全文获取类型
收费全文 | 598篇 |
免费 | 9篇 |
专业分类
607篇 |
出版年
2021年 | 7篇 |
2020年 | 5篇 |
2019年 | 6篇 |
2017年 | 12篇 |
2016年 | 13篇 |
2015年 | 9篇 |
2014年 | 8篇 |
2013年 | 87篇 |
2012年 | 23篇 |
2011年 | 26篇 |
2010年 | 21篇 |
2009年 | 16篇 |
2008年 | 28篇 |
2007年 | 17篇 |
2006年 | 16篇 |
2005年 | 6篇 |
2004年 | 4篇 |
2002年 | 8篇 |
1999年 | 5篇 |
1998年 | 8篇 |
1997年 | 6篇 |
1996年 | 5篇 |
1995年 | 8篇 |
1994年 | 7篇 |
1993年 | 13篇 |
1992年 | 10篇 |
1991年 | 12篇 |
1990年 | 4篇 |
1989年 | 15篇 |
1988年 | 7篇 |
1987年 | 16篇 |
1986年 | 13篇 |
1985年 | 9篇 |
1983年 | 6篇 |
1982年 | 7篇 |
1981年 | 10篇 |
1980年 | 12篇 |
1979年 | 11篇 |
1978年 | 9篇 |
1977年 | 6篇 |
1976年 | 8篇 |
1975年 | 9篇 |
1973年 | 8篇 |
1972年 | 13篇 |
1971年 | 9篇 |
1970年 | 5篇 |
1969年 | 10篇 |
1968年 | 8篇 |
1967年 | 5篇 |
1966年 | 7篇 |
排序方式: 共有607条查询结果,搜索用时 15 毫秒
41.
Capacity expansion models typically minimize the discounted cost of acquisition and operation over a given planning horizon. In this article we generalize this idea to one in which a capital supply curve replaces the usual discount rate. A capital supply curve is a means to model financial outlook, investment limits, and risk. We show that when such a curve is included in a capacity expansion model, it will, under certain conditions, provide a less capital intensive solution than one which incorporates a discount rate. In this article, we also provide an algorithm that solves capacity expansion models that incorporate a capital supply curve. The attractive feature of this algorithm is that it provides a means to utilize the “discount rate” models efficiently. Throughout, we give applications in power generation planning and computational experience for this application is also presented. 相似文献
42.
We formulate the set partitioning problem as a matching problem with simple side constraints. As a result we obtain a Lagrangian relaxation of the set partitioning problem in which the primal problem is a matching problem. To solve the Lagrangian dual we must solve a sequence of matching problems each with different edge-weights. We use the cyclic coordinate method to iterate the multipliers, which implies that successive matching problems differ in only two edge-weights. This enables us to use sensitivity analysis to modify one optimal matching to obtain the next one. We give theoretical and empirical comparisons of these dual bounds with the conventional linear programming ones. 相似文献
43.
44.
We consider the problem of scheduling a set of n jobs on a single batch machine, where several jobs can be processed simultaneously. Each job j has a processing time pj and a size sj. All jobs are available for processing at time 0. The batch machine has a capacity D. Several jobs can be batched together and processed simultaneously, provided that the total size of the jobs in the batch does not exceed D. The processing time of a batch is the largest processing time among all jobs in the batch. There is a single vehicle available for delivery of the finished products to the customer, and the vehicle has capacity K. We assume that K = rD, where and r is an integer. The travel time of the vehicle is T; that is, T is the time from the manufacturer to the customer. Our goal is to find a schedule of the jobs and a delivery plan so that the service span is minimized, where the service span is the time that the last job is delivered to the customer. We show that if the jobs have identical sizes, then we can find a schedule and delivery plan in time such that the service span is minimum. If the jobs have identical processing times, then we can find a schedule and delivery plan in time such that the service span is asymptotically at most 11/9 times the optimal service span. When the jobs have arbitrary processing times and arbitrary sizes, then we can find a schedule and delivery plan in time such that the service span is asymptotically at most twice the optimal service span. We also derive upper bounds of the absolute worst‐case ratios in both cases. © 2015 Wiley Periodicals, Inc. Naval Research Logistics 62: 470–482, 2015 相似文献
45.
F. G. Hoffman John Bew David French Nicolas Lewkowicz Thomas Rid Paul Staniland 《战略研究杂志》2013,36(5):777-795
46.
Victoria L. Zhang 《海军后勤学研究》1996,43(5):691-708
This article explores ordering policies for inventory systems with three supply modes. This model is particularly interesting because the optimal ordering decision needs to balance the inventory and purchase costs, as well as the costs for earlier and later periods. The latter cost trade-off is present only in inventory systems with three or more supply modes. Therefore, the result not only offers guidelines for the operation of the concerned inventory systems, but also provides valuable insight into the complex cost trade-offs when more supply modes are available. We assume that the difference between the lead times is one period, and the inventory holding and shortage costs are linear. We analyze two cases and obtain the structure of the optimal ordering policy. Moreover, in the first case, explicit formulas are derived to calculate the optimal order-up-to levels. In the second case, although the optimal order-up-to levels are functions of the initial inventory state and are not obtained in closed form, their properties are discussed. We also develop heuristic ordering policies based on the news-vendor model. Our numerical experiments suggest that the heuristic policies perform reasonably well. © 1996 John Wiley & Sons, Inc. 相似文献
47.
Many Markov chain models have very large state spaces, making the computation of stationary probabilities very difficult. Often the structure and numerical properties of the Markov chain allows for more efficient computation through state aggregation and disaggregation. In this article we develop an efficient exact single pass aggregation/disaggregation algorithm which exploits structural properties of large finite irreducible mandatory set decomposable Markov chains. The required property of being of mandatory set decomposable structure is a generalization of several other Markov chain structures for which exact aggregation/disaggregation algorithms exist. © 1995 John Wiley & Sons, Inc. 相似文献
48.
49.
计算了一类二次Hamilton微分系统的一阶Mel’nikov函数,通过此方法对该系统在三次多项式扰动下分岔的极限环个数进行了估计。 相似文献
50.