全文获取类型
收费全文 | 16076篇 |
免费 | 569篇 |
国内免费 | 212篇 |
专业分类
管理学 | 1869篇 |
劳动科学 | 2篇 |
民族学 | 63篇 |
人才学 | 3篇 |
人口学 | 317篇 |
丛书文集 | 779篇 |
理论方法论 | 355篇 |
综合类 | 7492篇 |
社会学 | 530篇 |
统计学 | 5447篇 |
出版年
2024年 | 20篇 |
2023年 | 128篇 |
2022年 | 223篇 |
2021年 | 248篇 |
2020年 | 367篇 |
2019年 | 468篇 |
2018年 | 529篇 |
2017年 | 669篇 |
2016年 | 548篇 |
2015年 | 562篇 |
2014年 | 894篇 |
2013年 | 2156篇 |
2012年 | 1185篇 |
2011年 | 1027篇 |
2010年 | 845篇 |
2009年 | 835篇 |
2008年 | 915篇 |
2007年 | 883篇 |
2006年 | 812篇 |
2005年 | 685篇 |
2004年 | 567篇 |
2003年 | 482篇 |
2002年 | 420篇 |
2001年 | 363篇 |
2000年 | 231篇 |
1999年 | 180篇 |
1998年 | 96篇 |
1997年 | 101篇 |
1996年 | 72篇 |
1995年 | 63篇 |
1994年 | 45篇 |
1993年 | 39篇 |
1992年 | 37篇 |
1991年 | 40篇 |
1990年 | 24篇 |
1989年 | 18篇 |
1988年 | 16篇 |
1987年 | 10篇 |
1986年 | 7篇 |
1985年 | 14篇 |
1984年 | 8篇 |
1983年 | 10篇 |
1982年 | 5篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
We used two statistical methods to identify prognostic factors: a log-linear model (logistic and COX regression, based on the notions of linearity and multiplicative relative risk), and the CORICO method (ICOnography of CORrelations) based on the geometric significance of the correlation coefficient. We applied the methods to two different situations (a "case-control study' and a "historical cohort'). We show that the geometric exploratory tool is particularly suited to the analysis of small samples with a large number of variables. It could save time when setting up new study protocols. In this instance, the geometric approach highlighted, without preconceived ideas, the potential role of multihormonality in the course of pituitary adenoma and the unexpected influence of the date of tumour excision on the risk attached to haemorrhage. 相似文献
12.
Cynthia Tojeiro Francisco Louzada-Neto Heleno Bolfarine 《Journal of applied statistics》2004,31(6):685-691
In this paper, we present a Bayesian methodology for modelling accelerated lifetime tests under a stress response relationship with a threshold stress. Both Laplace and MCMC methods are considered. The methodology is described in detail for the case when an exponential distribution is assumed to express the behaviour of lifetimes, and a power law model with a threshold stress is assumed as the stress response relationship. We assume vague but proper priors for the parameters of interest. The methodology is illustrated by a accelerated failure test on an electrical insulation film. 相似文献
13.
Jan C. H. van Eijkeren 《Risk analysis》2002,22(1):159-173
A mechanistic model is presented describing the clearance of a compound in a precision-cut liver slice that is incubated in a culture medium. The problem of estimating metabolic rate constants in PBPK models from liver slice experiments is discussed using identifiability analysis. From the identifiability problem analysis, it appears that in addition to the clearance, the compound's free fraction in the slice and the diffusion rate of the exchange of the compound between culture medium and liver slice should be identified. In addition, knowledge of the culture medium volume, the slice volume, the compound's free fraction, and octanol-water-based partition between medium and slice is presupposed. The formal solution for identification is discussed from the perspective of experimental practice. A formally necessary condition for identification is the sampling of parent compound in liver slice or culture medium. However, due to experimental limitations and errors, sampling the parent compound in the slice together with additional sampling of metabolite pooled from the medium and the slice is required for identification in practice. Moreover, it appears that identification results are unreliable when the value of the intrinsic clearance exceeds the value of the diffusion coefficient, a condition to be verified a posteriori. 相似文献
14.
发展了Baksalary和Drygas提出的一般Gauss-Markov模型中线性充分性、最小充分性和完全性的概念,用Rao的最小二乘统一理论,给出了这些概念的刻划定理。 相似文献
15.
