全文获取类型
收费全文 | 35801篇 |
免费 | 932篇 |
专业分类
管理学 | 4604篇 |
民族学 | 177篇 |
人才学 | 7篇 |
人口学 | 3285篇 |
丛书文集 | 199篇 |
教育普及 | 4篇 |
理论方法论 | 3259篇 |
现状及发展 | 1篇 |
综合类 | 626篇 |
社会学 | 17591篇 |
统计学 | 6980篇 |
出版年
2023年 | 172篇 |
2021年 | 185篇 |
2020年 | 556篇 |
2019年 | 772篇 |
2018年 | 853篇 |
2017年 | 1195篇 |
2016年 | 864篇 |
2015年 | 663篇 |
2014年 | 809篇 |
2013年 | 5993篇 |
2012年 | 1187篇 |
2011年 | 1067篇 |
2010年 | 810篇 |
2009年 | 791篇 |
2008年 | 853篇 |
2007年 | 904篇 |
2006年 | 796篇 |
2005年 | 879篇 |
2004年 | 815篇 |
2003年 | 742篇 |
2002年 | 750篇 |
2001年 | 880篇 |
2000年 | 790篇 |
1999年 | 766篇 |
1998年 | 585篇 |
1997年 | 551篇 |
1996年 | 566篇 |
1995年 | 531篇 |
1994年 | 519篇 |
1993年 | 480篇 |
1992年 | 599篇 |
1991年 | 585篇 |
1990年 | 515篇 |
1989年 | 530篇 |
1988年 | 490篇 |
1987年 | 444篇 |
1986年 | 451篇 |
1985年 | 476篇 |
1984年 | 510篇 |
1983年 | 500篇 |
1982年 | 403篇 |
1981年 | 342篇 |
1980年 | 353篇 |
1979年 | 389篇 |
1978年 | 335篇 |
1977年 | 304篇 |
1976年 | 269篇 |
1975年 | 260篇 |
1974年 | 231篇 |
1973年 | 203篇 |
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
71.
教学管理是教学工作运转的支柱,教学管理的优劣影响着教学质量。该文介绍了外语学院教学管理工作的基本内容,包括教学任务的布置落实、教学检查、教学文件的建设、学籍管理,以及结合学院的实际情况完善考试制度、制定成绩管理细则和考试结果奖励办法等。 相似文献
72.
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
73.
74.
This paper describes the design optimization of a robot sensor used for locating 3-D objects employing the Taguchi method in a computer simulation scenario. The location information from the sensor is to be utilized to control the movements of an industrial robot in a 'pick-and-place' or assembly operation. The Taguchi method, which is based on the Analysis-of-Variance (ANOVA) approach, is utilized to improve the performance of the sensor over a wider operating range. A review of the Taguchi method is presented along with step-by-step implementation details to identify and optimize the design parameters of the sensor. The method allows us to gauge the impact of various interactions present in the sensor system exclusively and permits us to single out those factors that have a dominant influence on the overall performance of the sensor. The investigation suggests that the Taguchi method is a more structured and efficient approach for achieving a robust design compared with the classical full factorial design approach. 相似文献
75.
Günter F. Müller 《Gruppendynamik und Organisationsberatung》2005,36(3):325-334
This paper outlines the conceptual bases, strategies, and psychological attributes of leadership by self-leadership. In addition, relations to other theories of leadership are drawn. Dimensions and correlates of self-leadership competence are described and discussed. Various approaches for developing self-leadership competence are discussed as well. 相似文献
76.
77.
Diane Hope Weixing Zhu Corinna Gries Jacob Oleson Jason Kaye Nancy B. Grimm Lawrence A. Baker 《Urban Ecosystems》2005,8(3-4):251-273
We explored variations in inorganic soil nitrogen (N) concentrations across metropolitan Phoenix, Arizona, and the surrounding
desert using a probability-based synoptic survey. Data were examined using spatial statistics on the entire region, as well
as for the desert and urban sites separately. Concentrations of both NO3-N and NH4-N were markedly higher and more heterogeneous amongst urban compared to desert soils. Regional variation in soil NO3-N concentration was best explained by latitude, land use history, population density, along with percent cover of impervious
surfaces and lawn, whereas soil NH4-N concentrations were related to only latitude and population density. Within the urban area, patterns in both soil NO3-N and NH4-N were best predicted by elevation, population density and type of irrigation in the surrounding neighborhood. Spatial autocorrelation
of soil NO3-N concentrations explained 49% of variation among desert sites but was absent between urban sites. We suggest that inorganic
soil N concentrations are controlled by a number of ‘local’ or ‘neighborhood’ human-related drivers in the city, rather than
factors related to an urban-rural gradient. 相似文献
78.
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
79.
Craig H. Mallinckrodt Christopher J. Kaiser John G. Watkin Michael J. Detke Geert Molenberghs Raymond J. Carroll 《Pharmaceutical statistics》2004,3(3):171-186
The last observation carried forward (LOCF) approach is commonly utilized to handle missing values in the primary analysis of clinical trials. However, recent evidence suggests that likelihood‐based analyses developed under the missing at random (MAR) framework are sensible alternatives. The objective of this study was to assess the Type I error rates from a likelihood‐based MAR approach – mixed‐model repeated measures (MMRM) – compared with LOCF when estimating treatment contrasts for mean change from baseline to endpoint (Δ). Data emulating neuropsychiatric clinical trials were simulated in a 4 × 4 factorial arrangement of scenarios, using four patterns of mean changes over time and four strategies for deleting data to generate subject dropout via an MAR mechanism. In data with no dropout, estimates of Δ and SEΔ from MMRM and LOCF were identical. In data with dropout, the Type I error rates (averaged across all scenarios) for MMRM and LOCF were 5.49% and 16.76%, respectively. In 11 of the 16 scenarios, the Type I error rate from MMRM was at least 1.00% closer to the expected rate of 5.00% than the corresponding rate from LOCF. In no scenario did LOCF yield a Type I error rate that was at least 1.00% closer to the expected rate than the corresponding rate from MMRM. The average estimate of SEΔ from MMRM was greater in data with dropout than in complete data, whereas the average estimate of SEΔ from LOCF was smaller in data with dropout than in complete data, suggesting that standard errors from MMRM better reflected the uncertainty in the data. The results from this investigation support those from previous studies, which found that MMRM provided reasonable control of Type I error even in the presence of MNAR missingness. No universally best approach to analysis of longitudinal data exists. However, likelihood‐based MAR approaches have been shown to perform well in a variety of situations and are a sensible alternative to the LOCF approach. MNAR methods can be used within a sensitivity analysis framework to test the potential presence and impact of MNAR data, thereby assessing robustness of results from an MAR method. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
80.
Estimated associations between an outcome variable and misclassified covariates tend to be biased when the methods of estimation that ignore the classification error are applied. Available methods to account for misclassification often require the use of a validation sample (i.e. a gold standard). In practice, however, such a gold standard may be unavailable or impractical. We propose a Bayesian approach to adjust for misclassification in a binary covariate in the random effect logistic model when a gold standard is not available. This Markov Chain Monte Carlo (MCMC) approach uses two imperfect measures of a dichotomous exposure under the assumptions of conditional independence and non-differential misclassification. A simulated numerical example and a real clinical example are given to illustrate the proposed approach. Our results suggest that the estimated log odds of inpatient care and the corresponding standard deviation are much larger in our proposed method compared with the models ignoring misclassification. Ignoring misclassification produces downwardly biased estimates and underestimate uncertainty. 相似文献