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   19055篇
  免费   518篇
  国内免费   1篇
管理学   2773篇
民族学   69篇
人才学   1篇
人口学   1866篇
丛书文集   76篇
教育普及   2篇
理论方法论   1715篇
现状及发展   1篇
综合类   257篇
社会学   9285篇
统计学   3529篇
  2021年   112篇
  2020年   274篇
  2019年   374篇
  2018年   437篇
  2017年   599篇
  2016年   472篇
  2015年   347篇
  2014年   456篇
  2013年   2983篇
  2012年   630篇
  2011年   608篇
  2010年   443篇
  2009年   369篇
  2008年   441篇
  2007年   458篇
  2006年   452篇
  2005年   438篇
  2004年   401篇
  2003年   375篇
  2002年   417篇
  2001年   519篇
  2000年   529篇
  1999年   461篇
  1998年   339篇
  1997年   310篇
  1996年   321篇
  1995年   302篇
  1994年   283篇
  1993年   288篇
  1992年   342篇
  1991年   316篇
  1990年   286篇
  1989年   290篇
  1988年   288篇
  1987年   250篇
  1986年   243篇
  1985年   277篇
  1984年   266篇
  1983年   250篇
  1982年   215篇
  1981年   180篇
  1980年   164篇
  1979年   194篇
  1978年   176篇
  1977年   159篇
  1976年   134篇
  1975年   157篇
  1974年   118篇
  1973年   115篇
  1972年   93篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
311.
This article reviews scientific and other literature during the 1990s that links migration and mobility with the spread of sexually transmitted diseases (STDs), including HIV/AIDS. The focus is on key population groups linked to the spread of HIV and STDs in West and Central Africa: migrant laborers, truck drivers, itinerant traders, commercial sex workers (CSWs), and refugees. Countries with high emigration and immigration tend to have high levels of HIV infection, with the exception of Senegal. The main destination of immigrants are Senegal, Nigeria, and Cote d'Ivoire in West Africa and Cameroon, Congo, Gabon, and Congo in Central Africa. The risk of infection and the spread of HIV is variable among migrants. There is little in the literature that substantiates hypotheses about the strong association between migration and HIV-positive status. Information is needed on the duration, frequency of return visits, living conditions, sexual activities with multiple partners, and information before departure, along the routes, at final destination, and at the time of returns. Action-based research in five West African countries (Burkina Faso, Cote d'Ivoire, Mali, Niger, and Senegal) should produce results in late 1998. Comparable studies in Central Africa are unknown. Regional studies should be complemented by local studies. Prevention would benefit from studies on the relative size of these five population groups by geographic location.  相似文献   
312.
313.
This study assessed the test–retest reliability and convergent validity of single items from the Assessment and Action Record (AAR), from Looking After Children (Ward, 1995). It also compared developmental outcomes of 43 children cared for by a Canadian child welfare agency and those of an approximate comparison group of 1,600 children from the National Longitudinal Survey of Children and Youth (Statistics Canada, 1995). High and low reliability and validity were found for different AAR items. The children in care had worse outcomes than the comparison children on indicators of educational success and negative behaviour, but not on measures of identity, social and family relationships, or prosocial behaviour.  相似文献   
314.
315.
This study explored the relationship between US immigration laws and their impact on the immigration of Asian professionals. The article relied on a 1996 Population Association presentation. Data were obtained from the US Immigration and Naturalization Service on legally admitted immigrants to the US. The authors describe the paths to admission, trends in immigration of professionals during 1972-94, and the Immigration Act of 1965 and its 4 amendments. Standardization-decomposition techniques are used to explain the relative differences in professional immigration across 1972-77, 1978-91, and 1992-94. The crude professional rate for all Asians declined by 19% during 1972-91. 62% of the decline was due to changes in the class of admission composition, and 25% was due to a decline in the class-specific professional rates. During 1992-94, the Asian crude professional rate increased 7%, most of which was due to changes in class composition, with the exception of Korean rates. Only the Vietnamese experienced a decline in rates. The 1965 law allowed for equity between countries in admission. The paths of immigration were family ties, job skills, or refugee status. During 1972-77, Chinese took advantage of family reunification, and Indians entered on employment preferences. The legal changes affected the size and share of each class of admission. The revisions indirectly affected the occupational selectivity of immigrant groups. 27% of the flow of Asians during 1972-77 was accounted for by employment preferences. Professionals were 44% of Asian immigrants during 1972-77, 26% during 1978-91, and 33% during 1992-94.  相似文献   
316.
