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排序方式: 共有890条查询结果,搜索用时 15 毫秒
91.
Sultan M Khan Tariq M Khan Richard D Wells David J Maslin Martin J Connock 《Journal of the science of food and agriculture》1992,58(3):443-445
An enzyme-based colorimetric assay for choline-containing phospholipids is described. When tested with egg yolk and serum, the method proved very sensitive, correlated well with other methods and avoided turbidity problems. The method is potentially applicable to a wide variety of samples. 相似文献
92.
93.
In 84 patients the wrist pulses were lost after diagnostic left heart catheterization via the brachial artery. Sixty-six of these patients underwent surgical exploration of the brachial artery for restoration of pulsatile arterial flow to the hand. This aim was achieved in 64 instances. In all cases, the artery was found to be occluded by fresh thrombus. In 36 patients, balloon thrombectomy and accurate arterial closure were successful. In the remainder, in addition to thrombectomy, indentification of an area of damage to the arterial wall required additional surgical measures, usually in the form of resection and anastomosis. The surgical approach to this problem and the importance of the recognition and treatment of arterial wall damage by the catheter are stressed in this paper. 相似文献
94.
Sufficient conditions are given which assure that the systemfrac{dx}{dt}= A(t)x + B(t)u + f(x,u,t) is globally or locally controllable. 相似文献
95.
The amount and mechanisms of metal loss has been studied for oblique and normal impact on copper, 70/30 brass, and precipitation
hardened Cu-2 pct Be, using steel ball bearings and velocities from 138 to 300 m/s. The weight losses are roughly the same
for the three alloys though the mecahnisms of flow and fracture change from highly plastic for copper to pronounced adiabatic
shear localization for the Cu-Be alloy. At these high velocities and ball sizes the deformation is adiabatic, thus localizing
the flow and enhancing loss compared to a slow isothermal indentation. Also, inertial forces are large at the base of any
extruded lip, thus playing a central role in removing metal. For normal impacts the principle weight loss occurs where the
impacts partially overlap, and stems from the concentration of strain at local irregularities in the surface.
Formerly a Graduate Student in the Department of Metallurgical Engineering, is now a Graduate Student in The Department of
Ceramic Engineering at Ohio State University, Columbus, OH 43210. 相似文献
96.
Ghulam Zakria Zailin Guan Yasser Riaz Mirza Jahanzaib Anwar Khan 《Frontiers of Mechanical Engineering in China》2010,5(2):157-164
In today’s fast-paced world, computer-aided design/computer-aided manufacturing (CAD/CAM) systems have become a necessary
element in manufacturing industries. Prior to investment in a CAD/CAM system, it is essential for investor to know how to
maximize their benefits from buying a new or by changing an existing CAD/CAM system. The purpose of this study is to provide
a methodology to assist small- and medium-sized manufacturing companies of Pakistan in selecting a CAD/CAM system. It will
also facilitate the software providers in recognizing the current state of affairs as well as preceding problems regarding
the application of CAD/CAM in manufacturing firms when assisting them in choosing the direction for future development simultaneously.
To accomplish this purpose, data have been collected about current CAD/CAM systems. Important criteria for system selection
and parameters for evaluation have also been identified and prioritized. Analytic hierarchy process (AHP) is used as a decision-making
technique for identifying and prioritizing important factors for CAD/CAM software selection. Expert Choice (AHP-based software)
has been used to validate the results. 相似文献
97.
Samarium (Sm) doped aluminum nitride (AlN) thin films are deposited on silicon (100) substrates at 77 K by rf magnetron sputtering
method. Thick films of 200 nm are grown at 100–200 watts RF power and 5–8 m Torr nitrogen, using a metal target of Al with
Sm. X-ray diffraction results show that films are amorphous. Cathodoluminescence (CL) studies are performed and four peaks
are observed in Sm at 564, 600, 648, and 707 nm as a result of 4G5/2 → 6H5/2, 4G5/2 → 6H7/2, 4G5/2 → 6H9/2, and 4G5/2 → 6H11/2 transitions. Photoluminescence (PL) provides dominant peaks at 600 and 707 nm while CL gives the intense peaks at 600 nm
and 648 nm, respectively. Films are thermally activated at 1,200 K for half an hour in a nitrogen atmosphere. Thermal activation
enhances the intensity of luminescence. 相似文献
98.
