全文获取类型
收费全文 | 26357篇 |
免费 | 508篇 |
国内免费 | 2篇 |
专业分类
管理学 | 3629篇 |
民族学 | 175篇 |
人才学 | 5篇 |
人口学 | 2584篇 |
丛书文集 | 158篇 |
教育普及 | 1篇 |
理论方法论 | 2435篇 |
现状及发展 | 1篇 |
综合类 | 426篇 |
社会学 | 12947篇 |
统计学 | 4506篇 |
出版年
2023年 | 158篇 |
2021年 | 160篇 |
2020年 | 446篇 |
2019年 | 603篇 |
2018年 | 744篇 |
2017年 | 973篇 |
2016年 | 753篇 |
2015年 | 532篇 |
2014年 | 649篇 |
2013年 | 4492篇 |
2012年 | 965篇 |
2011年 | 808篇 |
2010年 | 668篇 |
2009年 | 622篇 |
2008年 | 676篇 |
2007年 | 683篇 |
2006年 | 612篇 |
2005年 | 623篇 |
2004年 | 572篇 |
2003年 | 491篇 |
2002年 | 569篇 |
2001年 | 621篇 |
2000年 | 576篇 |
1999年 | 508篇 |
1998年 | 380篇 |
1997年 | 370篇 |
1996年 | 349篇 |
1995年 | 351篇 |
1994年 | 323篇 |
1993年 | 337篇 |
1992年 | 343篇 |
1991年 | 330篇 |
1990年 | 327篇 |
1989年 | 343篇 |
1988年 | 332篇 |
1987年 | 317篇 |
1986年 | 279篇 |
1985年 | 332篇 |
1984年 | 341篇 |
1983年 | 324篇 |
1982年 | 258篇 |
1981年 | 217篇 |
1980年 | 222篇 |
1979年 | 268篇 |
1978年 | 220篇 |
1977年 | 189篇 |
1976年 | 191篇 |
1975年 | 195篇 |
1974年 | 186篇 |
1973年 | 149篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
13.
Fire and restoration of the largest urban forest of the world in Rio de Janeiro City,Brazil 总被引:1,自引:1,他引:0
National Park of Tijuca in Rio de Janeiro (Brazil) is about 3,300 ha and considered the largest urban forest in the world. Its floristic composition is typical of Atlantic Rain Forest. The reserve is being altered because of fire occurrences and urban expansion. This study identified locations and causes of forest fires, and makes management recommendations to restore damaged areas. From 1991 to 2000, forest firefighters recorded an average of 75-fire occurrences/year. Identified causes included hot air balloons (24%), intentional (24%), rubbish burning (21%) and religious practices (17%). Primary fuels included invasive grasses and ferns. Although hot air balloons destroyed larger areas of forest in each occurrence, a greater number of fires started in the invasive vegetation along roads that bisect the forest. In response to recurrent forests, invasive vegetation has spread gradually into the forest increasing forest degradation. To decrease fire damage, sites with high fire frequencies and density of invasive vegetation were planted with less flammable species. Results indicate that fire frequency decreased and density of invasive vegetation declined. This approach appears to prevent fire incidence, reduce the need for fire fighting, and preserve existing biodiversity. 相似文献
14.
C. Eddie Palmer E. Joseph Savoie 《Sociological Practice: A Journal of Clinical and Applied Sociology》2002,4(1):89-97
Service-learning programs are not free from challenges brought about by lack of financial support, lack of widespread commitment from professors, community agencies, and recipients of service, and lack of knowledge and insight in students directly involved in such programs. While service-learning initiatives and programs serve positive functions for organizations and individuals, rhetorical accolades for service learning can distort or omit the realities of program implementation and sustained delivery. This paper specifically explores the following challenges connected to service-learning programs: (1) pedagogical difficulties; (2) student limitations; (3) time constraints; and (4) community cooperation. 相似文献
15.
Multiparameter evidence synthesis in epidemiology and medical decision-making: current approaches 总被引:1,自引:0,他引:1
A. E. Ades A. J. Sutton 《Journal of the Royal Statistical Society. Series A, (Statistics in Society)》2006,169(1):5-35
Summary. Alongside the development of meta-analysis as a tool for summarizing research literature, there is renewed interest in broader forms of quantitative synthesis that are aimed at combining evidence from different study designs or evidence on multiple parameters. These have been proposed under various headings: the confidence profile method, cross-design synthesis, hierarchical models and generalized evidence synthesis. Models that are used in health technology assessment are also referred to as representing a synthesis of evidence in a mathematical structure. Here we review alternative approaches to statistical evidence synthesis, and their implications for epidemiology and medical decision-making. The methods include hierarchical models, models informed by evidence on different functions of several parameters and models incorporating both of these features. The need to check for consistency of evidence when using these powerful methods is emphasized. We develop a rationale for evidence synthesis that is based on Bayesian decision modelling and expected value of information theory, which stresses not only the need for a lack of bias in estimates of treatment effects but also a lack of bias in assessments of uncertainty. The increasing reliance of governmental bodies like the UK National Institute for Clinical Excellence on complex evidence synthesis in decision modelling is discussed. 相似文献
16.
María del Carmen Méndez García 《Intercultural Education》2005,16(1):57-68
The sociocultural content of foreign language textbooks has become a concern of scholars and practitioners owing to the fact that the traditional emphasis on purely linguistic issues has been expanded to embrace a language in context approach. This paper studies the English‐speaking communities that are described in English language teaching textbooks marketed in Spain. It examines to what extent an international and/or intercultural approach is a constituent element in their design. 相似文献
17.
18.
A finite mixture model using the multivariate t distribution has been shown as a robust extension of normal mixtures. In this paper, we present a Bayesian approach for inference about parameters of t-mixture models. The specifications of prior distributions are weakly informative to avoid causing nonintegrable posterior distributions. We present two efficient EM-type algorithms for computing the joint posterior mode with the observed data and an incomplete future vector as the sample. Markov chain Monte Carlo sampling schemes are also developed to obtain the target posterior distribution of parameters. The advantages of Bayesian approach over the maximum likelihood method are demonstrated via a set of real data. 相似文献
19.
The Analysis of Verbal Behavior - 相似文献
20.