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   21652篇
  免费   292篇
  国内免费   1篇
管理学   2918篇
民族学   169篇
人才学   6篇
人口学   3471篇
丛书文集   38篇
理论方法论   1502篇
综合类   439篇
社会学   9568篇
统计学   3834篇
  2023年   110篇
  2022年   81篇
  2021年   118篇
  2020年   288篇
  2019年   335篇
  2018年   2025篇
  2017年   2126篇
  2016年   1449篇
  2015年   334篇
  2014年   427篇
  2013年   2214篇
  2012年   920篇
  2011年   1433篇
  2010年   1277篇
  2009年   990篇
  2008年   1063篇
  2007年   1230篇
  2006年   248篇
  2005年   440篇
  2004年   444篇
  2003年   361篇
  2002年   273篇
  2001年   223篇
  2000年   191篇
  1999年   188篇
  1998年   155篇
  1997年   156篇
  1996年   144篇
  1995年   123篇
  1994年   141篇
  1993年   120篇
  1992年   147篇
  1991年   134篇
  1990年   127篇
  1989年   122篇
  1988年   147篇
  1987年   110篇
  1986年   111篇
  1985年   129篇
  1984年   105篇
  1983年   109篇
  1982年   92篇
  1981年   88篇
  1980年   77篇
  1979年   98篇
  1978年   101篇
  1977年   70篇
  1976年   83篇
  1975年   84篇
  1973年   50篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
In sprawling metropolitan areas, residential landscaping is a major concern with respect to biodiversity conservation, and it could play a critical role in conserving wildlife habitat. In the United States, residential landscaping typically consists of maintained lawns with specimen plantings of non-native trees and shrubs; such designs provide poor habitat for urban wildlife species. We conducted a case study of Raleigh, North Carolina residents to determine how providing information about the benefits of native plant landscaping to bird species influenced urban residents’ landscaping preferences. We used Wilcoxon Signed Rank tests to determine if respondent preferences for 0, 50, 75 and 100 % native plant landscaping coverages changed after residents were informed about the benefits that native plants provide for birds. Initially, the 50 % native landscaping coverage was most preferred by residents; however, preferences for all four native plant landscaping coverage designs were significantly different after the informational treatment. Neutrality changed to opposition for the 0 % native plant coverage, while opposition changed to support and neutrality for the 75 and 100 % native plant coverage designs, respectively. After the informational treatment, the 50 and 75 % native plant landscaping coverage had the highest mean preference levels, although the 100 % design was ranked first more than any other design. Our findings suggest that residential support for native plant landscaping is higher than is reflected by typical residential landscaping practices, and that dissemination of information regarding the benefits of native plant landscaping to birds could alter public preferences for native plant landscaping.  相似文献   
992.
Green roofs are emerging engineered ecosystems that provide multiple benefits, but many are constructed with nutrient-rich substrate and have been found to leach out high levels of phosphorus (P) in runoff. It is unclear, however, how long green roofs act as sources of P or what mechanisms are responsible for these net losses. We measured P concentrations in runoff water over 4 years from a 1–5 year old extensive green roof in Cincinnati, OH, USA, produced a model to predict runoff P levels into the future, and validated predictions using runoff from 2 nearby extensive green roofs. P concentrations in runoff from the focal green roof were on par with heavily fertilized agroecosystems and displayed strong seasonal dynamics and a rapid decline over the 4-year study. Runoff measurements and changes in substrate P content over a 2-year period were used to estimate a mass balance for green roof P. P loss from the substrate was substantial (4.55 ± 2.3 g P/m2/yr), but only a small portion of the loss was attributable to leaching of P in runoff (0.19–0.65 g P/m2/yr). Missing P may be attributed to a combination of plant uptake and altered P form and binding strength, but further research is needed to precisely identify the mechanisms of P depletion. Our results also suggest that these and similar extensive green roofs are likely to act as environmentally significant sources of P for 10 or more years following roof installation, highlighting the need for reductions in initial substrate P content.  相似文献   
993.
