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   1260篇
  免费   82篇
  国内免费   9篇
管理学   107篇
民族学   3篇
人口学   32篇
丛书文集   45篇
理论方法论   56篇
综合类   200篇
社会学   141篇
统计学   767篇
  2023年   5篇
  2022年   10篇
  2021年   33篇
  2020年   30篇
  2019年   45篇
  2018年   56篇
  2017年   30篇
  2016年   44篇
  2015年   35篇
  2014年   42篇
  2013年   134篇
  2012年   67篇
  2011年   101篇
  2010年   65篇
  2009年   105篇
  2008年   80篇
  2007年   102篇
  2006年   27篇
  2005年   20篇
  2004年   18篇
  2003年   21篇
  2002年   14篇
  2001年   16篇
  2000年   6篇
  1999年   7篇
  1998年   2篇
  1997年   9篇
  1996年   5篇
  1995年   20篇
  1994年   15篇
  1993年   2篇
  1992年   2篇
  1989年   3篇
  1988年   2篇
  1986年   1篇
  1985年   19篇
  1984年   34篇
  1983年   30篇
  1982年   30篇
  1981年   15篇
  1980年   18篇
  1979年   8篇
  1978年   21篇
  1977年   2篇
排序方式: 共有1351条查询结果,搜索用时 31 毫秒
81.
This paper presents a class of estimators for the mean of a normal population and determines the conditions on characterizing scalars under which the class of estimators uniformly dominates over the conventional sample mean according to the mean-square-error criterion.  相似文献   
82.
在全球各区域经济合作中,东亚区域经济合作处于制度推进的初级阶段。在东亚合作约束条件序列中,经济整合度和贸易开放约束较小,主导国和主导力量约束次之,政治和文化约束最大。与欧洲和北美区域经济合作不同,东亚文化背景殊异;百年殖民历史伤痛犹新;放弃国家主权疑虑重重,还没有形成能够协调各方利益和促进区域经济合作的稳定制度机制。在内部和外部条件限制下,东亚经济一体化只能通过三个相互割裂的“东盟10 l”机制“迂回”推进,而且在相当长时期合作采取的是自由贸易区方式。  相似文献   
83.
3G“杀手级”业务的产生和培育   总被引:1,自引:1,他引:0  
3G时代的到来无疑为电信市场的发展带来了机遇和挑战,到底怎样的电信业务能在新时代中脱颖而出,成为业内人士心驰神往的“杀手级”业务,的确是个耐人寻味的问题。在对“杀手级”业务所应具备的基本条件作探讨的同时,对“杀手级”业务的培育策略进行了分析,认为“杀手级”业务本不存在,它的形成是市场多方因素共同努力的结果。  相似文献   
84.
A dynamic model of a heterogeneous population is studied. Particles belonging to a population are divided, at every time t, into a finite number of classes according to their types and the partition changes over time. The role of the occupancy numbers, namely the cardinality of each class, is highlighted. The relationship between the stochastic process of occupancy numbers and the process of particle types is analyzed. The main goal of this paper is the estimation of the lifetime of each particle at a given time t, when the observed data are the history of the process of the number of dead particles up to t. Furthermore, a discrete time approximation of the filter is given.  相似文献   
85.
The relative performance of a component of a series system in two different environments is considered. The conditional probability of the failure of the system due to the failure of the specified component given that the system failed before time t is regarded as a measure of relative importance of the component to the system. A U-statistic test for checking the equality of the relative importance of the component to the system in two different environments against the alternative that the relative importance is smaller in one of the environments, is proposed. Some simulation results for estimating the power of the test are reported. The proposed test is applied to one real data set and it is seen that a different aspect of the data is brought out by this comparison than that by the comparisons of the absolute importance functions such as the subsurvival functions, considered in earlier studies.  相似文献   
86.
This paper deals with models and methods for count data derived from observations on pairing phenomena. Pairs formed from “similar” members are excluded. Various models are considered and analyzed. Particular emphasis is on developing methods for testing whether particular pairs are prone to occur more or less often than expected by chance.  相似文献   
87.
引入域上典型群的生成问题所得的成果;对局部环R上典型群生成问题研究,构造度量函数及一平延,为局部环R上典型群向域F上的典型群导入,给出典型群的非双曲型.  相似文献   
88.
In a clinical trial comparing drug with placebo, where there are multiple primary endpoints, we consider testing problems where an efficacious drug effect can be claimed only if statistical significance is demonstrated at the nominal level for all endpoints. Under the assumption that the data are multivariate normal, the multiple endpoint-testing problem is formulated. The usual testing procedure involves testing each endpoint separately at the same significance level using two-sample t-tests, and claiming drug efficacy only if each t-statistic is significant. In this paper we investigate properties of this procedure. We show that it is identical to both an intersection union test and the likelihood ratio test. A simple expression for the p-value is given. The level and power function are studied; it is shown that the test may be conservative and that it is biased. Computable bounds for the power function are established.  相似文献   
89.
Fluctuations in aggregate crime rates contrary to recent shifts in the age distribution of the U.S. population have cast doubt on the predictive power of the age–crime hypothesis. By examining a longer time horizon, back to the early 1930s, we show that the percentage of the young population is a robust predictor of the observed large swings in the U.S. murder rate over time. However, changes in the misery index—the sum of the inflation and unemployment rates—significantly contribute to explaining changes in the murder rate. This applies, in particular, to those changes that are at odds with the long-run trend of the U.S. age distribution, such as the decline in the murder rate in the latter part of the 1970s or its increase starting around the middle of the 1980s.  相似文献   
90.
文章介绍了第四代移动通信的概念,主要应用的技术以及4G的发展前景.  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