全文获取类型
收费全文 | 91904篇 |
免费 | 2814篇 |
国内免费 | 3篇 |
专业分类
管理学 | 12601篇 |
民族学 | 551篇 |
人才学 | 25篇 |
人口学 | 7187篇 |
丛书文集 | 515篇 |
教育普及 | 1篇 |
理论方法论 | 9466篇 |
综合类 | 2149篇 |
社会学 | 43297篇 |
统计学 | 18929篇 |
出版年
2023年 | 512篇 |
2021年 | 576篇 |
2020年 | 1522篇 |
2019年 | 2210篇 |
2018年 | 2133篇 |
2017年 | 3222篇 |
2016年 | 2448篇 |
2015年 | 2056篇 |
2014年 | 2645篇 |
2013年 | 18862篇 |
2012年 | 2508篇 |
2011年 | 2321篇 |
2010年 | 2025篇 |
2009年 | 2201篇 |
2008年 | 2109篇 |
2007年 | 1923篇 |
2006年 | 2145篇 |
2005年 | 2305篇 |
2004年 | 2191篇 |
2003年 | 1918篇 |
2002年 | 2008篇 |
2001年 | 2062篇 |
2000年 | 1827篇 |
1999年 | 1732篇 |
1998年 | 1529篇 |
1997年 | 1376篇 |
1996年 | 1341篇 |
1995年 | 1366篇 |
1994年 | 1307篇 |
1993年 | 1301篇 |
1992年 | 1318篇 |
1991年 | 1249篇 |
1990年 | 1226篇 |
1989年 | 1058篇 |
1988年 | 1143篇 |
1987年 | 1010篇 |
1986年 | 917篇 |
1985年 | 1099篇 |
1984年 | 1154篇 |
1983年 | 1023篇 |
1982年 | 943篇 |
1981年 | 860篇 |
1980年 | 812篇 |
1979年 | 885篇 |
1978年 | 781篇 |
1977年 | 711篇 |
1976年 | 657篇 |
1975年 | 629篇 |
1974年 | 525篇 |
1973年 | 443篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
821.
The elimination or knockout format is one of the most common designs for pairing competitors in tournaments and leagues. In each round of a knockout tournament, the losers are eliminated while the winners advance to the next round. Typically, the goal of such a design is to identify the overall best player. Using a common probability model for expressing relative player strengths, we develop an adaptive approach to pairing players each round in which the probability that the best player advances to the next round is maximized. We evaluate our method using simulated game outcomes under several data-generating mechanisms, and compare it to random pairings, to the standard knockout format, and to two variants of the standard format. 相似文献
822.
Terence C. Mills 《Journal of applied statistics》2008,35(10):1131-1138
While body fat is the most accurate measure of obesity, its measurement requires special equipment that can be costly and time consuming to operate. Attention has thus typically focused on the easier to calculate body mass index (BMI). However, the ability of BMI to accurately identify obesity has been increasingly questioned. This paper focuses attention on whether more general body mass indices are appropriate measures of body fat. Using a data set of body fat, height, and weight measurements, general models are estimated which nest a wide variety of weight–height indices as special cases. In the absence of a race and gender categorisation, the conventional BMI was found to be the appropriate index with which to predict body fat. When such a categorisation was made, however, the BMI was never selected as the appropriate index. In general, predicted female body fat was some 10 kg higher than that of a male of identical build and predicted % body fat was over 11 percentage points higher, but age effects were smaller for females. Considerable racial differences in predicted body fat were found for males, but such differences were less marked for females. The implications of this finding for interpreting recent research on the effect of obesity on health, society, and economic factors are considered. 相似文献
823.
The authors provide an overview of optimal scaling results for the Metropolis algorithm with Gaussian proposal distribution. They address in more depth the case of high‐dimensional target distributions formed of independent, but not identically distributed components. They attempt to give an intuitive explanation as to why the well‐known optimal acceptance rate of 0.234 is not always suitable. They show how to find the asymptotically optimal acceptance rate when needed, and they explain why it is sometimes necessary to turn to inhomogeneous proposal distributions. Their results are illustrated with a simple example. 相似文献
824.
