首页 | 本学科首页   官方微博 | 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   5936篇
  免费   202篇
  国内免费   54篇
管理学   477篇
劳动科学   2篇
民族学   42篇
人口学   214篇
丛书文集   337篇
理论方法论   198篇
综合类   3214篇
社会学   176篇
统计学   1532篇
  2024年   3篇
  2023年   25篇
  2022年   44篇
  2021年   70篇
  2020年   121篇
  2019年   118篇
  2018年   154篇
  2017年   203篇
  2016年   157篇
  2015年   159篇
  2014年   296篇
  2013年   785篇
  2012年   365篇
  2011年   355篇
  2010年   277篇
  2009年   301篇
  2008年   323篇
  2007年   355篇
  2006年   330篇
  2005年   328篇
  2004年   265篇
  2003年   213篇
  2002年   216篇
  2001年   197篇
  2000年   118篇
  1999年   74篇
  1998年   46篇
  1997年   60篇
  1996年   35篇
  1995年   42篇
  1994年   24篇
  1993年   26篇
  1992年   21篇
  1991年   22篇
  1990年   17篇
  1989年   13篇
  1988年   12篇
  1987年   3篇
  1986年   4篇
  1985年   2篇
  1984年   3篇
  1983年   2篇
  1982年   4篇
  1981年   1篇
  1979年   2篇
  1978年   1篇
排序方式: 共有6192条查询结果,搜索用时 15 毫秒
131.
The literature on sequential estimation problems for negative exponential populations has been reviewed here, We attempt to bring in all the published and unpublished materials known to us in a fairly coherent fashion. Both the concepts and theoretical findings are discussed.  相似文献   
132.
This paper concludes our comprehensive study on point estimation of model parameters of a gamma distribution from a second-order decision theoretic point of view. It should be noted that efficient estimation of gamma model parameters for samples ‘not large’ is a challenging task since the exact sampling distributions of the maximum likelihood estimators and its variants are not known. Estimation of a gamma scale parameter has received less attention from the earlier researchers compared to shape parameter estimation. What we have observed here is that improved estimation of the shape parameter does not necessarily lead to improved scale estimation if a natural moment condition (which is also the maximum likelihood restriction) is satisfied. Therefore, this work deals with the gamma scale parameter estimation as a separate new problem, not as a by-product of the shape parameter estimation, and studies several estimators in terms of second-order risk.  相似文献   
133.
Stein's estimator and some other estimators of the mean of a K-variate normal distribution are known to dominate the maximum likelihood estimator under quadratic loss for K > 3, and are therefore minimax. In this paper it is shown that the minimax property of Stein's rule is preserved with respect to a generalized loss function.  相似文献   
134.
In this paper the generalized compound Rayleigh model, exhibiting flexible hazard rate, is high¬lighted. This makes it attractive for modelling survival times of patients showing characteristics of a random hazard rate. The Bayes estimators are derived for the parameters of this model and some survival time parameters from a right censored sample. This is done with respect to conjugate and discrete priors on the parameters of this model, under the squared error loss function, Varian's asymmetric linear-exponential (linex) loss function and a weighted linex loss function. The future survival time of a patient is estimated under these loss functions. A Monte Carlo simu¬lation procedure is used where closed form expressions of the estimators cannot be obtained. An example illustrates the proposed estimators for this model.  相似文献   
135.
No abstract available for this article.  相似文献   
136.
This paper describes the findings of a survey of 1109 lesbians who attended the Women's Music Festival held in Michigan in carly August 1985. The primary objectives of the study were to document the incidence of domestic violence in a non-random sample of lesbian relationships; to identify and describe the types of domestic violence experienced and/or perpetrated; and to ascertain thc availability and accessibility of community helping resources to survivors and perpetrators after an abusive episode. Comparisons with domestic violence in heterosexual relationships are also made, followed by a discussion on the research and practice implications of the findings.  相似文献   
137.
在气藏水平井中随着生产管柱倾斜角度的变化,井筒内液体的重力作用会发生改变,从而引起气液两相流型的变化。以产气为主的气井井筒内液体主要以液膜、液滴的形式出现,由此出现了液滴模型与液膜模型两种解释积液的理论。从这两种携液理论出发,考虑生产管柱倾斜角度的影响,对倾斜管内液滴、液膜进行受力分析,推导出了随管柱倾斜角度变化的连续携液临界流速的计算式,使之适用于水平井连续携液临界流量的计算。设计制作了水平气井连续携液实验装置并进行了实验研究,观测气藏水平井中气水两相运动与流型变化情况并测试其临界携液气量,结果表明,气藏水平井中水平井段的液体以液膜携带为主,但直井段中越接近井口,越以液滴携带为主,液滴模型也能适用于计算气藏水平井的连续携液临界流速。  相似文献   
138.
华庆地区长6深水沉积低渗透砂岩储层特征   总被引:1,自引:0,他引:1  
通过大量岩芯、铸体薄片、扫面电镜及物性资料分析,对鄂尔多斯盆地华庆地区长6段砂岩的沉积特征、岩石学特征、孔渗特征、成岩作用类型、孔隙结构及孔隙类型等进行了深入研究。研究表明,以深水浊积砂体为主的长6储层具有沉积物粒度偏细、成分成熟度较低、结构成熟度中等的岩石学特点;储集空间主要是原生粒间孔隙和次生溶蚀孔隙,孔隙结构以中、小孔细喉型为主。研究区孔隙度与渗透率具有较好的正相关性,为一套典型的低孔、低渗到特低孔、特低渗的储层。  相似文献   
139.
ABSTRACT

This paper reports a nearly two-year intervention with staff at a major urban pediatric facility. The authors worked as trainers and consultants for two groups–the Emergency Department (ED) and Chronic Care units (CC). Following two days of training about grief and loss, highlighting skill building for work with traumatized and grieving children and parents, the consultants worked to develop teams which could provide a Winnicottian holding environment for staff. The efficacy of this staff training is analyzed and support needs of staff members are identified. Findings include varied willingness to make use of group support. Chronic care participants are more likely to express willingness to engage in on-going support for one another, while ED staff members seem to prefer structured, educational training and episodic support. The holding environment of the processing groups must be adapted to fit the needs of the medical sub-culture.  相似文献   
140.
本文分析了朝鲜族人口减少的主要原因及负面影响,并提出了解决的对策.  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