全文获取类型
收费全文 | 8118篇 |
免费 | 189篇 |
国内免费 | 63篇 |
专业分类
管理学 | 273篇 |
劳动科学 | 2篇 |
民族学 | 73篇 |
人才学 | 1篇 |
人口学 | 48篇 |
丛书文集 | 711篇 |
理论方法论 | 176篇 |
综合类 | 4532篇 |
社会学 | 85篇 |
统计学 | 2469篇 |
出版年
2024年 | 3篇 |
2023年 | 21篇 |
2022年 | 26篇 |
2021年 | 51篇 |
2020年 | 78篇 |
2019年 | 98篇 |
2018年 | 118篇 |
2017年 | 234篇 |
2016年 | 127篇 |
2015年 | 162篇 |
2014年 | 292篇 |
2013年 | 1158篇 |
2012年 | 468篇 |
2011年 | 416篇 |
2010年 | 378篇 |
2009年 | 404篇 |
2008年 | 444篇 |
2007年 | 543篇 |
2006年 | 513篇 |
2005年 | 493篇 |
2004年 | 431篇 |
2003年 | 420篇 |
2002年 | 338篇 |
2001年 | 325篇 |
2000年 | 200篇 |
1999年 | 92篇 |
1998年 | 80篇 |
1997年 | 62篇 |
1996年 | 58篇 |
1995年 | 76篇 |
1994年 | 50篇 |
1993年 | 42篇 |
1992年 | 37篇 |
1991年 | 20篇 |
1990年 | 17篇 |
1989年 | 26篇 |
1988年 | 18篇 |
1987年 | 14篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 10篇 |
1983年 | 7篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有8370条查询结果,搜索用时 46 毫秒
121.
LetX1,X2, ..., be real-valued random variables forming a strictly stationary sequence, and satisfying the basic requirement of being either pairwise positively quadrant dependent or pairwise negatively quadrant dependent. LetF^ be the marginal distribution function of theXips, which is estimated by the empirical distribution functionFn and also by a smooth kernel-type estimateFn, by means of the segmentX1, ...,Xn. These estimates are compared on the basis of their mean squared errors (MSE). The main results of this paper are the following. Under certain regularity conditions, the optimal bandwidth (in the MSE sense) is determined, and is found to be the same as that in the independent identically distributed case. It is also shown thatn MSE(Fn(t)) andnMSE (F^n(t)) tend to the same constant, asn→∞ so that one can not discriminate be tween the two estimates on the basis of the MSE. Next, ifi(n) = min {k∈{1, 2, ...}; MSE (Fk(t)) ≤ MSE (Fn(t))}, then it is proved thati(n)/n tends to 1, asn→∞. Thus, once again, one can not choose one estimate over the other in terms of their asymptotic relative efficiency. If, however, the squared bias ofF^n(t) tends to 0 sufficiently fast, or equivalently, the bandwidthhn satisfies the requirement thatnh3n→ 0, asn→∞, it is shown that, for a suitable choice of the kernel, (i(n) ?n)/(nhn) tends to a positive number, asn→∞ It follows that the deficiency ofFn(t) with respect toF^n(t),i(n) ?n, is substantial, and, actually, tends to ∞, asn→∞. In terms of deficiency, the smooth estimateF^n(t) is preferable to the empirical distribution functionFn(t) 相似文献
122.
周日安 《佛山科学技术学院学报(社会科学版)》1996,(3)
体词谓语句是以体词作谓语,能够自由生存的句子,它是现代汉语中一种独立的句型而非动词句的省略。体词具备陈述功能,是其作谓语的语法条件,体谓句的陈述关系,主要是由两个单独体词间的并列、偏正关系,因修饰语的参与转化而来的。从语义角度说,体谓句中主谓两部分的逻辑关系、语义制约,以类的形式出现,是句子赖以存在的基础。 相似文献
123.
