首页 | 官方网站   微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   86篇
  完全免费   10篇
工业技术   96篇
  2020年   1篇
  2019年   1篇
  2018年   4篇
  2017年   3篇
  2016年   1篇
  2015年   6篇
  2014年   10篇
  2013年   8篇
  2012年   4篇
  2011年   13篇
  2010年   10篇
  2009年   5篇
  2008年   3篇
  2007年   4篇
  2006年   4篇
  2005年   3篇
  2004年   5篇
  2003年   1篇
  2002年   1篇
  2001年   2篇
  2000年   1篇
  1999年   1篇
  1998年   1篇
  1997年   2篇
  1994年   1篇
  1992年   1篇
排序方式: 共有96条查询结果,搜索用时 93 毫秒
1.
一定充气压力下, 子午胎的固有频率是由其材料和结构本身确定的。鉴于橡胶材料的粘弹性性质, 本文中以胎体为弹性基础、把子午胎模拟成一个胎面层具有粘弹性的圆环弹性基础模型, 并在此模型的基础上建立频率方程。本模型预报出的频率值能与实验值吻合。  相似文献   
2.
闫相桥  王友善 《轮胎工业》2000,20(5):270-275
作为轮胎结构有限元分析应用于轮胎结构优选方面的例子,探讨了载重子午线轮胎胎体反包高度的优选问题。通过对胎体反包端点、带束层点、胎户附近单元的应力分析参数及胎圈附近胎体张应力的综合分析,认为313低网格对应的胎体反包高度比313网格和313高网格对应的两种胎体包高度更合适。  相似文献   
3.
Drivers of accident preparedness and safety: evidence from the RMP Rule   总被引:1,自引:0,他引:1  
This paper provides an overview of recent results derived from the accident history data collected under 112(r) of the Clean Air Act Amendments (the Risk Management Program (RMP) Rule) covering the period 1994-2000, together with a preliminary assessment of the effectiveness of the RMP Rule as a form of Management System Regulation. These were undertaken at the University of Pennsylvania by a multi-disciplinary team of economists, statisticians and epidemiologists with the support of the US Environmental Protection Agency and its Office of Emergency Prevention, Preparedness and Response (OEPPR, formerly CEPPO). Section 112(r) of the Clean Air Act Amendments of 1990 requires that chemical facilities in the US that had on premises more than specified quantities of toxic or flammable chemicals file a 5-year history of accidents. The initial data reported under the RMP Rule covered roughly the period from mid-1994 through mid-2000, and provided details on economic, environmental and acute health affects resulting from accidents at some 15,000 US chemical facilities for this period. This paper reviews research based on this data. The research is in the form of a retrospective cohort study that considers the statistical associations between accident frequency and accident severity at covered facilities (the outcome variables of interest) and a number of facility characteristics (the available predictor variables provided by the RMP Rule), the latter including such facility characteristics as size, hazardousness, financial characteristics of parent company-owners of the facility, regulatory programs in force at the facility, and host community characteristics for the surrounding county in which the facility was located, as captured in the 1990 Census. Among the findings reviewed are: (1) positive associations with (a measure of) facility hazardousness and accident, injury and economic costs of accidents; (2) positive (resp., negative) associations between accident propensity and debt-equity ratios (resp., sales) of parent companies; (3) several interrelated associations between accident propensity and regulatory programs in force; and (4) strong associations between facility hazardousness, facility locations decisions, observed accident frequencies and community demographics.  相似文献   
4.
在地球高层大气组份分离扩散的初步研究基础上,讨论了一般情况下两种气体成份的大气重力分离扩散.  相似文献   
5.
高层大气各组份重力分离扩散过程的初步研究   总被引:1,自引:1,他引:0  
根据“稳恒态气体输运理论”的基本方法,对地球高层大气中不同成分的重力扩散分离现象给出了定量的解释.  相似文献   
6.
气体输运过程新理论的研究   总被引:2,自引:2,他引:0  
在两个主要假设的基础上直接得到了新的近似分布函数──合成分布函数。把这个新函数用于输运系数的计算时,得到了正确的表达式。如果以等效自由程“L”代替合成分布函数中的麦氏自由程“l”时,该分布函数将变得更为精确。  相似文献   
7.
速度住留理论新探   总被引:1,自引:1,他引:0  
在Jeans提出的速度住留概念的基础上,引入了速度“反住留”、分子“接续运动”等一些新概念,并由此对Jeans的速度住留理论作了合理引申,得到分子速度的各级有效住留及相应的“等效分子自由程”L.最后,用L代替分子自由程l,使用于气体的初级输运理论,结果表明经过完善化了的速度住留理论是相当成功的。  相似文献   
8.
UST条干仪测试的影响因素及控制   总被引:1,自引:0,他引:1  
分析 U ST条干仪测试原理 ,阐述长丝 UST条干仪测试误差、差错的产生及消除方法 ;操作环境对测试的影响及控制 ;正确选用测试条件的方法 ,以及稳定、正确操作的必要性。  相似文献   
9.
The evolution of yeast species and Saccharomyces cerevisiae genotypes during spontaneous fermentations of Muscat blanc planted in 1957 in Jingyang region of China was followed in this study. Using a combination of colony morphology on Wallerstein Nutrient (WLN) medium, sequence analysis of the 26S rDNA D1/D2 domain and 5.8S-ITS-RFLP analysis, a total of 686 isolates were identified at the species level. The six species identified were S. cerevisiae, Hanseniaspora uvarum, Hanseniaspora opuntiae, Issatchenkia terricola, Pichia kudriavzevii (Issatchenkia orientalis) and Trichosporon coremiiforme. This is the first report of T. coremiiforme as an inhabitant of grape must. Three new colony morphologies on WLN medium and one new 5.8S-ITS-RFLP profile are described. Species of non-Saccharomyces, predominantly H. opuntiae, were found in early stages of fermentation. Subsequently, S. cerevisiae prevailed followed by large numbers of P. kudriavzevii that dominated at the end of fermentations. Six native genotypes of S. cerevisiae were determined by interdelta sequence analysis. Genotypes III and IV were predominant. As a first step in exploring untapped yeast resources of the region, this study is important for monitoring the yeast ecology in native fermentations and screening indigenous yeasts that will produce wines with regional characteristics.  相似文献   
10.
以三聚氯氰和苯基次膦酸二叔丁酯为原料,合成新型阻燃剂三嗪三苯基次膦酸叔丁酯2,4,6-三(O-叔丁基–苯基次膦酰基)-1,3,5-三嗪化合物。讨论了反应时间、反应温度、原料配比等对合成反应的影响。其最佳反应条件为:三聚氯氰与苯基次膦酸二叔丁酯的物质的量之比为1∶3.4,分两次滴加苯基次膦酸二叔丁酯,在100℃反应5 h,收率为90.6%。采用傅里叶变换红外光谱、核磁共振、差热分析及极限氧指数等表征了产品的结构及阻燃应用性能。研究表明,该化合物对PE阻燃效能高,相容性好,且与MCA,MPP复配有很好的协同阻燃效果。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司    京ICP备09084417号-23

京公网安备 11010802026262号