全文获取类型
收费全文 | 21924篇 |
免费 | 322篇 |
专业分类
管理学 | 3139篇 |
民族学 | 148篇 |
人才学 | 1篇 |
人口学 | 3581篇 |
丛书文集 | 67篇 |
教育普及 | 1篇 |
理论方法论 | 1506篇 |
现状及发展 | 1篇 |
综合类 | 424篇 |
社会学 | 9958篇 |
统计学 | 3420篇 |
出版年
2023年 | 90篇 |
2021年 | 67篇 |
2020年 | 185篇 |
2019年 | 259篇 |
2018年 | 1912篇 |
2017年 | 2023篇 |
2016年 | 1352篇 |
2015年 | 236篇 |
2014年 | 302篇 |
2013年 | 2047篇 |
2012年 | 728篇 |
2011年 | 1475篇 |
2010年 | 1297篇 |
2009年 | 1035篇 |
2008年 | 1096篇 |
2007年 | 1266篇 |
2006年 | 259篇 |
2005年 | 489篇 |
2004年 | 505篇 |
2003年 | 431篇 |
2002年 | 333篇 |
2001年 | 293篇 |
2000年 | 298篇 |
1999年 | 276篇 |
1998年 | 185篇 |
1997年 | 175篇 |
1996年 | 196篇 |
1995年 | 164篇 |
1994年 | 133篇 |
1993年 | 151篇 |
1992年 | 169篇 |
1991年 | 145篇 |
1990年 | 158篇 |
1989年 | 182篇 |
1988年 | 162篇 |
1987年 | 136篇 |
1986年 | 148篇 |
1985年 | 167篇 |
1984年 | 166篇 |
1983年 | 157篇 |
1982年 | 123篇 |
1981年 | 105篇 |
1980年 | 103篇 |
1979年 | 137篇 |
1978年 | 88篇 |
1977年 | 88篇 |
1976年 | 87篇 |
1975年 | 81篇 |
1974年 | 80篇 |
1973年 | 74篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
Ricardo Maronna Matthias Fischer Jürgen Groß Andreas Karlsson 《Statistical Papers》2007,48(1):163-170
132.
133.
Over the first years of life, infants gradually develop the ability to retrieve their memories across cue and contextual changes. Whereas maturational factors drive some of these developments in memory ability, experiences occurring within the learning event may also impact infants' ability to retrieve memories in new situations. In 2 experiments we examined whether it was possible to facilitate 12‐month‐old infants' generalization of learning in the deferred imitation paradigm by varying experiences before or during the demonstration session, or during the retention interval. In Experiment 1, altering the length, timing, or variability of training had no impact on generalization; infants showed a low, but consistent level of memory retrieval. In Experiment 2, infants who experienced a unique context for encoding and retrieval exhibited generalization; infants who experienced the context prior to the demonstration session, or during the retention interval, did not. Specificity is a robust feature of infant memory and is not substantially altered by encoding experiences in an observational learning paradigm. Previous history with a learning environment can, however, impact the flexibility of memory retrieval. 相似文献
134.
C. A. Glasbey D. J. Allcroft 《Journal of the Royal Statistical Society. Series C, Applied statistics》2008,57(3):343-355
Summary. To investigate the variability in energy output from a network of photovoltaic cells, solar radiation was recorded at 10 sites every 10 min in the Pentland Hills to the south of Edinburgh. We identify spatiotemporal auto-regressive moving average models as the most appropriate to address this problem. Although previously considered computationally prohibitive to work with, we show that by approximating using toroidal space and fitting by matching auto-correlations, calculations can be substantially reduced. We find that a first-order spatiotemporal auto-regressive (STAR(1)) process with a first-order neighbourhood structure and a Matern noise process provide an adequate fit to the data, and we demonstrate its use in simulating realizations of energy output. 相似文献
135.
136.
The paper and the special issue focus on the activity of statistical consulting and its varieties.
This includes academic consulting, consulting to and in industry as well as statistics in public media. 相似文献
137.
138.
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
139.
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
140.
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