ABSTRACT

The article analyses the politics of ‘double discourse’ in relation to Roma that has evolved in contemporary neoliberal Europe. On the one hand, the double discourse promotes the integration, rights and equal opportunities of Roma, on the other, it denies recognition of, and ways to address, enduring structural violence and rising social insecurity. The article argues that the politics of ‘double discourse’, as a neoliberal approach towards Roma, is structured by two contradictory discourses that speak to different audiences, using duplicitous approaches to create anti-Roma consensus and maintain the critical difference and subordinated position of the racialised Romani populations in Europe. By studying the representation of Roma in the cases of so-called 'child theft' in Greece and Ireland, and in the recent ‘refugee crisis’, the paper identifies and discusses three dimensions of contemporary neoliberal double discourse: racialised de-Europeanisation, neoliberal undeservingness and (dis)articulation of citizenship.  相似文献   
994.
The aim is to refine recent discussion about the process of compensation under conditions of organic impairment in order to better understand how the concept has been addressed by cultural-historical researchers. From a dialogue among contemporary authors and the examination of the case of a student with multiple disabilities confronting the schooling process, we draw attention to how meaning has an effect upon complex functional systems and paves the way for new forms of human development. We conclude that it is important to challenge the relevance of the term compensation in its connection with the notion of human constitution.  相似文献   
995.
Does urbanization affect key life-history traits in native organisms? Some studies show that urban areas reduce diversity in certain taxa, but there is little insight into how these environments affect physiological and ecological traits. Urban areas have distinct physical structure and ecological processes compared to original habitats. The environmental changes associated with urban areas can influence the costs and benefits of different traits and behaviors of local organisms. Some of these effects have been explored in groups such as birds, but we might expect stronger effects in animals with reduced mobility, such as amphibians. Importantly, the effects of urban habitats on amphibians have not been explored, in spite that these are the most threatened vertebrate group in the world. Here, we compared three main traits related to the fitness of amphibians in urban and natural habitats: body size, body condition and immune response. To test the generality of our results, we assessed adult males of four amphibian species. We found that the body size was larger in urban environment populations in three of four studied species, while the body condition was better in the urban populations of two aquatic newt species. Finally, we found no effect of urbanization on the immune response of individuals of any species. In conclusion, we show that different species of amphibians may be affected differently by anthropogenic habitat alteration depending on their specific ecology.  相似文献   
996.
997.
Over the last decade, we have witnessed the emergence of an academic debate surrounding the relationship between youth and the ‘new media’, with a particular emphasis on the social uses of different digital technologies within the sphere of youth activity. A specific area of research has been dedicated to studying the use of digital media in the context of the so-called youth subcultures. With this article we expect to contribute to this ongoing debate, by examining the problem through an analysis of two interconnected case studies: protest rap and illegal graffiti. Both cases may be defined as subcultures, insofar as they are characterized as alternative, subterranean, and to a certain extent, subversive movements. The empirical ground for this discussion is based on several investigations, with a qualitative basis, carried out by the authors in the course of over a decade in Portugal. This extended time frame allowed ample access to a diversified and matured analytical material and enabled a better perspective of the developments and the mutations involving the appropriation of the digital media. Our researches have shown that digital media and technologies have been gradually integrated in these urban youth subcultures, accomplishing several strategic roles.  相似文献   
998.
999.
1000.
We present the results of the use of a cognitive behavioral therapeutic intervention tool to improve the mental, physical, and social health of a group of long-term unemployed women in Spain. Method: We sent automated text messages (SMS) to the mobile phones of long-term unemployed women selected at random from public social services. During a 28-day intervention period, women received four daily automated text messages on her mobile phone on a predetermined hourly schedule. We measured depression symptoms at the start and end of the intervention and we analyzed qualitative data to determine the acceptability of a remote SMS program. Results: Depression symptoms using the Personal Health Questionnaire-9 (PHQ-9), went from an average of 13.8 at baseline to 4.9 at the end of 28 days (p?=?0.89). One hundred percent of the women reported that they liked receiving the text messages and most found them helpful.  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