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71.
This study demonstrates that the use of high field 1H NMR spectroscopy permits individual detection of phosphatidylcholine and sphingomyelin molecules at the surface of native low density lipoprotein (LDL) particles. Distinct behaviour was observed for the choline head group -N(CH3)3 resonances of these different phospholipids revealing preferential immobilisation for phosphatidylcholine. This suggests the existence of reversible and irreversible phosphatidylcholine-apolipoprotein B interactions and is consistent with microdomain formation at the surface monolayer of LDL. The novel resonance assignment and results show that 1H NMR can provide efficient and practical means for future studies on the structure and dynamics at the LDL surface.  相似文献   
72.
We present a technique for in situ lens nucleus emulsification using low phaco power and high vacuum, a continuous curvilinear capsulorhexis, and hydrodelineation. Emulsification is done with the phaco tip slanted down 30 or 45 degrees. Cutting and aspiration do not cause an undesirable energy loss. This technique can be combined with the nuclear chopping or divide and conquer methods because of its ability to drill and hold the nucleus. Posterior capsular rupture is prevented because the separated epinucleus acts as a barrier between the nucleus and the cortex. The low power used minimizes the energy transfer to the corneal endothelium. This technique is particularly useful in eyes with brunescent cataract.  相似文献   
73.
74.
油砂地层中子-伽玛能谱Monte-Carlo模拟   总被引:2,自引:0,他引:2  
本工作应用自行研制开发的中子 伽玛能谱测井的中子 伽玛射线随空间、能量、时间分布的蒙特卡罗模拟软件包计算了裸眼井、井眼里无下井仪器、油饱和砂岩地层、井眼注油条件下沿井轴和井壁的中子 伽玛射线随能量、时间分布及沿井轴和沿井壁的中子 伽玛射线能谱 ,研究了源距对中子 伽玛射线随能量、时间分布以及井轴与井壁中子 伽玛射线能谱的影响。  相似文献   
75.
Sidle系统是运行在SUN工作站网络上的一组实用程序,利用空闲的处理机资源进行大粒度的并行计算.同其它远程执行设备相比,它能支持程序内部并行和嵌套的远程执行,允许一个服务员机接受多个远程执行任务.本文介绍了这些特点和透明性的实现方法.  相似文献   
76.
It is understood that grain boundary cavitation is one of the detrimental processes for the degradation of materials that reduces the creep-fatigue life at high temperatures. In a previous investigation, a model for life prediction under creep-fatigue conditions was proposed in terms of cavity nucleation and growth. In that model, the cavity nucleation factor (P) was introduced to correlate between the number of cavities and the plastic strain range from which athermal vacancies are generated. It was considered to be a material specific constant which was independent of the experimental conditions. However, in this study, it is found that the cavity nucleation factor is a function of the plastic strain range but is independent of the testing temperature at near 0.5 T m. In the light of this dependency, a new cavity nucleation factor (P'), is introduced. Using this new cavity nucleation factor (P'), a modified equation for life prediction is proposed, and it is shown that there is good agreement between predicted and experimental lives. Additionally, an interesting approach has been made to find the physical meaning of the new cavity nucleation factor (P'). According to this study, it is suggested that the new cavity nucleation factor, which is regarded as a material specific constant, is found to be strongly related to the density of the grain boundary precipitates with a linear relationship existing between them.  相似文献   
77.
On the basis of clinical signs and histological findings eight 9-month-old male rusa deer (Cervus timorensis) were diagnosed with sheep associated-malignant catarrhal fever. Following a variable course involving rectal temperatures around 40.5 degrees C, depression, inappetence, diarrhoea, corneal opacity and hypopyon all animals died or were euthanased over a 5-week period. Severe multifocal vasculitis, mainly periglomerular and in the arcuate vessels were consistent histological findings which in the past have been adequate to confirm clinical diagnosis of sheep associated-malignant catarrhal fever. A nested polymerase chain reaction test has been used to detect a sheep associated-malignant catarrhal fever PRC product, 238 base-pairs in size, in DNA extracted from lymphocyte preparations. The result supported the diagnosis of sheep associated-malignant catarrhal fever in these deer.  相似文献   
78.
The homogeneity of comminuted composites of 20 lb samples of apples, cabbage, and green beans containing field-incurred residues of p, p'-methoxychlor was studied to determine whether a 5 min comminution in a 40 qt vertical cutter mixer produces a homogeneous composite and whether the size of test portions used accurately represents the composite. Duplicate test portions of 100, 50, 25, 10, 5, and 2 g taken from each of 6 separate sections of the mixer were analyzed by standard pesticide residue methodology for p, p'-methoxychlor. Results of this study confirmed that comminution of fresh produce in a 40 qt vertical cutter mixer, according to instructions described in the U.S. Food and Drug Administration's Pesticide Analytical Manual, Volume I, Section 203B, produces a homogeneous composite. No significant differences were found in the data for the 3 crops taken from the 6 sections of the mixer. Test portion weights of 100, 50, and 25 g produced equivalent results for all 3 crops. Statistically significant differences were observed for cabbage at 2, 5, and 10 g and for green beans at 2 g.  相似文献   
79.
The partial oxidation of methanol to formaldehyde was studied over YBa2Cu3O7-x catalyst in a flow reactor. The structural change of YBa2Cu3O7-x before and after the reaction was measured by means of XRD and iodometric titration method. The catalytic characteristics of YBa2Cu3O7-x for the partial oxidation of methanol to formaldehyde was due to copper ions. It was found that Cu+2 was responsible for the higher selectivity for formaldehyde.  相似文献   
80.
The relationship of a member of the transmembrane dystrophin-associated glycoprotein (DAG) complex to acetylcholine receptors (AChRs) was investigated using immunofluorescence techniques at rat neuromuscular junctions (NMJs) viewed en face. These results were compared with those from a similar previous study of dystrophin and an autosomal homologue (utrophin or dystrophin-related protein, DRP) (Bewick et al. Neuro Report 1992; 3: 857-860). The region of highest 43 K DAG (43DAG) labelling projected beyond the AChRs by approximately 0.3 microns, as does that for dystrophin. By contrast DRP labelling precisely co-localizes with the AChRs. These results suggest that at the NMJ, the region of high 43DAG concentration encompasses the area of highest intensity labelling for both DRP and dystrophin.  相似文献   
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