Projecting losses associated with hurricanes is a complex and difficult undertaking that is wrought with uncertainties. Hurricane Charley, which struck southwest Florida on August 13, 2004, illustrates the uncertainty of forecasting damages from these storms. Due to shifts in the track and the rapid intensification of the storm, real-time estimates grew from 2 to 3 billion dollars in losses late on August 12 to a peak of 50 billion dollars for a brief time as the storm appeared to be headed for the Tampa Bay area. The storm hit the resort areas of Charlotte Harbor near Punta Gorda and then went on to Orlando in the central part of the state, with early poststorm estimates converging on a damage estimate in the 28 to 31 billion dollars range. Comparable damage to central Florida had not been seen since Hurricane Donna in 1960. The Florida Commission on Hurricane Loss Projection Methodology (FCHLPM) has recognized the role of computer models in projecting losses from hurricanes. The FCHLPM established a professional team to perform onsite (confidential) audits of computer models developed by several different companies in the United States that seek to have their models approved for use in insurance rate filings in Florida. The team's members represent the fields of actuarial science, computer science, meteorology, statistics, and wind and structural engineering. An important part of the auditing process requires uncertainty and sensitivity analyses to be performed with the applicant's proprietary model. To influence future such analyses, an uncertainty and sensitivity analysis has been completed for loss projections arising from use of a Holland B parameter hurricane wind field model. Uncertainty analysis quantifies the expected percentage reduction in the uncertainty of wind speed and loss that is attributable to each of the input variables. 相似文献
16.
Peter J. Robinson 《Risk analysis》1992,12(1):139-148
Because of the inherent complexity of biological systems, there is often a choice between a number of apparently equally applicable physiologically based models to describe uptake and metabolism processes in toxicology or risk assessment. These models may fit the particular data sets of interest equally well, but may give quite different parameter estimates or predictions under different (extrapolated) conditions. Such competing models can be discriminated by a number of methods, including potential refutation by means of strategic experiments, and their ability to suitably incorporate all relevant physiological processes. For illustration, three currently used models for steady-state hepatic elimination--the venous equilibration model, the parallel tube model, and the distributed sinusoidal perfusion model--are reviewed and compared with particular reference to their application in the area of risk assessment. The ability of each of the models to describe and incorporate such physiological processes as protein binding, precursor-metabolite relations and hepatic zones of elimination, capillary recruitment, capillary heterogeneity, and intrahepatic shunting is discussed. Differences between the models in hepatic parameter estimation, extrapolation to different conditions, and interspecies scaling are discussed, and criteria for choosing one model over the others are presented. In this case, the distributed model provides the most general framework for describing physiological processes taking place in the liver, and has so far not been experimentally refuted, as have the other two models. These simpler models may, however, provide useful bounds on parameter estimates and on extrapolations and risk assessments. 相似文献
17.
在讨论机载雷达地面杂波的基础上,利用最大熵估计法对机载雷达杂波进行抑制,并引入了cholcsky分解快速算法求解最大熵谱的AR模型参数。计算机模拟表明,基于最大熵谱估计的机载雷达杂波抑制技术有很高的谱分辨率,不仅能跟踪主杂波的频率位置而且能跟踪其谱宽度,因而具有较为满意的杂波对消化与改善因子。 相似文献
18.
黄映辉 《郑州轻工业学院学报(社会科学版)》2004,5(1):26-29
对应着项目的"一次性"和"多项活动复合性"的本质特征,项目管理有两种基本模式,即基于生命周期的项目管理和基于职能活动的项目管理,二者的内容体系不同,各有优劣,模式的选用要综合考虑项目的具体性质和企业的发展现状. 相似文献
19.
The authors consider the optimal design of sampling schedules for binary sequence data. They propose an approach which allows a variety of goals to be reflected in the utility function by including deterministic sampling cost, a term related to prediction, and if relevant, a term related to learning about a treatment effect To this end, they use a nonparametric probability model relying on a minimal number of assumptions. They show how their assumption of partial exchangeability for the binary sequence of data allows the sampling distribution to be written as a mixture of homogeneous Markov chains of order k. The implementation follows the approach of Quintana & Müller (2004), which uses a Dirichlet process prior for the mixture. 相似文献
20.
经济法教学实践性模式探讨 总被引:4,自引:0,他引:4
孟繁超 《江苏科技大学学报(自然科学版)》2008,8(4)
现行高校经济法教学模式一般只注重向学生传授基本的经济法学原理和相关法律知识,却忽视对学生实践能力、操作能力和思考能力的培养,造成教学和现实的脱节,同时也面临着学科自身发展瓶颈与学生就业前景暗淡的尴尬.针对经济法课程新、专、广的特点,本着培养学生经济法法律意识和法律实践能力的目的,从教学环节入手,以实践性理念为指导来设定教学目标、安排教学内容、运用多样化的教学方法和手段,构建经济法教学的实践性模式,不失为一条出路. 相似文献