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:      
  示例: 沙坡头地区,人工植被区,变化  检索词用空格隔开表示必须包含全部检索词,用“,”隔开表示只需满足任一检索词即可!
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   15100篇
  免费   51篇
  国内免费   1篇
管理学   2168篇
民族学   77篇
人口学   1360篇
丛书文集   54篇
理论方法论   1280篇
综合类   158篇
社会学   6682篇
统计学   3373篇
  2024年   72篇
  2023年   108篇
  2021年   91篇
  2020年   230篇
  2019年   337篇
  2018年   352篇
  2017年   510篇
  2016年   376篇
  2015年   255篇
  2014年   364篇
  2013年   2669篇
  2012年   450篇
  2011年   435篇
  2010年   321篇
  2009年   313篇
  2008年   335篇
  2007年   308篇
  2006年   353篇
  2005年   322篇
  2004年   295篇
  2003年   271篇
  2002年   314篇
  2001年   346篇
  2000年   361篇
  1999年   348篇
  1998年   265篇
  1997年   250篇
  1996年   224篇
  1995年   199篇
  1994年   237篇
  1993年   203篇
  1992年   237篇
  1991年   253篇
  1990年   239篇
  1989年   241篇
  1988年   171篇
  1987年   195篇
  1986年   179篇
  1985年   199篇
  1984年   182篇
  1983年   172篇
  1982年   148篇
  1981年   127篇
  1980年   130篇
  1979年   139篇
  1978年   128篇
  1977年   106篇
  1976年   101篇
  1975年   104篇
  1974年   95篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Several models are proposed in the literature for modeling fatigue data resulting from materials subject to cyclic stress and strain. Accelerated Weibull and accelerated Birnbaum–Saunders distributions are most commonly used models. Whereas the accelerated Weibull model is easier compared to accelerated Birnbaum–Saunders, it fails to represent the situation equally well. The present article focuses on Bayes analysis of the two models and provides a comparison based on some important Bayesian tools. Model compatibility study using predictive simulation ideas is preceded by the said comparison. Throughout, the posterior simulations are carried out by Markov chain Monte Carlo procedure.  相似文献   
102.
An alternate representation of the densities of some test statistics for the structural coefficients of the multivariate linear functional relationship model is proposed in this article. These statistics are distributed as the ratio of a linear combination of chi-square variÂtes over the root of a product of chi-square variÂtes. A computable representation of their densities has already been derived by Provost (1984) with the help of the technique of the inverse Mellin transform. The connection of the alternate representation to the densities of products of independent beta type-2 and of independent F-random variables is also discussed.  相似文献   
103.
In a multi-sample simple regression model, generally, homogeneity of the regression slopes leads to improved estimation of the intercepts. Analogous to the preliminary test estimators, (smooth) shrinkage least squares estimators of Intercepts based on the James-Stein rule on regression slopes are considered. Relative pictures on the (asymptotic) risk of the classical, preliminary test and the shrinkage least squares estimators are also presented. None of the preliminary test and shrinkage least squares estimators may dominate over the other, though each of them fares well relative to the other estimators.  相似文献   
104.
Nonparametric tests for the null hypothesis of no treatment effect in the mixed-model experiment which involves n randomly chosen subjects who respond once to each of ρ distinct treatments have been developed by Koch and Sen (1968), These tests were based on the assumption of compound symmetry of the error vectors and on the weaker assumption of diagonal symmetry of the error vectors. This paper considers an alternative (permutationally) distribution-free test under this latter assumption. The new test follows the same type of distribution theory as those in Koch and Sen, but utilizes the inherent invariance structure in a more visable and direct way.  相似文献   
105.
Simplified proofs are given of a standard result that establishes positive semi–definiteness of the difference of the inverses of two non–singular matrices, and of the extension of this result by Milliken and Akdeniz (1977) to the difference of the Moore–Penrose inverse of two singular matrices.  相似文献   
106.
This paper presents the sinplesr procedure that uses wodular aryithmetic for constructing confounded designs for mixed factorial experiments. The present procedure and the classical one for confounding in symmetrical factorial experiments are both at the same mathema.tical level. The present procedure is written for

practitioners and is lllustrared with several examples.  相似文献   
107.
A stepwise algorithm for selecting categories for the chisquared goodness-of-fit test with completely specified continuous null and alternative distributions is described in this paper. The procedure's starting point is an initial partitioning of the sample space into a large number of categories. A second partition with one fewer category is constructed by combining two categories of the original partition. The procedure continues until there are only two categories; the partition in the sequence with the highest estimated power is the one chosen. For illustartive purposes, the performance of the algorithm is evaluated for several hypothesis tests of the from H0: normal distribution vs. H1: a specific mixed normal distribution. For each test considered, the partition identified by the algorithm was compared to several equiprobable partitions, including the equiprobable partition with the highest estimated power. In all cases but one, the algorithm identified a parttion with higher estimated power than the best equiprobable partition. Applciations of the procedure are discussed.  相似文献   
108.
Consider a life testing experiment in which n units are put on test, successive failure times are recorded, and the observation is terminated either at a specified number r of failures or a specified time T whichever is reached first. This mixture of type I and type II censoring schemes, called hybrid censoring, is of wide use. Under this censoring scheme and the assumption of an exponential life distribution, the distribution of the maximum likelihood estimator of the mean life θ is derived. It is then used to construct an exact lower confidence bound for θ.  相似文献   
109.
This paper considers procedures for the detection of heteroscedasticity when it occurs at unknown points. First the number of points is assumed known apriori and then this assumption is relaxed so that both the position and the number of possible aberrant observations is unknown. Monte Carlo evidence is provided on the performance of both tests and they are found to perform reasonably.  相似文献   
110.
The problem of testing suspected outliers from a linear model with constant intraclass correlation is considered from a Bayesian viewpoint. The main objective of this paper is to develop an outlier test procedure based on the predictive distribution of suspected outlier observations given a set of existing inlier observations. The test procedure is easily performed with the usual F and t distributions.  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