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   28497篇
  免费   744篇
  国内免费   1篇
管理学   3457篇
民族学   150篇
人才学   9篇
人口学   2677篇
丛书文集   157篇
教育普及   2篇
理论方法论   2623篇
现状及发展   1篇
综合类   331篇
社会学   13969篇
统计学   5866篇
  2023年   141篇
  2022年   128篇
  2021年   146篇
  2020年   424篇
  2019年   638篇
  2018年   739篇
  2017年   996篇
  2016年   694篇
  2015年   572篇
  2014年   691篇
  2013年   5014篇
  2012年   986篇
  2011年   851篇
  2010年   705篇
  2009年   620篇
  2008年   709篇
  2007年   707篇
  2006年   686篇
  2005年   627篇
  2004年   581篇
  2003年   559篇
  2002年   577篇
  2001年   727篇
  2000年   623篇
  1999年   617篇
  1998年   483篇
  1997年   421篇
  1996年   475篇
  1995年   438篇
  1994年   423篇
  1993年   396篇
  1992年   469篇
  1991年   464篇
  1990年   430篇
  1989年   397篇
  1988年   402篇
  1987年   374篇
  1986年   339篇
  1985年   393篇
  1984年   391篇
  1983年   367篇
  1982年   283篇
  1981年   240篇
  1980年   252篇
  1979年   276篇
  1978年   225篇
  1977年   207篇
  1976年   175篇
  1975年   172篇
  1974年   155篇
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
981.
The researchers examined differential outcomes related to two distinct motivations for withdrawal (preference for solitude and shyness) as well as the possibility that support from important others (mothers, fathers, and best friends) attenuate any such links. Adolescents (159 males, 171 females) reported on their motivations to withdraw, internalizing symptoms, and relationship quality in eighth grade, as well as their anxiety and depression in ninth grade. Using structural equation modeling, the authors found that maternal support weakened the association between shyness and internalizing problems; friend support weakened the association between preference for solitude and depression; and friend support strengthened the association between shyness and depression. Results suggest that shy adolescents may not derive the same benefits from supportive friendships as their typical peers.  相似文献   
982.
Social, cultural, and institutional processes which see heterosexuality as natural and universal discriminate against individuals who differ from this norm. This article draws on interviews with lesbian, gay, bisexual, and transgender (LGBT) people in Swaziland to provide an enhanced understanding of the ways in which heterosexism operates in practice and impacts the sexual rights of LGBT communities in Swaziland, where same-sex practices are criminalised. These narratives show the importance of solidarity and activism in coping strategies to challenge social exclusion, improve lives, and advocate for social changes. These strategies include reframing, navigating interpersonal relationships, and advocacy. We consider key lessons that emerge from our research for policy, programmes, and activism in Swaziland, as well as other low- and middle-income contexts.  相似文献   
983.
The term “biodiversity” is often used to describe phenomena of nature, which can be studied without a reference to the socially constructed, evaluative, or indeed normative contexts. In our paper, we challenge this conception by focusing particularly on methodological aspects of biodiversity research. We thereby engage with the idea of interdisciplinary biodiversity research as a scientific approach directed at the recognition and management of contemporary society in its ecological embedding. By doing this, we explore how research on and assessments of biodiversity can be enhanced if meaning, aspiration, desires, and related aspects of agency are methodically taken into account. In six sections, we substantiate our claim that the discourse on biodiversity (including the IPBES (Intergovernmental science-policy Platform on Biodiversity and Ecosystem Services) debate) is incomplete without contributions from the social sciences and humanities. In the introduction, a brief overview of biodiversity’s conceptual history is provided showing that “biodiversity” is a lexical invention intended to create a strong political momentum. However, that does not impede its usability as a research concept. Section 2 examines the origins of the Convention on Biological Diversity (CBD) by way of sociological discourse analysis. Subsequently, it proposes a matrix as a means to structure the ambiguities and tensions inherent in the CBD. The matrix reemphasizes our main thesis regarding the need to bring social and ethical expertise to the biodiversity discourse. In Section 3, we offer a brief sketch of the different methods of the natural and social sciences as well as ethics. This lays the groundwork for our Section 4, which explains and illustrates what social sciences and ethics can contribute to biodiversity research. Section 5 turns from research to politics and argues that biodiversity governance necessitates deliberative discourses in which participation of lay people plays an important role. Section 6 provides our conclusions.  相似文献   
984.
This study takes an exploratory, qualitative approach to examine college students’ perceptions about divorce in the media. Findings suggest that participants perceived both positive and negative representations of divorced families in the media they consume, highlighting the complex nature of navigating and communicating through a divorce. Specifically, college students reported on aspects of the ex-spousal relationship, how children are affected, and the contrast between life pre- and postdivorce. An inductive theme analysis revealed several positive and negative media representations of divorce. Largely, college students perceive media messages about divorce to be accurate portrayals and impactful representations.  相似文献   
985.
