全文获取类型
收费全文 | 1417篇 |
免费 | 459篇 |
国内免费 | 213篇 |
专业分类
2089篇 |
出版年
2024年 | 4篇 |
2023年 | 18篇 |
2022年 | 18篇 |
2021年 | 35篇 |
2020年 | 36篇 |
2019年 | 36篇 |
2018年 | 29篇 |
2017年 | 72篇 |
2016年 | 109篇 |
2015年 | 61篇 |
2014年 | 119篇 |
2013年 | 118篇 |
2012年 | 134篇 |
2011年 | 100篇 |
2010年 | 88篇 |
2009年 | 135篇 |
2008年 | 88篇 |
2007年 | 106篇 |
2006年 | 139篇 |
2005年 | 117篇 |
2004年 | 93篇 |
2003年 | 73篇 |
2002年 | 56篇 |
2001年 | 54篇 |
2000年 | 31篇 |
1999年 | 44篇 |
1998年 | 37篇 |
1997年 | 30篇 |
1996年 | 18篇 |
1995年 | 16篇 |
1994年 | 11篇 |
1993年 | 12篇 |
1992年 | 14篇 |
1991年 | 16篇 |
1990年 | 16篇 |
1989年 | 5篇 |
1987年 | 1篇 |
排序方式: 共有2089条查询结果,搜索用时 0 毫秒
621.
Statistical analysis for masked system life data from Marshall‐Olkin Weibull distribution under progressive hybrid censoring 下载免费PDF全文
This paper considers the statistical analysis of masked data in a series system, where the components are assumed to have Marshall‐Olkin Weibull distribution. Based on type‐I progressive hybrid censored and masked data, we derive the maximum likelihood estimates, approximate confidence intervals, and bootstrap confidence intervals of unknown parameters. As the maximum likelihood estimate does not exist for small sample size, Gibbs sampling is used to obtain the Bayesian estimates and Monte Carlo method is employed to construct the credible intervals based on Jefferys prior with partial information. Numerical simulations are performed to compare the performances of the proposed methods and one data set is analyzed. 相似文献
622.
In the literature two common macroscopic evacuation planning approaches exist: The dynamic network flow approach and the Cell–Transmission–Based approach. Both approaches have advantages and disadvantages. Many efficient solution approaches for the dynamic network flow approach exist so that realistic problem instances can be considered. However, the consideration of (more) realistic aspects (eg, density dependent travel times) results in non‐linear model formulations. The Cell‐Transmission‐Based approach on the other hand considers realistic traffic phenomena like shock waves and traffic congestion, but this approach leads to long computational times for realistic problem instances. In this article, we combine the advantages of both approaches: We consider a Cell‐Transmission‐Based Evacuation Planning Model (CTEPM) and present a network flow formulation that is equivalent to the cell‐based model. Thus, the computational costs of the CTEPM are enormously reduced due to the reformulation and the detailed representation of the traffic flow dynamics is maintained. We investigate the impacts of various evacuation scenario parameters on the evacuation performance and on the computational times in a computational study including 90 realistic instances. 相似文献
623.
624.
625.
随机滤波模型在变速箱剩余寿命预测中的应用研究 总被引:1,自引:0,他引:1
摘要:基于变速箱加速寿命实验的振动信号,提取信号的多种特征参量.通过分析各特征参量的敏感性和稳定性,选择幅域裕度指标、峰值指标、波形指标和RMS(RootMeanSquare)作为特征参量,建立一种基于随机滤波的变速箱剩余寿命预测模型,给出剩余寿命后验概率密度的递推公式,设计了极大似然估计方法求解模型参数,并经实例验证模型的有效性和实用性. 相似文献
626.
齐紫微 《军械工程学院学报》2013,(2):66-69
基于复杂网络理论,分析了信息化作战系统网络结构,构建了传统作战系统和信息化作战系统拓扑模型的生成算法,并通过对传统作战系统和信息化作战系统结构拓扑模型度量性质的比较,说明了信息化战争下的作战系统结构特点,为进一步研究网络化战争提供了良好的模型基础. 相似文献
627.
João Ricardo Faria 《Defence and Peace Economics》2013,24(5):431-445
This article presents a dynamic model in which counterterrorism policies have the potential to generate positive public support for terrorism via a backlash that may fuel terror recruitment. For an optimizing government aiming at maximizing security, this phenomenon produces a natural bound on proactive counterterror policy that is related to the dynamic path of conflict. Moreover, terror is a persistent phenomenon that requires patience on the part of the target government for optimal counterterror policies to be realized. Finally, the potential for backlash yields insights into the need for target governments to fight an information war to change public opinion regarding its own policies and the ultimate effect of terror attacks. 相似文献
628.
629.
630.
在声纳搜索水雷任务中,为提高剩余雷数估计的准确性,加强作战辅助决策能力,针对现有评估模型未考虑漏搜区和重叠区,评估结果误差和离散性较大的问题,提出一种修正发现雷数的方法:对任务区建立网格,根据记录航迹获得的覆盖次数分布情况,从中提取出漏搜信息,并用其修正发现雷数向量。该方法有效解决了评估向量误差大、维数偏低的缺陷,显著提高了合理性。对典型情况的大量仿真试验证明,该方法能大幅度提高评估结果的准确性,降低离散性,并具有更强的适应性。 相似文献