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681.
采用气相色谱一质谱联用技术对二异丙氨基甲基膦酸乙基酯和N,N-双(2-甲基膦酸乙基酯乙基)甲基胺2个合成样品进行了分析,比较深入地研究了2个化合物的质谱裂解规律,并推断了样品中相关杂质的结构。 相似文献
682.
装配式管线是一种重要的油料保障装备,用于地面铺设,属于典型的薄壁弱约束管线系统。根据装配式管线的特点,应用管道弹性变形理论,推导了水力瞬变状态下装配式管线的非线性流固耦合5-方程模型。该模型充分考虑了管道与流体之间的耦合互动效应,耦合形式包含了泊松耦合、摩擦耦合、结合部耦合,以及管线系统的轴向、横向和径向振动耦合,并计及了管道结构阻尼的影响。针对装配式管线的特殊连接约束方式,提出了一种带有扭转弹簧的铰支型约束边界,可通过确定扭转弹簧的弹性系数来建立管线两端的约束边界方程。 相似文献
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围绕地空导弹抗干扰性能评估问题,建立了模糊综合评估模型.针对传统模糊综合评估模型采用常权面临的突出问题,引入了变权的思想与方法,构建了基于变权的模糊综合评估模型.实例表明,相对于传统模型,采用基于变权的模糊综合评估模型,可以得出更加合理的评估结果. 相似文献
685.
Frank Meisel 《海军后勤学研究》2011,58(7):619-636
The quay crane scheduling problem consists of scheduling tasks for loading and unloading containers on cranes that are assigned to a vessel for its service. This article introduces a new approach for quay crane scheduling, where the availability of cranes at a vessel is restricted to certain time windows. The problem is of practical relevance, because container terminal operators frequently redeploy cranes among vessels to speed up the service of high‐priority vessels while serving low‐priority vessels casually. This article provides a mathematical formulation of the problem and a tree‐search‐based heuristic solution method. A computational investigation on a large set of test instances is used to evaluate the performance of the heuristic and to identify the impact of differently structured crane time windows on the achievable vessel handling time. © 2011 Wiley Periodicals, Inc. Naval Research Logistics, 2011 相似文献
686.
We study a supply chain in which a manufacturer relies on a salesperson to sell the products to the consumers. The sales outcome is determined by a random market condition and the salesperson's service level, both of which are privately observed by the salesperson. Apart from them, there are two types of resellers: a knowledgeable reseller observes the market condition, whereas a diligent reseller can monitor the service level. While delegating to a reseller enhances information acquisition, it may also result in double marginalization and inefficiency. We identify several operating regimes in which double marginalization can be eliminated via simple contracts and establish the benefit of monitoring the salesperson over monitoring the market. Our dominance result is not prone to our model characteristics regarding the complementarity of market condition and sales effort, the relative importance of adverse selection and moral hazard, and the contract form. We then generalize our model and re‐establish the dominance result in the presence of reseller's risk aversion or private monitoring expertise. We also quantify the performance gaps among different selling schemes under various scenarios. © 2011 Wiley Periodicals, Inc. Naval Research Logistics, 2011 相似文献
687.
针对优化中收敛速度和优化解全局性的问题,提出了一种联合优化方法:构造原问题的近似模型,使用全局优化方法对近似函数进行优化,得到优化点作为初值,再使用局部优化方法对原问题进行优化.为了获得对原问题更好的近似,改进了径向基插值方法,以优化误差的方法来选择参数.利用临近空间机翼模型的优化对算法进行了测试,结果表明,优化参数的... 相似文献
688.
针对人工势能场方法容易陷入局部极值的缺陷,提出了有虚拟势能点的避障算法.该算法在编队进入对队形影响较大的复杂环境中引入额外的虚拟势能点,利用虚拟势能点的作用力使智能体脱离局部障碍物陷阱,进行队形重组,提高了编队队形保持能力;编队运动通过不同的地形时,队形变化程度不一,单一队形控制方法难以在各种环境下保持高效性、有效性,... 相似文献
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This paper studies a periodic‐review pricing and inventory control problem for a retailer, which faces stochastic price‐sensitive demand, under quite general modeling assumptions. Any unsatisfied demand is lost, and any leftover inventory at the end of the finite selling horizon has a salvage value. The cost component for the retailer includes holding, shortage, and both variable and fixed ordering costs. The retailer's objective is to maximize its discounted expected profit over the selling horizon by dynamically deciding on the optimal pricing and replenishment policy for each period. We show that, under a mild assumption on the additive demand function, at the beginning of each period an (s,S) policy is optimal for replenishment, and the value of the optimal price depends on the inventory level after the replenishment decision has been done. Our numerical study also suggests that for a sufficiently long selling horizon, the optimal policy is almost stationary. Furthermore, the fixed ordering cost (K) plays a significant role in our modeling framework. Specifically, any increase in K results in lower s and higher S. On the other hand, the profit impact of dynamically changing the retail price, contrasted with a single fixed price throughout the selling horizon, also increases with K. We demonstrate that using the optimal policy values from a model with backordering of unmet demands as approximations in our model might result in significant profit penalty. © 2005 Wiley Periodicals, Inc. Naval Research Logistics, 2006 相似文献