首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   107篇
  免费   12篇
  国内免费   7篇
  2021年   1篇
  2020年   6篇
  2019年   1篇
  2018年   3篇
  2017年   11篇
  2016年   7篇
  2015年   1篇
  2014年   11篇
  2013年   33篇
  2012年   3篇
  2011年   9篇
  2010年   4篇
  2009年   3篇
  2008年   3篇
  2007年   5篇
  2006年   9篇
  2005年   5篇
  2004年   4篇
  2003年   1篇
  2002年   3篇
  2001年   2篇
  1999年   1篇
排序方式: 共有126条查询结果,搜索用时 0 毫秒
111.
This article develops a mathematical model and heuristic algorithm to design recreational boating mooring fields. The boating industry is important to the Florida economy, and boat storage is becoming a concern among those in the industry. The mooring field design problem is formulated to maximize the total number of boat feet moored in the mooring field. In the model, we allow two adjacent moorings to overlap, which introduces a risk that under certain conditions the boats on these moorings could contact each other. We identify the conditions when contact is possible and quantify the probability of contact. The mooring field design problem is formulated as a nonlinear mixed‐integer programming problem. To solve the problem, we decompose it into two separate models, a mooring radii assignment model and a mooring layout model, which are solved sequentially. The first is solved via exhaustive enumeration and the second via a depth‐first search algorithm. Two actual mooring fields are evaluated, and in both cases our model leads to better layouts than ones experts developed manually. The mooring field design model rationalizes the mooring field design and shows that in one case by increasing the risk from 0 to 1%, the mooring efficiency increases from 74.8% to 96.2%. © 2009 Wiley Periodicals, Inc. Naval Research Logistics, 2009  相似文献   
112.
“Evergreening” is a strategy wherein an innovative pharmaceutical firm introduces an upgrade of its current product when the patent on this product expires. The upgrade is introduced with a new patent and is designed to counter competition from generic manufacturers that seek to imitate the firm's existing product. However, this process is fraught with uncertainty because the upgrade is subject to stringent guidelines and faces approval risk. Thus, an incumbent firm has to make an upfront production capacity investment without clarity on whether the upgrade will reach the market. This uncertainty may also affect the capacity investment of a competing manufacturer who introduces a generic version of the incumbent's existing product but whose market demand depends on the success or failure of the upgrade. We analyze a game where capacity investment occurs before uncertainty resolution and firms compete on prices thereafter. Capacity considerations that arise due to demand uncertainty introduce new factors into the evergreening decision. Equilibrium analysis reveals that the upgrade's estimated approval probability needs to exceed a threshold for the incumbent to invest in evergreening. This threshold for evergreening increases as the intensity of competition in the generic market increases. If evergreening is optimal, the incumbent's capacity investment is either decreasing or nonmonotonic with respect to low end market competition depending on whether the level of product improvement in the upgrade is low or high. If the entrant faces a capacity constraint, then the probability threshold for evergreening is higher than the case where the entrant is not capacity constrained. Finally, by incorporating the risk‐return trade‐off that the incumbent faces in terms of the level of product improvement versus the upgrade success probability, we can characterize policy for a regulator. We show that the introduction of capacity considerations may maximize market coverage and/or social surplus at incremental levels of product improvement in the upgrade. This is contrary to the prevalent view of regulators who seek to curtail evergreening involving incremental product improvement. © 2016 Wiley Periodicals, Inc. Naval Research Logistics 63: 71–89, 2016  相似文献   
113.
ABSTRACT

