全文获取类型
收费全文 | 14923篇 |
免费 | 284篇 |
专业分类
管理学 | 1940篇 |
民族学 | 113篇 |
人才学 | 1篇 |
人口学 | 2087篇 |
丛书文集 | 64篇 |
教育普及 | 1篇 |
理论方法论 | 1114篇 |
现状及发展 | 1篇 |
综合类 | 220篇 |
社会学 | 7003篇 |
统计学 | 2663篇 |
出版年
2023年 | 80篇 |
2021年 | 56篇 |
2020年 | 168篇 |
2019年 | 230篇 |
2018年 | 769篇 |
2017年 | 857篇 |
2016年 | 650篇 |
2015年 | 195篇 |
2014年 | 257篇 |
2013年 | 1987篇 |
2012年 | 485篇 |
2011年 | 753篇 |
2010年 | 614篇 |
2009年 | 543篇 |
2008年 | 563篇 |
2007年 | 641篇 |
2006年 | 255篇 |
2005年 | 336篇 |
2004年 | 336篇 |
2003年 | 299篇 |
2002年 | 272篇 |
2001年 | 290篇 |
2000年 | 296篇 |
1999年 | 273篇 |
1998年 | 185篇 |
1997年 | 173篇 |
1996年 | 179篇 |
1995年 | 164篇 |
1994年 | 137篇 |
1993年 | 151篇 |
1992年 | 170篇 |
1991年 | 146篇 |
1990年 | 156篇 |
1989年 | 183篇 |
1988年 | 160篇 |
1987年 | 138篇 |
1986年 | 154篇 |
1985年 | 172篇 |
1984年 | 173篇 |
1983年 | 158篇 |
1982年 | 122篇 |
1981年 | 111篇 |
1980年 | 106篇 |
1979年 | 138篇 |
1978年 | 89篇 |
1977年 | 87篇 |
1976年 | 87篇 |
1975年 | 82篇 |
1974年 | 80篇 |
1973年 | 73篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
981.
Mark Steyvers Thomas S. Wallsten Edgar C. Merkle Brandon M. Turner 《Risk analysis》2014,34(3):435-452
We propose the use of signal detection theory (SDT) to evaluate the performance of both probabilistic forecasting systems and individual forecasters. The main advantage of SDT is that it provides a principled way to distinguish the response from system diagnosticity, which is defined as the ability to distinguish events that occur from those that do not. There are two challenges in applying SDT to probabilistic forecasts. First, the SDT model must handle judged probabilities rather than the conventional binary decisions. Second, the model must be able to operate in the presence of sparse data generated within the context of human forecasting systems. Our approach is to specify a model of how individual forecasts are generated from underlying representations and use Bayesian inference to estimate the underlying latent parameters. Given our estimate of the underlying representations, features of the classic SDT model, such as the receiver operating characteristic (ROC) curve and the area under the ROC curve (AUC), follow immediately. We show how our approach allows ROC curves and AUCs to be applied to individuals within a group of forecasters, estimated as a function of time, and extended to measure differences in forecastability across different domains. Among the advantages of this method is that it depends only on the ordinal properties of the probabilistic forecasts. We conclude with a brief discussion of how this approach might facilitate decision making. 相似文献
982.
983.
Urban and agricultural soils: conflicts and trade-offs in the optimization of ecosystem services 总被引:2,自引:0,他引:2
H. Setälä R. D. Bardgett K. Birkhofer M. Brady L. Byrne P. C. de Ruiter F. T. de Vries C. Gardi K. Hedlund L. Hemerik S. Hotes M. Liiri S. R. Mortimer M. Pavao-Zuckerman R. Pouyat M. Tsiafouli W. H. van der Putten 《Urban Ecosystems》2014,17(1):239-253
On-going human population growth and changing patterns of resource consumption are increasing global demand for ecosystem services, many of which are provided by soils. Some of these ecosystem services are linearly related to the surface area of pervious soil, whereas others show non-linear relationships, making ecosystem service optimization a complex task. As limited land availability creates conflicting demands among various types of land use, a central challenge is how to weigh these conflicting interests and how to achieve the best solutions possible from a perspective of sustainable societal development. These conflicting interests become most apparent in soils that are the most heavily used by humans for specific purposes: urban soils used for green spaces, housing, and other infrastructure and agricultural soils for producing food, fibres and biofuels. We argue that, despite their seemingly divergent uses of land, agricultural and urban soils share common features with regards to interactions between ecosystem services, and that the trade-offs associated with decision-making, while scale- and context-dependent, can be surprisingly similar between the two systems. We propose that the trade-offs within land use types and their soil-related ecosystems services are often disproportional, and quantifying these will enable ecologists and soil scientists to help policy makers optimizing management decisions when confronted with demands for multiple services under limited land availability. 相似文献
984.
985.
