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21.
稀土元素铈对快速镍刷镀工艺及镀层性能的影响 总被引:2,自引:0,他引:2
研究了稀土元素铈对快速镍刷镀工艺及镀层性能的影响,结果表明,在镍镀液中加入一定量的稀土化合物硫酸铈能有效地提高镀速及刷镀层硬度,降低刷镀层的孔隙率,且刷镀层与基体结合良好,但对镀液稳定性影响不大。 相似文献
22.
Fat globule membrane of sow milk as a target for adhesion of K88-positive Escherichia coli 总被引:1,自引:0,他引:1
F Atroshi T Alaviuhkola R Schildt M Sandholm 《Comparative immunology, microbiology and infectious diseases》1983,6(3):235-245
Membrane adhesion of K88-positive Escherichia coli was studied on intestinal brush-border membranes on 237 Finnish Landrace pigs. Forty-one per cent of the brush-border membrane preparations aggregated E. coli (positive adhesion). Similar dualism of adherence/nonadherence was observed on sow milk fat globule membranes. Washed milk fat globules (washed cream) can be used as a convenient source of material for adhesion studies. Bacterial adherence on to milk fat globules is evident as agglutination of the globules (dark-field microscopy). By this procedure the sows can be typed according to their receptor phenotype. This simple principle of fat globule agglutination due to receptors for K88-positive E. coli might be complicated by SigA-mediated bacterial adherence. Fat globule membranes were shown to contain SigA, which may act as a mediator of bacterial adherence onto fat globules. The significance of this adhesive property of milk fat globule might be to provide alternative receptors for E. coli thus preventing bacterial adhesion on to gastro-intestinal epithelium of the offspring. Sow milk fat globules can be used for typing E. coli for membrane adhesiveness. The adhesiveness of the strains showed a good correlation with the presence of the K88 antigen, as well as the hydrophobicity of the bacterial strain as determined by an association on Phenyl-Sepharose beads. 相似文献
23.
The mechanism of electrochemical reduction for species Cu(I)-EDTA in eiectroless copper plating was studied by means of polarization curve,rotating disc electrode,chrono-potentiometry and chronocoulometry.The result of reaction order determination indicat 相似文献
24.
DG3型割灌机振动的实验研究 总被引:2,自引:2,他引:0
该文对国产DG3型割灌机的振动频谱以及各振源点与手柄间的振动传递函数进行了实验分析.结果表明,在工作转速(6000r/min)下的振动加速度几乎都集中在60~200Hz范围内,并且76Hz,100Hz和152Hz是3个主要支配性峰值,它们是减振的主要对象频率;轴承B1,B2,B3处与手柄A点的振动传递函数值比其它大,而且B1的影响最主要;长轴上各激振点上下方向(z方向)与A点左右方向(x方向)之间的传递函数在60~80Hz之间存在一个峰值 相似文献
25.
In order to protect the system of fiber Bragg grating (FBG) and keep its sensing performance on a high score, an adhesive-free bond which is considered as the alternative for epoxy adhesive technology is demanded. An electroless Ni-P plating process without coarsing for fiber Bragg grating was presented. With this plating method, the FBG was coated with a metal clad of Ni-P. By Scanning Electron Microscope (SEM), Energy Dispersive Spectrometer (EDS), X-ray diffraction (XRD) and Temperature vibration tests, the composition, structure and adhesion force of the plating coatings were analyzed. And the results indicate that the coating is smooth, flat and compact. The solder ability of Ni-P clad was tested by welding the FBG into metal components, and the results reveal that the coating films can meet the requirements of an adhesive-free bond. 相似文献
26.
C.S. Dannhauser 《African Journal of Range and Forage Science》2013,30(3):120-121
A small plot experiment with Digitaria eriantha, Panicum maximum and Anthephora pubescens, established on Valsrivier and Westleigh soil forms, was conducted at Potchefstroom during the 1986/87 and 1987/88 seasons. The yield of P. maximum was the highest of the three species during the drier 1986/87 season (478 mm), while the yield of D. eriantha was the highest during the wetter 1987/88 season (803 mm). Yield was not influenced significantly by soil form. The quality of all species, in terms of protein and digestibility, was adequate for animal production. 相似文献
27.
Jessica Schenck Annika Djurle Dan Funck Jensen Cecilia Müller Martin O'Brien Rolf Sprndly 《Grass and Forage Science》2019,74(1):29-41
The use of wrapped forage bales with high dry‐matter (DM) content implies risk of fungal growth inside the wrapping, and impaired feed quality. Since fungi may be unevenly distributed in bales, the method of sampling can influence the outcome of the analysis. Three common sampling methods for detection of fungi in wrapped forage were compared: direct plating of visible mouldy patches on bale surfaces (Method I), direct plating of pieces of foliage from drilled core samples (Method II) and quantitative analysis dilution series of drilled core samples (Method III). All samples were cultured on two media at two temperatures. Samples were collected from 124 farms in Sweden and Norway. Using Methods I, II and III, fungi were detected on 52%, 77% and 56% of the farms respectively. Fifty‐two fungal species were identified using a combination of culturing and molecular methods. The most predominant species were Arthrinium spp., found on 55% of the farms, followed by Penicillium roqueforti at 48% of the farms. Incubation at 25°C resulted in higher numbers of all genera, except Aspergillus, compared to incubation at 37°C. The different methods of sampling and culturing did not identify the same fungal species within the same bale. Analysing one bale per farm resulted in detection of less than half the number of species compared to analysing three bales. Of the sampling and culturing methods compared, direct plating of drilled core samples cultivated at malt extract agar at 25°C performed best in terms of qualitative analysis of fungi species. 相似文献
28.
新型无轴承无刷直流电动机结构与模型研究 总被引:4,自引:4,他引:0
目前研究的无轴承电机均是将电机和转子悬浮磁路合为一体,两个磁场的叠加一方面容易造成磁饱和,使电机的承载能力下降,影响电机的稳定悬浮;另一方面电磁转矩与径向悬浮力之间具有很强的非线性耦合,而实现解耦控制是非常复杂的.将无刷直流电机的优点与磁悬浮轴承的优点结合,提出一种六自由度可控的无轴承无刷直流电动机结构,通过研究其悬浮原理和运行原理,建立了转子偏心时的精确数学模型和PWM(脉宽调制)调速的精确数学模型,经仿真测试,表明了这种电机结构的合理性.主要特点是承载能力高且电磁转矩控制与径向悬浮力的控制相互独立,无需复杂的非线性解耦控制. 相似文献
29.
30.
研究了在车用节温器表面进行化学镀镍工艺,利用SEM分析了镀镍层表面显微组织和相结构;采用HXZ-100显微硬度计测试了镀层的硬度;对镀镍层在10%NaCl,10%HCl,10%NaOH溶液中进行了耐蚀性的对比研究。结果表明:施镀40 min后,镀层均匀、致密、无明显缺陷;在上述溶液中浸泡48 h,无腐蚀孔出现;镀层在29.4 N压力下研磨也不会发生脱落,表明其附着力极好,达到车用节温器表面性能的要求。 相似文献