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   3171篇
  免费   63篇
  国内免费   1篇
管理学   493篇
民族学   15篇
人才学   1篇
人口学   252篇
丛书文集   25篇
理论方法论   335篇
综合类   23篇
社会学   1688篇
统计学   403篇
  2023年   18篇
  2021年   12篇
  2020年   36篇
  2019年   54篇
  2018年   68篇
  2017年   77篇
  2016年   78篇
  2015年   52篇
  2014年   66篇
  2013年   524篇
  2012年   96篇
  2011年   86篇
  2010年   77篇
  2009年   83篇
  2008年   101篇
  2007年   100篇
  2006年   100篇
  2005年   103篇
  2004年   101篇
  2003年   104篇
  2002年   110篇
  2001年   61篇
  2000年   54篇
  1999年   65篇
  1998年   53篇
  1997年   65篇
  1996年   70篇
  1995年   41篇
  1994年   47篇
  1993年   48篇
  1992年   44篇
  1991年   48篇
  1990年   45篇
  1989年   36篇
  1988年   32篇
  1987年   33篇
  1986年   21篇
  1985年   25篇
  1984年   42篇
  1983年   40篇
  1982年   35篇
  1981年   46篇
  1980年   31篇
  1979年   25篇
  1978年   23篇
  1977年   30篇
  1976年   29篇
  1975年   17篇
  1974年   11篇
  1973年   21篇
排序方式: 共有3235条查询结果,搜索用时 15 毫秒
81.

There have been few studies investigating the relationship between the built environment and the status of bird distributions in small island tropical urban areas. We present a study investigating the relationship between bird species richness, abundance and assemblage to the built environment in Suva, Fiji. Field surveys were taken at 54 randomly selected sites throughout the city, stratified by three building density classes and the central business district (CBD). At each site bird counts were recorded, along with environmental data such as average building height, within a 150 m radius. Land-use information was obtained from screen digitized high-resolution satellite imagery within the same radius. Distance to undeveloped patches of land within the urban area was calculated using a GIS. Analysis of the effects of the built environment was carried out for all species, and for exotic and native species separately. Abundance of exotics was significantly higher in the central business district (CBD) than all other urban density classes, and significantly higher than natives in all other density classes. We found a negative relationship between native species richness and distance to undeveloped patches, but no relationship for exotics. Species assemblage was not related to urban density class. We conclude that the status of native and exotic bird species in Suva is similar to what has been found in urban areas in temperate climates, and conservation efforts should focus on minimizing the amount of heavily urbanized “core areas” and protecting undeveloped areas of forested vegetation to improve bird biodiversity in small tropical islands cities.

  相似文献   
82.

High population growth in the tropics is driving urbanisation, removing diverse natural ecosystems. This is causing native species to suffer while introduced synanthropes flourish. City planners are developing urban greenspace networks, in part trying to address this issue. Architects contribute to these greenspace networks by designing elevated and ground level green spaces on large-scale buildings. However, little evidence is available on whether building green spaces support native fauna. This is true for birds in tropical Singapore that support important ecosystem services and have existence value. Therefore, in this study, we conducted bird surveys and statistical analyses to determine, if and how vegetation on three building green space types (ground gardens, roof gardens and green walls) have a positive impact on native or introduced bird species. We found that elevated greenery (roof gardens and green walls) on large-scale buildings supported a higher richness of birds and abundance of urban native birds than control roofs and walls without vegetation. Ground gardens supported similar levels of native species as roof gardens but also a larger proportion of generalist synanthropes. However, we found no tropical forest habitat specialists across any space type. Therefore, we recommend roof gardens and ground gardens as a potential space for urban natives outside of a less competitive ground-level urban environment. Our study also found certain building design elements (height of elevated space, presence of specific plants) supported different species groups. Therefore, we suggest that these ecological requirements for different species groups are considered when designing a building’s green space.

  相似文献   
83.

There have been many advances in statistical methodology for the analysis of recurrent event data in recent years. Multiplicative semiparametric rate-based models are widely used in clinical trials, as are more general partially conditional rate-based models involving event-based stratification. The partially conditional model provides protection against extra-Poisson variation as well as event-dependent censoring, but conditioning on outcomes post-randomization can induce confounding and compromise causal inference. The purpose of this article is to examine the consequences of model misspecification in semiparametric marginal and partially conditional rate-based analysis through omission of prognostic variables. We do so using estimating function theory and empirical studies.

