全文获取类型
收费全文 | 3431篇 |
免费 | 84篇 |
国内免费 | 1篇 |
专业分类
3516篇 |
出版年
2021年 | 38篇 |
2019年 | 90篇 |
2018年 | 55篇 |
2017年 | 86篇 |
2016年 | 82篇 |
2015年 | 63篇 |
2014年 | 67篇 |
2013年 | 741篇 |
2010年 | 37篇 |
2009年 | 40篇 |
2008年 | 50篇 |
2007年 | 52篇 |
2006年 | 38篇 |
2005年 | 46篇 |
2004年 | 57篇 |
2003年 | 43篇 |
2002年 | 57篇 |
1999年 | 42篇 |
1998年 | 47篇 |
1997年 | 49篇 |
1996年 | 63篇 |
1995年 | 44篇 |
1994年 | 59篇 |
1993年 | 65篇 |
1992年 | 60篇 |
1991年 | 75篇 |
1990年 | 41篇 |
1989年 | 72篇 |
1988年 | 79篇 |
1987年 | 71篇 |
1986年 | 71篇 |
1985年 | 65篇 |
1984年 | 36篇 |
1983年 | 42篇 |
1982年 | 43篇 |
1981年 | 47篇 |
1980年 | 51篇 |
1979年 | 46篇 |
1978年 | 49篇 |
1977年 | 45篇 |
1976年 | 45篇 |
1975年 | 47篇 |
1974年 | 52篇 |
1973年 | 51篇 |
1972年 | 52篇 |
1971年 | 44篇 |
1970年 | 40篇 |
1969年 | 40篇 |
1968年 | 34篇 |
1967年 | 35篇 |
排序方式: 共有3516条查询结果,搜索用时 15 毫秒
21.
New closure theorems for shock models in reliability theory are presented. If the number of shocks to failure and the times between the arrivals of shocks have probability distributions of phase type, then so has the time to failure. PH-distributions are highly versatile and may be used to model many qualitative features of practical interest. They are also well-suited for algorithmic implementation. The computational aspects of our results are discussed in some detail. 相似文献
22.
We consider the problem of scheduling n tasks on two identical parallel processors. We show both in the case when the processing times for the n tasks are independent exponential random variables, and when they are independent hyperexponentials which are mixtures of two fixed exponentials, that the policy of performing tasks with longest expected processing time (LEPT) first minimizes the expected makespan, and that in the hyperexponential case the policy of performing tasks with shortest expected processing time (SEPT) first minimizes the expected flow time. The approach is simpler than the dynamic programming approach recently employed by Bruno and Downey. 相似文献
23.
J. G. Shanthikumar 《海军后勤学研究》1979,26(2):305-309
This paper discusses a class of queueing models in which the service time of a customer al a single server facility is dependent on the queue size at the onset of its service. The Laplace transform for the wait in queue distribution is derived and the utilization of the server is given when the arrival is a homogeneous Poisson process. 相似文献
24.
John P. Matthews 《海军后勤学研究》1977,24(4):679-690
The purpose of this paper and the accompanying tables is to facilitate the calculation of constrained optimum order quantities and reorder points for an inventory control system where the criterion of optimality is the minimization of expected inventory holding, ordering, and time-weighted backorder costs. The tables provided in the paper allow the identification of the optimal solution when order quantities and/or reorder points are restricted to a set of values which do not include the unconstrained optimal solution. 相似文献
25.
Today, few countries fight alone; most fight as allies or partners in multilateral campaigns. The end of the Cold War opened a window of opportunity for multinational military operations (MMOs). These have seen varying degrees of participation, enthusiasm, and success. This special forum is devoted to the politics of multilateral warfare including their formation, maintenance, and durability. The introduction sketches past research and derives some key questions of continuing relevance. The contributions shed light on the domestic and international politics of MMOs, focusing on the implementation of national restrictions and their repercussions for MMOs, party politics of military intervention, the conditions under which states decide to defect from military operations, and the role of junior partners in MMOs. In sum, this forum offers a fresh look at the politics of MMOs, including conceptual contributions to the study of national restrictions, domestic constraints, and coalition warfare. 相似文献
26.
In this article, we are concerned with scheduling stochastic jobs in a flowshop with m machines and zero intermediate storage. We assume that there are n - 2 identically distributed and 2 fast stochastic jobs. Roughly, the main result states that the makespan is stochastically minimized by placing one of the fast jobs first and the other last. 相似文献
27.
28.
A common problem in life testing is to demonstrate that the mean time to failure, θ, exceeds some minimum acceptable value, say θ1, with a given confidence coefficient γ. When this is true, it is said that “θ1 has been demonstrated with a confidence γ”. In this paper a Sequential Bayes Procedure (SBP) for demonstrating (by means of. a probability statement) that θ exceeds θ1 is presented. The SBP differs from the classical procedure in the sense that a prior distribution is assumed on the parameter θ, calling for a Bayesian approach. The procedure is based on the sequence of statistics. 相似文献
29.
Under certain conditions, the re-supply capability of a combatant force may be limited by the characteristics of the transportation network over which supplies must flow. Interdiction by an opposing force may be used to reduce the capacity of that network. The effects of such efforts vary for differing missions and targets. With only a limited total budget available, the interdictor must decide which targets to hit, and with how much effort. An algorithm is presented for determining the optimum interdiction plan for minimizing network flow capacity when the minimum capacity on an arc is positive and the cost of interdiction is a linear function of arc capacity reduction. 相似文献
30.
This paper presents a general solution for the M/M/r queue with instantaneous jockeying and r > 1 servers. The solution is obtained in matrices in closed form without recourse to the generating function arguments usually used. The solution requires the inversion of two (Zr?1) × (2r?1) matrices. The method proposed is extended to allow different queue selection preferences of arriving customers, balking of arrivals, jockeying preference rules, and queue dependent selection along with jockeying. To illustrate the results, a problem previously published is studied to show how known results are obtained from the proposed general solution. 相似文献