317.
This article sets out to examine the role of masculinity in the development of a gendered organizational culture over time. The development of images of masculinity within one company — British Airways — is examined through content analysis of company newsletters, advertising copy, annual reports, internal memoranda, and written rules and regulations. Exploring the notion of ‘multiple masculinities’, the article traces the prominent forms of masculinity that emerged in British Airways and assesses their impact on the ways that organizational practices were developed, maintained and understood. Four key corporate images of masculinity are examined — the pilot, the steward, the engineer and the ‘native boy’— and it is argued that those images contributed to the exclusion of women and people of colour from those occupations by laying down cultural rules about the ideal typical characteristics of the job holder. The article concludes by raising questions about the value of a multiple masculinities focus in explaining changing and contradictory practices of discrimination; the primacy of extra-organizational over organizational practices; and the relationship between multiple masculinities and hegemonic masculinity. Further research is suggested into the extent to which hegemonic masculinity is undermined, over time, by changing and contradictory forms of masculinity within definite sites of gender construction.  相似文献   
318.
A non-linear model for examining genotypic responses across an array of environments is contrasted with the 'joint regression' formulation, and a rigorous approach to hypothesis testing using the conditional error principle is demonstrated. The model is extended to cater for situations where single straight-line response patterns fail to characterize genotypic behaviors over an environmental array: a combination of two straight lines, with slope in below-average and in above-average environments, is offered as the 1 2 simplest representation of convex and concave patterns. A protocol for classifying genotypes according to the results of hypothesis tests, i.e. H( = ) and H( = = = 1), is 1 2 1 2 presented . A doubly desirable response pattern is convex ( < 1< ), while a doubly 1 2 undesirable pattern is concave ( > 1> ). 1 2  相似文献   
319.
Sample selection in radiocarbon dating   总被引:1,自引:0,他引:1  
Archaeologists working on the island of O'ahu, Hawai'i, use radiocarbon dating of samples of organic matter found trapped in fish-pond sediments to help them to learn about the chronology of the construction and use of the aquicultural systems created by the Polynesians. At one particular site, Loko Kuwili, 25 organic samples were obtained and funds were available to date an initial nine. However, on calibration to the calendar scale, the radiocarbon determinations provided date estimates that had very large variances. As a result, major issues of chronology remained unresolved and the archaeologists were faced with the prospect of another expensive programme of radiocarbon dating. This paper presents results of research that tackles the problems associated with selecting samples from those which are still available. Building on considerable recent research that utilizes Markov chain Monte Carlo methods to aid archaeologists in their radiocarbon calibration and interpretation, we adopt the standard Bayesian framework of risk functions, which allows us to assess the optimal samples to be sent for dating. Although rather computer intensive, our algorithms are simple to implement within the Bayesian radiocarbon framework that is already in place and produce results that are capable of direct interpretation by the archaeologists. By dating just three more samples from Loko Kuwili the expected variance on the date of greatest interest could be substantially reduced.  相似文献   
320.
A common problem in environmental epidemiology is the estimation and mapping of spatial variation in disease risk. In this paper we analyse data from the Walsall District Health Authority, UK, concerning the spatial distributions of cancer cases compared with controls sampled from the population register. We formulate the risk estimation problem as a nonparametric binary regression problem and consider two different methods of estimation. The first uses a standard kernel method with a cross-validation criterion for choosing the associated bandwidth parameter. The second uses the framework of the generalized additive model (GAM) which has the advantage that it can allow for additional explanatory variables, but is computationally more demanding. For the Walsall data, we obtain similar results using either the kernel method with controls stratified by age and sex to match the age–sex distribution of the cases or the GAM method with random controls but incorporating age and sex as additional explanatory variables. For cancers of the lung or stomach, the analysis shows highly statistically significant spatial variation in risk. For the less common cancers of the pancreas, the spatial variation in risk is not statistically significant.  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