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   118篇
  免费   12篇
电工技术   2篇
化学工业   22篇
金属工艺   3篇
机械仪表   3篇
建筑科学   1篇
矿业工程   1篇
能源动力   7篇
轻工业   45篇
水利工程   1篇
石油天然气   1篇
无线电   5篇
一般工业技术   14篇
冶金工业   17篇
原子能技术   1篇
自动化技术   7篇
  2024年   1篇
  2023年   2篇
  2022年   5篇
  2021年   6篇
  2020年   4篇
  2019年   6篇
  2018年   4篇
  2017年   8篇
  2016年   11篇
  2015年   5篇
  2014年   6篇
  2013年   8篇
  2012年   7篇
  2011年   9篇
  2010年   6篇
  2009年   7篇
  2008年   5篇
  2007年   6篇
  2006年   3篇
  2004年   2篇
  2003年   3篇
  2001年   3篇
  2000年   4篇
  1997年   2篇
  1996年   4篇
  1995年   2篇
  1993年   1篇
排序方式: 共有130条查询结果,搜索用时 15 毫秒
1.
A spectral Integral method (SIM) for layered media   总被引:2,自引:0,他引:2  
A spectral integral method is presented for electromagnetic scattering from dielectric and perfectly electric conducting (PEC) objects with a closed boundary embedded in a layered medium. Two-dimensional layered medium Green's functions are computed adaptively by using Gaussian quadratures. The singular terms in the Green's functions and the non-smooth terms in their derivatives are handled appropriately to achieve exponential convergence. Numerical results, compared with the ones obtained by using other methods, demonstrate the spectral accuracy and high efficiency of the proposed method. They also confirm that the spectral integral method (SIM) is applicable to concave objects.  相似文献   
2.
The results of current investigation demonstrate that mechanochemical processing can be used to synthesize high purity Fe2B nanocrystals by selecting well-optimized milling conditions, reaction paths and proper starting materials. Microstructure, phase analyses, specific surface area, and magnetic properties of the synthesized nanocrystals were examined by using X-ray diffraction/spectroscopy, electron microscopy, nitrogen adsorption–desorption methods following Brunauer-Emmett-Teller equation and vibrating sample magnetometer techniques, respectively. Removal of MgO impurity phase by leaching the resulting powder in the acetic acid solution yielded single phase Fe2B nanocrystals with the crystallite size and specific surface area of 12.5 nm and 29 m2/g, respectively. Magnetization results clearly indicated the ferromagnetic behavior of Fe2B nanocrystals with saturation magnetization observed around 96.26 emu·g?1. Electron microscope images revealed coaxial/spherical powder shape and morphology of the single-phase Fe2B nanocrystals.  相似文献   
3.
4.
Kuru  Cihan  Alaf  Mirac  Simsek  Yunus E.  Tocoglu  Ubeyd 《Catalysis Letters》2022,152(2):315-323
Catalysis Letters - Here, we successfully fabricated sulfurized Co-Mo alloy thin film electrodes with different compositions and studied their catalytic properties for hydrogen evolution reaction...  相似文献   
5.
Nutritional intake appears to be an important factor contributing to aging. In the present study we describe changes in physical health related to nutritional intake among elderly persons in a 10-y longitudinal study. Among 304 healthy elderly participants (median age 72 y on entry into the study in 1980), 97 (34.2%) are still in good health 10 y later in 1990, 74 (26.5%) have become frail or sick, 54 (19.1%) have died, and 57 (20.1%) have dropped out of the study. Women with lower or higher energy intakes (in 1980 and 1981) than the current Recommended Daily Allowance (RDA; between 25 and 30 kcal/kg) were more likely to become frail or sick or to die in 1990 than those with energy intake in the midrange (below RDA, odds ratio (OR) = 3.3, confidence interval (CI) = 1.2-8.6; above RDA, OR = 3.4, CI: 1.1-10.7). Moreover, women with protein intakes greater than the midrange of 0.8-1.2 g/kg of body weight (1.20-1.76 g/kg in 1980 and 1981) tended to have fewer health problems over the next 10 y than those with protein intakes < 0.8 g/kg, suggesting that the mean protein requirement in elderly adults is greater than that established by the 1985 joint World Health Organization/ FAO/UNU Expert Committee. Moreover, a decrease in energy intake was greater in elderly persons who died or dropped out of the study because of illness.  相似文献   
6.
7.
8.
The performance of a photovoltaic (PV) panel is affected by its orientation and its tilt angle with the horizontal plane. This is because both of these parameters change the amount of solar energy received by the surface of the PV panel. A mathematical model was used to estimate the total solar radiation on the tilted PV surface, and to determine optimum tilt angles for a PV panel installed in Sanliurfa, Turkey. The optimum tilt angles were determined by searching for the values of angles for which the total radiation on the PV surface was maximum for the period studied. The study also investigated the effect of two-axis solar tracking on energy gain compared to a fixed PV panel. This study determined that the monthly optimum tilt angle for a PV panel changes throughout the year with its minimum value as 13° in June and maximum value as 61° in December. The results showed that the gains in the amount of solar radiation throughout the year received by the PV panel mounted at monthly optimum tilt angles with respect to seasonal optimum angles and tilt angel equal to latitude were 1.1% and 3.9%, respectively. Furthermore, daily average of 29.3% gain in total solar radiation results in an daily average of 34.6% gain in generated power with two-axis solar tracking compared to a south facing PV panel fixed at 14° tilt angle on a particular day in July in Sanliurfa, Turkey.  相似文献   
9.
We consider a simple one-dimensional system whose observations are sent to a state estimator over a noisy binary communication link. The interesting thing about the system is that it is unstable. The problem is to design an encoding scheme and a decoder such that the estimation error is stable. We explicitly construct a simple but efficient estimator for the binary symmetric channel (BSC). We are not aware of any such previous "codes" for the BSC. We compare our results to the nonconstructive bounds of Sahai.  相似文献   
10.
Byler's syndrome is a rare form of autosomal recessive intrahepatic cholestasis that is fatal in children. A 10-year-old girl diagnosed with Byler's syndrome underwent reduced-size liver transplantation using lateral segments of her living mother's liver. The donor's and the recipient's liver functions after transplantation were evaluated using Tc-99m disofenin and Tc-99m SC to investigate morphology, liver perfusion, and hepatobiliary function.  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