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   3516篇
  免费   51篇
  国内免费   149篇
教育   1732篇
科学研究   725篇
各国文化   14篇
体育   287篇
综合类   147篇
文化理论   4篇
信息传播   807篇
  2024年   5篇
  2023年   23篇
  2022年   52篇
  2021年   94篇
  2020年   151篇
  2019年   100篇
  2018年   124篇
  2017年   55篇
  2016年   58篇
  2015年   96篇
  2014年   219篇
  2013年   337篇
  2012年   300篇
  2011年   274篇
  2010年   237篇
  2009年   234篇
  2008年   245篇
  2007年   242篇
  2006年   194篇
  2005年   155篇
  2004年   122篇
  2003年   115篇
  2002年   93篇
  2001年   54篇
  2000年   39篇
  1999年   19篇
  1998年   17篇
  1997年   8篇
  1996年   13篇
  1995年   1篇
  1994年   3篇
  1993年   3篇
  1992年   3篇
  1990年   1篇
  1989年   2篇
  1985年   5篇
  1984年   3篇
  1983年   3篇
  1982年   3篇
  1981年   4篇
  1978年   5篇
  1977年   1篇
  1976年   3篇
  1957年   1篇
排序方式: 共有3716条查询结果,搜索用时 62 毫秒
191.
Communication researchers and social scientists are quickly discovering the value of data that exists in the postings of members of Internet e-mail, Usenet, and real-time groups. The ability to communicate with one's peers, no matter how esoteric the interests, is causing an explosion in the number of new virtual communities. The interpersonal dynamics of these groups are increasingly coming under the scrutiny of academic research. The publicly available archived records of Internet virtual communities are being analyzed for a wide variety of research interests. The ability to do naturalistic observations of group dynamics, as they are exhibited in these exchanges of text, has captured the attention of many researchers. The institutional review boards of major universities are granting researchers exempt or expedited (exempt from full review) status for this work, due to the public nature of the notes being analyzed. These studies often involve the lack of informed consent, where the group members under study are unaware they are being monitored. There is a potential for psychological harm to the members of these groups, depending on the way results are reported. This article explores the ethical considerations that must be taken into account to protect cyberspace participants. The guidelines proposed are based on the American Psychological Association ethical guidelines for use of human subjects in research. An explanation is offered as to how such guidelines can best be applied to the study of Internet communities. The constructs of Group Accessibility (the public/private nature of the actual cyberspace occupied by a group) and Perceived Privacy (the level of privacy that group members assume they have) are defined and proposed as two dimensions by which individual Internet communities may be evaluated in order to assure the ethical reporting of research findings.  相似文献   
192.
概要介绍了中国科学院拉萨高原生态试验站建站10年的定位观测和试验研究进展。拉萨站科研人员通过对以高原农田为主的生态系统长期定位监测和试验研究,在高原环境背景特征、能量传输和能量平衡、生态系统结构和生产力的形成、作物光合生理生态以及碳循环过程研究等方面进行了深入的研究,并以生态学理论为指导,在作物和牧草品种引种筛选和模式建立、人工草地建设和利用、蔬菜栽培和农业产业结构调整等方面为地方农牧业发展做出了贡献。  相似文献   
193.
白鸟库吉东洋史学研究的学术背景源于西方,研究方法受德国史学家路得维格.里斯影响,注重考据与实证,而纵观其整个学术历程,满鲜历史地理调查部的相关工作构建了其东洋史学研究的最初框架。本文将就满鲜历史地理调查部的设立过程与白鸟库吉东洋史学理念的发端、取得的成果与白鸟库吉东洋史学泰斗地位的确立、运作过程对白鸟库吉东洋史学研究的影响等方面进行探讨,力图廓清满鲜历史地理调查部与白鸟库吉的东洋史学研究之间的联系。  相似文献   
194.
为适应基础教育改革和发展对高师院校提出的研究型教师培养要求,作为初等教育专业主干课程的小学教育研究方法,主要从以下几方面进行课程与教学改革:改革课程内容,增强课程的针对性和适用性;改革教学模式与教学方法,探索"讲授—体验—反思—评价"四环节研究性教学模式,采用多种教学方法,突出学生的自主探究和操作体验;改革评价方法,突出评价的发展功能;促进教师专业发展职前职后一体化。  相似文献   
195.
