全文获取类型
收费全文 | 107篇 |
免费 | 6篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 3篇 |
综合类 | 8篇 |
化学工业 | 3篇 |
金属工艺 | 12篇 |
机械仪表 | 10篇 |
矿业工程 | 1篇 |
轻工业 | 2篇 |
石油天然气 | 1篇 |
无线电 | 6篇 |
一般工业技术 | 60篇 |
冶金工业 | 2篇 |
原子能技术 | 1篇 |
自动化技术 | 7篇 |
出版年
2023年 | 2篇 |
2021年 | 1篇 |
2020年 | 4篇 |
2019年 | 1篇 |
2017年 | 1篇 |
2016年 | 3篇 |
2015年 | 2篇 |
2014年 | 2篇 |
2013年 | 2篇 |
2012年 | 2篇 |
2011年 | 10篇 |
2010年 | 4篇 |
2009年 | 7篇 |
2008年 | 24篇 |
2007年 | 4篇 |
2006年 | 1篇 |
2005年 | 8篇 |
2004年 | 8篇 |
2003年 | 2篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1983年 | 5篇 |
1982年 | 2篇 |
排序方式: 共有116条查询结果,搜索用时 15 毫秒
1.
We have fabricated and tested a high-Tc dc-SQUID magnetometer patterned on a YBCO thin film deposited on a SrTiO3 bicrystal substrate. The measurement of noise spectrum at 77 K showed that the magnetometer has a white noise of 333 fT/Hz1/2 without superconducting shield, corresponding to a flux sensitivity of 14.5 μΦ0/Hz1/2. We constructed a test system for eddy current non-destructive evaluation of conducting aluminum plates by using the magnetometer. Flaws over 10 mm below the surface can be clearly identified. By mapping the magnetic field distribution, we can locate the flaw position. The signals caused by flaw were expanded due to the use of double-D type driving coil with a wider central slit. The experimental results confirmed that this test system could operate in a magnetic unshielded environment. 相似文献
2.
John P. Wikswo Jr. Nestor G. Sepulveda Yu Pei Ma W. Patrick Henry Daniel J. Staton Duane Crum 《Journal of Nondestructive Evaluation》1993,12(2):109-119
A SQUID magnetometer can be used to measure the magnetic field produced by flaws in a two-dimensional, conducting plate carrying a current. Identification of the flaw-induced magnetic field is difficult because of the large magnetic field associated with the edges of the plate and the current in the leads that connect the plate to the power supply. We have developed a technique by which the wire and edge fields can be cancelled prior to mapping the magnetic field. In this technique, a similar unflawed conducting sheet is placed adjacent to the flawed plate, with a connection between the sheet and the plate at one edge, and with the opposite edges of the sheet and of the plate connected to the two conductors of a coaxial cable. Thus, an applied current will flow along one conductor of the cable, across the cancelling sheet, cross into the flawed plate, return along the plate, and then return to the power supply along the other conductor of the coaxial cable. As a result of this geometry, there is no magnetic field from the lead-in wires because they are coaxial, and the magnetic field due to the edges of the plate is cancelled by the opposing magnetic field of the edges in the adjacent sheet. The extent of cancellation is determined primarily by the separation between the plate and the cancelling sheet, by the thickness of the plate, and by macroscopic inhomogeneities in their electrical conductivities. 相似文献
3.
4.
《低温学》2016
A closed-cycle helium recycler was developed for continuous uninterrupted operation for magnetometer-based whole-head magnetoencephalography (MEG) systems. The recycler consists of a two stage 4 K pulse-tube cryocooler and is mounted on the roof of a magnetically shielded room (MSR). A flexible liquid helium (LHe) return line on the recycler is inserted into the fill port of the MEG system in the MSR through a slotted opening in the ceiling. The helium vapor is captured through a line that returns the gas to the top of the recycler assembly. A high-purity helium gas cylinder connected to the recycler assembly supplies the gas, which, after it is liquefied, increases the level of LHe in the MEG system during the start-up phase. No storage tank for evaporated helium gas nor a helium gas purifier is used. The recycler is capable of liquefying helium with a rate of ∼17 L/d after precooling the MEG system. It has provided a fully maintenance-free operation under computer control for 7 months without refill of helium. Although the recycler is used for single-orientation operation at this initial testing site, it is designed to operate at ±20° orientations, allowing the MEG system to be tilted for supine and reclining positions. Vibration of the recycler is dampened to an ultra-low level by using several vibration isolation methods, which enables uninterrupted operation during MEG measurements. Recyclers similar to this system may be quite useful even for MEG systems with 100% magnetometers. 相似文献
5.
