全文获取类型
收费全文 | 713篇 |
免费 | 238篇 |
国内免费 | 36篇 |
出版年
2024年 | 3篇 |
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 15篇 |
2020年 | 22篇 |
2019年 | 17篇 |
2018年 | 16篇 |
2017年 | 44篇 |
2016年 | 34篇 |
2015年 | 30篇 |
2014年 | 57篇 |
2013年 | 109篇 |
2012年 | 38篇 |
2011年 | 35篇 |
2010年 | 38篇 |
2009年 | 29篇 |
2008年 | 26篇 |
2007年 | 43篇 |
2006年 | 36篇 |
2005年 | 43篇 |
2004年 | 38篇 |
2003年 | 26篇 |
2002年 | 25篇 |
2001年 | 40篇 |
2000年 | 15篇 |
1999年 | 24篇 |
1998年 | 20篇 |
1997年 | 21篇 |
1996年 | 22篇 |
1995年 | 16篇 |
1994年 | 42篇 |
1993年 | 15篇 |
1992年 | 8篇 |
1991年 | 13篇 |
1990年 | 10篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1987年 | 3篇 |
排序方式: 共有987条查询结果,搜索用时 15 毫秒
811.
812.
The Selection Allocation Problem (SAP) is a single period decision problem which involves selecting profit‐maximizing (or cost‐minimizing) activities from various distinct groups, and determining the volume of those activities. The activities in each group are selected subject to the availability of that group's resource, which is provided by either pooling or blending raw inputs from several potential sources. Imbedded in the decision process is the additional task of determining how much raw input is to be allocated to each group to form the resource for that group. Instances of this problem can be found in many different areas, such as in tool selection for flexible manufacturing systems, facility location, and funding for social services. Our goal in this paper is to identify and exploit special structures in the (SAP) and use those structures to develop an efficient solution procedure. © 1999 John Wiley & Sons, Inc. Naval Research Logistics 46: 707–725, 1999 相似文献
813.
互联网端到端的设计原则没有区分端系统和网络间接口,使得用户分组处理期望无法告知网络,降低了网络效能。首次提出用户转发意图概念,端系统凭此向网络通告其意图,并借助网络边缘计算能力得以执行,实现用户意图在网络节点转发决策中的主动使能,构成新型主动表意网络i-ECAN。主动表意网络可以在视频直播加速、物联网数据融合、端系统安全认证等场景中得到应用。基于CORE模拟器构建网络演示环境,对无线网络切换和基于主动表意网络的无线网络切换的延迟进行比较,证明了主动表意网络机制的合理性和可行性。主动表意网络扩展了新的端系统和网络之间的接口,为人-网协同提供了基础。 相似文献
814.
This article reassesses the foreign policy legacy of George W. Bush in light of the emerging historical record of his administration. We conclude that, whereas Bush’s foreign policy was in widespread disrepute when he left office in 2009, that reputation is likely to improve – perhaps significantly – in the coming years. We identify six particular arguments that lend credence to an emerging ‘Bush revisionism.’ To be clear, we do not necessarily argue that the balance sheet on Bush’s foreign policy was positive, but the arguments presented here are likely to generate a more sympathetic and favorable historical assessment of Bush’s presidency over time. 相似文献
815.
The rhino is going extinct due to poaching at a rate which far outstrips current law enforcement or conservation efforts to halt their decline. A critical aspect of counter-poaching failures to date is an inaccurate view of the nature of poaching as a crime. Rather than demand-side efforts, attacking elusive smuggling networks or expensive technical solutions like drones, this article notes how a quasi-military tactical approach of ‘combat tracking’ offers the best way to protect the species. Based on wide ranging interviews and fieldwork across dozens of parks in southern Africa, it demonstrates how the current restricted range of the rhino, and the rarity of skilled poachers, makes a tactical solution the most effective to date. 相似文献
816.
817.
Jahara Matisek 《Defense & Security Analysis》2018,34(3):267-290
ABSTRACTThe United States has provided substantial amounts of military assistance and aid since the end of World War Two. During the Cold War, it proved vital in protecting numerous regimes from communist takeovers. Successful outcomes occurred when American leaders made large initial aid commitments, and the states had the capacity and political willpower to use it effectively. However, Vietnam was an example of how U.S. support lagged, as leaders in Saigon preferred political survival instead of creating regime legitimacy. Following 9/11, American security aid focused on making weak countries develop stronger security forces. Unfortunately, this created Fabergé egg militaries: expensive and easily broken by insurgents. This article suggests long-term strategic commitments need to be made alongside more resources for the American State Department and similar organizations to focus on the politics of state-building. Finally, this article suggests strategies, such as “whole-of-government” approaches, to improve long-term security and political institution building. 相似文献
818.
介绍了知识库更新的基本概念,并且在命题知识库的范围内研究了知识库更新的方法,结合实际应用给出了一种特殊情况下知识不相容的判定方法。 相似文献
819.
在考虑多种约束关系基础上 ,提出一种并行与分布式系统中多约束关系的任务分配与调度的共同进化遗传算法。仿真试验结果表明所给算法比传统单种遗传算法更能有效地进行多任务分配与调度 ,具有一定的工程价值 相似文献
820.