Altmetrics have been proposed as a way to assess the societal impact of research. Although altmetrics are already in use as impact or attention metrics in different contexts, it is still not clear whether they really capture or reflect societal impact. This study is based on altmetrics, citation counts, research output and case study data from the UK Research Excellence Framework (REF), and peers’ REF assessments of research output and societal impact. We investigated the convergent validity of altmetrics by using two REF datasets: publications submitted as research output (PRO) to the REF and publications referenced in case studies (PCS). Case studies, which are intended to demonstrate societal impact, should cite the most relevant research papers. We used the MHq’ indicator for assessing impact – an indicator which has been introduced for count data with many zeros. The results of the first part of the analysis show that news media as well as mentions on Facebook, in blogs, in Wikipedia, and in policy-related documents have higher MHq’ values for PCS than for PRO. Thus, the altmetric indicators seem to have convergent validity for these data. In the second part of the analysis, altmetrics have been correlated with REF reviewers’ average scores on PCS. The negative or close to zero correlations question the convergent validity of altmetrics in that context. We suggest that they may capture a different aspect of societal impact (which can be called unknown attention) to that seen by reviewers (who are interested in the causal link between research and action in society).  相似文献   
196.
We develop and propose a new counting method at the aggregate level for contributions to scientific publications called modified fractional counting (MFC). We show that, compared to traditional complete-normalized fractional counting, it eliminates the extreme differences in contributions over time that otherwise occur between scientists that mainly publish alone or in small groups and those that publish with large groups of co-authors. As an extra benefit we find that scientists in different areas of research turn out to have comparable average contributions to scientific articles. We test the method on scientists at Norway’s largest universities and find that, at an aggregate level, it indeed supports comparability across different co-authorship practices as well as between areas of research. MFC is thereby useful whenever the research output from institutions with different research profiles are compared, as e.g., in the Leiden Ranking. Finally, as MFC is actually a family of indicators, depending on a sensitivity parameter, it can be adapted to the circumstances.  相似文献   
197.
Research assessment exercises have now become common evaluation tools in a number of countries. These exercises have the goal of guiding merit-based public funds allocation, stimulating improvement of research productivity through competition and assessing the impact of adopted research support policies. One case in point is Italy's most recent research assessment effort, VQR 2011–2014 (Research Quality Evaluation), which, in addition to research institutions, also evaluated university departments, and individuals in some cases (i.e., recently hired research staff and members of PhD committees). However, the way an institution's score was divided, according to VQR rules, between its constituent departments or its staff members does not enjoy many desirable properties well known from coalitional game theory (e.g., budget balance, fairness, marginality). We propose, instead, an alternative score division rule that is based on the notion of Shapley value, a well known solution concept in coalitional game theory, which enjoys the desirable properties mentioned above. For a significant test case (namely, Sapienza University of Rome, the largest university in Italy), we present a detailed comparison of the scores obtained, for substructures and individuals, by applying the official VQR rules, with those resulting from Shapley value computations. We show that there are significant differences in the resulting scores, making room for improvements in the allocation rules used in research assessment exercises.  相似文献   
198.
Traditionally, citation count has served as the main evaluation measure for a paper's importance and influence. In turn, many evaluations of authors, institutions and journals are based on aggregations upon papers (e.g. h-index). In this work, we explore measures defined on the citation graph that offer a more intuitive insight into the impact of a paper than the superficial count of citations. Our main argument is focused on the identification of influence as an expression of the citation density in the subgraph of citations built for each paper. We propose two measures that capitalize on the notion of density providing researchers alternative evaluations of their work. While the general idea of impact for a paper can be viewed as how many researchers have shown interest to a piece of work, the proposed measures are based on the hypothesis that a piece of work may have influenced some papers even if they do not contain references to that piece of work. The proposed measures are also extended to researchers and journals.  相似文献   
199.
The present work investigates the relations between amplitude and type of collaboration (intramural, extramural domestic or international) and output of specialized versus diversified research. By specialized or diversified research, we mean within or beyond the author’s dominant research topic. The field of observation is the scientific production over five years from about 23,500 academics. The analyses are conducted at the aggregate and disciplinary level. The results lead to the conclusion that in general, the output of diversified research is no more frequently the fruit of collaboration than is specialized research. At the level of the particular collaboration types, international collaborations weakly underlie the specialized kind of research output; on the contrary, extramural domestic and intramural collaborations are weakly associated with diversified research. While the weakness of association remains, exceptions are observed at the level of the individual disciplines.  相似文献   
200.
The journal impact factor (JIF) is the average of the number of citations of the papers published in a journal, calculated according to a specific formula; it is extensively used for the evaluation of research and researchers. The method assumes that all papers in a journal have the same scientific merit, which is measured by the JIF of the publishing journal. This implies that the number of citations measures scientific merits but the JIF does not evaluate each individual paper by its own number of citations. Therefore, in the comparative evaluation of two papers, the use of the JIF implies a risk of failure, which occurs when a paper in the journal with the lower JIF is compared to another with fewer citations in the journal with the higher JIF. To quantify this risk of failure, this study calculates the failure probabilities, taking advantage of the lognormal distribution of citations. In two journals whose JIFs are ten-fold different, the failure probability is low. However, in most cases when two papers are compared, the JIFs of the journals are not so different. Then, the failure probability can be close to 0.5, which is equivalent to evaluating by coin flipping.  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