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   286篇
  免费   16篇
管理学   48篇
民族学   5篇
人口学   44篇
理论方法论   16篇
综合类   6篇
社会学   143篇
统计学   40篇
  2023年   3篇
  2022年   9篇
  2021年   7篇
  2020年   11篇
  2019年   15篇
  2018年   29篇
  2017年   32篇
  2016年   21篇
  2015年   3篇
  2014年   12篇
  2013年   51篇
  2012年   31篇
  2011年   5篇
  2010年   11篇
  2009年   10篇
  2008年   10篇
  2007年   7篇
  2006年   5篇
  2005年   4篇
  2004年   7篇
  2003年   2篇
  2002年   4篇
  2001年   1篇
  2000年   1篇
  1999年   5篇
  1998年   1篇
  1997年   2篇
  1990年   2篇
  1985年   1篇
排序方式: 共有302条查询结果,搜索用时 15 毫秒
41.
Vision formation, and vision articulation, is held to be a central component of leader performance. Less is known, however, about the variables giving rise to viable visions. In the present effort, the impact of forecasting on vision formation was examined. Study participants were asked to write a speech describing their vision for a new school. Prior to writing this speech, participants were asked to forecast the outcomes of vision implementation. It was found that the extent of forecasting, along with forecasting of temporal and resources considerations, influenced the quality of vision statements. Forecasting was improved when people thought about causes, as opposed to goals, and implications, as opposed to facts. The implications of these findings for understanding leader performance in vision formation are discussed.  相似文献   
42.
Interest is in evaluating, by Markov chain Monte Carlo (MCMC) simulation, the expected value of a function with respect to a, possibly unnormalized, probability distribution. A general purpose variance reduction technique for the MCMC estimator, based on the zero-variance principle introduced in the physics literature, is proposed. Conditions for asymptotic unbiasedness of the zero-variance estimator are derived. A central limit theorem is also proved under regularity conditions. The potential of the idea is illustrated with real applications to probit, logit and GARCH Bayesian models. For all these models, a central limit theorem and unbiasedness for the zero-variance estimator are proved (see the supplementary material available on-line).  相似文献   
43.
A study on the robustness of the adaptation of the sample size for a phase III trial on the basis of existing phase II data is presented—when phase III is lower than phase II effect size. A criterion of clinical relevance for phase II results is applied in order to launch phase III, where data from phase II cannot be included in statistical analysis. The adaptation consists in adopting the conservative approach to sample size estimation, which takes into account the variability of phase II data. Some conservative sample size estimation strategies, Bayesian and frequentist, are compared with the calibrated optimal γ conservative strategy (viz. COS) which is the best performer when phase II and phase III effect sizes are equal. The Overall Power (OP) of these strategies and the mean square error (MSE) of their sample size estimators are computed under different scenarios, in the presence of the structural bias due to lower phase III effect size, for evaluating the robustness of the strategies. When the structural bias is quite small (i.e., the ratio of phase III to phase II effect size is greater than 0.8), and when some operating conditions for applying sample size estimation hold, COS can still provide acceptable results for planning phase III trials, even if in bias absence the OP was higher.

Main results concern the introduction of a correction, which affects just sample size estimates and not launch probabilities, for balancing the structural bias. In particular, the correction is based on a postulation of the structural bias; hence, it is more intuitive and easier to use than those based on the modification of Type I or/and Type II errors. A comparison of corrected conservative sample size estimation strategies is performed in the presence of a quite small bias. When the postulated correction is right, COS provides good OP and the lowest MSE. Moreover, the OPs of COS are even higher than those observed without bias, thanks to higher launch probability and a similar estimation performance. The structural bias can therefore be exploited for improving sample size estimation performances. When the postulated correction is smaller than necessary, COS is still the best performer, and it also works well. A higher than necessary correction should be avoided.  相似文献   
44.
This paper contributes to studies on dynamic capabilities (DCs) by showing that a neglected environmental contingency – i.e. the occurrence of a jolt – shapes the DCs–performance relationship. We focus on high-tech entrepreneurial ventures because these are the firms that jolts affect most; in so doing, we also advance the understanding of DCs in the entrepreneurship field. We argue that, in the aftermath of an environmental jolt, the high-tech entrepreneurial ventures that use internationalization and new product development capabilities to modify their resource configuration and regain environmental fit enjoy better performance. Econometric estimates on a sample of 340 Italian high-tech entrepreneurial ventures confronting the consequences of the global economic crisis that began in 2008 confirm that separately using these two DCs has a positive performance effect. This effect is stronger for relatively smaller ventures. Interestingly, despite synergies should arise from the combined use of the two DCs, we do not detect any superadditive effects.  相似文献   
45.
