considerable interest in using RAR designs in drug development for rare diseases, where traditional designs are not either feasible or ethically questionable. In this paper, we discuss and address a major criticism levelled at RAR: namely, type I error inflation due to an unknown time trend over the course of the trial. The most common cause of this phenomenon is changes in the characteristics of recruited patients—referred to as patient drift. This is a realistic concern for clinical trials in rare diseases due to their lengthly accrual rate. We compute the type I error inflation as a function of the time trend magnitude to determine in which contexts the problem is most exacerbated. We then assess the ability of different correction methods to preserve type I error in these contexts and their performance in terms of other operating characteristics, including patient benefit and power. We make recommendations as to which correction methods are most suitable in the rare disease context for several RAR rules, differentiating between the 2‐armed and the multi‐armed case. We further propose a RAR design for multi‐armed clinical trials, which is computationally efficient and robust to several time trends considered.  相似文献   
92.
In the contemporary multicentric world, sovereign states have to manage carefully the construction of their image, defining their role and aspirations. With the re-definition of the state centric politics, stories become relevant: communication is a form of power, and networked forms of communication are becoming progressively a way to conquer the transnational public spheres. Through strategic narratives of foreign politics, states try to set up the ‘tales’ of international affairs and foreign strategies, to suggest a world vision, a causal interpretation, determining frames that affect transnational actors’ position in the international environment. Sovereign states develop these kind of frame using tools and theories referred to the commercial branding tradition to promote and support their own policies and identity. We decided to investigate how that process is made through information diffusion on digital platforms.

In this work, it has been analyzed the content presented through Twitter posts by the Foreign Ministries accounts of four different States dissimilar for geopolitical positioning and security concerns (USA; Israel; France; Sweden), for a period of three months (9/1/2015-11/30/2015); leading to the identification of different models and characteristic patterns of self-representation.

The thematic content analysis, based on the identification of macrocategories and micro-issues, has led to the identification of different models and characteristic patterns of self-representation, determined by domestic vicissitudes, and has shown some regularities, caused by the branding vocation of autobiographical online contents.  相似文献   

