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471.
    
Canada is now at a crossroads unlike any other period in its history and needs to carefully consider which path to take. With the new Trudeau government comfortably ensconced since the defeat of the Harper government in the fall of 2015, a variety of competing interests have emerged in an attempt to turn Canadian policy back to a more nostalgic period of the 1970s that some see as preferable to the institutional lash-up that existed since the rolling out of the Canada First policy in the 2000s. That nostalgic period is, however, misunderstood both willfully for political purposes but also through a lack of historical context. Firmly rooting future actions in a blunt analysis of national interests is preferable to the alternative.  相似文献   
472.
    
Decades ago, simulation was famously characterized as a “method of last resort,” to which analysts should turn only “when all else fails.” In those intervening decades, the technologies supporting simulation—computing hardware, simulation‐modeling paradigms, simulation software, design‐and‐analysis methods—have all advanced dramatically. We offer an updated view that simulation is now a very appealing option for modeling and analysis. When applied properly, simulation can provide fully as much insight, with as much precision as desired, as can exact analytical methods that are based on more restrictive assumptions. The fundamental advantage of simulation is that it can tolerate far less restrictive modeling assumptions, leading to an underlying model that is more reflective of reality and thus more valid, leading to better decisions. Published 2015 Wiley Periodicals, Inc. Naval Research Logistics 62: 293–303, 2015  相似文献   
473.
    
The anthrax attacks of 2001 energized research directed toward reducing health consequences from airborne contaminants by augmenting current heating ventilation and air-conditioning (HVAC) systems. Even during peacetime, interest will continue in improving HVAC components to reduce biocontaminants associated with sick building syndrome. Current HVAC design uses numerical simulation methods of ordinary differential equations to predict approximate performance. The authors show that state-space Laplace Transform calculations actually solve the underlying differential equations and yield algebraic expressions that provide new insight. To sharpen the arguments in favor of this methodology, attention is restricted to improving existing HVAC systems to increase protection from an external release of hazardous particulates. By nearly eliminating the need for dynamical simulation, the resulting methods can be applied to far more complex HVAC designs with little additional computational effort. The new methods reduce the time required for computation by three orders of magnitude. These algebraic methods also can be extended to disparate technical problems including internal particulate release, gas masks, and designing new protective buildings.  相似文献   
474.
    
Recent counterinsurgency experiences in Iraq and Afghanistan have demonstrated that the local operating environment often is dominated by indigenous power-holders. As counterinsurgents seek to establish control over the local population, collaboration with these agents has become an essential aspect of contemporary counterinsurgency. Although the practice of constructing collaborative relationships with indigenous power-holders might be perceived as unconventional by today's counterinsurgents, the approach itself goes back to the colonial era in which modern counterinsurgency has its roots. This article explores the dynamics, benefits, and dangers of collaborative relationships with indigenous power-holders by analysing an infamous episode in Dutch colonial history, the case of the collaboration between Dutch colonial authorities and warlord Teuku Uma during the Aceh War (1873–1913). This relationship ended in disaster for the Dutch as Uma departed their side at the moment he had become their pivotal asset in the local political landscape. The article explains that the Dutch succeeded to co-opt Uma, but failed to control him as they lacked the will and means to do so. Furthermore this case study provides an insight in the way the Dutch colonial authorities dealt with the complex process of intelligence-gathering in a fragmented indigenous society.  相似文献   
475.
    
Casualty figures suggest that the US/Allied Counter Improvised Explosive Device (C-IED) policy and the present allocation of national assets, resources, and intellectual capital have not been very successful. A number of explanations for why this has been the case are discussed and critiqued here.  相似文献   
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478.
    
This article presents a flexible days‐on and days‐off scheduling problem and develops an exact branch and price (B&P) algorithm to find solutions. The main objective is to minimize the size of the total workforce required to cover time‐varying demand over a planning horizon that may extend up to 12 weeks. A new aspect of the problem is the general restriction that the number of consecutive days on and the number of consecutive days off must each fall within a predefined range. Moreover, the total assignment of working days in the planning horizon cannot exceed some maximum value. In the B&P framework, the master problem is stated as a set covering‐type problem whose columns are generated iteratively by solving one of three different subproblems. The first is an implicit model, the second is a resource constrained shortest path problem, and the third is a dynamic program. Computational experiments using both real‐word and randomly generated data show that workforce reductions up to 66% are possible with highly flexible days‐on and days‐off patterns. When evaluating the performance of the three subproblems, it was found that each yielded equivalent solutions but the dynamic program proved to be significantly more efficient. © 2013 Wiley Periodicals, Inc. Naval Research Logistics 60: 678–701, 2013  相似文献   
479.
    
States confronting cross-border intrusions of terrorism, illegal immigration, and/or drug trafficking weigh the costs of such intrusions against the costs of imposing barriers to prevent or curb the intrusions. In such situations, the degree of national security afforded a state depends, in large measure, upon the degree of border openness the state chooses. Depending upon the intensity and frequency of the intrusions – expressed in terms of opportunity-cost functions – a state might have little choice but to pursue a border policy of zero openness. It is this relationship of border openness to national security that explains why many states choose to construct security fences. In the 49 cases of security fences examined, many – among them Israel vis-à-vis the West Bank, India vis-à-vis Pakistan, Turkey vis-à-vis Greece in Cyprus – the construction of security fences becomes more complicated by their placement on lands whose sovereignties are disputed.  相似文献   
480.
    
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