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   863篇
  免费   11篇
教育   634篇
科学研究   68篇
各国文化   8篇
体育   63篇
文化理论   4篇
信息传播   97篇
  2022年   4篇
  2021年   11篇
  2020年   13篇
  2019年   27篇
  2018年   37篇
  2017年   31篇
  2016年   48篇
  2015年   20篇
  2014年   35篇
  2013年   191篇
  2012年   15篇
  2011年   25篇
  2010年   16篇
  2009年   30篇
  2008年   43篇
  2007年   26篇
  2006年   28篇
  2005年   28篇
  2004年   14篇
  2003年   15篇
  2002年   17篇
  2001年   20篇
  2000年   14篇
  1999年   15篇
  1998年   9篇
  1997年   10篇
  1996年   6篇
  1995年   8篇
  1994年   7篇
  1993年   10篇
  1992年   5篇
  1991年   4篇
  1990年   8篇
  1989年   12篇
  1988年   4篇
  1987年   5篇
  1986年   5篇
  1985年   9篇
  1984年   4篇
  1983年   10篇
  1982年   2篇
  1980年   3篇
  1979年   4篇
  1978年   4篇
  1977年   2篇
  1976年   5篇
  1974年   2篇
  1973年   2篇
  1933年   1篇
  1899年   2篇
排序方式: 共有874条查询结果,搜索用时 343 毫秒
31.
32.
复杂系统、知识管理与组织学习过程动态模型研究   总被引:13,自引:0,他引:13  
知识经济时代的组织是一个具有无尺度网络结构的复杂系统。知识管理是知识经济时代的必然要求。组织学习作为组织获取核心竞争力和可持续发展能力的重要手段,是一个动态的过程。本文在系统回顾相关研究成果的基础上,从复杂系统的视角对知识经济时代复杂环境下的组织学习动态复杂过程进行了系统的模型整合和创新,并对构建学习型组织可能遇到的障碍进行了一系列对策分析。  相似文献   
33.
The acquisition of reading skills is known to rely on early phonological abilities, but only a few studies have investigated the independent contribution of the different steps involved in phonological processing. This 1‐year longitudinal study, spanning the initial year of reading instruction, aimed at specifying the development of phonological discrimination, awareness and various aspects of phonological memory and at assessing their respective contributions to early reading acquisition. Our results show an increase in performance at each phonological processing step, but also suggest a qualitative evolution in their relative importance. Hierarchical regression analyses indicate that reading skills are mainly predicted by phonological awareness measured at the kindergarten stage and, subsequently, by phonological memory abilities measured at the end of first grade. More precisely short‐term memory for serial‐order information seems to contribute to the development of decoding abilities, while phonological knowledge stored in long‐term memory seems to influence word recognition.  相似文献   
34.
We provide causal evidence that regulation induced product shocks significantly impact aggregate demand and firm performance in pharmaceutical markets. Event study results suggest an average loss between $569 million and $882 million. Affected products lose, on average, $186 million over their remaining effective patent life. This leaves a loss of between $383 million and $696 million attributable to declines in future innovation. Our findings complement research that shows drugs receiving expedited review are more likely to suffer from regulation induced product shocks. Thus, it appears we may be trading off quicker access to drugs today for less innovation tomorrow. Results remain robust to variation across types of relabeling, market sizes, and levels of competition.  相似文献   
35.
This paper addresses the role that scientific status plays in initial public offerings of technology focused firms. The paper builds on the literature of the sociology of science as well as the work of Spence (1974) and Podolny (1993) and argues that the presence of a Nobel laureate affiliated with a firm making an IPO provides a signal of firm quality to potential investors. Moreover, and building on the work of Podolny and Scott Morton (1999) and Stuart et al. (1999) we hypothesize that the importance of status diminishes as other measures of firm quality become available. We test our hypothesis for two periods of initial public offerings in biotechnology. We document that there is a clear difference in “maturity” of the firms across the two windows on a number of metrics. Consistent with our hypothesis that Nobel laureates play an important role as a non-financial signal of firm quality, we find that first-window firms with a Nobel laureate affiliate realize greater IPO proceeds in the amount of $24 million. In the second window the amount of money raised is not significantly different between Nobel and non-Nobel firms. This finding is consistent with the signaling literature that argues that the importance of a signal is inversely related to the availability of cogent information on firm quality. Consistent with this view, we also find a change between the two windows in the importance of other non-financial metrics used to convey value. Our research is one of the first to examine the dynamic nature of signals. Because we are unable to distinguish the extent to which the reduction in uncertainty at the firm level is correlated with the reduction of uncertainty at the industry level, the question remains as to the extent to which the diminished importance of signals in our second period is due to a change in market uncertainty versus a change in firm uncertainty.  相似文献   
36.