The basic assumption underlying the concept of ranked set sampling is that actual measurement of units is expensive, whereas ranking is cheap. This may not be true in reality in certain cases where ranking may be moderately expensive. In such situations, based on total cost considerations, k-tuple ranked set sampling is known to be a viable alternative, where one selects k units (instead of one) from each ranked set. In this article, we consider estimation of the distribution function based on k-tuple ranked set samples when the cost of selecting and ranking units is not ignorable. We investigate estimation both in the balanced and unbalanced data case. Properties of the estimation procedure in the presence of ranking error are also investigated. Results of simulation studies as well as an application to a real data set are presented to illustrate some of the theoretical findings. 相似文献
825.
This study examined the emergence of affect specificity in infancy. In this study, infants received verbal and facial signals of 2 different, negatively valenced emotions (fear and sadness) as well as neutral affect via a television monitor to determine if they could make qualitative distinctions among emotions of the same valence. Twenty 12‐ to 14‐month‐olds and 20 16‐ to 18‐month‐olds were examined. Results suggested that younger infants showed no evidence of referential specificity, as they responded similarly to both the target and distracter toys, and showed no evidence of affect specificity, showing no difference in play between affect conditions. Older infants, in contrast, showed evidence both of referential and affect specificity. With respect to affect specificity, 16‐ to 18‐month‐olds touched the target toy less in the fear condition than in the sad condition and showed a larger proportion of negative facial expressions in the sad condition versus the fear condition. These findings suggest a developmental emergence after 15 months of age for affect specificity in relating emotional messages to objects. 相似文献
826.
Vivyan C. Adair 《Sociology Compass》2008,2(5):1655-1671
Class theorists of embodiment in Sociology point to and illuminate both an over‐ and an under‐exposed body and experience that ultimately mark the bodies of the poor as ideologically, discursively and materially abject. In this essay, I map out theories of the bodies of the poor, including those of Marx, Engels, Elias, Bourdieu, Foucault, Donzelot and Adair. I suggest that an understanding of the ways in which the bodies of the poor are positioned as abject can facilitate a flexible and reflexive heuristic through which we can negotiate epistemic shifts between material and discursive categories, as well as providing us with a template through which we can come to understand even the most profoundly abject bodies, those of poor women in a welfare state, as potential sites of embodied agency and resistance, all central to the ethical and holistic study of sociology. 相似文献
827.
Darren E. Lund 《Intercultural Education》2003,14(1):3-16
This paper presents an argument for further engagement between educational scholars and school-based social justice activists. An analysis of one segment of the broad field of social justice education focuses on multicultural and antiracist education, particularly as they are understood in the Canadian socio-political context. A brief overview of the literature from UK and US sources highlights their complex and often overlapping concerns, and the need for more dialogue across national boundaries toward progressive social change. Excerpts from in-depth interviews with four Canadian teacher-activists reveal the potential for educators to take up various debates and findings from the academic literature in their daily struggles to work for social justice. 相似文献
828.
蒋士强 《福建农林大学学报(哲学社会科学版)》2003,(2)
本文概叙了入世后中国农业面临的农产品品质 安全性及价格的三重冲击和应采取的应对措施 着重分析了农产品安全问题和食品安全保障体系的构建 论述了分析测试技术和科学仪器的七项重任 相似文献
829.
D. R. Cox 《Journal of the Royal Statistical Society. Series A, (Statistics in Society)》2003,166(2):241-246
Summary. Possible health hazards from mobile phones arise from the use of the phones themselves and via the base stations that relay signals. Except for an increase in traffic accidents induced by the use of mobile phones in cars the evidence for a health hazard is at most indirect, but it cannot be entirely dismissed; the phones have not been widely used for sufficiently long for direct epidemiological studies to have high sensitivity for detecting any induced incidence of cancer, for example. The background and evidence are briefly reviewed and the steps taken in the UK to make information widely available described. 相似文献
830.
Julia R. Irwin 《Infancy》2003,4(4):503-516
This study examined whether perceivers can detect infant distress in the visual and acoustic signals within the cry. Parent and nonparent perceivers rated distress in 3‐, 6‐, 8‐, and 12‐month‐old infants' cries that were manipulated to separate facial, vocal, and bodily action. Mean perceiver ratings differed for high‐ and low‐distress cries at each infant age on the basis of facial and vocal action, but not bodily movement. Perceivers rated the cry sound as more distressed and the cry face as less distressed with increasing infant age. Parents rated the cries as less distressed overall than did nonparents. The results suggest that information about distress is available for perceivers in the crying infant's face and voice. 相似文献