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排序方式: 共有87条查询结果,搜索用时 15 毫秒
1.
I Hutás 《Canadian Metallurgical Quarterly》1996,137(12):619-622
The author expounds the fairly obscure history of BCG vaccination. Summarises the efficiency of accomplished vaccinations of different geographical areas. He accounts the diversity of results by the distinction of technical and methodical conditions and disparity in virulence of BCG strains. Overviews the Inland and European routine and the risk of possible complications. The favourable position of domestic childhood tuberculosis is due to the effective preventive arrangements. Considering the international and national epidemiology of tuberculosis in adults the administration of BCG vaccine, by chance in modified form, is recommended further on. 相似文献
2.
Banding formation and eutectic lamellar growth in a directionally solidified Ni50Al20Fe30 alloy were investigated. It was found that the banding area consists of two layers. The first layer is a γ layer, while the
subsequent one is a γ layer. The composition of various phases around the banding area changes with the solidification process.
The banding is formed by two steps process and caused by factors such as the fractions during the sample growth process. It
was found that the band was found at relatively low growth rate. Therefore. this study indicates that increasing the growth
rate is an effective method to eliminate the band formation. Eutectic lamellae nucleate and grow again after the banding formation.
During the initial transition lamellar growth, the relationship between the square lamellar spacing, γ2, and the distance from, the banding, d, can be described by the following equation: γ2 = K [1-exp(A.d)] where K and A are constant. 相似文献
3.
High‐Performance Piezoelectric Nanogenerators with Imprinted P(VDF‐TrFE)/BaTiO3 Nanocomposite Micropillars for Self‐Powered Flexible Sensors
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Xiaoliang Chen Xiangming Li Jinyou Shao Ningli An Hongmiao Tian Chao Wang Tianyi Han Li Wang Bingheng Lu 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(23)
Piezoelectric nanogenerators with large output, high sensitivity, and good flexibility have attracted extensive interest in wearable electronics and personal healthcare. In this paper, the authors propose a high‐performance flexible piezoelectric nanogenerator based on piezoelectrically enhanced nanocomposite micropillar array of polyvinylidene fluoride‐trifluoroethylene (P(VDF‐TrFE))/barium titanate (BaTiO3) for energy harvesting and highly sensitive self‐powered sensing. By a reliable and scalable nanoimprinting process, the piezoelectrically enhanced vertically aligned P(VDF‐TrFE)/BaTiO3 nanocomposite micropillar arrays are fabricated. The piezoelectric device exhibits enhanced voltage of 13.2 V and a current density of 0.33 µA cm?2, which an enhancement by a factor of 7.3 relatives to the pristine P(VDF‐TrFE) bulk film. The mechanisms of high performance are mainly attributed to the enhanced piezoelectricity of the P(VDF‐TrFE)/BaTiO3 nanocomposite materials and the improved mechanical flexibility of the micropillar array. Under mechanical impact, stable electricity is stably generated from the nanogenerator and used to drive various electronic devices to work continuously, implying its significance in the field of consumer electronic devices. Furthermore, it can be applied as self‐powered flexible sensor work in a noncontact mode for detecting air pressure and wearable sensors for detecting some human vital signs including different modes of breath and heartbeat pulse, which shows its potential applications in flexible electronics and medical sciences. 相似文献
4.
为了探究稻壳类生物质油替代石油沥青的微观作用机理,以稻壳类生物质油和6种石油沥青为原材料,制备稻壳类生物沥青。采用针入度、软化点和延度指标评价稻壳类生物沥青的物理性能,通过傅里叶红外光谱实验(FTIR)和高温凝胶色谱实验(GPC)探究稻壳类生物沥青的微观作用机理。研究表明,稻壳类生物质油会使石油沥青的针入度和延度增大,同时使软化点略有降低;稻壳类生物质油与6种石油沥青的官能团相似,且生物沥青制备时未产生新的官能团;随着稻壳类生物质油的掺加,6种生物沥青中的小分子和中分子含量增加,大分子的含量变化不大,稻壳类生物质油小分子和中分子含量较多,生物沥青的数均分子量Mn和重均分子量Mw均降低。稻壳类生物质油的加入,使石油沥青的低温性能提高,流动性增大,高温性能稍有降低但并不会降低石油沥青的高温等级,稻壳类生物质油可以作为石油沥青的替代材料使用。 相似文献
5.
采用HSB微生物菌种技术和缺氧一好氧组合工艺处理焦化废水。研究表明:该技术处理焦化废水有很好的效果,其中COD指标从3000mg/L左右降至150mg/L以下,处理效率96.7%以上;NH3-N指标从500mg/L降至15mg/L以下,处理效率97%以上;出水酚、氰、油等污染物均可达排放标准(GB8978-1996)。 相似文献
6.
We report preparation of graphene oxide (GO) from expanded graphite (EG) via a modified Hummers method. GO/PVDF composites films were obtained using solvent N, N‐Dimethylformamide (DMF) and cosolvent comprising deionized water/DMF combination. X‐ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses revealed that the main crystal structure of the composite films is β‐phase, and use cosolvent method tends to favor the formation of β‐phase. Scanning electron microscopy (SEM) was used to investigate the microstructure of composite films. Storage modulus and loss modulus were measured by Dynamic mechanical analysis (DMA). Broadband dielectric spectrum tests showed an increase in the dielectric constant of the GO/PVDF composite films with the rising content of GO, and by cosolvent method could improve the dielectric constant while reducing the dielectric loss. Our method that uses GO as an additive and deionized water/DMF as the cosolvent provides a promising and low‐cost pathway to obtain high dielectric materials. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41577. 相似文献
7.
SBS改性沥青的黏温特性研究 总被引:1,自引:0,他引:1
SBS改性沥青的黏温特性与普通沥青不同。用目前的黏度测试方法测试SBS改性沥青黏度,根据黏温曲线确定的SBS改性沥青混合料的拌和与压实温度过高,过高的拌和与压实温度会引起SBS改性沥青的老化、环境和生产安全问题。从改性沥青的高温流变特性入手,分析改性沥青的黏度试验方法,研究SBS改性沥青的黏度变化规律。由试验结果可知,当温度低于150℃时,黏度对温度的依赖性很大,但是当温度高于150℃时,黏度对温度的依赖性逐渐减小;随着温度的升高,SBS改性沥青的黏度值对剪切速率的依赖性逐渐减弱。因此在测试SBS改性沥青的黏度时,必须在试验温度下规定相应的剪切速率,这对合理确定SBS改性沥青的拌和与压实温度至关重要。 相似文献
8.
Nakasone A. Miura K. Prendinger H. Hut P. Holland S. Makino J. 《Computer Graphics and Applications, IEEE》2009,29(5):69-81
Developed in the Second Life 3D online multiuser environment, AstroSim (astrophysics simulation) provides synchronous collaborative visualization for astronomers. Users can play, halt, and rewind simulations and annotate stars interactively to track individual stars and gain a better understanding of stellar dynamics and astrophysics phenomena. This article is part of a special issue on collaborative visualization. 相似文献
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