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   263篇
  免费   0篇
  国内免费   1篇
系统科学   23篇
丛书文集   1篇
教育与普及   5篇
理论与方法论   1篇
现状及发展   1篇
综合类   233篇
  2016年   1篇
  2015年   2篇
  2012年   7篇
  2011年   11篇
  2010年   15篇
  2009年   35篇
  2008年   1篇
  2007年   1篇
  2005年   5篇
  2004年   19篇
  2003年   17篇
  2002年   9篇
  2001年   9篇
  1999年   2篇
  1998年   24篇
  1997年   37篇
  1996年   31篇
  1995年   20篇
  1994年   6篇
  1993年   6篇
  1992年   4篇
  1990年   1篇
  1988年   1篇
排序方式: 共有264条查询结果,搜索用时 15 毫秒
131.
NHR-200定位格架的设计研究   总被引:1,自引:0,他引:1  
定位格架是反应堆燃料组件的重要组成部分。200MW核供热堆(NHR-200)燃料组件定位格架主要由条带、围带及角部片簧组成。本文分析了该格架在组件装卸过程中的导向性能,论述了格架三弯弹簧的设计、刚度分析、预变形范围的计算以及弹簧夹持力的确定等。格架条带三弯弹簧的试制实验研究结果表明NHR-200组件定位格架结构设计合理、弹簧选型科学,完全满足供热堆格架设计的要求。  相似文献   
132.
根据200MW核供热堆(NHR-200)主换热器的设计工况,针对其传热管振动时流体弹性不稳定、旋涡脱落和湍流激振的主要机理,依目前换热器设计所通常采用的防振判据,对主换热器传热管振动作了详细分析。结果表明:NHR-200主换热器在其设计工况下运行时,不会发生流体弹性不稳定所导致的大振幅振动,如果运行偏离设计工况,那么U型管的弯管区是首先引起注意的区域;在设计工况下,传热管各区不会产生疲劳破坏,传热管的相互碰撞和剪切与磨损的破坏。  相似文献   
133.
注硼系统是确保反应堆安全的重要设施。文中实验研究了喷射泵在核反应堆注硼系统中作为安全装置使用的可行性和可靠性,实验的压力为0.1~1.5MPa,温度为20~198℃,喷射泵工作喷嘴直径为1~8mm,注入流量为0.1~0.8kgs-1。实验表明合理设计的喷射泵能满足“正向”注硼和“反向”阻断液位下降的双重作用。以实验研究为基础设计制造的喷射泵已首次应用于5MW核供热堆注硼系统中。  相似文献   
134.
HTR-10蒸汽发生器试验回路及其水动力特性分析   总被引:1,自引:0,他引:1  
10MW高温气冷堆(HTR-10)蒸汽发生器的两相流动稳定性问题是设计中必须考虑的问题,文中分析了HTR-10蒸汽发生器恒热流和强迫循环一次热源的静态水动力特性。论述了用恒热流所得判别各类稳定性准则作为He加热的HTR-10蒸汽发生器设计依据是不足的。有必要进行He加热HTR-10蒸汽发生器工程模型两相流稳定性试验。还介绍了HTR-10蒸汽发生器工程模型试验回路及本体,以及在该试验回路上预期达到研究成果。  相似文献   
135.
为了保证 200 MW供热堆堆芯结构在地震时的完整性、控制棒通道在地震时畅通,和供热堆的抗震安全,有必要进行全尺寸的堆芯单元模型的抗震试验。从 200 MW供热堆堆芯结构的特点出发,研究了模型设计的原则和动力学相似的问题,重点对堆内支承,燃料组件和锆盒等重要部件的动力学简化原则进行了阐述,利用有限元法分析了堆芯结构的动力学特性,讨论了试验模型和计算模型的关系,以及支架的设计问题,为台架试验打下了基础。通过本研究,不仅可对供热堆设计方案的性能进行恰当的评价,而且可指出进一步改善设计使结构达到优化的方向,保证供热堆的安全运行。  相似文献   
136.
为了尽量减轻固定网络负荷 ,设计了一种容易实现的IP移动方案 ,即一种轻量级的位置管理方法———类似组播的地址查询机制M-LQ及相应的IP移动解决方案—MS-MLQ .  相似文献   
137.
The paper describes a novel low-power CMOS voltage-controlled oscillator (VCO) with dual-band local oscillating (LO) signal outputs for 5/2. 5-GHz wireless local area network (WLAN) transceivers. The VCO is based on an on-chip symmetrical spiral inductor and a differential varactor. The 2. 5-GHz quadrature LO signals are generated using the injection-locked frequency divider (ILFD) technique. The ILFD structure is similar to the VCO structure with its wide tracking range. The design tool ASITIC was used to optimize all on-chip symmetrical inductors. The power consumption was kept low with differential LC tanks and the ILFD technique. The circuit was implemented in a 0.18-fim CMOS process. Hspice and SpectreRF simulations show the proposed circuit could generate low phase noise 5/2. 5-GHz dual band LO signals with a wide tuning range. The 2. 5-GHz LO signals are quadrature with almost no phase and amplitude errors. The circuit consumes less than 5. 3mW in the tuning range with a power supply voltage of 1  相似文献   
138.
Analytical solutions are presented for the wave equation for the electrode-piezoelectric-electrode sandwich structure in film bulk acoustic resonators (FBAR). The impedance for lead-zirconate-titanate (PZT)-based FBAR was derived using the proper boundary conditions and material parameters. A method is presented to adjust the resonant frequency based on the process and material properties. Ferroelectric-based radio-frequency filters were designed using FBARs. An accurate result is given for the filter impedance which can be used for other piezoelectric devices.  相似文献   
139.
To study water quality problems associated with groundwater recharge, a tertiary treatment process, consisting of coagulation, sand filtration, and granular activated carbon (GAC) adsorption, was used in combination with a simulated soil aquifer treatment. The process significantly improved secondary effluent quality. GAC adsorption reduced organic substances expressed by UV-254, dissolved organic carbon as well as partially adsorbable organic halogens. The results of the Ames test show that the secondary effluent contains a high concentration of mutagens. GAC filtration removed adsorbable organic bromine slightly whereas GAC adsorption removed mutagens effectively. The simulated soil aquifer treatment was able to further reduce UV-254, dissolved organic carbon, and adsorbable organic halogens through biodegradation. Adsorbable organic bromine levels were also reduced by the soil aquifer treatment process. The given reclamation technology used for groundwater recharge is of benefit to the removal of dissolved organic carbon, UV-254, adsorbable organic halogens, and rnutagenicity.  相似文献   
140.
The dynamic effects of inertial loads on the interface stresses between a residual limb and the trans-tibial prosthetic socket were investigated. A 3-D nonlinear finite element model, based on the actual geometry of the residual limb, including internal bones and socket liner, was developed to study the mechanical interaction between the socket and the residual limb during walking. To simulate the friction/slip boundary conditions between the skin and liner, automated surface-to-surface contact was used. The results show that interface pressure and shear stress have a similar double-peaked waveform shape in the stance phase. The average difference in interface stresses between the cases with and without consideration of inertial forces is 8.4% in the stance phase and 20.1% in the swing phase. The results suggest that the dynamic effects of inertial loads on interface stress distribution during walking must be considered in prosthetic socket design.  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