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   2115篇
  免费   129篇
  国内免费   17篇
管理学   252篇
民族学   10篇
人口学   54篇
丛书文集   162篇
理论方法论   111篇
综合类   744篇
社会学   224篇
统计学   704篇
  2024年   4篇
  2023年   27篇
  2022年   39篇
  2021年   33篇
  2020年   65篇
  2019年   76篇
  2018年   85篇
  2017年   86篇
  2016年   78篇
  2015年   72篇
  2014年   119篇
  2013年   299篇
  2012年   141篇
  2011年   138篇
  2010年   115篇
  2009年   93篇
  2008年   113篇
  2007年   99篇
  2006年   92篇
  2005年   79篇
  2004年   91篇
  2003年   63篇
  2002年   62篇
  2001年   44篇
  2000年   39篇
  1999年   19篇
  1998年   17篇
  1997年   13篇
  1996年   11篇
  1995年   5篇
  1994年   5篇
  1993年   4篇
  1992年   6篇
  1991年   5篇
  1990年   4篇
  1989年   2篇
  1988年   5篇
  1986年   3篇
  1985年   4篇
  1984年   1篇
  1983年   5篇
排序方式: 共有2261条查询结果,搜索用时 15 毫秒
1.
The uneven economic recovery from the pandemic-induced global recession of 2020 is expected to disrupt a multi-decade trend of per capita income convergence between advanced and emerging market and developing economies (EMDEs). This stands in contrast to the global recession following the global financial crisis. Should downside risks to the global recovery, in particular financial market stress, materialize, they are likely to set back growth in EMDEs more than in advanced economies in part because of the more limited policy space remaining in EMDEs, and would further widen per capita income divergence.  相似文献   
2.
Work on democratization typically considers the diffusion of democracy through interstate partnerships. However, such partnerships constitute complex networks that scholars have yet to fully explore as vectors for the spread of democracy. We develop a network theory of democratization which characterizes these networks as epistemic communities that influence elites’ attitudes towards favorable regime types. Our theory predicts, and our empirical strategy confirms, that direct and indirect ties in the alliance network are vectors for democratization. In contrast to conventional wisdom, we find that direct influence is only transmitted through the defensive alliance network and find evidence of higher-order effects.  相似文献   
3.
The increasing elderly population puts significant health, economic, and social burdens on society. Physical activity is one of the most cost-effective ways to maintain the health of the elderly. This study adopts a treatment effects model to investigate the causal relationship between environment attributes and physical activity among the elderly, while taking endogeneity into account. The data were collected from 274 participants by face-to-face interviews in Taichung, Taiwan. Performing physical activity regularly in parks is the most important measure of the amount of physical activity by the elderly. Providing sufficient and accessible parks in metropolitan residential neighborhoods could be one of the most cost-effective ways to promote physical activity for the elderly living in midsize Asian cities.  相似文献   
4.
5.
In analyzing data from unreplicated factorial designs, the half-normal probability plot is commonly used to screen for the ‘vital few’ effects. Recently, many formal methods have been proposed to overcome the subjectivity of this plot. Lawson (1998) (hereafter denoted as LGB) suggested a hybrid method based on the half-normal probability plot, which is a blend of Lenth (1989) and Loh (1992) method. The method consists of fitting a simple least squares line to the inliers, which are determined by the Lenth method. The effects exceeding the prediction limits based on the fitted line are candidates for the vital few effects. To improve the accuracy of partitioning the effects into inliers and outliers, we propose a modified LGB method (hereafter denoted as the Mod_LGB method), in which more outliers can be classified by using both the Carling’s modification of the box plot (Carling, 2000) and Lenth method. If no outlier exists or there is a wide range in the inliers as determined by the Lenth method, more outliers can be found by the Carling method. A simulation study is conducted in unreplicated 24 designs with the number of active effects ranging from 1 to 6 to compare the efficiency of the Lenth method, original LGB methods, and the proposed modified version of the LGB method.  相似文献   
6.
Proportional hazards are a common assumption when designing confirmatory clinical trials in oncology. This assumption not only affects the analysis part but also the sample size calculation. The presence of delayed effects causes a change in the hazard ratio while the trial is ongoing since at the beginning we do not observe any difference between treatment arms, and after some unknown time point, the differences between treatment arms will start to appear. Hence, the proportional hazards assumption no longer holds, and both sample size calculation and analysis methods to be used should be reconsidered. The weighted log‐rank test allows a weighting for early, middle, and late differences through the Fleming and Harrington class of weights and is proven to be more efficient when the proportional hazards assumption does not hold. The Fleming and Harrington class of weights, along with the estimated delay, can be incorporated into the sample size calculation in order to maintain the desired power once the treatment arm differences start to appear. In this article, we explore the impact of delayed effects in group sequential and adaptive group sequential designs and make an empirical evaluation in terms of power and type‐I error rate of the of the weighted log‐rank test in a simulated scenario with fixed values of the Fleming and Harrington class of weights. We also give some practical recommendations regarding which methodology should be used in the presence of delayed effects depending on certain characteristics of the trial.  相似文献   
7.
