全文获取类型
| 收费全文 | 384篇 |
| 免费 | 15篇 |
| 国内免费 | 6篇 |
专业分类
| 405篇 |
出版年
| 2025年 | 7篇 |
| 2024年 | 1篇 |
| 2023年 | 10篇 |
| 2022年 | 5篇 |
| 2021年 | 12篇 |
| 2020年 | 4篇 |
| 2019年 | 6篇 |
| 2018年 | 2篇 |
| 2017年 | 12篇 |
| 2016年 | 22篇 |
| 2015年 | 9篇 |
| 2014年 | 30篇 |
| 2013年 | 17篇 |
| 2012年 | 20篇 |
| 2011年 | 20篇 |
| 2010年 | 13篇 |
| 2009年 | 19篇 |
| 2008年 | 23篇 |
| 2007年 | 25篇 |
| 2006年 | 17篇 |
| 2005年 | 14篇 |
| 2004年 | 11篇 |
| 2003年 | 13篇 |
| 2002年 | 10篇 |
| 2001年 | 9篇 |
| 2000年 | 8篇 |
| 1999年 | 10篇 |
| 1998年 | 9篇 |
| 1997年 | 4篇 |
| 1996年 | 7篇 |
| 1995年 | 6篇 |
| 1994年 | 9篇 |
| 1993年 | 8篇 |
| 1992年 | 6篇 |
| 1991年 | 6篇 |
| 1989年 | 1篇 |
排序方式： 共有405条查询结果，搜索用时 0 毫秒
301.
In order to study the influences of confining pressure and strain rate on the mechanical properties of the Nitrate Ester Plasticized Polyether (NEPE) propellant, uniaxial tensile tests were conducted using the self-made confining pressure system and material testing machine. The stress-strain responses of the NEPE propellant under different confining pressure conditions and strain rates were obtained and analyzed. The results show that confining pressure and strain rate have a remarkably influence on the mechanical responses of the NEPE propellant. As confining pressure increases (from 0 to 5.4 MPa), the maximum tensile stress and ultimate strain increase gradually. With the coupled effects of confining pressure and strain rate, the value of the maximum tensile stress and ultimate strain at 5.4 MPa and 0.0667 s−1 is 2.03 times and 2.19 times of their values under 0 MPa and 0.00333 s−1, respectively. Afterwards, the influence mechanism of confining pressure on the NEPE propellant was analyzed. Finally, based on the viscoelastic theory and continuous damage theory, a nonlinear constitutive model considering confining pressure and strain rate was developed. The damage was considered to be rate-dependent and pressure-dependent. The constitutive model was validated by comparing experimental data with predictions of the constitutive model. The whole maximum stress errors of the model predictions are lower than 4% and the corresponding strain errors are lower than 7%. The results show that confining pressure can suppress the damage initiation and evolution of the NEPE propellant and the nonlinear constitutive model can describe the mechanical responses of the NEPE propellant under various confining pressure conditions and strain rates. This research can lay a theoretical foundation for analyzing the structural integrity of propellant grain accurately under working pressure loading. 相似文献
302.
Jorge Navarro 《海军后勤学研究》2007,54(8):820-828
We study tail hazard rate ordering properties of coherent systems using the representation of the distribution of a coherent system as a mixture of the distributions of the series systems obtained from its path sets. Also some ordering properties are obtained for order statistics which, in this context, represent the lifetimes of k‐out‐of‐n systems. We pay special attention to systems with components satisfying the proportional hazard rate model or with exponential, Weibull and Pareto type II distributions. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007 相似文献
303.
Ward Whitt 《海军后勤学研究》2007,54(5):476-484
One traditional application of queueing models is to help set staffing requirements in service systems, but the way to do so is not entirely straightforward, largely because demand in service systems typically varies greatly by the time of day. This article discusses ways—old and new—to cope with that time‐varying demand. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007 相似文献
304.
305.
306.
Burn‐in is a widely used method to improve the quality of products or systems after they have been produced. In this paper, we consider the problem of determining bounds to the optimal burn‐in time and optimal replacement policy maximizing the steady state availability of a repairable system. It is assumed that two types of system failures may occur: One is Type I failure (minor failure), which can be removed by a minimal repair, and the other is Type II failure (catastrophic failure), which can be removed only by a complete repair. Assuming that the underlying lifetime distribution of the system has a bathtub‐shaped failure rate function, upper and lower bounds for the optimal burn‐in time are provided. Furthermore, some other applications of optimal burn‐in are also considered. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2004 相似文献
307.
This article considers the problem of monitoring Poisson count data when sample sizes are time varying without assuming a priori knowledge of sample sizes. Traditional control charts, whose control limits are often determined before the control charts are activated, are constructed based on perfect knowledge of sample sizes. In practice, however, future sample sizes are often unknown. Making an inappropriate assumption of the distribution function could lead to unexpected performance of the control charts, for example, excessive false alarms in the early runs of the control charts, which would in turn hurt an operator's confidence in valid alarms. To overcome this problem, we propose the use of probability control limits, which are determined based on the realization of sample sizes online. The conditional probability that the charting statistic exceeds the control limit at present given that there has not been a single alarm before can be guaranteed to meet a specified false alarm rate. Simulation studies show that our proposed control chart is able to deliver satisfactory run length performance for any time‐varying sample sizes. The idea presented in this article can be applied to any effective control charts such as the exponentially weighted moving average or cumulative sum chart. © 2013 Wiley Periodicals, Inc. Naval Research Logistics 60: 625–636, 2013 相似文献
308.
309.
通过顺解法,利用录取的目标现在点数据,已知的射表数据及对有关偏差量的修正,可求解出斜距离４５００ｍ,高低角０°至８４°范围内的标准值 相似文献
310.
Cao Taiyue 《国防科技大学学报》1995,17(3):119-125
ＣＡＬＣＵＬＡＴＩＯＮＯＦＢＵＲＮＩＮＧＲＡＴＥＣＨＡＲＡＣＴＥＲＩＳＴＩＣＳＩＮＡＣＣＥＬＥＲＡＴＥＤＦＩＥＬＤＦＯＲＳＯＭＥＡＬＵＭＩＮＩＺＥＤＳＯＬＩＤＰＲＯＰＥＬＬＡＮＴＳＣａｏＴａｉｙｕｅ（ＤｅｐａｒｔｍｅｎｔｏｆＡｅｒｏｓｐａｃｅＴｅｃｈ... 相似文献