Growing human populations make it imperative for ecologists to identify strategies to conserve biodiversity in human-dominated landscapes, such as cities. Effects of urbanization on birds are particularly well-studied, but questions remain regarding the best conservation approaches. Debate about the relative utility of focusing conservation efforts on nature reserves versus developed lands has focused largely on comparing species abundance or presence, with few studies addressing underlying behavioral or demographic mechanisms. Here we evaluated differences in avian reproductive success in nature reserves and matrix habitats to test the assumption that nest predation is lower within areas protected from development. Specifically, we investigated 1) whether nest survival differed in replicated pairs of forest parks and residential neighborhoods and 2) whether differences in nest survival were associated with changes in which species most frequently depredated nests. From April–August 2007–2014, we monitored nests of two native birds, American robin (Turdus migratorius) and northern cardinal (Cardinalis cardinalis), and video-documented nest predators in paired forest-matrix habitats in the Columbus, Ohio metropolitan area. We found similar rates of nest survival in the two habitats for both robins (Χ21?=?0.715, p?=?0.398, n?=?741 nests) and cardinals (Χ21?=?0.926, p?=?0.336, n?=?1156 nests), but interactions between predators and prey differed. In particular, domestic cats (Felis catus) were over five times as likely to depredate cardinal nests in matrix habitats versus forest parks (Χ21?=?7.24, simulated p?=?0.010; nforest?=?3, nmatrix?=?7). Our results suggest that at least in some circumstances, nest success of native birds may be equivalent between nature reserves and adjacent residential matrix habitats, and thus residential neighborhoods may contribute positively to bird conservation in urban landscapes.  相似文献   
986.
Recent concern over increasing loss of biodiversity has prompted considerable interest in the role of urban green spaces as reservoirs of local biodiversity. This study assessed the diversity of three indicator taxa - plants, ants and birds - on golf courses spanning a wide range of environmental variation in terms of climate, elevation, course age, size and connectivity to native woodland. Species richness and community composition was further compared between contrasting on-course habitat types that reflect different management intensities. We identified a set of taxon-specific environmental correlates indicating an intricate interplay of landscape- and local-scale variables that affect local species diversity. Our results show that floristic diversity is positively associated with the amount of rainfall, whereas ant and bird diversity are related to local-scale factors, particularly the number of trees and the size of water features on a site. The amount of on-course native habitat was a strong predictor of plant and ant diversity and was also associated with the number of unique species at the site level; this reinforces the value of remnant habitat patches as local biodiversity reservoirs that represent mini hot-spots in an otherwise species-poor urban landscape. Community composition for all three taxa differed markedly between non-playing and playing areas, with boundary and remnant habitats generally having more diverse, species-rich communities. Our results suggest that local floral and faunal biodiversity on urban golf courses can be enhanced by creating woody non-playing areas and, especially, by preserving, restoring or expanding remnant habitats.  相似文献   
987.
Time of peak bat activity during the night differs among bat species due to temperature, prey availability, habitat availability, and/or interactions between species. Habitat availability is altered in urban areas, which may affect insect prey availability and interspecies interactions. Our objectives were to use mobile acoustic monitoring to determine when bat species were active in a single night in urban and nonurban sites and if nightly bat activity patterns differed in urban versus nonurban sites. Bat echolocation call sequences were recorded using Anabat acoustic detectors while driving transects through the night at five sites (three “urban” and two “nonurban”) located in the Piedmont region of north-central North Carolina from May through August 2016. Transects were driven three times per night starting 45 min, 180 min, and 300 min after sunset. Recorded echolocation call sequences were analyzed manually using AnalookW and automatically using Bat Call Identification and Echoclass software. Total bat activity was not different between urban and nonurban sites. However, total bat activity was lower later in the night in urban sites, but stayed the same in nonurban sites. Species specifically, there were more Eptesicus fuscus, Lasionycteris noctivagans, and Tadarida brasiliensis call sequences and fewer Lasiurus borealis, Nycticeius humeralis, and Perimyotis subflavus call sequences in urban sites than nonurban sites. There were also fewer E. fuscus, L. noctivagans, and N. humeralis call sequences later in the night in both urban and nonurban sites. Only Lasiurus borealis activity in urban sites later in the night reduced and L. borealis activity in nonurban sites remained at the same. These results suggest that bats in urban areas partition time differently, which is important to consider for urban conservation efforts and planning.  相似文献   
988.
Urbanization causes species loss around the world, but its effects on phylogenetic diversity are poorly known in tropical forests. Using a patch-landscape approach in an urbanizing region of the Brazilian Atlantic Forest, we tested whether the increase in landscape urbanization reduces plant species density, phylogenetic richness and divergence, and increases the relatedness among co-occurring individuals and species. We assessed plant responses to urbanization in adult (diameter at breast height?>?10 cm) and sapling communities (2.5–10 cm diameter) separately, as saplings are proxies of the future flora. We sampled 2860 woody plants belonging to 155 species in nine circular landscapes with urbanization level varying from 0% to 45%, and estimated the relatedness among the species that have increased and decreased in relative abundance in more urbanized landscapes (winner and losers, respectively). As expected, species density and phylogenetic richness decreased with the increase in urbanization. These responses were consistent for adult and sapling communities, suggesting a persistent loss of species and lineages in more urbanized landscapes. Contrary to our expectations, phylogenetic divergence and structure did not respond to urbanization, indicating that the more urbanized landscapes still retain much evolutionary history. However, because the relatedness among winners was greater than among losers, it is likely that the phylogenetic divergence gradually reduces and the relatedness increases, resulting in impoverished forests with uncertain ability to provide ecosystem services such as carbon storage and pest control. This environmental cost should be taken into account to align urban sprawl with biodiversity conservation.  相似文献   
989.
990.
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