全文获取类型
收费全文 | 500篇 |
免费 | 9篇 |
出版年
2021年 | 5篇 |
2020年 | 4篇 |
2019年 | 8篇 |
2018年 | 7篇 |
2017年 | 11篇 |
2016年 | 17篇 |
2015年 | 12篇 |
2014年 | 13篇 |
2013年 | 72篇 |
2012年 | 23篇 |
2011年 | 26篇 |
2010年 | 21篇 |
2009年 | 17篇 |
2008年 | 28篇 |
2007年 | 13篇 |
2006年 | 15篇 |
2005年 | 5篇 |
2004年 | 3篇 |
2002年 | 3篇 |
2001年 | 4篇 |
1998年 | 6篇 |
1997年 | 6篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 10篇 |
1992年 | 7篇 |
1991年 | 6篇 |
1989年 | 12篇 |
1988年 | 3篇 |
1987年 | 10篇 |
1986年 | 10篇 |
1985年 | 7篇 |
1984年 | 2篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 8篇 |
1980年 | 9篇 |
1979年 | 11篇 |
1978年 | 4篇 |
1977年 | 6篇 |
1976年 | 7篇 |
1975年 | 7篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 12篇 |
1971年 | 3篇 |
1970年 | 3篇 |
1969年 | 9篇 |
1968年 | 7篇 |
1966年 | 3篇 |
排序方式: 共有509条查询结果,搜索用时 15 毫秒
381.
382.
We investigate the problem in which an agent has to find an object that moves between two locations according to a discrete Markov process (Pollock, Operat Res 18 (1970) 883–903). At every period, the agent has three options: searching left, searching right, and waiting. We assume that waiting is costless whereas searching is costly. Moreover, when the agent searches the location that contains the object, he finds it with probability 1 (i.e. there is no overlooking). Waiting can be useful because it could induce a more favorable probability distribution over the two locations next period. We find an essentially unique (nearly) optimal strategy, and prove that it is characterized by two thresholds (as conjectured by Weber, J Appl Probab 23 (1986) 708–717). We show, moreover, that it can never be optimal to search the location with the lower probability of containing the object. The latter result is far from obvious and is in clear contrast with the example in Ross (1983) for the model without waiting. © 2009 Wiley Periodicals, Inc. Naval Research Logistics 2009 相似文献
383.
姿态确定系统是卫星姿态控制系统中的重要组成部分,卫星姿态确定的精度直接影响卫星控制精度.为得到高姿态精度,针对由惯性测量单元(Inertial Measurement Unit),红外地平仪和太阳敏感器组成的卫星姿态确定系统,分别采用BP网络算法和径向基(RBF)网络算法对不同的姿态敏感器的输出数据进行融合,并用STK(Satellite Tool Kit)数据进行了仿真.仿真分析结果表明这两种学习算法均可以提高卫星定姿精度,相对而言,RBF网络无论是精度上还是收敛速度上均优于BP网络. 相似文献
384.
As a result of imperfect production and inspection by suppliers, pilferage, and/or damage in transit, it is common that procurement orders may contain defective items. This article deals with a continuous-review inventory system with Poisson demand arrivals and constant resupply time. Items in resupply lots may not be of perfect quality. The operating characteristics of such a system are analyzed. For purposes of computational savings, an approximation scheme for the operating characteristics is presented. As a result of the approximation, the determination of the optimal ordering policy becomes much simpler. Extensive numerical tests suggest that the approximation scheme is very effective in giving the optimal or near-optimal ordering policies for such a system. 相似文献
385.
In this article we extend the work of Mehrez and Stulman [5] on the expected value of perfect information (EVPI) to the expected value of sample information (EVSI) for a class of economic problems dealing with the decision to reject or accept an investment project. It is shown that shifting the mean of the underlying a priori distribution of X, the project's monetary value from zero in either direction will decrease the associated EVSI of Y, the random sampled information. A theorem is then presented which gives an upper bound on the EVSI over all distributions of Y, as well as the structure of the posterior mean E[X|Y] for which this upper bound is achieved. Finally, the case where E[X|Y] is linear in Y is discussed and its performance compared with that of the optimal case. 相似文献
386.
Björn Kauder 《Defence and Peace Economics》2016,27(4):503-519
We examine whether government ideology was correlated with the growth in military expenditure in Germany over the period 1951–2011. Using various measures of government ideology, the results do not show any effect. The exception is an ideology measure based on the Comparative Manifesto Project (left-right scale): using this measure, the results show that the growth in military expenditure increased by about 2.4 percentage points, when the ideology variable (right-wing) increased by one standard deviation. This effect, however, is based on observations until the early 1960s and cannot be generalized. The major political parties agreed on how to evaluate international risks and threats. Government ideology retired to the background. We conjecture that the consensus among the major parties will persist – even if military spending needs to be increased in response to new international risks and threats. 相似文献
387.
388.
389.
390.