全文获取类型
收费全文 | 592篇 |
免费 | 55篇 |
国内免费 | 36篇 |
专业分类
电工技术 | 139篇 |
综合类 | 50篇 |
化学工业 | 24篇 |
金属工艺 | 60篇 |
机械仪表 | 101篇 |
建筑科学 | 6篇 |
矿业工程 | 3篇 |
能源动力 | 9篇 |
轻工业 | 3篇 |
水利工程 | 1篇 |
石油天然气 | 1篇 |
武器工业 | 2篇 |
无线电 | 40篇 |
一般工业技术 | 125篇 |
冶金工业 | 11篇 |
原子能技术 | 5篇 |
自动化技术 | 103篇 |
出版年
2024年 | 2篇 |
2023年 | 15篇 |
2022年 | 20篇 |
2021年 | 15篇 |
2020年 | 19篇 |
2019年 | 14篇 |
2018年 | 20篇 |
2017年 | 21篇 |
2016年 | 24篇 |
2015年 | 21篇 |
2014年 | 32篇 |
2013年 | 23篇 |
2012年 | 28篇 |
2011年 | 36篇 |
2010年 | 27篇 |
2009年 | 21篇 |
2008年 | 52篇 |
2007年 | 49篇 |
2006年 | 34篇 |
2005年 | 32篇 |
2004年 | 28篇 |
2003年 | 23篇 |
2002年 | 25篇 |
2001年 | 13篇 |
2000年 | 11篇 |
1999年 | 16篇 |
1998年 | 12篇 |
1997年 | 4篇 |
1996年 | 14篇 |
1995年 | 8篇 |
1994年 | 4篇 |
1993年 | 6篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1984年 | 1篇 |
1979年 | 1篇 |
1977年 | 2篇 |
排序方式: 共有683条查询结果,搜索用时 15 毫秒
1.
2.
R. Masui 《International Journal of Thermophysics》2002,23(4):921-935
The development of a magnetic suspension densimeter that has been built for measurement of the density of compressed liquid at pressures up to 30 MPa in the temperature range 20 to 150°C is described. The densimeter was first built by the author and his coworkers at NIST. We describe here further improvements made on a second system built at NMIJ based on the same principle. The densimeter uses a small coil suspended from an electronic balance. Within the coil is placed a sample cell in which the pressurized sample and a buoy, which is a permanent magnet, are enclosed. For measurement of density, balance readings are recorded (1) with the buoy at rest and (2) with the buoy in magnetic suspension. The measurement procedure is basically a hydrostatic weighing, which is simpler than those of conventional magnetic densimetry. As an example, measurements of toluene density performed as part of an inter-laboratory comparison are presented. The data agreed with reliable literature values to within a few hundredths of a per cent. 相似文献
3.
Shunsuke Ohashi 《Electrical Engineering in Japan》2005,150(1):71-77
Magnetic bearing using pinning force of a permanent magnet and a high‐temperature superconductor has been developed. Additional permanent magnet is introduced to increase the levitation force of the magnetic bearing. In this hybrid magnetic bearing system, levitation force is mainly given by the repulsive force of the permanent magnets, and stability for the lateral direction is given by pinning force of the superconductor. The experimental device is developed. A ring‐type superconductor and a bulk one are examined. Levitation characteristics of the hybrid magnetic bearing are measured. The bulk superconductor shows better characteristics of both levitation and lateral stability than the ring one. Levitation force of the hybrid system becomes about twice as large as that of the nonhybrid one. Although, the repulsive force of the permanent magnet decreases the lateral stability of the system, its influence becomes small by choosing an adequate position of the permanent magnets and the superconductor. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(1): 71–77, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10350 相似文献
4.
E. Gorges L. M. Raez A. Schillings I. Egry 《International Journal of Thermophysics》1996,17(5):1163-1172
Electromagnetic levitation is a useful tool for measuring thermophysical properties of high-temperature melts such as liquid metals. Due to its noncontact nature, the undercooled regime is also accessible. Density and thermal expansion of a levitated drop can be derived from volume measurements, if its mass is known. Assuming cylindrical symmetry, the volume of a drop can be determined from its cross section. Using photography, such measurements on liquid metals have been performed in the past. Here we present an improvement of this method, which replaces the photographic camera with a CCD videocamera and subsequent digital image processing. This reduces the time effect required to obtain the results and allows one to average over disturbing surface oscillations. The specific problems of digital image processing, namely resolution and edge detection, are addressed and results on nickel are presented.Paper presented at the Fourth International Workshop on Subsecond Thermophysics, June 27–29, 1991, Köln, Germany. 相似文献
5.
李国栋 《稀有金属材料与工程》2002,31(6):449-451
综述了磁性功能材料研究和应用在2000年-2001年间的新进展,其内容包括:(1)自旋电子学;(2)Bi-Fe氧化物的磁性;(3)稀有和稀土金属垂直磁记录材料;(4)新的多层膜磁性材料;(5)磁浮列车。 相似文献
6.
NUMERICAL SIMULATION OF ALTERNATIVE HORIZONTAL LEVITATION ELECTROMAGNETIC CONTINUOUS CASTING(Ⅱ) 总被引:1,自引:0,他引:1
NUMERICALSIMULATIONOFALTERNATIVEHORIZONTALLEVITATIONELECTROMAGNETICCONTINUOUSCASTING(Ⅱ)¥ZhuShoujun;RenZhongming;DengKang;Jian... 相似文献
7.
1 INTRODUCTIONTb Dy Fealloy ,asarareearth (RE)magneticfunctionalmaterial,isofsignificanttechnologicalin terests ,becauseofitsgiantmagnetostrictionatroomtemperatureaswellashighenergydensityandfastresponsevelocityatlowfrequency[1] .Wideapplica tionfieldshavebeenidentifiedsincethematerialhadbeenexploited[2 ] .Thecompetitiongrowthbetweentheperitecticphase— (Tb Dy)Fe2 (REFe2 )andtheprimiaryphase— (TbDy)Fe3(REFe3)existsinthesolidificationprocessingoftheperitecticTb Dy Feal loys ,which… 相似文献
8.
Sn-Sb包晶合金的快速凝固 总被引:3,自引:0,他引:3
设计了一种用于Sn-Sb等滑动轴承合金的无容器接触深过冷快速凝固装置.并以热流分析为基础,利用传热模型和物理模型计算了Sn-16%Sb(质量分数)过包晶合金在本装置中的冷却速度.结果表明:在粒子直径为4mm时,粒子的冷却速度为3.1×102K/s;当粒子直径为0.1mm时,冷却速度达到了105K/s.Sn-Sb包晶合金组织显著细化,初生相SnSb化合物高度弥散化. 相似文献
9.
针对瞬时悬浮力与瞬时转矩非线性强耦合的特点,分析了单绕组磁悬浮开关磁阻电机的运行机理,以提高电机动态运行性能为目标,提出瞬时悬浮力与平均转矩分相产生的控制策略。构建单绕组磁悬浮开关磁阻电机悬浮力与平均转矩的数学模型,运用等效电流法,将实际控制电流等效为转矩电流和悬浮电流。引入超前角θm,考虑磁饱和因素,分析推导出θm计算流程,得到电机运行控制策略。有限元和simulink仿真的结果表明当电机转子发生偏心时,采用所述控制策略,转子可以在极短的时间内恢复到平衡位置,闭环系统具有良好的动静态性能。 相似文献
10.