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   5238篇
  免费   204篇
管理学   922篇
民族学   43篇
人才学   1篇
人口学   426篇
丛书文集   22篇
理论方法论   624篇
综合类   69篇
社会学   2678篇
统计学   657篇
  2023年   50篇
  2022年   28篇
  2021年   40篇
  2020年   103篇
  2019年   167篇
  2018年   156篇
  2017年   226篇
  2016年   155篇
  2015年   148篇
  2014年   157篇
  2013年   857篇
  2012年   209篇
  2011年   253篇
  2010年   170篇
  2009年   149篇
  2008年   163篇
  2007年   196篇
  2006年   177篇
  2005年   165篇
  2004年   163篇
  2003年   133篇
  2002年   148篇
  2001年   125篇
  2000年   97篇
  1999年   94篇
  1998年   67篇
  1997年   69篇
  1996年   55篇
  1995年   54篇
  1994年   46篇
  1993年   62篇
  1992年   54篇
  1991年   52篇
  1990年   52篇
  1989年   54篇
  1988年   51篇
  1987年   40篇
  1986年   42篇
  1985年   32篇
  1984年   51篇
  1983年   39篇
  1982年   42篇
  1981年   40篇
  1980年   38篇
  1979年   31篇
  1978年   25篇
  1977年   19篇
  1976年   20篇
  1975年   21篇
  1974年   15篇
排序方式: 共有5442条查询结果,搜索用时 604 毫秒
111.
The standardized hazard ratio for univariate proportional hazards regression is generalized as a scalar to multivariate proportional hazards regression. Estimators of the standardized log hazard ratio are developed, with corrections for bias and for regression to the mean in high-dimensional analyses. Tests of point and interval null hypotheses and confidence intervals are constructed. Cohort sampling study designs, commonly used in prospective–retrospective clinical genomic studies, are accommodated.  相似文献   
112.
We develop methodology for a multistage-decision problem with flexible number of stages in which the rewards are survival times that are subject to censoring. We present a novel Q-learning algorithm that is adjusted for censored data and allows a flexible number of stages. We provide finite sample bounds on the generalization error of the policy learned by the algorithm, and show that when the optimal Q-function belongs to the approximation space, the expected survival time for policies obtained by the algorithm converges to that of the optimal policy. We simulate a multistage clinical trial with flexible number of stages and apply the proposed censored-Q-learning algorithm to find individualized treatment regimens. The methodology presented in this paper has implications in the design of personalized medicine trials in cancer and in other life-threatening diseases.  相似文献   
113.
114.
Inheritance is a significant means of transferring wealth from one generation to the next, and therefore increasingly attracts attention from researchers and policy-makers working on intergenerational and multidimensional poverty. However, until now disabled persons have been overlooked in these discussions. This oversight is particularly unfortunate because, as a group, the estimated one billion people with disabilities (some 15% of the world’s population) are among the poorest and most marginalized of the global population. Over the past decade, a small but growing literature has examined the recursive connections between poverty and disability throughout the developing world. In this paper, we argue that disabled individuals are routinely denied inheritance rights in many low-income and middle-income countries, and that this is a significant and largely unrecognized contributor to their indigence. The denial of inheritance is both a social justice issue and a practice that can no longer be overlooked if disabled persons are to be brought into the development mainstream.  相似文献   
115.
Since decades, the financial industry has experienced a continuous evolution in service delivery due to digitalization. This evolution is characterized by expanded connectivity and enhanced speed of information processing both at the customer interface and in back-office processes. Recently, there has been a shift in the focus of digitalization from improving the delivery of traditional tasks to introducing fundamentally new business opportunities and models for financial service companies. Digital Finance encompasses a magnitude of new financial products, financial businesses, finance-related software, and novel forms of customer communication and interaction—delivered by FinTech companies and innovative financial service providers. Against this backdrop, the research on finance and information systems has started to analyze these changes and the impact of digital progress on the financial sector. Therefore, this article reviews the current state of research in Digital Finance that deals with these novel and innovative business functions. Moreover, it gives an outlook on potential future research directions. As a conceptual basis for reviewing this field, the Digital Finance Cube, which embraces three key dimensions of Digital Finance and FinTech, i.e., the respective business functions, the technologies and technological concepts applied as well as the institutions concerned, is introduced. This conceptualization supports researchers and practitioners when orientating in the field of Digital Finance, allows for the arrangement of academic research relatively to each other, and enables for the revelation of the gaps in research.  相似文献   
116.
