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   899篇
  免费   54篇
管理学   156篇
民族学   7篇
人口学   75篇
丛书文集   5篇
理论方法论   128篇
综合类   14篇
社会学   477篇
统计学   91篇
  2023年   9篇
  2022年   4篇
  2021年   9篇
  2020年   19篇
  2019年   27篇
  2018年   34篇
  2017年   50篇
  2016年   40篇
  2015年   23篇
  2014年   28篇
  2013年   121篇
  2012年   42篇
  2011年   43篇
  2010年   34篇
  2009年   28篇
  2008年   39篇
  2007年   36篇
  2006年   35篇
  2005年   27篇
  2004年   41篇
  2003年   30篇
  2002年   28篇
  2001年   20篇
  2000年   19篇
  1999年   11篇
  1998年   14篇
  1997年   12篇
  1996年   11篇
  1995年   4篇
  1994年   7篇
  1993年   9篇
  1992年   9篇
  1991年   8篇
  1990年   10篇
  1987年   7篇
  1986年   3篇
  1985年   6篇
  1984年   4篇
  1982年   9篇
  1981年   3篇
  1980年   5篇
  1979年   2篇
  1978年   6篇
  1977年   4篇
  1976年   3篇
  1975年   2篇
  1974年   3篇
  1973年   2篇
  1972年   2篇
  1971年   2篇
排序方式: 共有953条查询结果,搜索用时 250 毫秒
81.
This exploratory study examines the effects of rural and urban population change on forest cover at the local level across the southern United States. Using county‐level data from the National Land Cover Database and other U.S. government sources, we regressed the total area of forest cover on rural and urban population size in spatial panel models with two‐way fixed effects. When we controlled for several other factors, including the number of forestry operations at the county level, regression results indicate that urban change had no effect, but rural population size was positively related to total forest area, and this effect was most pronounced in and around Georgia. Thus, in areas of the southern United States, rural growth was associated with afforestation, not deforestation. We speculate on how this unusual finding contributes to the debate between ecological modernization and urban political economy implicated in previous cross‐national research.  相似文献   
82.
ABSTRACT

Social media data are increasingly used by researchers to gain insights on individuals’ behaviors and opinions. Platforms like Twitter provide access to individuals’ postings, networks of friends and followers, and the content to which they are exposed. This article presents the methods and results of an exploratory study to supplement survey data with respondents’ Twitter postings, networks of Twitter friends and followers, and information to which they were exposed about e-cigarettes. Twitter use is important to consider in e-cigarette research and other topics influenced by online information sharing and exposure. Further, Twitter metadata provide direct measures of user’s friends and followers as opposed to survey self-reports. We find that Twitter metadata provide similar information to survey questions on Twitter network size without inducing recall error or other measurement issues. Using sentiment coding and machine learning methods, we find Twitter can elucidate on topics difficult to measure via surveys such as online expressed opinions and network composition. We present and discuss models predicting whether respondents’ tweet positively about e-cigarettes using survey and Twitter data, finding the combined data to provide broader measures than either source alone.  相似文献   
83.
We provide evidence on the existence of short-run trade diversion effects towards third countries as a consequence of tariff shocks. We exploit sudden policy changes in the context of the trade dispute between the United States and China in 2018. Based on a data set covering monthly product-level information on US imports from 30 countries for the period 2016 until May 2019, we employ a difference-in-differences estimation framework. Doing so, we can show a strong negative direct effect of US tariffs on US imports from China, but do not find evidence for significant short-run trade diversion effects towards third countries.  相似文献   
84.
Objectives. We aim to understand why blacks are significantly less likely than whites to perpetuate their middle-class status across generations. To do so, we focus on the potentially different associations between parental job loss and youth's educational attainment in black and white middle-class families.Methods. We use data from the Panel Study of Income Dynamics (PSID), following those children “born” into the survey between 1968 and 1979 and followed through age 21. We conduct multivariate regression analyses to test the association between parental job loss during childhood and youth's educational attainment by age 21.Results. We find that parental job loss is associated with a lesser likelihood of obtaining any postsecondary education for all offspring, but that the association for blacks is almost three times as strong. A substantial share of the differential impact of job loss on black and white middle-class youth is explained by race differences in household wealth, long-run measures of family income, and, especially, parental experience of long-term unemployment.Conclusions. These findings highlight the fragile economic foundation of the black middle class and suggest that intergenerational persistence of class status in this population may be highly dependent on the avoidance of common economic shocks.  相似文献   
85.
86.
87.
88.
89.
This article develops a new methodology for a more comprehensive and useful analysis of the costs and benefits of fundraising, as well as the total costs and net benefits associated with development efforts in general. This approach does a better job of linking the timing of return of fundraising efforts and measuring the actual return on investments in fundraising (as opposed to the reported return) than the widely used guidelines from the Council for Advancement and Support of Education and the National Association of College and University Business Officers (CASE/NACUBO) (1990). The implications are a better methodology for practitioners that they can use to enhance internal decision making and a better methodology for boards to use in evaluating performance and accountability. Recently, other large, public universities have begun using several of these concepts in the assessment of their development offices (Rooney, 1998).  相似文献   
90.
Some studies generate data that can be grouped into clusters in more than one way. Consider for instance a smoking prevention study in which responses on smoking status are collected over several years in a cohort of students from a number of different schools. This yields longitudinal data, also cross‐sectionaliy clustered in schools. The authors present a model for analyzing binary data of this type, combining generalized estimating equations and estimation of random effects to address the longitudinal and cross‐sectional dependence, respectively. The estimation procedure for this model is discussed, as are the results of a simulation study used to investigate the properties of its estimates. An illustration using data from a smoking prevention trial is given.  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