全文获取类型
收费全文 | 509篇 |
免费 | 73篇 |
国内免费 | 22篇 |
出版年
2023年 | 1篇 |
2022年 | 10篇 |
2021年 | 11篇 |
2020年 | 13篇 |
2019年 | 4篇 |
2018年 | 1篇 |
2017年 | 16篇 |
2016年 | 7篇 |
2015年 | 22篇 |
2014年 | 20篇 |
2013年 | 35篇 |
2012年 | 35篇 |
2011年 | 49篇 |
2010年 | 54篇 |
2009年 | 45篇 |
2008年 | 59篇 |
2007年 | 30篇 |
2006年 | 36篇 |
2005年 | 34篇 |
2004年 | 29篇 |
2003年 | 11篇 |
2002年 | 18篇 |
2001年 | 21篇 |
2000年 | 11篇 |
1999年 | 5篇 |
1998年 | 6篇 |
1997年 | 4篇 |
1996年 | 1篇 |
1995年 | 6篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1986年 | 1篇 |
排序方式: 共有604条查询结果,搜索用时 15 毫秒
91.
摘要:针对单小批量武器装备保障的特殊需求,对传统的质量屋模型进行了改进,建立了基于装备保障需求与保障规则的质量屋模型,利用整数规划技术进行求解,使得单小批量武器的装备保障规则按照实际保障需求重新排列优先次序,并通过对某型火炮保障方案的筛选验证了模型的正确性.新的质量屋模型发展完善了质量屋的理论与方法,有助于提高单小批量武器的装备保障能力. 相似文献
92.
GAF协议是一种基于地理信息的无线传感器网络路由协议,由于采用多跳传输,将导致热区的产生。提出了一种优化邻居表算法,可以有效辨识GAF虚拟网格内的节点密度,从而选择密度大的网格通行,以均衡热区能耗,延长网络寿命。仿真结果验证了该算法的可行性。 相似文献
93.
94.
针对弹道导弹中段拦截产生的空间碎片可能对在轨航天器的影响进行了分析,弹道导弹中段拦截产生的空间碎片的质量、速度和运行时间都很有限,本质上为亚轨道残骸,不会对在轨航天器造成重大影响,对在轨航天器的威胁主要来自流星和以往空间任务产生的轨道残骸. 相似文献
95.
How to deal with China's hegemonic ascension is a matter of pressing policy concern and growing academic interest. With the premise that managing China's growing power is a security concern for other parties concerned and China itself, this article discusses how China and members of the Association for Southeast Asian Nations (ASEAN) have taken care to manage an increasingly stronger China through a combination of bilateral diplomacy and multilateral networks. The evidence suggests that ASEAN's engagement policy has largely been successful. The article then delineates an ASEAN‐style engagement strategy and draws some implications for the debate about how to cope with China in general. 相似文献
96.
为充分利用多导脑电信息,首次提出运用有向传递函数(DTF)方法,对不同中枢疲劳状态下导联间信息流的强度和方向的变化进行分析。研究结果表明,脑电功能耦合中额一到一顶方向的信息流是大脑皮层联系的一个固有特征,可以有效地刻画安静清醒和疲劳两个状态,长时间脑力劳动任务引起中枢疲劳的增加,进而导致整个频率段占优势的信息流的方向发生了反转,信息流占优势的方向从实验前的顶一到一额方向,转变为实验后的额一到一顶方向。 相似文献
97.
98.
Firms form various alliances or use brand extensions to enter new markets in order to improve their operational efficiency and create a positive spillover. However, they do not always know the implications of these strategies for market entry and multimarket competition because the sale of products in one market can have negative spillover effects on product sales in other markets. We present an analytical framework to examine whether and how (i.e., by choosing alliance entry or independent entry) competing firms should enter a market in a situation where market spillovers occur when a firm enters a spillover-producing market to sell products that may increase or decrease the consumers' willingness to pay for products in the primary market. Our analysis shows that the operational efficiency (or quality differentiation ability) of firms in a spillover-producing market varies, and hence, the impact of market spillovers differs for firms. We identify the key factors, such as bargaining power, brand value difference in the primary market, and the extent of efficiencies and spillovers, that determine the firms benefitting from the different entry strategies. Specifically, we show that firms would be more willing to choose an alliance strategy to enter a spillover-producing market if the negative spillover is small and alliance efficiency is high. In contrast, if an alliance entry is not favored, the firms' relative operational efficiency is crucial for them to decide whether to enter the market independently under moderate spillover conditions. Finally, we show the implications of market entry strategies for managers. 相似文献
99.
The responses of AI/PTFE reactive materials (RMs) under shock compression were investigated by a single-stage gas gun.A 3D mesoscale-model was established based on micro-computed tomography(micro-CT) slice images and confirmed with experimental results.In the high-pressure stage,the com-posites reacted partially,whereas there were no deviations between the partially reacted Hugoniot and the inert simulation results.The simulation reveals that the Teflon matrix melting on the high shock pressure.Melts and decomposition of the PTFE accelerated the diffusion of the atoms.Thus,the reactions of the Al/PrFE composites are more like a combustion rather than a detonation. 相似文献
100.