A challenge for large‐scale environmental health investigations such as the National Children's Study (NCS), is characterizing exposures to multiple, co‐occurring chemical agents with varying spatiotemporal concentrations and consequences modulated by biochemical, physiological, behavioral, socioeconomic, and environmental factors. Such investigations can benefit from systematic retrieval, analysis, and integration of diverse extant information on both contaminant patterns and exposure‐relevant factors. This requires development, evaluation, and deployment of informatics methods that support flexible access and analysis of multiattribute data across multiple spatiotemporal scales. A new “Tiered Exposure Ranking” (TiER) framework, developed to support various aspects of risk‐relevant exposure characterization, is described here, with examples demonstrating its application to the NCS. TiER utilizes advances in informatics computational methods, extant database content and availability, and integrative environmental/exposure/biological modeling to support both “discovery‐driven” and “hypothesis‐driven” analyses. “Tier 1” applications focus on “exposomic” pattern recognition for extracting information from multidimensional data sets, whereas second and higher tier applications utilize mechanistic models to develop risk‐relevant exposure metrics for populations and individuals. In this article, “tier 1” applications of TiER explore identification of potentially causative associations among risk factors, for prioritizing further studies, by considering publicly available demographic/socioeconomic, behavioral, and environmental data in relation to two health endpoints (preterm birth and low birth weight). A “tier 2” application develops estimates of pollutant mixture inhalation exposure indices for NCS counties, formulated to support risk characterization for these endpoints. Applications of TiER demonstrate the feasibility of developing risk‐relevant exposure characterizations for pollutants using extant environmental and demographic/socioeconomic data.  相似文献   
117.
118.
In this study, we examined the moderating influences of gender and age with respect to testing the heritability of leadership emergence. A large data base of 12,112 twins from Sweden was used in the current study to decompose the variance of emergent leadership into an unobservable genetic component and environmental components that are either common or unshared among twin pairs. Consistent with prior leadership research on genetics, we found that a genetic factor is able to explain a significant proportion of the variation across individuals in predicting how twins perceive their emergent leadership behavior (about 44% for women and 37% for men). Furthermore, we also found that the magnitude of genetic influence on emergent leadership varied with age, but only for women with the heritability estimate being highest for the mid-age women versus lowest for the older women. Implications for advancing research on the genetic and environmental influences on leadership emergence are discussed.  相似文献   
119.
In recent years there has been a marked increase in the study of the influence of leadership on creativity, and the effects of this relationship on organizational performance. While a number of explanations have been broached with regard to the positive effects of leadership on creativity, many of these studies propose different, and often contradictory, methods for leaders to achieve these positive effects on creativity within their organizations and work groups. Additionally, little work has been done examining the effects of leadership on highly creative people in fields requiring creativity. The purpose of this study is to examine two existing leadership theories with regard to their viability as models to explain creative performance of eminent scientists. Eminent scientists represent a population of leaders of highly creative individuals in a field that values the production of innovative ideas and products as a marker of performance. Ninety-three excerpts from the biographies of scientists were content coded for leader behaviors and performance criteria. The results of this analysis indicate that a model based on strategic planning and product championing may serve to explain the positive effects of leadership on creativity in a highly creative population.  相似文献   
120.
By 15–18 months, infants’ skill in interpreting familiar words, or lexical processing efficiency (LPE), improves substantially and is correlated with vocabulary size concurrently and several months later. Prior to this age LPE is quite poor, and to date there is little evidence that it is related to vocabulary size. If this relation only emerges once infants have relatively good LPE, and also know a substantial number of words, it could suggest that the processes that support the rapid growth in vocabulary commonly observed as infants approach age 2 may not yet be functional in the earlier stages of lexical development. However, using a modified LPE task we found that 12‐month‐olds with better LPE understood more words at that age and also produced more words several months later. These results suggest that meaningful individual differences in LPE are already emerging by 12 months and may support lexical development across the second year.  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