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   313篇
  免费   9篇
管理学   55篇
民族学   1篇
人口学   45篇
理论方法论   25篇
综合类   2篇
社会学   117篇
统计学   77篇
  2023年   6篇
  2021年   9篇
  2020年   10篇
  2019年   16篇
  2018年   20篇
  2017年   12篇
  2016年   10篇
  2015年   7篇
  2014年   11篇
  2013年   80篇
  2012年   16篇
  2011年   15篇
  2010年   7篇
  2009年   4篇
  2008年   9篇
  2007年   13篇
  2006年   12篇
  2005年   6篇
  2004年   6篇
  2003年   4篇
  2002年   4篇
  2001年   1篇
  2000年   6篇
  1999年   7篇
  1998年   3篇
  1997年   2篇
  1996年   2篇
  1995年   2篇
  1994年   2篇
  1993年   1篇
  1992年   3篇
  1991年   1篇
  1990年   2篇
  1988年   1篇
  1987年   1篇
  1986年   3篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
  1979年   1篇
  1976年   2篇
  1968年   2篇
排序方式: 共有322条查询结果,搜索用时 234 毫秒
31.
32.
Abstract

Objectives, Participants, Methods: Drinking game participation has increased in popularity among college students and is associated with increased alcohol consumption and alcohol-related problems. The current study investigated drinking game participation among 133 undergraduates attending National Alcohol Screening Day (NASD) in April of 2007. Results: A large percentage of the sample reported lifetime (77%) and recent (52%) drinking game participation. Males were more likely to report recent participation and reported higher levels of consumption while playing drinking games. Drinking game participants were more likely to experience a range of alcohol-related problems, and the relationship between drinking game participation and alcohol-related problems was mediated by weekly alcohol consumption. Conclusions: These results suggest that drinking game participation is a risk factor for elevated levels of alcohol consumption and alcohol-related problems. Programs should be developed to educate students about the risks of drinking game participation, and prevention programs like NASD should address drinking games.  相似文献   
33.
The plant community in the karst forest is influenced by mesoclimatic conditions, such as temperature and humidity and these conditions are in turn influenced by topographic features. Urban areas adjacent to karstic forest remnants also have the potential to influence mesoclimatic variables and may serve as a source of exotic species. We described the temperature and relative humidity of karstic forest remnants at slopes with combinations of either southeast (SE) or northwest (NW) aspect, and adjacent to either urban (URB) or secondary forest (SF). We also compared forest structure and composition on these slopes to understand the interaction between forest aspect and adjacent land use on the plant community. URB-SE slopes had highest temperature and lowest humidity among all adjacent land use-aspect combinations. Understory species in SE slopes had similar richness and diversity independently of adjacent land use, however within NW aspect, slopes adjacent to urban areas showed higher values than slopes adjacent secondary forest. Canopy trees species in slopes adjacent to secondary forest were more diverse and rich in SE than in NW, although no differences between aspects were detected within URB-adjacent slopes. Understory species composition was different among the four land use-aspect combinations. However, composition of canopy trees species was different only between aspect types. Most exotic species in the sites were associated with previous agricultural practices and not with current land use. Our results show a temporal and spatial influence of anthropogenic systems on the plant community in karstic forest remnants at a suburban area of Puerto Rico.  相似文献   
34.
Population and Deforestation in Costa Rica   总被引:5,自引:0,他引:5  
This paper addresses a central debate in research and policy on population and environment, namely the extent to which rapid population growth is associated with the massive deforestation currently underway in the tropics. We utilize the experience of Costa Rica during the last forty years to illustrate what the main issues are, discuss the history of deforestation in that country, and present results from conventional regression methods and from the application of spatial analyses. These analyses enable us to estimate the magnitude of the relation between population and deforestation and to identify the factors that are responsible for the linkage between them.  相似文献   
35.
36.
Highly skewed outcome distributions observed across clusters are common in medical research. The aim of this paper is to understand how regression models widely used for accommodating asymmetry fit clustered data under heteroscedasticity. In a simulation study, we provide evidence on the performance of the Gamma Generalized Linear Mixed Model (GLMM) and log-Linear Mixed-Effect (LME) model under a variety of data-generating mechanisms. Two case studies from health expenditures literature, the cost of strategies after myocardial infarction randomized clinical trial on the cost of strategies after myocardial infarction and the European Pressure Ulcer Advisory Panel hospital prevalence survey of pressure ulcers, are analyzed and discussed. According to simulation results, the log-LME model for a Gamma response can lead to estimations that are biased by as much as 10% of the true value, depending on the error variance. In the Gamma GLMM, the bias never exceeds 1%, regardless of the extent of heteroscedasticity, and the confidence intervals perform as nominally stated under most conditions. The Gamma GLMM with a log link seems to be more robust to both Gamma and log-normal generating mechanisms than the log-LME model.  相似文献   
37.
38.
39.
The effects of the pace of childbearing and breastfeeding practices on infant mortality have rarely been considered together. In this paper, we design and use a set of methodological tools to test a variety of hypotheses postulating the effects of breastfeeding and pace of childbearing on mortality in infancy and early childhood, the mechanisms through which those effects operate, and the contingencies that strengthen or weaken them. The strong effects of both length of breastfeeding and the pace of childbearing on the risks of child death suggest that neither of them exerts an impact on mortality totally mediated by the other. Social and demographic factors (such as age of child, education of mother, and region of residence) also condition the impact of breastfeeding and pace of childbearing on mortality.  相似文献   
40.
Alberto Palloni 《Demography》1979,16(3):455-473
The paper presents new estimates of infant mortality for Colombia and El Salvador for the years 1950--1970. These estimates are obtained by using a technique which improves on Brass's method in that it suppresses the assumption of constant mortality and introduces instead assumptions about linear and nonlinear changes in mortality risks affecting various cohorts of individuals.  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