全文获取类型
收费全文 | 15528篇 |
免费 | 249篇 |
国内免费 | 1篇 |
专业分类
管理学 | 1983篇 |
民族学 | 82篇 |
人才学 | 4篇 |
人口学 | 1422篇 |
丛书文集 | 85篇 |
理论方法论 | 1361篇 |
综合类 | 124篇 |
社会学 | 7479篇 |
统计学 | 3238篇 |
出版年
2023年 | 74篇 |
2021年 | 85篇 |
2020年 | 226篇 |
2019年 | 297篇 |
2018年 | 393篇 |
2017年 | 529篇 |
2016年 | 367篇 |
2015年 | 316篇 |
2014年 | 359篇 |
2013年 | 2884篇 |
2012年 | 508篇 |
2011年 | 421篇 |
2010年 | 374篇 |
2009年 | 288篇 |
2008年 | 362篇 |
2007年 | 358篇 |
2006年 | 341篇 |
2005年 | 334篇 |
2004年 | 282篇 |
2003年 | 295篇 |
2002年 | 325篇 |
2001年 | 402篇 |
2000年 | 365篇 |
1999年 | 329篇 |
1998年 | 258篇 |
1997年 | 224篇 |
1996年 | 262篇 |
1995年 | 244篇 |
1994年 | 248篇 |
1993年 | 214篇 |
1992年 | 242篇 |
1991年 | 262篇 |
1990年 | 238篇 |
1989年 | 206篇 |
1988年 | 249篇 |
1987年 | 234篇 |
1986年 | 169篇 |
1985年 | 214篇 |
1984年 | 225篇 |
1983年 | 212篇 |
1982年 | 153篇 |
1981年 | 132篇 |
1980年 | 125篇 |
1979年 | 152篇 |
1978年 | 129篇 |
1977年 | 111篇 |
1976年 | 90篇 |
1975年 | 91篇 |
1974年 | 85篇 |
1973年 | 78篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Stuart G. Baker Barnett S. Kramer 《Journal of the Royal Statistical Society. Series C, Applied statistics》2005,54(5):941-954
Summary. When evaluating potential interventions for cancer prevention, it is necessary to compare benefits and harms. With new study designs, new statistical approaches may be needed to facilitate this comparison. A case in point arose in a proposed genetic substudy of a randomized trial of tamoxifen versus placebo in asymptomatic women who were at high risk for breast cancer. Although the randomized trial showed that tamoxifen substantially reduced the risk of breast cancer, the harms from tamoxifen were serious and some were life threaten-ing. In hopes of finding a subset of women with inherited risk genes who derive greater bene-fits from tamoxifen, we proposed a nested case–control study to test some trial subjects for various genes and new statistical methods to extrapolate benefits and harms to the general population. An important design question is whether or not the study should target common low penetrance genes. Our calculations show that useful results are only likely with rare high penetrance genes. 相似文献
32.
James P. Davis 《Journal of popular culture》2005,38(6):1011-1021
33.
34.
The authors review the trends in the use of computers in the delivery and support of career guidance and counseling identified at the symposium International Perspectives on Career Development. The papers presented emphasized that 20th‐century computer‐based systems continue to be used, mainly delivered via the World Wide Web. These systems are enhanced through audio, video, graphics, strategies to provide needs assessment, and support by cybercounselors or expert system design. The papers also revealed a new trend: the use of elegant Web sites to store and search immense libraries of resources needed by professionals and clients and to facilitate communication and collaboration among professionals in cyberspace. Concerns, issues, and resources related to many areas, including the readiness of clients to use computer‐based systems, were also raised; existing sources of guidelines are noted. 相似文献
35.
Christian P. Robert Xiao-Li Meng Jesper Møller Jeffrey S Rosenthal C Jennison M. A Hurn F Al-Awadhi Peter McCullagh Christophe Andrieu Arnaud Doucet Petros Dellaportas Ioulia Papageorgiou Ricardo S Ehlers Elena A Erosheva Stephen E Fienberg Jonathan J Forster Roger C Gill Nial Friel Peter Green David Hastie R King Hans R Künsch N. A. Lazar C Osinski 《Journal of the Royal Statistical Society. Series B, Statistical methodology》2003,65(1):39-55
36.
