全文获取类型
收费全文 | 3334篇 |
免费 | 85篇 |
国内免费 | 1篇 |
专业分类
3420篇 |
出版年
2021年 | 37篇 |
2019年 | 89篇 |
2018年 | 53篇 |
2017年 | 82篇 |
2016年 | 79篇 |
2015年 | 62篇 |
2014年 | 64篇 |
2013年 | 699篇 |
2010年 | 38篇 |
2009年 | 37篇 |
2008年 | 48篇 |
2007年 | 52篇 |
2006年 | 36篇 |
2005年 | 42篇 |
2004年 | 56篇 |
2003年 | 42篇 |
2002年 | 57篇 |
1999年 | 41篇 |
1998年 | 46篇 |
1997年 | 49篇 |
1996年 | 61篇 |
1995年 | 41篇 |
1994年 | 59篇 |
1993年 | 63篇 |
1992年 | 58篇 |
1991年 | 74篇 |
1990年 | 39篇 |
1989年 | 72篇 |
1988年 | 78篇 |
1987年 | 68篇 |
1986年 | 71篇 |
1985年 | 65篇 |
1984年 | 36篇 |
1983年 | 42篇 |
1982年 | 43篇 |
1981年 | 46篇 |
1980年 | 51篇 |
1979年 | 45篇 |
1978年 | 49篇 |
1977年 | 45篇 |
1976年 | 45篇 |
1975年 | 46篇 |
1974年 | 52篇 |
1973年 | 50篇 |
1972年 | 52篇 |
1971年 | 43篇 |
1970年 | 40篇 |
1969年 | 40篇 |
1968年 | 34篇 |
1967年 | 34篇 |
排序方式: 共有3420条查询结果,搜索用时 15 毫秒
91.
Observations from inspection by a “test” method and a standard method are combined to provide estimators of population proportion, and of probabilities of misclassification for the test method. Results of Hochberg and Tenenbein [3] and of Albers and Veldman [1] are extended to the case where the standard method is not perfect, but its misclassification probabilities have known values. Both moment and maximum-likelihood estimators are considered and some asymptotic properties of the resulting estimators are compared. 相似文献
92.
Stephen F. Burgess 《Contemporary Security Policy》2016,37(1):111-143
This article synthesizes three elements of power and balancing in the South China Sea (SCS): analytical perspectives on China's behaviour and intentions, the American rebalance to Asia and the dispositions of American allies and partners. Based on extensive interviews and theoretical analysis, it concludes that ‘soft balancing’ backed by American military power provides the optimum chance for resolving the growing dispute. Short to medium-term weakness of Malaysia, Philippines and Vietnam, as well as Japan, means the United States must provide much of the military power while working to build their forces. The most promising alternative is multilateral diplomacy through the Association of Southeast Asian Nations’ Regional Forum, a vehicle for negotiating a Code of Conduct and implementation of the UN Convention on the Law of the Sea. If China remains motivated mainly by defense of realist interests, the costs imposed against expansion will eventually cause recalculation of Beijing's strategy, and soft balancing by the United States and its partners has a chance of working. The constructivist perspective, stressing self-conceptualization of Chinese strategic culture, supports Chinese confidence that patience will eventually bring dominance. If China tries offensively to change the status quo, soft balancing is less likely to influence Beijing. President Xi Jin Ping appears to be offensively asserting power, seeking regional dominance before he is due to step down in 2023. This supports the finding of enhanced risks of unintended escalation in the SCS and the East China Sea. 相似文献
93.
Joseph O. Chapa 《Journal of Military Ethics》2017,16(3-4):256-271
In this paper I argue that a remotely piloted aircraft (RPA) pilot’s act of killing remotely, when it is done in the defense of another person, can be viewed as an act of sacrifice. This argument concludes from two premises. First, the RPA pilot faces psychological risk to self by carrying out such an action; second, the RPA pilot is motivated to some significant degree by something other than self-interest. Moreover, I challenge both the view that RPA represent merely an incremental development in technology yielding an incremental expansion of the distance between the war-fighter and the target and the view that RPA is revolutionary in some fundamental sense. I instead argue that, based upon the natural geometric boundary imposed by the earth’s shape, RPA have maximized the physical distance between the war-fighter and the target and, over time, this fact will change, not only the psychological effects on the RPA pilot, but also the way we view killing and distance in general. When taken together, these two broad claims, that other-defense can justify killing in war and that there is a psychological cost paid by remote killers, yield a conception of remote killing as an act of sacrifice that will inform the broader conversation about ethics, risk, killing, and RPA. 相似文献
94.
