全文获取类型
收费全文 | 3000篇 |
免费 | 114篇 |
国内免费 | 1篇 |
专业分类
管理学 | 419篇 |
民族学 | 9篇 |
人口学 | 262篇 |
丛书文集 | 18篇 |
理论方法论 | 345篇 |
综合类 | 36篇 |
社会学 | 1240篇 |
统计学 | 786篇 |
出版年
2023年 | 20篇 |
2021年 | 19篇 |
2020年 | 55篇 |
2019年 | 79篇 |
2018年 | 108篇 |
2017年 | 120篇 |
2016年 | 70篇 |
2015年 | 80篇 |
2014年 | 96篇 |
2013年 | 607篇 |
2012年 | 122篇 |
2011年 | 103篇 |
2010年 | 79篇 |
2009年 | 64篇 |
2008年 | 82篇 |
2007年 | 79篇 |
2006年 | 63篇 |
2005年 | 59篇 |
2004年 | 47篇 |
2003年 | 30篇 |
2002年 | 51篇 |
2001年 | 61篇 |
2000年 | 56篇 |
1999年 | 47篇 |
1998年 | 40篇 |
1997年 | 41篇 |
1996年 | 32篇 |
1995年 | 33篇 |
1994年 | 41篇 |
1993年 | 36篇 |
1992年 | 47篇 |
1991年 | 48篇 |
1990年 | 35篇 |
1989年 | 34篇 |
1988年 | 43篇 |
1987年 | 19篇 |
1986年 | 26篇 |
1985年 | 38篇 |
1984年 | 31篇 |
1983年 | 41篇 |
1982年 | 27篇 |
1981年 | 23篇 |
1980年 | 22篇 |
1979年 | 23篇 |
1978年 | 40篇 |
1977年 | 20篇 |
1976年 | 26篇 |
1975年 | 25篇 |
1974年 | 15篇 |
1972年 | 14篇 |
排序方式: 共有3115条查询结果,搜索用时 203 毫秒
851.
852.
Aaron Kupchik 《Sociological Forum》2020,35(3):813-821
In this essay, I examine the problem of excessive and racially disproportionate school discipline. I begin by considering how each of the four most popular Democratic candidates in the presidential primary race as of January 2020 addresses this issue. Excessive and racially disproportionate school discipline harms students, schools, and communities, and it deepens existing racial inequalities. Each candidate promises some remedy, and all represent a step in the right direction. However, all of their proposals are shallow. To fruitfully address these issues, policymakers must consider the cultural embeddedness of school discipline, how it is implemented within complex school bureaucracies, and the underlying racial inequality that shapes school discipline. Policymakers must also draw attention to the fact that schools are, overall, safe and do not require the massive investments in security personnel and technology that draw funds away from more effective supports for students. 相似文献
853.
Covariate adjusted regression (CAR) is a recently proposed adjustment method for regression analysis where both the response and predictors are not directly observed [?entürk, D., Müller, H.G., 2005. Covariate adjusted regression. Biometrika 92, 75–89]. The available data have been distorted by unknown functions of an observable confounding covariate. CAR provides consistent estimators for the coefficients of the regression between the variables of interest, adjusted for the confounder. We develop a broader class of partial covariate adjusted regression (PCAR) models to accommodate both distorted and undistorted (adjusted/unadjusted) predictors. The PCAR model allows for unadjusted predictors, such as age, gender and demographic variables, which are common in the analysis of biomedical and epidemiological data. The available estimation and inference procedures for CAR are shown to be invalid for the proposed PCAR model. We propose new estimators and develop new inference tools for the more general PCAR setting. In particular, we establish the asymptotic normality of the proposed estimators and propose consistent estimators of their asymptotic variances. Finite sample properties of the proposed estimators are investigated using simulation studies and the method is also illustrated with a Pima Indians diabetes data set. 相似文献
854.
We propose an estimation method that incorporates the correlation/covariance structure between repeated measurements in covariate-adjusted regression models for distorted longitudinal data. In this distorted data setting, neither the longitudinal response nor (possibly time-varying) predictors are directly observable. The unobserved response and predictors are assumed to be distorted/contaminated by unknown functions of a common observable confounder. The proposed estimation methodology adjusts for the distortion effects both in estimation of the covariance structure and in the regression parameters using generalized least squares. The finite-sample performance of the proposed estimators is studied numerically by means of simulations. The consistency and convergence rates of the proposed estimators are also established. The proposed method is illustrated with an application to data from a longitudinal study of cognitive and social development in children. 相似文献
855.
