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101.
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Traditional methods of due-date assignment presented in the literature and used in practice generally assume cost-of-earliness and cost-of-tardiness functions that may bear little resemblance to true costs. For example, practitioners using ordinary least-squares (OLS) regression implicitly minimize a quadratic cost function symmetric about the due date, thereby assigning equal second-order costs to early completion and tardy behavior. In this article the consequences of such assumptions are pointed out, and a cost-based assignment scheme is suggested whereby the cost of early completion may differ in form and/or degree from the cost of tardiness. Two classical approaches (OLS regression and mathematical programming) as well as a neural-network methodology for solving this problem are developed and compared on three hypothetical shops using simulation techniques. It is found for the cases considered that: (a) implicitly ignoring cost-based assignments can be very costly; (b) simpler regression-based rules cited in the literature are very poor cost performers; (c) if the earliness and tardiness cost functions are both linear, linear programming and neural networks are the methodologies of choice; and (d) if the form of the earliness cost function differs from that of the tardiness cost function, neural networks are statistically superior performers. Finally, it is noted that neural networks can be used for a wide range of cost functions, whereas the other methodologies are significantly more restricted. © 1997 John Wiley & Sons, Inc. 相似文献
103.
The effect of military expenditure on employment is a matter of considerable importance. However, few of the standard economic analyses of unemployment take any explicit account of variations in military expenditure in their models. The purpose of this paper is to assess whether the prevalent neglect of this variable in labour economics is justified. The paper briefly surveys previous estimates made of the employment effects of military expenditure. It then considers evidence from the simple dynamic reduced form regressions estimated on long historical series for the US and the UK and pooled post‐war data for 11 OECD countries. It does not suggest that the share of military expenditure is a significant influence on the unemployment rate. This implies that in analysing unemployment no special account need be taken of military expenditure and that the fear that reductions in the share of military expenditure will be associated with higher average unemployment levels is misplaced. 相似文献
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Dr Paul Jackson 《Small Wars & Insurgencies》2013,24(2):145-160
Fourth Generation Warfare is a theory of contemporary warfare that posits a number of different ideas that are able to shed light on current conflicts. Whilst much of the debate has been concentrated on the linear development of warfare and also on analysis of the current situation of US forces in Iraq, it has resonance for a number of different conflicts taking place in Africa, if only because the US has become involved in contemporary conflicts in Somalia and the Mahgreb. There are clearly significant issues with the US-centric, flawed linear approach to history, but the actual analysis of modes of warfare has much to offer policymakers in a continent that is under-represented in the literature, and is also in danger of being forgotten in the shadow of analysis of Iraq. This paper moves on from criticising the stepped approach to history and looks at patterns of warfare in contemporary Africa, arguing that there is much in the theory that could be used to explain seemingly illogical tactics or patterns, and thus has much to tell policymakers engaged in conflict analysis. Rebellions can be made 2 per cent active in a striking force, and 98 per cent passively sympathetic.1 相似文献
107.
Kenneth M Pollack Dr 《战略研究杂志》2013,36(3):471-503
In the aftermath of Israel's stunning victory over Egyptian, Jordanian and Syrian forces during the 1967 Six-Day War, accolades for the victory were often showered upon the Israeli Air Force (IAF). Indeed, many believed that it had been Israeli air power that had been the decisive element in the war by first eliminating the Arab air forces and then obliterating the Arab armies in turn. While the IAF did play an extremely important role in the fighting, it was not the decisive element of Israeli victory, and its impact was felt in very different ways from the common perception. Indeed, an appreciation of the true role of Israeli air power in the war reinforces both the importance of psychological factors in combat, and the ability of air forces to have a psychological impact disproportionate to their physical impact. 相似文献
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Paul E. Roitsch 《Small Wars & Insurgencies》2013,24(3):497-517
From 2006 to 2011, al Qaeda's East African proxy, al Shabaab, served as de facto ruling party of Somalia despite the efforts of the internationally recognized Transitional Federal Government (TFG). During these five years, a violent struggle between al Shabaab and the Burundian and Ugandan Peacekeepers of the African Union Mission in Somalia (AMISOM) resulted in thousands of dead civilians, hundreds of thousands of internally displaced persons, and a strategic environment inhospitable to reconciliation, recovery, or development. Beginning in August 2011, AMISOM was able to break the deadlock and force al Shabaab from Mogadishu, then subsequently, Kismayo, and ultimately to consolidate and reorganize in the Somali hinterland. In order to continue the momentum, the African Union and other partner nations must support the newly recognized Somali Federal Government (SFG), neutralize al Shabaab, and provide good governance to its constituents. Al Shabaab's revenue streams must be shut down and their offensive capability must be degraded while the strategic environment is shaped to ensure that conditions conducive to a revival do not exist. Failure to do so will likely see Somalia continuing to produce Islamic extremists and pirates to menace international maritime traffic in the Western Indian Ocean, destabilize East Africa, and adversely impact millions. 相似文献
109.
There are two main sources of information about the Arms Trade, SIPRI and ACDA. These two sources give very different pictures of the evolution of the market, primarily because their measures are designed to capture conceptually different features. Although they are both expressed in constant dollars, the SIPRI series is designed to be a volume index of physical transfers, the ACDA series a constant price value index. Thus in principle, the ratio of the ACDA to SIPRI series should provide an implicit price index of arms; though in practice there are many measurement problems. In this paper, we discuss the basis of these indices and show that the ratio, the implicit price, not only looks plausible in the light of the evolution of the market, but has a significant negative effect on the demand for arms imports in an econometric equation. 相似文献
110.
Sidescan sonars are used in detecting hostile targets on the seabed. An accurate representation of the sensor performance is required to carefully plan and execute searches. We studied several confidence interval methods for assessing the accuracy of detection performance as a function of range from hostile targets. Using simulation, we determined that the best approach for modeling sensor data was piecewise logistic regression with cubic B‐splines at carefully selected knots. This method was demonstrated on real data collected from the CITADEL sea trial. © 2012 Wiley Periodicals, Inc. Naval Research Logistics, 2012 相似文献