全文获取类型
收费全文 | 25477篇 |
免费 | 413篇 |
专业分类
管理学 | 3515篇 |
民族学 | 160篇 |
人才学 | 1篇 |
人口学 | 3599篇 |
丛书文集 | 94篇 |
教育普及 | 4篇 |
理论方法论 | 1959篇 |
综合类 | 447篇 |
社会学 | 12458篇 |
统计学 | 3653篇 |
出版年
2021年 | 87篇 |
2020年 | 195篇 |
2019年 | 284篇 |
2018年 | 1908篇 |
2017年 | 2037篇 |
2016年 | 1371篇 |
2015年 | 283篇 |
2014年 | 358篇 |
2013年 | 3057篇 |
2012年 | 729篇 |
2011年 | 1530篇 |
2010年 | 1316篇 |
2009年 | 1067篇 |
2008年 | 1145篇 |
2007年 | 1299篇 |
2006年 | 396篇 |
2005年 | 567篇 |
2004年 | 544篇 |
2003年 | 478篇 |
2002年 | 381篇 |
2001年 | 358篇 |
2000年 | 354篇 |
1999年 | 351篇 |
1998年 | 231篇 |
1997年 | 216篇 |
1996年 | 311篇 |
1995年 | 266篇 |
1994年 | 273篇 |
1993年 | 276篇 |
1992年 | 288篇 |
1991年 | 272篇 |
1990年 | 290篇 |
1989年 | 266篇 |
1988年 | 248篇 |
1987年 | 213篇 |
1986年 | 218篇 |
1985年 | 227篇 |
1984年 | 230篇 |
1983年 | 167篇 |
1982年 | 158篇 |
1981年 | 143篇 |
1980年 | 149篇 |
1979年 | 158篇 |
1978年 | 138篇 |
1977年 | 117篇 |
1976年 | 120篇 |
1975年 | 124篇 |
1974年 | 83篇 |
1973年 | 71篇 |
1971年 | 74篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
A sample size justification should be given for all clinical investigations. However, sometimes the objective of a trial is to estimate an effect with a view to planning a later definitive study. This paper describes the calculations for designing studies where one wishes to adopt an estimation approach through using confidence intervals around the overall response. Calculations are given for data anticipated to take a Normal form. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
42.
Sets of relatively short time series arise in many situations. One aspect of their analysis may be the detection of outlying
series. We examine the performance of standard normal outlier tests applied to the means, or to simple functions of the means,
of AR(1) series, not necessarily of equal lengths. Although unequal lengths of series implies that the means have unequal
variances, that are only known approximately, it is shown that nominal significance levels hold good under most circumstances.
Thus a standard outlier test can usefully be applied, avoiding the complication of estimating the time series' parameters.
The test's power is affected by unequal lengths, being higher when the slippage occurs in one of the longer series 相似文献
43.
Bram Thuysbaert 《Journal of Economic Inequality》2008,6(1):33-55
Empirical applications of poverty measurement often have to deal with a stochastic weighting variable such as household size.
Within the framework of a bivariate distribution function defined over income and weight, I derive the limiting distributions
of the decomposable poverty measures and of the ordinates of stochastic dominance curves. The poverty line is allowed to depend
on the income distribution. It is shown how the results can be used to test hypotheses concerning changes in poverty. The
inference procedures are briefly illustrated using Belgian data.
An erratum to this article can be found at 相似文献
44.
Children may be more susceptible to toxicity from some environmental chemicals than adults. This susceptibility may occur during narrow age periods (windows), which can last from days to years depending on the toxicant. Breathing rates specific to narrow age periods are useful to assess inhalation dose during suspected windows of susceptibility. Because existing breathing rates used in risk assessment are typically for broad age ranges or are based on data not representative of the population, we derived daily breathing rates for narrow age ranges of children designed to be more representative of the current U.S. children's population. These rates were derived using the metabolic conversion method of Layton (1993) and energy intake data adjusted to represent the U.S. population from a relatively recent dietary survey (CSFII 1994–1996, 1998). We calculated conversion factors more specific to children than those previously used. Both nonnormalized (L/day) and normalized (L/kg-day) breathing rates were derived and found comparable to rates derived using energy estimates that are accurate for the individuals sampled but not representative of the population. Estimates of breathing rate variability within a population can be used with stochastic techniques to characterize the range of risk in the population from inhalation exposures. For each age and age-gender group, we present the mean, standard error of the mean, percentiles (50th, 90th, and 95th), geometric mean, standard deviation, 95th percentile, and best-fit parametric models of the breathing rate distributions. The standard errors characterize uncertainty in the parameter estimate, while the percentiles describe the combined interindividual and intra-individual variability of the sampled population. These breathing rates can be used for risk assessment of subchronic and chronic inhalation exposures of narrow age groups of children. 相似文献
45.
Singh et al. ([13]) pointed out that the Randomized response (RR) technique proposed by Moors ([9]) is not desirable because
it fails to protect the confidentiality of the respondents and they provided two alternative strategies free from the above
drawback but limited to SRSWOR sampling only. In this paper, generalization of one of the strategies is provided for complex
survey designs, wider class of estimators and for quantitative characteristics. Relative efficiency of the modified strategy
is tested through empirical investigations.
An erratum to this article is available at . 相似文献
46.
47.
48.
Lukas D. Tsitsipis 《Journal of Sociolinguistics》2004,8(4):569-594
Through the use of two central Bakhtinian concepts, authoritative and internally persuasive discourse (word), this paper examines the tension between the ideology of linguistic hegemony as a source of power in the Greek public sphere and the condition of language shift faced by the Albanian‐speaking communities of modern Greece. I argue here that a cautious application of these two notions, which are relevant to linguistic ideology, can reveal crucial aspects of two processes: that of subordination to and that of questioning of the dominant linguistic ideology by local Albanian‐speaking communities. Thus, in language shift contexts, it is possible that no simple relations obtain that place social agents in unquestionable and easily predictable positions. Such an approach proves useful for the sociolinguistic study of threatened language communities. 相似文献
49.
50.