首页 | 本学科首页   官方微博 | 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   60篇
  免费   0篇
化学   17篇
力学   1篇
数学   2篇
物理学   3篇
综合类   37篇
  2019年   1篇
  2003年   12篇
  1999年   14篇
  1998年   4篇
  1997年   1篇
  1996年   3篇
  1994年   3篇
  1985年   2篇
  1984年   3篇
  1983年   1篇
  1981年   3篇
  1980年   2篇
  1978年   2篇
  1977年   2篇
  1976年   2篇
  1975年   2篇
  1974年   2篇
  1973年   1篇
排序方式: 共有60条查询结果,搜索用时 15 毫秒
11.
12.
利用两步MacCormack显示格式对气动激光器喷管内的平衡、非平衡流动进行了研究.算例表明,该差分格式具有高效、简易、易收敛的特点,适用于拟一维喷管内平衡、非平衡流计算.在二振型二温度弛豫模型及典型CO2-N2-H2O组分条件下,对弛豫时间的实验数据进行了综合整理及分析,在此基础上,研究了弛豫时间对计算结果的影响  相似文献   
13.
建立了覆冰数学模型,以 Wilson θ法为基础推导了舞动方程的数值求解方法.以湖北中山口大跨越三分裂导线为实例,应用模拟冰型的风洞试验气动数据,对中山口大跨越发生的扭控舞动作了数值计算,结果与现场观察情况基本一致.  相似文献   
14.
研究了基于自适应神经元的一类工业过程控制问题,分析了闭环系统稳定性与神经元控制器参数的关系,给出了闭环系统稳定的充分条件及神经元学习参数初值的一种方法及学习的收敛性证明。理论分析表明,神经元智能过程控制系统有很强的鲁棒性和适应性,仿真结果表明了其优良的性能。  相似文献   
15.
甘薯水分关系的主分量分析   总被引:1,自引:0,他引:1  
运用多元统计数学中主分量分析的方法计算和比较了甘薯离体叶片的水势、相对含水量、束缚水、水分饱和亏缺、质膜透性、丙二醛和游离脯氨酸含量等植物水分生理指标的变化。结果指出:水势、相对含水量和丙二醛等对水分胁迫作出反应的敏感程度较高。表明主分量分析方法是综合评价甘薯抗旱生理指标的一种好的研究方法。  相似文献   
16.
The reaction of polystyrene with hydroxyl radicals, generated by the photolysis (λ > 300 nm) of H2O2, has been studied at 25° in dichloromethane solution, both under vacuum conditions and in presence of O2. Spectroscopic analyses suggest the presence of phenols and hydroxymucondialdehydes (when O2 is present) among the reaction products, indicating that OH addition occurs at the phenyl groups of the polymer. By comparison with initiated oxidation reactions under the same conditions, it is concluded that the OH radicals undergo mainly addition reactions. A mechanism has been produced to account for the products. The significance of OH addition reactions in the oxidation of polystyrene is considered, the OH radicals being produced by hydroperoxide decomposition during oxidation, and the products having been previously identified as containing mucondialdehydes.  相似文献   
17.
将水压力脉动测试、流场测试以及初生空化观测等实测结果进行对比分析,研究水轮机活动导叶开口的变化对尾水管水压力脉动的影响,为进一步研究并建立尾水管水压力脉动数学模型提供依据  相似文献   
18.
分析了进口卷取机跑偏控制系统 ( E P C 系统)的特点,指出增大油缸工作面积 A 会减小 E P C 系统的速度,提出了适合该系统的约束归纳优化法.介绍了 E P C 系统优化中约束归纳的过程和网络算法的原理,同时对优化结果进行了仿真分析.增载改造的实践,证明了该优化结果的正确.  相似文献   
19.
A computational model was developed to numerically analyse fatigue striations. The inclined strip yield model with continuous distributions of infinitesimal dislocations was utilized to express the crack tip plasticity in this model. The fatigue crack tip blunting process was approximated by sequential activation of two slip lines under loading, and crack closure during unloading was taken into account. The plastic zone at a growing fatigue crack tip at the maximum load was independent of the crack growth up to ten cycles while the reversed plastic zone decreased in a size to one twentieth of that at the maximum load as the crack grew. The ratio of these plastic zone sizes and also the crack tip opening displacement were quite different from the simple prediction by J.R. Rice for a stationary crack. The computed striation spacings were compared with the observed ones and moderate agreement between them obtained.  相似文献   
20.
Photolysis of hydrogen sulphide in argon, nitrogen and carbon monoxide matrices at 20 K produces HS radicals and S atoms. On warming the matrix, H2S2 and S2 molecules are formed as a result of recombination reactions. The latter are identified by a blue-purple emission observed during warm-up of the matrix.  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