The maximum likelihood estimation for the critical points of the failure rate and the mean residual life function are presented
in the case of mixture inverse Gaussian model. Several important data sets are analyzed from this point of view. For each
of the data sets, Bootstrapping is used to construct confidence intervals of the critical points. 相似文献
124.
同类异质产品市场博弈Nash均衡最优策略模型 总被引:4,自引:1,他引:4
本文按照Nash均衡解的要求,建立同类异质产品市场用户需求分布及效用结构模型,导出不同定位的企业所实施竞争策略的若干最优条件,通过计算不同策略设计下产品相应的临界功能效用值,参与竞争的企业可找到适合于市场需求的最优决策。 相似文献
125.
中国股市收益率分布函数研究 总被引:14,自引:6,他引:14
本文在考察了文献中描述股票收益率的各类分布函数的基础上,以稳定Paretian分布与t分布为备择,研究了沪、深股市各类综指收益率的分布函数的形式,并对分布函数的参数进行了估计。 相似文献
126.
127.
This paper presents a genetic algorithm (GA) for parallel redundancy optimization in series-parallel power systems exhibiting
multi-state behavior, optimizing the reliability subject to constraints. The components are binary and chosen from a list
of products available in the market, and are being characterized by their feeding capacity, reliability, cost and weight.
System reliability is defined as the ability to satisfy consumer demand and is presented as a piecewise cumulative load curve.
In GA, to handle infeasible solutions penalty strategies are used. Penalty technique keep a certain amount of infeasible solutions
in each generation so as to enforce genetic search towards an optimal solution from sides of, both, feasible and infeasible
regions. We here present a dynamic adaptive penalty function which helps the algorithm to search efficiently for optimal/near
optimal solution. To evaluate system reliability, a fast procedure, based on universal generating function, is used. An example
considering a multi-state series-parallel power system is solved considering both homogeneous and heterogeneous types of redundancy.
Also an example considering price discounts is solved. The effectiveness of the penalty function and the proposed algorithm
is studied and shown graphically. 相似文献
128.
F. H. Chang H. B. Chen J. Y. Guo F. K. Hwang Uriel G. Rothblum 《Journal of Combinatorial Optimization》2006,11(3):321-339
Consider the problem of partitioning n nonnegative numbers into p parts, where part i can be assigned ni numbers with ni lying in a given range. The goal is to maximize a Schur convex function F whose ith argument is the sum of numbers assigned to part i.
The shape of a partition is the vector consisting of the sizes of its parts, further, a shape (without referring to a particular
partition) is a vector of nonnegative integers (n1,..., np) which sum to n. A partition is called size-consecutive if there is a ranking of the parts which is consistent with their sizes, and all
elements in a higher-ranked part exceed all elements in the lower-ranked part. We demonstrate that one can restrict attention
to size-consecutive partitions with shapes that are nonmajorized, we study these shapes, bound their numbers and develop algorithms
to enumerate them. Our study extends the analysis of a previous paper by Hwang and Rothblum which discussed the above problem
assuming the existence of a majorizing shape.
This research is partially supported by ROC National Science grant NSC 92-2115-M-009-014. 相似文献
129.
测试实数编码遗传算法的困难度 总被引:3,自引:0,他引:3
分析了遗传算法困难度测试在遗传算法研究中的重要意义. 鉴于当前这方面的研究集
中于二进制编码遗传算法,对实数编码遗传算法的困难度测试进行了分析. 探讨了实数编码遗
传算法困难度分析的适应值与距离相关系数测试法与基于随机游走模型的相关函数测试法,
提出了最佳一阶函数逼近测试法,做了大量实验,并根据实证分析结果对三种方法进行了比较
与评价. 相似文献
130.
生产函数与成本函数的关系研究 总被引:6,自引:1,他引:6
本文给出了生产函数与成本函数之间的一般关系,并证明齐次生产函数与齐次成本函数之间存在着一种齐次对应关系:齐次生产函数在厂商的成本最小化决策下必然产生齐次的成本函数且齐次成本函数必然产生对应于齐次的生产函数。 相似文献