China’s defense science, technology, and industrial system has been undergoing a far-reaching transformation over the past two decades and the single biggest factor behind this turnaround is the role of external technology and knowledge transfers and the defense industry’s improving ability to absorb these inputs and convert into localized output. China is pursuing an intensive campaign to obtain defense and dual-use civil–military foreign technology transfers using a wide variety of means, which is explored in this article.  相似文献   
114.
马骏  罗赓 《国防科技》2016,37(5):97-100
信息化条件下,面向实战的靶场试验任务针对性训练发生了深刻的变化,文章通过分析新形势下试验任务针对性训练存在的主要问题,研究信息化条件下实战化针对性训练的内容及趋势,总结与探索新的训练方法,建立健全考核与评价制度,提升试验任务针对性训练的质量效益及实战化能力。  相似文献   
115.
为了客观准确地评估各作战部队的信息化水平,针对目前作战部队信息化发展建设水平评估方法难、评估指标体系变量多的特点,依据建立的评估指标体系,运用主成分分析法的基本思想,建立数学模型,列出分析步骤,计算各作战部队信息化水平的主成分,通过对主成分进行选择,综合得出新的评估指标变量,实现了更加快捷、直观地对作战部队信息化水平进行评估,有利于正确引导军队信息化建设的方向。  相似文献   
116.
在以知识经济为背景的高速经济增长时代 ,高新技术产业作为经济增长支柱的作用日益突出。由于高新技术产业不同于传统产业的特点 ,客观上要求政府采取有力的措施来促进高新技术产业的发展。  相似文献   
117.
Russia's 2006 renationalisation of its aerospace industry heralded a new era in industrial policy. Symbolising a return to the importance of securing sovereignty over the Federation's strategic assets, it also posits, powerfully, that sectors like aerospace and shipbuilding are too important to be left to the market. In what now appears a reversal of this policy approach, Moscow is promoting partial privatisation and encouraging partnership with Western aerospace companies. Foreign infusion of capital and technology is viewed as the catalyst for Russian dominance in the global military and commercial aerospace industries.  相似文献   
118.
The US has embarked upon a major transformation of its approach to defence industrial base planning. Although bureaucratic and industrial inertia, as well as budgetary constraints, may delay transformation, its effects will lead to radical changes in the US defence industrial base with new entrants and new combinations of players. The UK, with more modest defence ambitions, capabilities and budget, will seek to keep in touch with the US. However, a commercially‐led drive to embed UK industry even more deeply in the US defence market could be the last step in creating a largely US–UK North Atlantic relationship, with much of Europe very much a subsidiary business concern. This contains a risk that the UK will become increasingly dependent on the US for design and integration of major systems and national defence industrial capability focused on a limited number of niche technologies.  相似文献   
119.
Defense budgets in Japan have been complicated compromises from numerous inputs ‐ including threat perceptions, domestic industrial/technological base development, support for the bilateral security treaty with the United States and internal bureaucratic politics ‐ but with the fall of the former Soviet Union, the clearest justification for higher spending disappeared. Double‐digit defense spending increases that were common in the 1980s have been replaced by annual increases lower than present inflation rates, resulting in negative real growth in the country's defense budget. Domestic economic problems and consistent government pressures for smaller budgets have further slowed annual growth in total spending and have contributed to lower procurement budgets. As a result, the domestic Japanese defense industry is facing far more constrained conditions from the growth years of a decade before.

Government policymakers are examining Japan's regional security environment as well as its alliance with the United States to determine the appropriate course for the country to take in the coming years. The formal security treaty with the United States is likely to remain a major element of government positions, but other aspects of the country's overall security posture are open to debate. Perceptions of a reduced threat environment are fueling additional pressures for defense budget cuts.

The domestic defense industry seeks means to assure its survival in domestic defense markets in this constrained environment. Expansion into overseas markets to offset declining domestic markets is an option that currently is constrained by policy restrictions on arms exports. Industry is advocating re‐examination of those policies and unlike earlier years, government appears willing to respond positively but cautiously to this lobbying.  相似文献   
120.
The misuse of biological research is increasingly becoming a prominent policy concern. One regulatory measure that has gained considerable support over the last few years in response to this is voluntary self-governance by the scientific community, and in particular codes of conduct. This article charts the rise of the policy debate on codes, highlighting the involvement of the scientific community. Shifting the focus from policy to practice, it explores the effectiveness of codes of conduct as a regulatory measure by examining our experiences of how another voluntary self-governance regime in the biosciences has worked in practice. Noting limitations with voluntary self-governance as a regulatory tool to prevent misuse, this article includes a reflection on the attention paid to codes of conduct in policy discussions, arguing that there are at least three possible interpretations.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号