A Cryotiger® gas-mixture cooler was applied for cooling of three high-Tc SQUID magnetometers. These SQUID magnetometers were mounted on an alumina holder in an axial gradiometer configuration. From 20 Hz upward, the system noise was about 0.1 pT/√Hz. Below this frequency, the noise gradually increased to a level of 10 pT/√Hz at 1 Hz. This low-frequency excess noise appeared to be due to remnant magnetization of the Cryotiger cold head. Movement of magnetic cold-head parts with respect to the SQUIDs are induced by pressure fluctuations in the heat exchanger lines. By using one SQUID as a reference for the cooler noise, a first-order gradiometer can be formed in which the cooler noise is eliminated. To establish a proper second-order gradiometer either a fourth SQUID has to be added, or the spatial separation between cold head and SQUIDs has to be increased significantly. 相似文献
6.
7.
K. N. Yugay A. B. Muravjev K. K. Yugay G. M. Seropyan S. A. Sychev K. B. Konovalenko Y. Huh D. S. Pashkevich A. V. Stupak J.-U. Kim 《Journal of Superconductivity》2004,17(6):755-760
Strained films of YBCO in which stresses caused by mismatching of film and substrate lattices and thermal expansion coefficients are frozen by quenching are grown on substrates LAO (1 0 0) by laser ablation method. Critical current in these films is suppressed about 2–3 orders of magnitude. The strained films have unusual temperature dependences with the minimum at the temperature range of 55–57~K. In spite of granular films with the same critical current the strained films are stable to thermocycles. DC-SQUIDs are manufactured on the base of the strained films with the sensitivity by flux up to 4.5 mk 0/ Hz. 相似文献
8.
A.P. Rijpma H.J.G. Krooshoop M.W. Lefevere E.P. van Leeuwen H.J. Holland B. ten Haken H.J.M. ter Brake 《低温学》2008,48(1-2):61-67
A cryocooler-cooled low-Tc SQUID gradiometer system was designed and constructed. It is based on a 4 K GM-cooler that is positioned several meters from the measuring head containing the SQUID sensors. The cooling power is transported by means of a circulating helium flow. Thus, there are three main components: the cooler vessel, the measuring head and the connecting flow-line.In stable operation, the SQUID and gradiometric pick-up loop are about 4.3 K. The overall heat loads to the cooler 1st and 2nd stages are estimated at 17 W and 0.3 W, respectively. The overall system noise was about 10 fT/√Hz although a number of peaks were observed in the spectrum. As an example, an adult heart beat was recorded. 相似文献
9.
简述了生物磁测量原理、测量难点以及国内外水平.着重提出了开展这一研究的相关的关键技术,并提出了今后开展这一研究工作的建议。 相似文献
10.
D. P. Pappas S. T. Halloran R. R. Owings F. C. S. da Silva 《Journal of research of the National Institute of Standards and Technology》2008,113(1):1-10
In this paper we present the development of a magnetic moment reference material for low moment magnetic samples. We first conducted an inter-laboratory comparison to determine the most useful sample dimensions and magnetic properties for common instruments such as vibrating sample magnetometers (VSM), SQUIDs, and alternating gradient field magnetometers. The samples were fabricated and then measured using a vibrating sample magnetometer. Their magnetic moments were calibrated by tracing back to the NIST YIG sphere, SRM 2853. 相似文献