Valeria Bordone Francesco C. Billari Gianpiero Dalla Zuanna 《Statistical Methods and Applications》2009,18(3):445-451
The own-children method (OCM) applied to the Italian Labour Force Survey (ILFS) is an alternative way to give information
on fertility for the years before the survey. By deriving children information and the population at risk on the basis of
parents’ characteristics, a large-scale dataset for fertility analysis in Italy becomes available, also to reconstruct event
histories. The quality assessment provided by comparing the total fertility rate (TFR) calculated on ILFS with the official
regional and national TFRs by ISTAT gives us usable outcomes. 相似文献
986.
Arijit Chaudhuri Tasos C. Christofides Amitava Saha 《Statistical Methods and Applications》2009,18(3):389-418
In estimating the proportion of people bearing a sensitive attribute A, say, in a given community, following Warner’s (J Am Stat Assoc 60:63–69, 1965) pioneering work, certain randomized response
(RR) techniques are available for application. These are intended to ensure efficient and unbiased estimation protecting a
respondent’s privacy when it touches a person’s socially stigmatizing feature like rash driving, tax evasion, induced abortion,
testing HIV positive, etc. Lanke (Int Stat Rev 44:197–203, 1976), Leysieffer and Warner (J Am Stat Assoc 71:649–656, 1976),
Anderson (Int Stat Rev 44:213–217, 1976, Scand J Stat 4:11–19, 1977) and Nayak (Commun Stat Theor Method 23:3303–3321, 1994)
among others have discussed how maintenance of efficiency is in conflict with protection of privacy. In their RR-related activities
the sample selection is traditionally by simple random sampling (SRS) with replacement (WR). In this paper, an extension of
an essential similarity in case of general unequal probability sample selection even without replacement is reported. Large
scale surveys overwhelmingly employ complex designs other than SRSWR. So extension of RR techniques to complex designs is
essential and hence this paper principally refers to them. New jeopardy measures to protect revelation of secrecy presented
here are needed as modifications of those in the literature covering SRSWR alone. Observing that multiple responses are feasible
in addressing such a dichotomous situation especially with Kuk’s (Biometrika 77:436–438, 1990) and Christofides’ (Metrika
57:195–200, 2003) RR devices, an average of the response-specific jeopardizing measures is proposed. This measure which is
device dependent, could be regarded as a technical characteristic of the device and it should be made known to the participants
before they agree to use the randomization device.
The views expressed are the authors’, not of the organizations they work for. Prof Chaudhuri’s research is partially supported
by CSIR Grant No. 21(0539)/02/EMR-II. 相似文献
987.
Reliability sampling plans provide an efficient method to determine the acceptability of a product based upon the lifelengths
of some test units. Usually, they depend on the producer and consumer’s quality requirements and do not admit closed form
solutions. Acceptance sampling plans for one- and two-parameter exponential lifetime models, derived by approximating the
operating characteristic curve, are presented in this paper. The accuracy of these approximate plans, which are explicitly
expressible and valid for failure and progressive censoring, is assessed. The approximation proposed in the one-parameter
case is found to be practically exact. Explicit lower and upper bounds on the smallest sample size are given in the two-parameter
case. Some additional advantages are also pointed out. 相似文献
988.
In recent years, the Australian university sector has undergone large-scale organizational change, including restructuring, downsizing and government funding cuts. At the same time, research from across the globe reports an alarming increase in the occupational stress experienced by university staff. We report on the first phase of a longitudinal investigation of occupational stress. A total of 22 focus groups were conducted with a representative sample of 178 academic and general staff from 15 Australian universities. The groups focused on understanding staff 's experience of occupational stress, and perceptions of the sources, consequences and moderators of stress. Both general and academic staff reported a dramatic increase in stress during the previous 5 years. As a group, academic staff reported higher levels of stress than general staff. Five major sources of stress were identified including: insufficient funding and resources; work overload; poor management practice; job insecurity; and insufficient recognition and reward. The majority of groups reported that job-related stress was having a deleterious impact on their professional work and personal welfare. Aspects of the work environment (support from co-workers and management, recognition and achievement, high morale, flexible working conditions), and personal coping strategies (stress management techniques, work/ non-work balance, tight role boundaries and lowering standards), were reported to help staff cope with stress. The findings provide a timely insight into the experience of stress within universities. 相似文献
989.
Gart (1972) ottered a Statistic on testing the hypothesis of no second-order interaction in a 2×s×t contingency table. The statistic was tn be used as an asymptotic chi-square with (s-1) (t-1) degrees of freedom. We show that this statistic suiters from the drawback that unless certain side conditions hold, the statistic would reject the null hypothesis with probability approaching one asymptotically even in the null case. Hence the statistic is not strictly valid for the hypothesis for which it was intended. 相似文献
990.
Because outliers and leverage observations unduly affect the least squares regression, the identification of influential observations is considered an important and integrai part of the analysis. However, very few techniques have been developed for the residual analysis and diagnostics for the minimum sum of absolute errors, L1 regression. Although the L1 regression is more resistant to the outliers than the least squares regression, it appears that outliers (leverage) in the predictor variables may affect it. In this paper, our objective is to develop an influence measure for the L1 regression based on the likelihood displacement function. We illustrate the proposed influence measure with examples. 相似文献