全文获取类型
收费全文 | 749篇 |
免费 | 158篇 |
国内免费 | 38篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 3篇 |
2021年 | 13篇 |
2020年 | 25篇 |
2019年 | 22篇 |
2018年 | 8篇 |
2017年 | 29篇 |
2016年 | 42篇 |
2015年 | 32篇 |
2014年 | 53篇 |
2013年 | 89篇 |
2012年 | 41篇 |
2011年 | 44篇 |
2010年 | 47篇 |
2009年 | 55篇 |
2008年 | 54篇 |
2007年 | 54篇 |
2006年 | 47篇 |
2005年 | 40篇 |
2004年 | 51篇 |
2003年 | 28篇 |
2002年 | 25篇 |
2001年 | 23篇 |
2000年 | 24篇 |
1999年 | 16篇 |
1998年 | 12篇 |
1997年 | 10篇 |
1996年 | 10篇 |
1995年 | 4篇 |
1994年 | 8篇 |
1993年 | 13篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1989年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有945条查询结果,搜索用时 15 毫秒
781.
软件结构测试数据生成一直是软件测试领域一个较为复杂的问题,方法和手段尚未成熟。基于程序直接执行的测试数据生成方法因其动态性,显示出一定的优越性,本文主要针对该方法的核心部分——搜索算法进行讨论,探讨了有助于改善其功能的若干手段,目的在于提高算法效率,提高其实用化程度,显示出较好的实验效果。 相似文献
782.
We consider a two‐stage supply chain, in which multi‐items are shipped from a manufacturing facility or a central warehouse to a downstream retailer that faces deterministic external demand for each of the items over a finite planning horizon. The items are shipped through identical capacitated vehicles, each incurring a fixed cost per trip. In addition, there exist item‐dependent variable shipping costs and inventory holding costs at the retailer for items stored at the end of the period; these costs are constant over time. The sum of all costs must be minimized while satisfying the external demand without backlogging. In this paper we develop a search algorithm to solve the problem optimally. Our search algorithm, although exponential in the worst case, is very efficient empirically due to new properties of the optimal solution that we found, which allow us to restrict the number of solutions examined. Second, we perform a computational study that compares the empirical running time of our search methods to other available exact solution methods to the problem. Finally, we characterize the conditions under which each of the solution methods is likely to be faster than the others and suggest efficient heuristic solutions that we recommend using when the problem is large in all dimensions. © 2005 Wiley Periodicals, Inc. Naval Research Logistics, 2006. 相似文献
783.
Apurva Jain 《海军后勤学研究》2006,53(5):363-382
We consider the scheduling problem in a make‐to‐stock queue with two demand classes that can be differentiated based on their variability. One class experiences Poisson arrivals and the other class experiences hyperexponential renewal arrivals. We provide an exact analysis of the case where the demand class with higher variability is given non‐preemptive priority. The results are then used to compare the inventory cost performance of three scheduling disciplines, first‐come first‐serve and priority to either class. We then build on an existing dynamic scheduling heuristic to propose a modification that works well for our system. Extensions of the heuristic to more than two classes and to the case where demand state is known are also discussed. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006. 相似文献
784.
In this study, we propose a new parsimonious policy for the stochastic joint replenishment problem in a single‐location, N‐item setting. The replenishment decisions are based on both group reorder point‐group order quantity and the time since the last decision epoch. We derive the expressions for the key operating characteristics of the inventory system for both unit and compound Poisson demands. In a comprehensive numerical study, we compare the performance of the proposed policy with that of existing ones over a standard test bed. Our numerical results indicate that the proposed policy dominates the existing ones in 100 of 139 instances with comparably significant savings for unit demands. With batch demands, the savings increase as the stochasticity of demand size gets larger. We also observe that it performs well in environments with low demand diversity across items. The inventory system herein also models a two‐echelon setting with a single item, multiple retailers, and cross docking at the upper echelon. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006 相似文献
785.
The quay crane scheduling problem consists of determining a sequence of unloading and loading movements for cranes assigned to a vessel in order to minimize the vessel completion time as well as the crane idle times. Idle times originate from interferences between cranes since these roll on the same rails and a minimum safety distance must be maintained between them. The productivity of container terminals is often measured in terms of the time necessary to load and unload vessels by quay cranes, which are the most important and expensive equipment used in ports. We formulate the quay crane scheduling problem as a vehicle routing problem with side constraints, including precedence relationships between vertices. For small size instances our formulation can be solved by CPLEX. For larger ones we have developed a branch‐and‐cut algorithm incorporating several families of valid inequalities, which exploit the precedence constraints between vertices. © 2005 Wiley Periodicals, Inc. Naval Research Logistics, 2006 相似文献
786.
787.
788.
综合运用馈电信息基本理论,提出了一个基于馈电信息的故障诊断技术.该技术通过对馈电信息的比较、分析,从而实现对工作状态的监测和故障的检测;通过检测、分析馈电相关的频谱或相关的模式,实现状态分析和故障定位,完成对电子装备的故障诊断. 相似文献
789.
为评估炸药在封闭容器内爆炸产生的振动效应对周围环境的影响,对封闭式爆炸容器小药量TNT炸药爆炸产生的爆炸振动效应进行了爆源邻近实地监测和测试。结果表明:小药量炸药爆炸引起的爆炸振动效应对距爆源100 m以外的普通砖结构民用住宅产生的速度强度远低于其临界峰值速度,不会对其结构产生明显影响。 相似文献
790.
运用随机点过程方法,从理论上对可修系统能否进行分段试验进行了研究.论证了对于泊松过程模型分段试验的可行性,并研究了分段试验对参数估计的影响. 相似文献