93.
In this article, an agent‐based framework to quantify the seismic resilience of an electric power supply system (EPSS) and the community it serves is presented. Within the framework, the loss and restoration of the EPSS power generation and delivery capacity and of the power demand from the served community are used to assess the electric power deficit during the damage absorption and recovery processes. Damage to the components of the EPSS and of the community‐built environment is evaluated using the seismic fragility functions. The restoration of the community electric power demand is evaluated using the seismic recovery functions. However, the postearthquake EPSS recovery process is modeled using an agent‐based model with two agents, the EPSS Operator and the Community Administrator. The resilience of the EPSS–community system is quantified using direct, EPSS‐related, societal, and community‐related indicators. Parametric studies are carried out to quantify the influence of different seismic hazard scenarios, agent characteristics, and power dispatch strategies on the EPSS–community seismic resilience. The use of the agent‐based modeling framework enabled a rational formulation of the postearthquake recovery phase and highlighted the interaction between the EPSS and the community in the recovery process not quantified in resilience models developed to date. Furthermore, it shows that the resilience of different community sectors can be enhanced by different power dispatch strategies. The proposed agent‐based EPSS–community system resilience quantification framework can be used to develop better community and infrastructure system risk governance policies.  相似文献   
94.
Public support for nuclear power generation has decreased in Japan since the Fukushima Daiichi nuclear accident in March 2011. This study examines how the factors influencing public acceptance of nuclear power changed after this event. The influence factors examined are perceived benefit, perceived risk, trust in the managing bodies, and pro‐environmental orientation (i.e., new ecological paradigm). This study is based on cross‐sectional data collected from two online nationwide surveys: one conducted in November 2009, before the nuclear accident, and the other in October 2011, after the accident. This study's target respondents were residents of Aomori, Miyagi, and Fukushima prefectures in the Tohoku region of Japan, as these areas were the epicenters of the Great East Japan Earthquake and the locations of nuclear power stations. After the accident, trust in the managing bodies was found to have a stronger influence on perceived risk, and pro‐environmental orientation was found to have a stronger influence on trust in the managing bodies; however, perceived benefit had a weaker positive influence on public acceptance. We also discuss the theoretical and practical implications of these findings.  相似文献   
95.
Information before unblinding regarding the success of confirmatory clinical trials is highly uncertain. Current techniques using point estimates of auxiliary parameters for estimating expected blinded sample size: (i) fail to describe the range of likely sample sizes obtained after the anticipated data are observed, and (ii) fail to adjust to the changing patient population. Sequential MCMC-based algorithms are implemented for purposes of sample size adjustments. The uncertainty arising from clinical trials is characterized by filtering later auxiliary parameters through their earlier counterparts and employing posterior distributions to estimate sample size and power. The use of approximate expected power estimates to determine the required additional sample size are closely related to techniques employing Simple Adjustments or the EM algorithm. By contrast with these, our proposed methodology provides intervals for the expected sample size using the posterior distribution of auxiliary parameters. Future decisions about additional subjects are better informed due to our ability to account for subject response heterogeneity over time. We apply the proposed methodologies to a depression trial. Our proposed blinded procedures should be considered for most studies due to ease of implementation.  相似文献   
96.
This study examined how Turkey uses social media as a tool for public diplomacy and how the state’s soft-power efforts have recently changed on the global stage. The researchers constructed a dataset of 2769 Twitter posts by the Turkish government’s most influential public diplomacy accounts. The analyses revealed that the focus of Turkey’s Twitter public diplomacy has become concentrated on the Middle East and North Africa (MENA) region and is thematically focused on the political values embodied by the Turkish president. The findings suggest that public diplomacy remains to be the diplomacy of the government, not of the public, and social media is used as just another tool for propaganda, not as a means of engagement with foreign publics. Further, the findings indicate the emergence of a “new” cult of personality in public diplomacy and point out the instrumental role of social media in changing the dynamics of leader-follower relationship. The study contributes to public relations theory and practice by advancing the burgeoning public diplomacy scholarship at the intersection of social media and relational approaches.  相似文献   
97.
Pimps, or male managers of female sex workers, are commonly represented in popular culture as hypermasculine and as a ubiquitous part of sex work. However, there is little empirical scholarship on pimps or the construction of their masculinity. Drawing on ethnographic and interview data, this article demonstrates how pimps produce a “revanchist masculinity” that seeks to reclaim power from women and establish status over other men. Pimps are suspicious of sex workers’ motives and deny them decision‐making power and profit sharing—processes that highlight how work practices can structure gender identity construction.  相似文献   
98.
20世纪70年代的国际石油危机有着深厚的历史根源,它源于国际石油权力结构的急剧变革。60年代后期开始,随着国际石油市场日趋紧张,产油国的地位日益改善,它们从石油公司获得越来越多的石油权力,其中国际石油公司与产油国签订的"德黑兰协定"和"的黎波里协定"发挥了至关重要的作用,是产油国能够针对西方国家使用减产、禁运和提价等石油武器的前提条件。  相似文献   
99.
In this paper, a variable repetitive group sampling plans based on one-sided process capability indices is proposed to deal with lot sentencing for one-sided specifications. The parameters of the proposed plans are tabulated for some combinations of acceptance quality levels with commonly used producer's risk and consumer's risk. The efficiency of the proposed plan is compared with the Pearn and Wu [Critical acceptance values and sample sizes of a variables sampling plan for very low fraction of defectives. Omega – Int J Manag Sci. 2006;34(1):90–101] plan in terms of sample size and the power curve. One example is given to illustrate the proposed methodology.  相似文献   
100.
伴随着阶级和国家的产生,关于意识形态的争论从来没有停止过。意识形态之争的表象是话语权、信奉者和影响力、感召力的争夺;意识形态之争的根基源于意识形态的科学性、传播方式和经济基础;意识形态之争的实质归于阶级和国家利益的维护。当前,认清意识形态争论的表象、阐明意识形态争论的根基、揭示意识形态争论的本质对于我国主流意识形态的建设具有重要意义。  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