A major issue when proposing a new prognostic index is its generalisibility to daily clinical practice. Validation is therefore
required. Most validation techniques assess whether “on average” the results obtained by the prognostic index in classifying
patients in a new sample of patients are similar to the results obtained in the construction set. We introduce a new important
aspect of the generalisibility of a prognostic index: the heterogeneity of the prognostic index risk group hazard ratios over
different centers. If substantial variability between centers exists, the prognostic index may have no discriminatory capability
in some of the centers. To model such heterogeneity, we use a frailty model including a random center effect and a random
prognostic index by center interaction. Statistical inference is based on a Bayesian approach using a Laplacian approximation
for the marginal posterior distribution of the variances of the random effects. We investigate different ways to summarize
the information available from this marginal posterior distribution. Our approach is applied to a real bladder cancer database
for which we demonstrate how to investigate and interpret heterogeneity in prognostic index effect over centers. 相似文献
856.
In this paper, we study, by a Monte Carlo simulation, the effect of the order p of “Zhurbenko-Kolmogorov” taper on the asymptotic properties of semiparametric estimators. We show that p = [d + 1/2] + 1 gives the smallest variances and mean squared errors. These properties depend also on the truncation parameter
m. Moreover, we study the impact of the short-memory components on the bias and variances of these estimators. We finally carry
out an empirical application by using four monthly seasonally adjusted logarithm Consumer Price Index series.
相似文献
857.
The perceived usefulness of information is an important construct for the design of management information systems. Yet an examination of existing measures of perceived usefulness shows that the instruments developed have not been validated nor has their reliability been verified. In this paper a new instrument for measuring two dimensions of perceived usefulness is developed. The results of an empirical study designed to test the reliability and construct validity of this instrument in a capital-budgeting setting are presented. 相似文献
858.
A comparison of soil organic carbon stocks between residential turf grass and native soil 总被引:4,自引:3,他引:1
A central principle in urban ecological theory implies that in urbanized landscapes anthropogenic drivers will dominate natural
drivers in the control of soil organic carbon storage (SOC). To assess the effect of urban land-use change on the storage
of SOC, we compared SOC stocks of turf grass and native cover types of two metropolitan areas (Baltimore, MD, and Denver,
CO) representing climatologically distinct regions in the United States. We hypothesized that introducing turf grass and management
will lead to higher SOC densities in the arid Denver area and lower densities in the mesic Baltimore area relative to native
cover types. Moreover, differences between turf grass soils will be less than differences between the native soils of each
metropolitan region. Within Baltimore, turf grass had almost a 2-fold higher SOC density at 0- to 1-m and 0- to 20-cm depths
than in rural forest soils, whereas there were no differences with soils of urban forest remnants. Moreover, urban forest
remnants had more than 70% higher SOC densities than rural forest soils. Within Denver, turf grass (>25 years of age) had
more than 2-fold higher SOC densities than in shortgrass steppe soils, while having similar densities to Baltimore turf grass
soils. By contrast, the native soils of Baltimore were almost 2-fold higher than the native steppe grass soils of Denver using
SOC densities of remnant forests as representative of native soils in the Baltimore region. These results supported our hypothesis
that turf grass systems will be similar in SOC densities across regional variations in climate, parent material, and topography.
These similarities are apparently due to greater management efforts in the Denver region to offset the constraint of climate,
i.e., anthropogenic factors (management supplements) overwhelmed native environmental factors that control SOC storage. 相似文献
859.
Many public transit agencies consider increasing fares when faced with budget shortfalls. This paper analyzes the Alameda–Contra Costa (AC) Transit District's five alternative fare proposals introduced for public discussion in March 2005. The proposals combined fare hikes, base fare reductions, eliminations of free transfers, and discontinuation of periodic passes. Using the agency's 2002 on-board survey data, the study assessed the impacts of individual fare proposals on different subsets of riders and evaluated if they were equitable; and estimated potential fare revenues, using alternative price elasticities to estimate changes in ridership due to changes in price. The analysis revealed that proposals that increased the cost of transfers or eliminated unlimited-use passes produced dramatically unequal impacts on certain riders. Proposals for flat fares per ride were found to be least equitable, even when the base fare was lowered, because lower income riders, youth, and minorities made more trips and transferred more frequently than their more affluent counterparts. Proposals that maintained existing pass instruments and allowed transfers for small fees were the most favorable. The paper demonstrates the utility of on-board surveys and details an approach that could be widely used for evaluation of equity in public transit and other areas. 相似文献
860.
This article investigates the foundations of cooperative identity and how it is constructed by the organization. More specifically, our research focuses on a financial cooperative in the simultaneously emerging and consolidating cultural sector. The originality of this article lies in the methodology used – textual analysis. We use the Economies of Worth model developed by Boltanski and Thévenot (2006), which accounts for a plurality of legitimate forms of evaluation used in the processes of critique and justification. 相似文献