  相似文献   
84.
Assessment of analytical similarity of tier 1 quality attributes is based on a set of hypotheses that tests the mean difference of reference and test products against a margin adjusted for standard deviation of the reference product. Thus, proper assessment of the biosimilarity hypothesis requires statistical tests that account for the uncertainty associated with the estimations of the mean differences and the standard deviation of the reference product. Recently, a linear reformulation of the biosimilarity hypothesis has been proposed, which facilitates development and implementation of statistical tests. These statistical tests account for the uncertainty in the estimation process of all the unknown parameters. In this paper, we survey methods for constructing confidence intervals for testing the linearized reformulation of the biosimilarity hypothesis and also compare the performance of the methods. We discuss test procedures using confidence intervals to make possible comparison among recently developed methods as well as other previously developed methods that have not been applied for demonstrating analytical similarity. A computer simulation study was conducted to compare the performance of the methods based on the ability to maintain the test size and power, as well as computational complexity. We demonstrate the methods using two example applications. At the end, we make recommendations concerning the use of the methods.  相似文献   
85.
Discrimination reduces the matching probability and output in the skill‐intensive differentiated‐product sector so that discrimination‐induced comparative advantage may overshadow technological comparative advantage in determining the pattern of trade. Trade liberalization generates a decrease in the skilled‐worker wage gap in the country that is an exporter of goods from the simple sector but increases it in the country that is a net exporter of differentiated products. Trade liberalization has an opposite effect on firms. In the country that is an exporter of simple goods, trade liberalization reduces the profits of the nondiscriminatory firms by more than those of the discriminatory firms. (JEL F16, F66, J71)  相似文献   
86.
Viral videos offer contemporary activists a nimble, provocative tool with which to disseminate humanitarian messages. This article historicizes anti-trafficking video media that imagine a new potential with which to alter behavioral norms around cocoa and chocolate. The article engages theories and approaches to historical and contemporary modalities of naming and shaming, spanning three centuries to the present day. Videos are examined for style, format, and content, with the view to describing a ‘blood chocolate’ visual and textual metonymy. Recurring themes include transnational power, corporate responsibility, and the horrific scale of exploitation. But viral videos also appear deeply influenced by neoliberal economics that celebrate lawful enterprise and promote consumer-driven solutions to exploitative child labor.  相似文献   
87.
Intercollegiate athletics represent an industry prone to challenges of work addiction and life balance. Work addiction and life balance domains in male and female intercollegiate athletic coaches and administrators (N = 245) were examined using multiple regression analysis. Higher levels of stress/anxiety, sleep disturbance, and career satisfaction and lower levels of quality of relationships and friendships were the strongest predictors of work addiction. Counseling focused on reducing the negative aspects of work addiction, while maintaining job performance, may benefit this population.  相似文献   
88.
This paper examines the construction of prisoners’ identity through rap in England’s high security prisons. While hip hop studies has often addressed rap’s connection to the social practices of criminalized youths, prison rap cultures have received scant attention. This paper draws on a series of rap workshops and interviews with prisoners to investigate the experiences of black prisoners in high security prisons and how identities are produced and negotiated through rap. Rap is associated with the production of a range of identities and identifications, enabling prisoners to accommodate themselves to the conditions of their incarceration and to challenge aspects of the criminal justice system that they experience as unfair or illegitimate.  相似文献   
89.

Background

The increasing prevalence of obesity in sub-Saharan African women is not well understood, and black South African women in the region are particularly vulnerable. This study aimed to examine whether the relationship of socioeconomic status (SES) with changes in body mass index (BMI) and waist circumference (WC) is mediated by physical activity in ageing African women.

Methods

In a longitudinal analysis of the 518 caregivers associated with the Birth to Twenty Plus study, the role of SES associated with 10-year changes in BMI and WC was tested using structural equation modelling (SEM). The degree of mediation of moderate-vigorous physical activity (MVPA) and sitting time in this association was also assessed.

Results

The prevalence of obesity increased significantly from baseline to follow-up (p?<?0.0001). In the SEM models, baseline SES had a direct positive effect on changes in BMI (β, 95% CI, 0.02 (0.005 to 0.04), and a direct negative effect on changes in MVPA (β, 95% CI, ??3.81 (??6.92 to ??0.70). Baseline MVPA had a direct negative effect (β, 95% CI, ??0.002 (??0.003 to ??0.0003) and indirect positive effect via change in MVPA (β, 95% CI, 0.01 (0.0001 to 0.001) on change in WC.

Conclusions

Our study demonstrates the role and interaction of sociodemographic and behavioural predictors of obesity, and suggests a multifaceted approach to management of the crisis in communities of ageing urban African women.
  相似文献   
90.
Globally, social enterprise is used increasingly by nonprofit organizations to create new funding streams in the face of dwindling public funds. In light of evidence that institutions of higher education are making similar adaptations, this study explores the extent to which academic centers in US schools of social work are using social enterprise strategies to fund mission efforts. Interviews with the directors of 16 social work research centers in 14 states reveal incentives and barriers that exist at multiple levels and considerably impact the potential viability of social enterprise in the social work academic setting. Implications for institutions of higher education and social work scholars are discussed.  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