The aim of this study was to examine the effectiveness of either a standard care programme (n = 9) or a 12-week supported exercise programme (n = 10) on glycaemic control, β-cell responsiveness, insulin resistance, and lipid profiles in newly diagnosed Type 2 diabetes patients. The standard care programme consisted of advice to exercise at moderate to high intensity for 30 min five times a week; the supported exercise programme consisted of three 60-min supported plus two unsupported exercise sessions per week. Between-group analyses demonstrated a difference for changes in low-density lipoprotein cholesterol only (standard care programme 0.01 mmol · L(-1), supported exercise programme -0.6 mmol · L(-1); P = 0.04). Following the standard care programme, within-group analyses demonstrated a significant reduction in waist circumference, whereas following the supported exercise programme there were reductions in glycosylated haemoglobin (6.4 vs. 6.0%; P = 0.007), waist circumference (101.4 vs. 97.2 cm; P = 0.021), body mass (91.7 vs. 87.9 kg; P = 0.007), body mass index (30.0 vs. 28.7 kg · m(-2); P = 0.006), total cholesterol (5.3 vs. 4.6 mmol · L(-1); P = 0.046), low-density lipoprotein cholesterol (3.2 vs. 2.6 mmol · L(-1); P = 0.028), fasting β-cell responsiveness (11.5 × 10(-9) vs. 7.0 × 10(-9) pmol · kg(-1) · min(-1); P = 0.009), and insulin resistance (3.0 vs. 2.1; P = 0.049). The supported exercise programme improved glycaemic control through enhanced β-cell function associated with decreased insulin resistance and improved lipid profile. This research highlights the need for research into unsupported and supported exercise programmes to establish more comprehensive lifestyle advice for Type 2 diabetes patients.  相似文献   
37.
The current study used a pretest–posttest randomized control group design with 73 Head Start students, ages 3–5 years. The researcher served as the interactive writing teacher for the treatment group, rotating to five different classrooms in one Head Start center 3–4 days a week for 13 weeks. Children in the treatment group received a 10–15 min interactive writing lesson each day in small groups within their own classroom settings. Children in the control group received standard literacy instruction in small groups with their own classroom teachers. Child outcome data on upper case, lower case, and letter sound identification were collected before and after the intervention for both groups. Based on the large frequency of zeros on outcomes, zero-inflated Poisson regression analyses were performed. The results of the study showed that children receiving interactive writing identified more lower case and upper case letters at the end of the study relative to children in the control, but no differences were observed on letter sounds. While continued evaluation of the interactive writing strategy is needed in the preschool setting, the evidence from the current study shows encouraging trends in alphabet knowledge skill development as a result of this strategy.  相似文献   
38.
Science education studies have revealed that students often have misconceptions about how nature works, but what happens to misconceptions after a conceptual change remains poorly understood. Are misconceptions rejected and replaced by scientific conceptions, or are they still present in students' minds, coexisting with newly acquired scientific conceptions? In this study, we use functional magnetic resonance imaging (fMRI) to compare brain activation between novices and experts in science when they evaluate the correctness of simple electric circuits. Results show that experts, more than novices, activate brain areas involved in inhibition when they evaluate electric circuits in which a bulb lights up, even though there is only one wire connecting it to the battery. These findings suggest that experts may still have a misconception encoded in the neural networks of their brains that must be inhibited in order to answer scientifically.  相似文献   
39.
40.
This paper describes the structure and use of LabAssistant, a software shell purposely written to run alongside engineering laboratory exercises and provide support to students undertaking the exercises. The structure of LabAssistant enables tutors to deliver their own laboratory sessions within the shell using only basic spreadsheet skills. LabAssistant is intended to be used in conjunction with in-depth, analytical laboratory exercises and its features include text entry, numerical input and checking (including verification of calculated values and provision of appropriate feedback), graph sketching, data plotting and report generation. Feedback from students confirms that LabAssistant has enhanced the learning experience, encouraging active engagement, building confidence and assisting progression through the exercise, even using the data and information input during the session to generate the majority of their laboratory write-up automatically. From the tutor's perspective, the provision of immediate and continual help to the students is a significant enhancement to the quality of the learning experience. LabAssistant complements the tutor who is now able to deal effectively with deeper conceptual difficulties and larger student numbers. The facility to verify all calculated values and the creation of a report in a standard electronic format are significant aids to the marking of student submissions.  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