Silphids in urban forests: Diversity and function 总被引:2,自引:0,他引:2
Many ecologists have examined the process of how urbanization reduces biological diversity but rarely have its ecological consequences been assessed. We studied forest-dwelling burying beetles (Coleoptera: Silphidae)—a guild of insects that requires carrion to complete their life cycles—along an urban-rural gradient of land use in Maryland. Our objective was to determine how forest fragmentation associated with urbanization affects (1) beetle community diversity and structure and (2) the ecological function provided by these insects, that is, decomposition of vertebrate carcasses. Forest fragmentation strongly reduced burying beetle diversity and abundance, and did so far more pervasively than urbanization of the surrounding landscape. The likelihood that beetles interred experimental baits was a direct, positive function of burying beetle diversity. We conclude that loss of burying beetle diversity resulting from forest fragmentation could have important ecological consequences in urban forests. 相似文献
37.
James Wickham 《Innovation: The European Journal of Social Science Research》2004,17(3):187-204
This paper investigates whether EU research programmes have led to innovations in European social research. This is based on an assessment of a group of EU‐funded projects on the changing nature of work in Europe. EU‐funded projects have contributed to the creation of a European social space for European researchers, but at the cost of consolidating English as the lingua franca of European social research. Such projects tend to involve heterogeneous research actors and are oriented towards policy issues. To some extent they are therefore representative of a ‘Mode 2’ form of knowledge production. More clearly, they have ensured that social research about Europe is no longer simply comparative research. The new EU Sixth Framework Programme on RTD will undermine many of these achievements through its focus on conventional definitions of ‘excellence’ and the insistence on large‐scale research instruments. 相似文献
38.
39.
S. Vansteelandt E. Goetghebeur 《Journal of the Royal Statistical Society. Series B, Statistical methodology》2003,65(4):817-835
Summary. We estimate cause–effect relationships in empirical research where exposures are not completely controlled, as in observational studies or with patient non-compliance and self-selected treatment switches in randomized clinical trials. Additive and multiplicative structural mean models have proved useful for this but suffer from the classical limitations of linear and log-linear models when accommodating binary data. We propose the generalized structural mean model to overcome these limitations. This is a semiparametric two-stage model which extends the structural mean model to handle non-linear average exposure effects. The first-stage structural model describes the causal effect of received exposure by contrasting the means of observed and potential exposure-free outcomes in exposed subsets of the population. For identification of the structural parameters, a second stage 'nuisance' model is introduced. This takes the form of a classical association model for expected outcomes given observed exposure. Under the model, we derive estimating equations which yield consistent, asymptotically normal and efficient estimators of the structural effects. We examine their robustness to model misspecification and construct robust estimators in the absence of any exposure effect. The double-logistic structural mean model is developed in more detail to estimate the effect of observed exposure on the success of treatment in a randomized controlled blood pressure reduction trial with self-selected non-compliance. 相似文献
40.
Lisa A. Gennetian Greg Duncan Virginia Knox Wanda Vargas Elizabeth Clark‐Kauffman Andrew S. London 《Journal of research on adolescence》2004,14(4):399-423
Using data from 8 random assignment studies and employing meta‐analytic techniques, this article provides systematic evidence that welfare and work policies targeted at low‐income parents have small adverse effects on some school outcomes among adolescents ages 12 to 18 years at follow‐up. These adverse effects were observed mostly for school performance outcomes and occurred in programs that required mothers to work or participate in employment‐related activities and those that encouraged mothers to work voluntarily. The most pronounced negative effects on school outcomes occurred for the group of adolescents who had a younger sibling, possibly because of the increased home and sibling care responsibilities they assumed as their mothers increased their employment. 相似文献