首页 | 官方网站   微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3675篇
  免费   820篇
社会科学   4495篇
  2023年   7篇
  2021年   77篇
  2020年   153篇
  2019年   324篇
  2018年   145篇
  2017年   245篇
  2016年   291篇
  2015年   285篇
  2014年   264篇
  2013年   522篇
  2012年   219篇
  2011年   218篇
  2010年   184篇
  2009年   146篇
  2008年   184篇
  2007年   131篇
  2006年   154篇
  2005年   117篇
  2004年   117篇
  2003年   104篇
  2002年   78篇
  2001年   86篇
  2000年   70篇
  1999年   32篇
  1998年   15篇
  1997年   21篇
  1996年   17篇
  1995年   14篇
  1994年   17篇
  1993年   32篇
  1992年   15篇
  1991年   16篇
  1990年   12篇
  1989年   16篇
  1988年   16篇
  1987年   12篇
  1986年   7篇
  1985年   7篇
  1984年   5篇
  1983年   8篇
  1982年   8篇
  1981年   7篇
  1980年   7篇
  1979年   15篇
  1978年   9篇
  1977年   14篇
  1976年   6篇
  1975年   14篇
  1974年   8篇
  1973年   7篇
排序方式: 共有4495条查询结果,搜索用时 15 毫秒
171.
In geostatistics and also in other applications in science and engineering, it is now common to perform updates on Gaussian process models with many thousands or even millions of components. These large‐scale inferences involve modelling, representational and computational challenges. We describe a visualization tool for large‐scale Gaussian updates, the ‘medal plot’. The medal plot shows the updated uncertainty at each observation location and also summarizes the sharing of information across observations, as a proxy for the sharing of information across the state vector (or latent process). As such, it reflects characteristics of both the observations and the statistical model. We illustrate with an application to assess mass trends in the Antarctic Ice Sheet, for which there are strong constraints from the observations and the physics.  相似文献   
172.
With competing risks data, one often needs to assess the treatment and covariate effects on the cumulative incidence function. Fine and Gray proposed a proportional hazards regression model for the subdistribution of a competing risk with the assumption that the censoring distribution and the covariates are independent. Covariate‐dependent censoring sometimes occurs in medical studies. In this paper, we study the proportional hazards regression model for the subdistribution of a competing risk with proper adjustments for covariate‐dependent censoring. We consider a covariate‐adjusted weight function by fitting the Cox model for the censoring distribution and using the predictive probability for each individual. Our simulation study shows that the covariate‐adjusted weight estimator is basically unbiased when the censoring time depends on the covariates, and the covariate‐adjusted weight approach works well for the variance estimator as well. We illustrate our methods with bone marrow transplant data from the Center for International Blood and Marrow Transplant Research. Here, cancer relapse and death in complete remission are two competing risks.  相似文献   
173.
This paper deals with the problem of predicting the real‐valued response variable using explanatory variables containing both multivariate random variable and random curve. The proposed functional partial linear single‐index model treats the multivariate random variable as linear part and the random curve as functional single‐index part, respectively. To estimate the non‐parametric link function, the functional single‐index and the parameters in the linear part, a two‐stage estimation procedure is proposed. Compared with existing semi‐parametric methods, the proposed approach requires no initial estimation and iteration. Asymptotical properties are established for both the parameters in the linear part and the functional single‐index. The convergence rate for the non‐parametric link function is also given. In addition, asymptotical normality of the error variance is obtained that facilitates the construction of confidence region and hypothesis testing for the unknown parameter. Numerical experiments including simulation studies and a real‐data analysis are conducted to evaluate the empirical performance of the proposed method.  相似文献   
174.
Input from consumers has become an important part of quality improvement in long-term care and for consumer decision-making. This paper documents the development of the Ohio Nursing Home Resident Satisfaction Survey (ONHRSS) through a partnership of state government, research, and industry experts. The instrument was tested and refined through two waves of data--a pretest phase and later with statewide data. Exploratory and confirmatory analyses with statewide data identified eight primary factors along with an underlying, secondary Global Satisfaction factor. Reliability of the domains ranged from .69 to .95. Recommendations for further refinement and testing of the instrument are discussed along with policy and practice implications.  相似文献   
175.
176.
By building on a genetic‐inspired attribute‐based conceptual framework for safety risk analysis, we propose a novel approach to define, model, and simulate univariate and bivariate construction safety risk at the situational level. Our fully data‐driven techniques provide construction practitioners and academicians with an easy and automated way of getting valuable empirical insights from attribute‐based data extracted from unstructured textual injury reports. By applying our methodology on a data set of 814 injury reports, we first show the frequency‐magnitude distribution of construction safety risk to be very similar to that of many natural phenomena such as precipitation or earthquakes. Motivated by this observation, and drawing on state‐of‐the‐art techniques in hydroclimatology and insurance, we then introduce univariate and bivariate nonparametric stochastic safety risk generators based on kernel density estimators and copulas. These generators enable the user to produce large numbers of synthetic safety risk values faithful to the original data, allowing safety‐related decision making under uncertainty to be grounded on extensive empirical evidence. One of the implications of our study is that like natural phenomena, construction safety may benefit from being studied quantitatively by leveraging empirical data rather than strictly being approached through a managerial perspective using subjective data, which is the current industry standard. Finally, a side but interesting finding is that in our data set, attributes related to high energy levels (e.g., machinery, hazardous substance) and to human error (e.g., improper security of tools) emerge as strong risk shapers.  相似文献   
177.
178.
179.
Explaining the survival and failure of firms is an important issue for researchers and managers of firms in society. Ecological approaches to the study of firms have existed for over 100 years, and have been increasingly popular during the past 40 years, especially since the pioneering works of Hannan and Freeman on one hand, and Aldrich on the other. This paper, in keeping with recent developments elsewhere in mainstream ecology outlines and positions the theoretical and philosophical foundations of an alternative ecological approach, autecology, that has not yet been formulated for the study of firms. The autecological approach affords the individual firm more autonomy in creating its own future evolutionary trajectory. The idea of an ecological complex is developed to provide clear focus on what is central to the application of autecology to the study of firms. The paper also considers several emergent research opportunities that highlight the potential value of employing an autecological approach to the study of firms.  相似文献   
180.
The term gridlock describes the occurrence of rigid patterns in couples’ conflict. This study aimed to describe strategies of conflict resolution and gridlock prevention from the perspectives of couples and couple therapists. Participants were couple therapists and highly adjusted couples scored by the dyadic adjustment scale (DAS), distributed according to traditional and non‐traditional position in life and duration of relationships. Conflict gridlock scenarios were used to create video stimulus that were presented to participants. A qualitative methodology was used to analyse couples’ and therapists’ commentaries on the scenarios. Results showed differences in preventing conflict gridlock among sub‐groups of couples. Long‐term traditional couples focused on loyalty to a common project and value sacrificing to a higher good; long‐term non‐traditional couples prioritised caring and validating the bond in the relationship. Short‐term traditional couples focused on mutual love and the relief of hurt while short‐term non‐traditional couples supported the value of equity.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司    京ICP备09084417号-23

京公网安备 11010802026262号