95.
Finite-capacity queues arise naturally in many practical situations, notably in communications and manufacturing engineering. In this article, the matrix formalism of probability distributions of phase type is used to develop fast algorithms to compute various steady-state distributions for the finite-capacity PH/PH/1 queue. This algorithm is an important ingredient in solving nontraditional but significant design problems. Some of these are described as illustrative examples. 相似文献
96.
Michael J. Armstrong 《海军后勤学研究》2004,51(1):28-43
In the context of both discrete time salvo models and continuous time Lanchester models we examine the effect on naval combat of lethality: that is, the relative balance between the offensive and defensive attributes of the units involved. We define three distinct levels of lethality and describe the distinguishing features of combat for each level. We discuss the implications of these characteristics for naval decision‐makers; in particular, we show that the usefulness of the intuitive concept “more is better” varies greatly depending on the lethality level. © 2003 Wiley Periodicals, Inc. Naval Research Logistics, 2004. 相似文献
97.
Fractional fixed-charge problems arise in numerous applications, where the measure of economic performance is the time rate of earnings or profit (equivalent to an interest rate on capital investment). This paper treats the fractional objective function, after suitable transformation, as a linear parametric fixed-charge problem. It is proved, with wider generality than in the case of Hirsch and Dantzig, that some optimal solution to the generalized linear fixed-charge problem is an extreme point of the polyhedral set defined by the constraints. Furthermore, it is shown that the optimum of the generalized fractional fixed-charge problem is also a vertex of this set. The proof utilizes a suitable penalty function yielding an upper bound on the optimal value of the objective function; this is particularly useful when considering combinations of independent transportation-type networks. Finally, it is shown that the solution of a fractional fixed-charge problem is obtainable through that of a certain linear fixed-charge one. 相似文献
98.
In this paper, we examine the current state of knowledge in the economics literature on the conduct of reconstruction activities in Iraq and Afghanistan. As stabilisation and reconstruction missions grow in importance for units deployed to these regions, it becomes more important to understand what activities can promote economic growth at the local level. While military operations focus on interdicting the insurgency, successful counter-insurgency campaigns have typically addressed the conditions conducive to the insurgency. Mitigating the incentives for individuals to participate in an insurgency is imperative. Well-crafted and timed reconstruction activities can, we argue, attenuate these incentives. 相似文献
99.
Charles A. Holloway 《海军后勤学研究》1977,24(2):377-380
Using the general computational strategy of restriction, necessary conditions for optimality provide an alternative criterion for entering variables when degeneracies arises in linear programming problems. Although cycling may still occur, it is shown that if it is possible to make progress at the next iteration, the criterion is guaranteed to identify a non-basic variable which increases the value of the basic solution, thereby reducing stalling. An alternative method for determining variables to exit the basis when degeneracies occur is also suggested. 相似文献
100.
In 2013, the staff of the U.S. Nuclear Regulatory Commission estimated the reduction of the off-site economic losses from a fire in a drained U.S. spent fuel pool if fuel that had cooled for more than five years were transferred to dry cask storage—an option it called “expedited transfer.” In this article, it is shown that the savings would be much higher than the NRC estimated. Savings increase to about $2 trillion if: losses beyond 50 miles are included; the land-contamination threshold for long-term population relocation is changed to that used for the Chernobyl and Fukushima accidents and recommended by the U.S. Environmental Protection Agency; and, based on the experience of Japan, decontamination of land areas to levels acceptable for population return is assumed to take at least four years. If expedited transfer were implemented, the off-site economic losses would be reduced by about 98%. 相似文献