全文获取类型
收费全文 | 346篇 |
免费 | 183篇 |
国内免费 | 10篇 |
出版年
2022年 | 2篇 |
2021年 | 7篇 |
2020年 | 2篇 |
2019年 | 3篇 |
2017年 | 1篇 |
2016年 | 2篇 |
2015年 | 10篇 |
2014年 | 14篇 |
2013年 | 27篇 |
2012年 | 5篇 |
2011年 | 10篇 |
2010年 | 18篇 |
2009年 | 16篇 |
2008年 | 16篇 |
2007年 | 22篇 |
2006年 | 17篇 |
2005年 | 12篇 |
2004年 | 4篇 |
2003年 | 1篇 |
2001年 | 7篇 |
2000年 | 6篇 |
1999年 | 58篇 |
1998年 | 53篇 |
1997年 | 41篇 |
1996年 | 31篇 |
1995年 | 23篇 |
1994年 | 21篇 |
1993年 | 24篇 |
1992年 | 17篇 |
1991年 | 16篇 |
1990年 | 19篇 |
1989年 | 4篇 |
1988年 | 10篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 3篇 |
1983年 | 3篇 |
1982年 | 3篇 |
排序方式: 共有539条查询结果,搜索用时 265 毫秒
311.
We consider a stochastic counterpart of the well-known earliness-tardiness scheduling problem with a common due date, in which n stochastic jobs are to be processed on a single machine. The processing times of the jobs are independent and normally distributed random variables with known means and known variances that are proportional to the means. The due dates of the jobs are random variables following a common probability distribution. The objective is to minimize the expectation of a weighted combination of the earliness penalty, the tardiness penalty, and the flow-time penalty. One of our main results is that an optimal sequence for the problem must be V-shaped with respect to the mean processing times. Other characterizations of the optimal solution are also established. Two algorithms are proposed, which can generate optimal or near-optimal solutions in pseudopolynomial time. The proposed algorithms are also extended to problems where processing times do not satisfy the assumption in the model above, and are evaluated when processing times follow different probability distributions, including general normal (without the proportional relation between variances and means), uniform, Laplace, and exponential. © 1997 John Wiley & Sons, Inc. Naval Research Logistics 44, 531–557, 1997. 相似文献
312.
研究了不等距多重网格法,可用于区域形状任意和有内电极的实际电子光学系统轴对称电场的计算,特别是对于求解区域大、部分区域电场精度要求高的场合,较好地解决了计算精度与划分网格点数之间的矛盾,可广泛应用于分析设计静电聚焦像管的电子光学系统,以及摄像管电子枪的发射系统等. 相似文献
313.
刘少奇根据地政权建设的思想理论和实践十分丰富,是无产阶级政权建设思想的重要组成部分。其主要内容包括:抗日根据地建设的核心是民主政权建设;抗日民主政权建设的关键是民主政治建设;坚持党的领导是巩固民主政权的根本保障。在抗日战争的艰苦岁月里,刘少奇亲自主持了华中抗日根据地的政权建设,打开了华中抗日游击战争的新局面,为中国民主政权建设作出了突出贡献。 相似文献
314.
We consider the multitasking scheduling problem on unrelated parallel machines to minimize the total weighted completion time. In this problem, each machine processes a set of jobs, while the processing of a selected job on a machine may be interrupted by other available jobs scheduled on the same machine but unfinished. To solve this problem, we propose an exact branch‐and‐price algorithm, where the master problem at each search node is solved by a novel column generation scheme, called in‐out column generation, to maintain the stability of the dual variables. We use a greedy heuristic to obtain a set of initial columns to start the in‐out column generation, and a hybrid strategy combining a genetic algorithm and an exact dynamic programming algorithm to solve the pricing subproblems approximately and exactly, respectively. Using randomly generated data, we conduct numerical studies to evaluate the performance of the proposed solution approach. We also examine the effects of multitasking on the scheduling outcomes, with which the decision maker can justify making investments to adopt or avoid multitasking. 相似文献
315.
A critical issue for many governments is boosting the adoption rates of products or technologies that enhance consumer surplus or total social welfare. Governments may, for example, pay subsidies to producers or to consumers to stimulate the manufacture or consumption of specific products, for example, energy-efficient appliances or more effective drugs. This research proposes a strategic government investment policy, namely, share acquisition, and demonstrates its effectiveness in reaching societal objectives. We consider a Cournot quantities-choice market comprised of homogeneous firms where the government intervenes to buy shares, and turning private firms into state-owned enterprises. We recognize that purchasing a single private firm is the optimal policy for the government to reach its societal objectives. Additionally, taking into consideration financial constraints, we find that the optimal stake increases with the budget. Compared with the optimal output-based subsidy policy, when the budget is low, the optimal government investment policy induces a higher consumer surplus. In addition, in differentiated Cournot competition, under which firms compete in selling substitutable products, we find that when the budget is sufficient, the optimal stake purchased first decreases and then increases according to the substitutability level among products. 相似文献
316.
针对极限学习机(Extreme Learning Machine,ELM)的性能必须依赖于大量隐层节点的问题,提出了基于改进烟花算法(Improved Fireworks Algorithm,IFWA)的ELM分类模型。用改进的烟花算法进行迭代搜索,求得N个最优的烟花;选择ELM测试数据集的RMSE作为改进烟花算法的适应度值函数,来优化ELM每个隐层节点的输入权值和偏置,使得节点的决策水平提高,从而使ELM的决策性能显著提高;采用KDD99数据集验证表明:改进烟花算法的极限学习机(IFWAELM)能够以较少的隐层节点得到更高的测试平均正确率,提高了极限学习机的泛化性能。5种同类算法性能对比实验也表明IFWAELM是效果最优的。 相似文献
317.
318.
319.
唐冬寿 《军队政工理论研究》2010,11(3)
进一步增强当代革命军人核心价值观培育的效果,要着眼增强培育工作的针对性,努力实现从自发到自觉的转变;着眼增强培育工作的思想性,努力实现从感性到理性的升华;着眼增强培育工作的科学性,努力实现从零碎到系统的集成. 相似文献
320.