全文获取类型
收费全文 | 436篇 |
免费 | 153篇 |
国内免费 | 16篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 7篇 |
2021年 | 16篇 |
2020年 | 6篇 |
2019年 | 5篇 |
2018年 | 3篇 |
2017年 | 4篇 |
2016年 | 2篇 |
2015年 | 20篇 |
2014年 | 23篇 |
2013年 | 30篇 |
2012年 | 13篇 |
2011年 | 23篇 |
2010年 | 26篇 |
2009年 | 23篇 |
2008年 | 27篇 |
2007年 | 33篇 |
2006年 | 23篇 |
2005年 | 12篇 |
2004年 | 10篇 |
2003年 | 6篇 |
2002年 | 5篇 |
2001年 | 14篇 |
2000年 | 8篇 |
1999年 | 52篇 |
1998年 | 43篇 |
1997年 | 30篇 |
1996年 | 22篇 |
1995年 | 20篇 |
1994年 | 18篇 |
1993年 | 17篇 |
1992年 | 11篇 |
1991年 | 16篇 |
1990年 | 15篇 |
1989年 | 1篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1983年 | 1篇 |
1982年 | 3篇 |
排序方式: 共有605条查询结果,搜索用时 15 毫秒
351.
首先简述潜艇兵力的使命任务和作战特点 ,然后从作战的角度分析了攻击型潜艇战斗系统与海军战役系统的关系 ,提出了潜艇战斗系统的组成 ,探讨了潜艇战斗系统的功能及其动态特性。 相似文献
352.
捷联惯导系统姿态算法研究 总被引:11,自引:1,他引:10
姿态算法是捷联惯导系统算法中的一个重要组成部分,研究了一种新的递推补偿方法并在BorlandC语言环境下进行了仿真,使其更接近工程实践. 相似文献
353.
党的第三代领导核心江泽民在世纪之交、千年更替的新的历史条件下 ,全面继承和创造性地发展了毛泽东邓小平的党建理论 ,为推进党建的伟大工程做出了重大新贡献 :提出了跨世纪党建工程的总目标和总方针 ;进一步确立和发展了党的基本理论、基本路线和基本纲领 ;大力倡导“一个中心”、“三个着眼于”的马克思主义学风 ;坚持不懈地用为人民服务的宗旨教育全党不动摇 ;把提高执政、建设、治国三大本领作为党的建设的重要任务。在加强干部队伍建设、反腐倡廉、党的制度建设、党性党风建设、基层组织建设、思想政治建设和加强“三个代表”的党的全面建设等方面提出了许多新的理论观点 ,实践上也走出了一条新路子 ,对新世纪党的建设具有重要的指导意义。 相似文献
354.
为得到不同温度下石英杂化酚醛材料的渗透率,自主搭建了材料气体渗透率测试平台,提出基于Darcy定律的复合材料气体渗透率的测试方法。对不同温度下石英杂化材料进行研究,测量渗透过程中试验件上下表面气体压力变化和流过试验件的气体流量,进而得到复合材料的渗透率。结果表明:该实验平台可以用来测量复杂孔隙复合材料的渗透率。石英杂化酚醛材料渗透率与热解温度呈正相关,热解温度越高,复合材料的渗透率越大,材料渗透率和热解温度满足关系式K=9.5×10-15T-6.32×10-12。673 K热解温度下,复合材料渗透率为10-13 m2量级;873 K和1 073 K热解温度下,其渗透率在10-12 m2量级。本试验结果丰富了该类树脂基复合材料的基础物性数据,为材料渗透和热质扩散特性分析提供了依据。 相似文献
355.
本文在建立磁悬浮线性模型基础上,设计变结构控制器,进行了仿真计算,并用模拟电路进行实验,给出了仿真和实验结果 相似文献
356.
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
357.
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
358.
359.
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
360.
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