Over the last decade we have witnessed an unprecedented growth in the number of cross-border R&D investments towards large emerging countries such as China and India. However, small middle-income countries have played a marginal role as recipients of R&D-related FDI despite increasing policy efforts. In particular, several Latin American countries have recently launched new policy programs with the aim of attracting this kind of investments, but it remains uncertain whether public incentives can be useful to compensate for other locational disadvantages. The case of Chile provides an interesting empirical setting to explore these issues because during the last decade its government has been actively promoting R&D-related FDI through a new policy mix. This article suggests that for national innovation systems to benefit from the attraction of internationally-mobile R&D it is critical for public policies to ensure that appropriate linkages are established with local actors that hold absorptive capacities. Equally important for a small emerging economy like Chile is to prioritize R&D-related FDI in strategic technology niches where the country can realistically attain critical mass.  相似文献   
46.
This paper contributes to the ongoing debate on the nature of living apart together (LAT) relationships by focusing on two contrasting family settings: France and Italy. First, we corroborate the view that being “single” in residential terms does not mean being “without a partner” in relationship terms. To assume otherwise would be an erroneous characterisation of more than one quarter of the individuals in both countries. Second, our findings cannot be reconciled with any notion of a simple, uniform, and uni-directional view of LAT relationships. In Italy, LAT relationships are popular in the early phases of the life course, when young adults must often face difficult economic situations as well as social pressure to marry. In France, LAT relationships are more the result of a conscious choice, especially in later phases of the life course. We discuss these results in light of the second demographic transition narrative.  相似文献   
47.
The authors examined the relationship between career adaptability, future orientation, and vocational interests. Specifically, they tested the role of career adaptability and future orientation in promoting a broader range of vocational interests, based on the principle that experiencing more interests can be useful in giving one's best in multiple occupations and in planning a broad range of career goals. A total of 762 Italian adolescents (383 males, 379 females) participated in the study. Results highlight the mediating role of future orientation in the relationship between 4 career adaptability resources and breadth of vocational interests. These results underscore that specific interventions in career adaptability and future orientation may foster a broader range of vocational interests, providing more opportunity for adolescents to respond to the demands of the current job market.  相似文献   
48.
Many empirical studies find that parents are not as happy as non-parents or that parenthood exerts a negative effect on subjective well-being (SWB). We add to these findings by arguing that there is a key moderating factor that has been overlooked in previous research, i.e. the level of work–family conflict. We hypothesize that the birth of a child means an increase in the level of work–family tension, which may be substantial for some parents and relatively weak for others. To outline such an approach, we estimate fixed-effects models using panel data from the Household, Income and Labor Dynamics in Australia survey. We find that childbearing negatively affects SWB only when parents, mothers in particular, face a substantial work–family conflict, providing thus support for our hypothesis.  相似文献   
49.
This literature review analyzes leading international business and management journals from 2000 to 2012 in order to explore the role of national culture in international business research. Through the analysis of the 265 selected articles, the study thematically maps the field and identifies research challenges and opportunities. It reflects on avenues for future research related to both thematic and methodological issues, among them: research focused on the impact of the home/host national culture on internationalization processes (as existing literature mainly focuses on cultural distance); the role to be played by new theoretical frameworks; and the need to consider cultural positions and cultural friction rather than traditional cultural distance when analyzing internationalization decisions.  相似文献   
50.
Air pollution has been linked to an increased risk of several respiratory diseases in children, especially respiratory tract infections. The present study aims to evaluate the association between pediatric emergency department (PED) presentations for bronchiolitis and air pollution. PED presentations due to bronchiolitis in children aged less than 1 year were retrospectively collected from 2007 to 2018 in Padova, Italy, together with daily environmental data. A conditional logistic regression based on a time-stratified case-crossover design was performed to evaluate the association between PED presentations and exposure to NO2, PM2.5, and PM10. Models were adjusted for temperature, relative humidity, atmospheric pressure, and public holidays. Delayed effects in time were evaluated using distributed lag non-linear models. Odds ratio for lagged exposure from 0 to 14 days were obtained. Overall, 2251 children presented to the PED for bronchiolitis. Infants’ exposure to higher concentrations of PM10 and PM2.5 in the 5 days before the presentation to the PED increased the risk of accessing the PED by more than 10%, whereas high concentrations of NO2 between 2 and 12 days before the PED presentation were associated with an increased risk of up to 30%. The association between pollutants and infants who required hospitalization was even greater. A cumulative effect of NO2 among the 2 weeks preceding the presentation was also observed. In summary, PM and NO2 concentrations are associated with PED presentations and hospitalizations for bronchiolitis. Exposure of infants to air pollution could damage the respiratory tract mucosa, facilitating viral infections and exacerbating symptoms.  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