“Chasing” behavior, whereby individuals, driven by a desire to break even, continue a risky activity (RA) despite incurring large losses, is a commonly observed phenomenon. We examine whether the desire to break even plays a wider role in decisions to stop engaging in financially motivated RA in a naturalistic setting. We test hypotheses, motivated by this research question, using a large data set: 707,152 transactions of 5,379 individual financial market spread traders between September 2004 and April 2013. The results indicate strong effects of changes in wealth around the break‐even point on the decision to cease an RA. An important mediating factor was the individual's historical long‐term performance. Those with a more profitable trading history were less affected by a fall in cash balance below the break‐even point compared to those who had been less profitable. We observe that break‐even points play an important role in the decision of nonpathological risk takers to stop RAs. It is possible, therefore, that these nonpathological cognitive processes, when occurring in extrema, may result in pathological gambling behavior such as “chasing.” Our data set focuses on RAs in financial markets and, consequently, we discuss the implications for institutions and regulators in the effective management of risk taking in markets. We also suggest that there may be a need to consider carefully the nature and role of “break‐even points” associated with a broader range of nonfinancially‐focused risk‐taking activities, such as smoking and substance abuse.  相似文献   
8.
Longitudinal studies are the gold standard of empirical work and stress research whenever experiments are not plausible. Frequently, scales are used to assess risk factors and their consequences, and cross-lagged effects are estimated to determine possible risks. Methods to translate cross-lagged effects into risk ratios to facilitate risk assessment do not yet exist, which creates a divide between psychological and epidemiological work stress research. The aim of the present paper is to demonstrate how cross-lagged effects can be used to assess the risk ratio of different levels of psychosocial safety climate (PSC) in organisations, an important psychosocial risk for the development of depression. We used available longitudinal evidence from the Australian Workplace Barometer (N?=?1905) to estimate cross-lagged effects of PSC on depression. We applied continuous time modelling to obtain time-scalable cross effects. These were further investigated in a 4-year Monte Carlo simulation, which translated them into 4-year incident rates. Incident rates were determined by relying on clinically relevant 2-year periods of depression. We suggest a critical value of PSC?=?26 (corresponding to ?1.4 SD), which is indicative of more than 100% increased incidents of persistent depressive disorder in 4-year periods compared to average levels of PSC across 4 years.  相似文献   
9.
Higher educated people tend to be more accepting of homosexuality than lower educated people. This has inspired claims that education leads to a higher acceptance of homosexuality. Alternatively, the association between education and acceptance of homosexuality could be confounded by (un)observed family background and stable individual characteristics. This study investigated the association between education and acceptance of homosexuality and the role of potential confounders in a unique longitudinal sample of British siblings. Multilevel and fixed effects analyses show that both perspectives apply. A large part of the association between education and acceptance of homosexuality could be attributed to family background and observed individual characteristics (one third), as well as unobserved individual characteristics (an additional third), but the positive association remains. Findings are discussed in light of existing explanations regarding the effect of education on the acceptance of homosexuality.  相似文献   
10.
为了从外部性角度说明目前陕西省交通基础设施的建设和投资在地域上存在的问题,为陕西省交通基础设施建设方向提供理论帮助,基于陕西省2009~2017年间各市相关数据,在交通基础设施对经济增长效应研究的直接效应和溢出效应基础上,加入空间要素,构建生产函数和空间权重矩阵,通过自相关检验(莫兰指数)、LM检验和 Hausman检验,选取合适的空间面板计量模型对陕西省交通基础设施的经济溢出情况进行研究。研究认为,2009~2017年间陕西省交通基础设施对经济增长的溢出效应(显著)整体为负,但依然存在正溢出的局部地区,即以西安为首的经济聚集区(西安、宝鸡、咸阳)和榆林、延安联合的陕北经济聚集区,资源过于集中和两个高地之间缺乏互联互通是整体呈现负溢出的重要原因。在地域分配的量和质上应充分考虑交通基础设施的溢出效应,避免资源过度集中在西安,在两个经济高地之间打通一条经济要道,并重点扶持相对落后又有发展前景的城市可促使陕西经济发展由总体集聚向总体扩散转变。  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