Determination of gamma emitting radionuclides in shallow marine sediments off the Sindh coast has been carried out using a gamma spectrometry technique. The activity concentration measured in various sediment samples off the Sindh coast has been found to vary from 15.93 +/- 5.22 to 30.53 +/- 4.70 Bq kg(-1) for 226Ra, from 11.72 +/- 1.22 to 33.94 +/- 1.86 Bq kg(-1) for 228Ra and from 295.22 +/- 32.83 to 748.47 +/- 28.75 Bq kg(-1) for 40K. The calculated mean values of radium equivalent activity, absorbed dose rate and effective dose are 98 Bq kg(-1), 49 nGy h(-1) and 0.06 mSv y(-1), respectively. No artificial radionuclide was detected in the samples measured from the study area. As no data on radioactivity of the coastal environment of Pakistan are available, the data presented here will serve as baseline information on radionuclide concentration in shallow sea sediments off the Sindh coast. The data will also be useful for tracking pollution inventories from unusual radiological events (if any) in the territorial waters of the study area. Further, the information presented will contribute to modelling of a regional radioactivity database from the perspectives of the International Atomic Energy Agency's Asia-Pacific Marine Radioactivity Database and Global Marine Radioactivity Database. 相似文献
99.
Zdolec N Hadžiosmanović M Kozačinski L Cvrtila Z Filipović I Skrivanko M Leskovar K 《Meat science》2008,80(2):480-487
The influence of the bacteriocinogenic culture Lactobacillus sakei (105/g) and semi-purified bacteriocin mesenterocin Y (2560 AU/kg) on the safety and quality of traditional Croatian fermented sausages was investigated. The addition of Lb. sakei and/or mesenterocin Y reduced microbial counts (P < 0.05) in the final products. After 28 days of ripening, coagulase-negative cocci decreased 1.5–2.0 log, yeasts 1.2–1.4 log and enterococci 1.7–2.7 log. In the case of the addition of Lb. sakei, the lactic acid bacteria count was significantly (P < 0.05) higher at day 7 of ripening, and was accompanied by a lower pH and a higher amount of lactic acid (P < 0.05). In the final product the amount of acetic acid was significantly lower. More intensive proteolysis and an increase in ammonia content were found at the beginning of fermentation, and in the second phase of ripening in the control samples, respectively. The free fatty acid concentration was significantly lower during the entire ripening process compared to the control (P < 0.05). Semi-purified mesenterocin Y did not affect the sensory properties of the sausages, whilst the addition of Lb. sakei enhanced them. 相似文献
100.
Phenol content,antioxidant activity and metal composition of Croatian wines deriving from organically and conventionally grown grapes 总被引:2,自引:0,他引:2
Ivana Vinković Vrček Mirza Bojić Irena Žuntar Gordana Mendaš Marica Medić-Šarić 《Food chemistry》2011
The present study was performed to evaluate the antioxidant capacity, the polyphenol and metal content of conventionally and organically produced wines, which underwent similar winemaking processes. The wine grapes were grown under well-defined organic and conventional conditions from the two different wine-growing sub-regions of Croatia, Prigorje and Southern Dalmatia. The values of antioxidant activity, as evaluated by two free radical methods, ABTS and DPPH, was found systematically higher in organic wines compared to conventional ones. In a reversed phase HPLC analysis, used in order to characterise the phenol fraction of wines, higher concentrations of chlorogenic acid, ferulic acid, catechin, trans-resveratrol, all studied hydroxybenzoic acids and flavonols were found in the organically produced wines. No apparent trend was found in the metal contents of the wines, but ICP-MS analysis confirmed that both wine productions, organic and conventional, were well within the toxicological safety limits. 相似文献