全文获取类型
收费全文 | 1465篇 |
免费 | 138篇 |
国内免费 | 15篇 |
专业分类
管理学 | 119篇 |
民族学 | 5篇 |
人口学 | 19篇 |
丛书文集 | 88篇 |
理论方法论 | 125篇 |
综合类 | 638篇 |
社会学 | 85篇 |
统计学 | 539篇 |
出版年
2024年 | 3篇 |
2023年 | 10篇 |
2022年 | 19篇 |
2021年 | 25篇 |
2020年 | 24篇 |
2019年 | 69篇 |
2018年 | 58篇 |
2017年 | 39篇 |
2016年 | 51篇 |
2015年 | 59篇 |
2014年 | 65篇 |
2013年 | 132篇 |
2012年 | 88篇 |
2011年 | 104篇 |
2010年 | 81篇 |
2009年 | 114篇 |
2008年 | 104篇 |
2007年 | 93篇 |
2006年 | 66篇 |
2005年 | 40篇 |
2004年 | 43篇 |
2003年 | 36篇 |
2002年 | 36篇 |
2001年 | 38篇 |
2000年 | 18篇 |
1999年 | 20篇 |
1998年 | 14篇 |
1997年 | 16篇 |
1996年 | 10篇 |
1995年 | 10篇 |
1994年 | 17篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 8篇 |
1984年 | 21篇 |
1983年 | 12篇 |
1982年 | 15篇 |
1981年 | 6篇 |
1980年 | 10篇 |
1979年 | 4篇 |
1978年 | 12篇 |
1977年 | 1篇 |
排序方式: 共有1618条查询结果,搜索用时 218 毫秒
201.
Recursive estimates of a probability density function (pdf) are known. This paper presents recursive estimates of a derivative of any desired order of a pdf. Let f be a pdf on the real line and p?0 be any desired integer. Based on a random sample of size n from f, estimators f(p)n of f(p), the pth order derivatives of f, are exhibited. These estimators are of the form , where δjp depends only on p and the jth observation in the sample, and hence can be computed recursively as the sample size increases. These estimators are shown to be asymptotically unbiased, mean square consistent and strongly consistent, both at a point and uniformly on the real line. For pointwise properties, the conditions on f(p) have been weakened with a little stronger assumption on the kernel function. 相似文献
202.
David G. Gil 《Children and youth services review》1984,6(4):299-309
This paper examines consequences for child development and well-being of the prevailing institutional order and ideology of the United States and concludes that child development in our country is severely obstructed because of socially structured violence which permeates our way of life. The paper ends with comments on prospects for social transformation which seems necessary to assure the development and well-being of every child. 相似文献
203.
For testing the hypothesis that several (s?2) linear regression surfaces Xki=αk+βkcki+Zki (k=1,…,s) are parallel to one another, i.e., β1=?=βs, a class of rank-order tests are considered. The tests are shown to be asymptotically distribution-free, and their asymptotic efficiency relative to the general likelihood ratio test is derived. Asymptotic optimality in the sense of Wald is also discussed. 相似文献
204.
We consider the problem of binary-image restoration. The image being restored is not random, and we make no assumption about the nature of its contents. The estimate of the colour at each site is a fixed (the same for all sites) function of the data available in a neighbourhood of that site. Under this restriction, the estimate minimizing the overall mean squared error of prediction is the conditional expectation of the true colour given the observations in the neighbourhood of a site. The computation of this conditional expectation leads to the formal definition of the local characteristics of an image, namely, the frequency with which each pattern appears in the true unobserved image. When the “true” distribution of the patterns is unknown, it can be estimated from the records. The conditional expectation described above can then be evaluated using the estimated distribution of the patterns, and this procedure leads to a very natural estimate of the colour at each site. We propose two unbiased and consistent estimates for the distribution of patterns when the noise is a Gaussian white noise. Since the size of realistic images is very large, the estimated pattern distribution is usually close to the true one. This suggests that the estimated conditional expectation can be expected to be nearly optimal. An interesting feature of the proposed restoration methods is that they do not require prior knowledge of the local or global properties of the true underlying image. Several examples based on synthetic images show that the new methods perform fairly well for a variety of images with different degrees of colour continuity or textures. 相似文献
205.
Vasant P. Bhapkar 《Journal of statistical planning and inference》1984,9(3):285-296
A unified development is offered for asymptotically distribution-free profile analysis of several multivariate samples. This includes as special cases procedures based on generalized U-statistics and also those based on linear rank statistics. Furthermore, it includes as special cases analysis of location profiles and also scalar profiles. Finally, asymptotic power and consistency properties are discussed for tests of hypotheses and subhypotheses of interest. 相似文献
206.
Hira L. Koul 《Revue canadienne de statistique》1978,6(2):249-271
A class of tests is proposed for testing H0 F?(x) = e?λx, λ > 0, x≥0 vs. H1 F?(x + y) ≤ F?(x)F?(y), x, y≥0, with strict inequality for some x, y ≥ 0 (F = new is better than used). Efficiency comparisons of some tests within the class are made and a new test is proposed on the basis of these comparisons. Consistency and the asymptotic normality of the class of tests is proved under fairly broad conditions on the underlying entities. 相似文献
207.
张祥发 《广东工业大学学报(社会科学版)》2005,5(4):44-47
随着生物技术的发展,对生物技术所必须的原材料-基因的保护迫在眉睫。文章提出了由于国际社会对基因资源缺乏强有力的保护而出现的“生物海盗”问题,阐述了世界贸易组织(WTO)历届部长会议对基因资源的讨论,然后论述了在世贸组织新一轮多边贸易谈判中如何修改《与贸易有关的知识产权协议》(TRIPs)第27条,将基因资源保护纳入到 TRIPs框架之内。文章还阐明了中国作为基因资源极其丰富的发展中国家对基因资源的保护应有的姿态。 相似文献
208.
On 3-Stage Clos Networks with Different Nonblocking Requirements on Two Types of Calls 总被引:1,自引:0,他引:1
Hwang and Lin introduced a new nonblocking requirement for 2-cast traffic which imposes different requirements on different types of coexisting calls. The requirement is strictly nonblocking for point-to-point calls among the 2-cast traffic, and is rearrangeable for genuine 2-cast calls. They conjectured that the 3-stage Clos network C(n,n,r,r,2n) satisfies the above requirement. We prove that C(n,n,4,r,2n) satisfies the above requirement.Supported in part by NSC91-2115-M009-002.Supported in part by the National Science Council under grant NSC91-2115-M009-010 and by the Li-Li-Tai-Yang Network Research Center of National Chiao Tung University. 相似文献
209.
Let Xi≤?≤Xm and Yi≤?≤Yn be two sets of independent order statistics from continous distributions with distribution functions F and G respectively. Let Ri denote the rank of Xi in the combined order sample. Steck (1980) has found an expression for P(bi≤Ri≤ai, all i) when F = h(G), h being the incomplete beta function with parameters (α,β?α+1). An alternative expression for the same probability is obtained which is computationally a substantial improvement on Steck's result. 相似文献
210.
Smiley W. Cheng 《Journal of statistical planning and inference》1980,4(3):259-265
The asymptotically best linear unbiased estimate (ABLUE) of the normal mean is discussed. The estimate is based on k selected order statistics chosen from a singly or doubly censored large sample of size n(>k). The coefficients, the asymptotic relative efficiency of the estimate, and the optimum spacing of k real numbers between 0 and 1 which determines the optimum ranks of order statistics, are provided. A comparison between the ABLUE and the iterated maximum likelihood estimate is made. 相似文献