全文获取类型
收费全文 | 559篇 |
免费 | 53篇 |
国内免费 | 1篇 |
出版年
2021年 | 16篇 |
2019年 | 20篇 |
2018年 | 10篇 |
2017年 | 11篇 |
2016年 | 12篇 |
2015年 | 12篇 |
2014年 | 13篇 |
2013年 | 97篇 |
2009年 | 8篇 |
2008年 | 8篇 |
2007年 | 7篇 |
2006年 | 6篇 |
2005年 | 11篇 |
2004年 | 10篇 |
2003年 | 6篇 |
2002年 | 7篇 |
2000年 | 10篇 |
1999年 | 24篇 |
1998年 | 26篇 |
1997年 | 28篇 |
1996年 | 10篇 |
1995年 | 6篇 |
1994年 | 15篇 |
1993年 | 8篇 |
1992年 | 9篇 |
1991年 | 16篇 |
1990年 | 6篇 |
1989年 | 12篇 |
1988年 | 7篇 |
1987年 | 14篇 |
1986年 | 8篇 |
1985年 | 6篇 |
1984年 | 5篇 |
1983年 | 9篇 |
1982年 | 11篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1979年 | 11篇 |
1978年 | 7篇 |
1977年 | 8篇 |
1976年 | 7篇 |
1975年 | 7篇 |
1974年 | 7篇 |
1973年 | 12篇 |
1972年 | 6篇 |
1971年 | 6篇 |
1970年 | 7篇 |
1969年 | 6篇 |
1968年 | 5篇 |
1967年 | 5篇 |
排序方式: 共有613条查询结果,搜索用时 15 毫秒
491.
介绍了一个用于目标自动跟踪仿真实验系统的视频图象实时处理器.该处理器硬件由图形图象处理芯片TMS34010和高速数字处理芯片TMS320C25构成,采用相关跟踪算法时,对目标模板32×32象素和搜索区64×64象素处理能达到实时. 相似文献
492.
Stewart M. Fraser 《Defense & Security Analysis》1998,14(3):335-337
Military operations and maritime preponderance by Charles E. Callwell, Edinburgh: William Blackwood & Sons, 1905. 相似文献
493.
提出了输入方式误差的新概念.以它为基础,对线性二次型最优控制问题进行修正设计后,可实现精密跟踪. 相似文献
494.
在对多种模型进行研究的基础上,提出了一种快速模拟三维彩色树木的高效算法。该算法不仅合理简化了树木的几何拓扑结构和生长规律特性,而且引入了特性良好、计算简单、参数易于控制的随机函数。因此生成树木的种类较多、图形逼真、速度很快,在普通微机上达到了实时的模拟效果。 相似文献
495.
大型复杂系统完成规定任务往往涉及多个阶段,并且在不同的任务阶段,系统通常由其各级子系统、单元以不同的功能组合形式构成,因而,其可靠性逻辑结构(框图)也随时间的改变而改变。当连续多阶段系统不能分阶段单独处理时,将引出所谓的时段延续相关性问题。本文重点研究了时变结构多阶段任务系统的时段延续相关性问题,对典型时变结构的可靠度进行了分析,提出了有效的解决方法并建立了相应的数学模型。研究成果已应用于某大型测控系统的可靠性分析任务中 相似文献
496.
The standard issue bayonet of the British Army immediately preceding and during the First World War was the Pattern 1907. This was manufactured at different times and in varying numbers during that period by one official body, the Royal Small Arms Factory at Enfield, and by five private contractors. These bayonets were made according to published official specifications issued by the War Department and based on a ‘pattern example’ provided by the Royal Small Arms Factory. The specifications indicate, inter alia, the quality of metal used in making the bayonets, methods of inspection and proofing, and the required maximum and minimum weight range of the completed bayonet. However, examination of a series of these bayonets in a private collection suggested that their weights varied considerably from the mid-point values of the allowed weight ranges in the original and amended specifications (16.5 oz. and 17 oz., respectively). To establish if this was a common feature among this class of bayonet as opposed to a chance factor, the weights of other surviving Pattern 1907 bayonets were determined and compared to establish the degree of variance from the official specifications as originally set out by the Royal Small Arms Factory. Seventy-six percent of the 142 bayonets surveyed were found to be above the mid-point of the allowed weight range given in the amended manufacturing specifications, with many being at the upper end of the allowed range. This is a statistically unusual result. It is speculated that the target weight may have been deliberately set higher by the individual manufacturers to eliminate the possibility of rejection of any underweight bayonets by the Royal Small Arms Factory inspectors and so a refusal of acceptance and payment for the work. 相似文献
497.
Terence M. Holmes 《战略研究杂志》2017,40(7):1039-1058
Clausewitz was much preoccupied with the apparent contradiction between real and absolute war. Why did war in history so rarely exhibit the extremes of violence and energy implied in the pure concept of war? Clausewitz’s commentators have usually followed him in thinking that this was a genuine problem in need of a solution, but I want to question that view. I will argue that Clausewitz did not have a coherent philosophy of absolute war, and therefore the contradiction he posited between real and absolute war was equally meaningless – as, too, was his effort to resolve it by claiming that some real wars approached or even attained the absolute form of war. The real problem was not the opposition of real and absolute war, but the self-contradictory theory of absolute war. 相似文献
498.
We consider stochastic scheduling models which have the natural character that jobs improve while being processed, but deteriorate (and may possibly leave the system altogether) while processing is diverted elsewhere. Such restless bandit problems are shown to be indexable in the sense of Whittle. A numerical study which elucidates the strong performance of the resulting index policy is complemented by a theoretical study which demonstrates the optimality of the index policy under given conditions and which develops performance guarantees for the index heuristic more generally. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 706–721, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/nav.10036 相似文献
499.
When solving location problems in practice it is quite common to aggregate demand points into centroids. Solving a location problem with aggregated demand data is computationally easier, but the aggregation process introduces error. We develop theory and algorithms for certain types of centroid aggregations for rectilinear 1‐median problems. The objective is to construct an aggregation that minimizes the maximum aggregation error. We focus on row‐column aggregations, and make use of aggregation results for 1‐median problems on the line to do aggregation for 1‐median problems in the plane. The aggregations developed for the 1‐median problem are then used to construct approximate n‐median problems. We test the theory computationally on n‐median problems (n ≥ 1) using both randomly generated, as well as real, data. Every error measure we consider can be well approximated by some power function in the number of aggregate demand points. Each such function exhibits decreasing returns to scale. © 2003 Wiley Periodicals, Inc. Naval Research Logistics 50: 614–637, 2003. 相似文献
500.
In this paper we analyze a two‐period supply contract which allows for order adjustment by the buyer. The buyer is required to place orders for two periods. After observing initial demand, the buyer is then allowed to adjust the second order, paying a per unit order adjustment penalty. We describe the optimal behavior of the buyer under such a contract, both in determining the initial order quantities and in subsequently adjusting the order. We compare the solution to a contract where no adjustment is allowed and to the case where adjustment is allowed without penalty. We demonstrate that flexible contracts can reduce the potentially negative effect of correlation of demand between two periods. Further, we investigate how the duration of the first period vis‐à‐vis the second period affects the profitability of the buyer as a function of the degree of correlation. © 2002 John Wiley & Sons, Inc. Naval Research Logistics, 49: 25–45, 2002; DOI 10.1002/nav.10002 相似文献