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441.
In hinterland container transportation the use of barges is getting more and more important. We propose a real‐life operational planning problem model from an inland terminal operating company, in which the number of containers shipped per barge is maximized and the number of terminals visited per barge is minimized. This problem is solved with an integer linear program (ILP), yielding strong cost reductions, about 20%, compared to the method used currently in practice. Besides, we develop a heuristic that solves the ILP in two stages. First, it decides for each barge which terminals to visit and second it assigns containers to the barges. This heuristic produces almost always optimal solutions and otherwise near‐optimal solutions. Moreover, the heuristic runs much faster than the ILP, especially for large‐sized instances. 相似文献
442.
Gregory D. Koblentz 《The Nonproliferation Review》2019,26(5-6):575-598
ABSTRACTInternational efforts to hold the government of President Bashar al-Assad accountable for the use of chemical weapons in the Syrian Civil War have entered a new phase. For the first time, the Organisation for the Prohibition of Chemical Weapons (OPCW), the international organization responsible for implementing the 1993 Chemical Weapons Convention, has been empowered to identify the perpetrators of chemical attacks in Syria. The Investigation and Identification Team (IIT), which was formed to conduct the OPCW’s new attribution mission, has announced its intention to investigate and identify the perpetrators of nine chemical attacks in Syria, including the April 7, 2018, attack in Douma. This article reviews recent efforts to attribute chemical attacks in Syria, describes what we know about the nine incidents to be investigated, summarizes what is known about the Syrian government officials, military commanders, and chemical-warfare scientists suspected of being responsible for these attacks, discusses what to expect during the next phase of the attribution process, and offers insights into how the international community can move beyond attribution to accountability. Accountability is necessary to provide justice for victims and to prevent future incidents by demonstrating that perpetrators of chemical attacks will be identified and punished. 相似文献
443.
Colin D. Robinson 《Defense & Security Analysis》2019,35(4):423-429
ABSTRACTBagayoko, Hutchful, and Luckham correctly argue that the structures, characteristics, and operating methods of official security institutions in Africa have been somewhat neglected, with a lack of much recent research. The Somali National Army (SNA) sits among these lacunae. Its formal structures can be used as a skeletal starting point and springboard to start to draw the network diagrams that chart informal linkages. This is why recent declassification decisions by U.S. intelligence bodies, coupled with period documents released to the UK National Archives, hold significance in helping us understand early hierarchical SNA arrangements. They show the steady build-up in size of the force, to 1987, to about the time the civil war began to fragment the state. 相似文献
444.
Lawrence E. Cline 《Defense & Security Analysis》2019,35(3):241-260
Most counterinsurgency campaigns have featured the use of some form of local defense forces. Such forces have had a somewhat mixed record, both in their usefulness in actually countering insurgents and in their longer-term impact on internal security. This article focuses on historical cases that provide lessons for the best operational and strategic uses of local defense forces and measures to control their activities. 相似文献
445.
Ana E. Juncos 《Contemporary Security Policy》2018,39(1):95-118
ABSTRACTAttempts to explain the failure to reform the security sectors in post-conflict countries have often resorted to two sets of explanatory factors: international and local factors. This article seeks to move from that unhelpful dichotomy to an explanation linking both factors. Drawing on a Foucauldian approach and the concept of “counter-conduct,” it examines the rationality and practices of European Union (EU) governmentality and how governing technologies are resisted and reversed by local elites involved in security sector reform (SSR). Instead of understanding power and resistance as binary opposites, this article argues that counter-conduct can be conceived as implicated in the very relations of power that it seeks to resist. To tease out these relations, the article analyzes the EU's efforts in SSR in Bosnia and Herzegovina, where it identifies four forms of counter-conduct: upholding European standards, using the local ownership trap, simulating reforms, and lowering the bar. 相似文献
446.
447.
The Akko 1 shipwreck is the remains of a 26-metre-long Egyptian armed vessel or auxiliary naval brig built at the beginning of the 19th century. Remains of six flintlock muskets were retrieved from the shipwreck, and characterised by various metallurgical methods. The research aimed to study the composition and microstructure of the musket fittings and their manufacturing processes, and if possible, to determine the date and origin of the raw materials. The lead isotope analysis of the fittings suggests that their raw material originated in Great Britain. Based on their typology and composition, the fittings were made in Great Britain of brass alloy and manufactured by casting, probably at the same workshop; and the staple was manufactured by casting and drawing. Considering the zinc content, combined with the manufacturing techniques, the fittings were manufactured between the latter part of the 18th and the early 19th centuries, which might indicate that they were purchased in the course of 19th century weapons trade to be used on board the Egyptian ship. 相似文献
448.
We consider the effects of cueing in a cooperative search mission that involves several autonomous agents. Two scenarios are discussed: one in which the search is conducted by a number of identical search‐and‐engage vehicles and one where these vehicles are assisted by a search‐only (reconnaissance) asset. The cooperation between the autonomous agents is facilitated via cueing, i.e., the information transmitted to the agents by a searcher that has just detected a target. The effect of cueing on the target detection probability is derived from first principles using a Markov chain analysis. In particular, it is demonstrated that the benefit of cueing on the system's effectiveness is bounded. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006 相似文献
449.
Donald P. Gaver Patricia A. Jacobs Gennady Samorodnitsky Kevin D. Glazebrook 《海军后勤学研究》2006,53(6):588-599
This paper describes modeling and operational analysis of a generic asymmetric service‐system situation in which (a) Red agents, potentially threatening, but in another but important interpretation, are isolated friendlies, such as downed pilots, that require assistance and “arrive” according to some partially known and potentially changing pattern in time and space; and (b) Reds have effectively limited unknown deadlines or times of availability for Blue service, i.e., detection, classification, and attack in a military setting or emergency assistance in others. We discuss various service options by Blue service agents and devise several approximations allowing one to compute efficiently those proportions of tasks of different classes that are successfully served or, more generally, if different rewards are associated with different classes of tasks, the percentage of the possible reward gained. We suggest heuristic policies for a Blue server to select the next task to perform and to decide how much time to allocate to that service. We discuss this for a number of specific examples. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006. 相似文献
450.
In the aftermath of the tragic events of 11 September 2001, numerous changes have been made to aviation security policy and operations throughout the nation's airports. The allocation and utilization of checked baggage screening devices is a critical component in aviation security systems. This paper formulates problems that model multiple sets of flights originating from multiple stations (e.g., airports, terminals), where the objective is to optimize a baggage screening performance measure subject to a finite amount of resources. These measures include uncovered flight segments (UFS) and uncovered passenger segments (UPS). Three types of multiple station security problems are identified and their computational complexity is established. The problems are illustrated on two examples that use data extracted from the Official Airline Guide. The examples indicate that the problems can provide widely varying solutions based on the type of performance measure used and the restrictions imposed by the security device allocations. Moreover, the examples suggest that the allocations based on the UFS measure also provide reasonable solutions with respect to the UPS measure; however, the reverse may not be the case. This suggests that the UFS measure may provide more robust screening device allocations. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2005. 相似文献