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排序方式: 共有454条查询结果,搜索用时 0 毫秒
41.
George J. Nasr 《国际水资源开发杂志》2009,25(1):107-122
Water management in the Levant often focuses on a ‘hydraulic imperative’. This was recently illustrated by the peace discussions between Israel and Syria, with their emphasis on the Golan's water. Such a focus limits policy makers to a purely hydrological perspective, and leads to a focus on securing water access and controlling ‘hydrostrategic territories’. This excludes or underestimates other salient issues, and disregards potentially useful managerial-technical solutions. For any peace settlement to be sustainable, a more comprehensive approach is needed, unbound by the single-issue ‘hydraulic imperative’ to better take into account the multifaceted aspects of the water. 相似文献
42.
The combination of chiral ligand exchange on Cu(II) complexes in aqueous base with circular dichroism spectropolarimetric detection provides excellent avenues to validate the chirality properties of oligopeptides and proteins. The method is quick and simple and has the potential for development into an automated, routine procedure for quality control applications. Target analytes used for this first study of a protein system are human, porcine, and bovine insulins prepared by different procedures and obtained from different sources, production lots, and manufacturers. The analytical specificity of the test makes the method a potentially useful technique for validating the chirality properties of many peptide and protein forms. 相似文献
43.
A simple and sensitive liquid chromatographic method was optimized and validated for the analysis of ethopabate residues in chicken muscles, liver, and eggs. Aqueous sodium dodecyl sulfate (SDS) solution was used for extraction. Analytical separation was performed in less than 8 min using a C18 column (150?×?4.6 mm internal diameter, 5 μm particle size) with fluorescence detection at 271/364 nm. A micellar solution composed of 0.1 M SDS, 10 % 1-propanol, and 0.3 % triethylamine in 0.02 M phosphoric acid adjusted to pH?4 was used as the mobile phase. The method was fully validated in accordance with International Conference on Harmonization guidelines. The micellar method was successfully applied to quantitatively determine ethopabate residues in spiked chicken muscles, liver, and eggs. It was also extended to the determination of ethopabate residues in chicken-based baby food. The recoveries obtained were in the 93.81–115.67 % range. The limit of detection was found to be 1.6 ng/g. High extraction efficiency for ethopabate was obtained without matrix interference and in the subsequent chromatographic determination. No organic solvent was used during the pretreatment step. 相似文献
44.
Torsades de pointes (TDP) is a ventricular tachycardia that can deteriorate into ventricular fibrillation. TDP has been associated with terfenadine use in cases of liver disease, electrolyte abnormalities, concomitant administration of drugs that inhibit cytochrome P-450, or deliberate overdose. This report describes the first case of TDP in a healthy patient taking the recommended therapeutic dosage of terfenadine. 相似文献
45.
Oil spills in Egyptian coastal waters have a direct impact on the national economy because of the potential environmental damage, and the corresponding negative effect on tourism. Computer simulations of oil spills were performed for four environmentally sensitive areas along Egyptian coasts using an existing oil spill model that incorporates the important variables and processes affecting oil transport in seawater. The expected slick trajectory and variation of oil properties with time were calculated for a proposed spill scenario at each site. Water current maps, the most critical model input parameter with respect to spill trajectory, were developed for each location. The simulations demonstrated that the most important oil property affecting spill response decisions and operations is the emulsion viscosity, in that it indicates when, where, and how responders can intervene for cleanup. 相似文献
46.
This paper sets out to investigate experimentally the use of electromagnetic valves in controlling production of water during cresting from homogeneous non-fractured thick-oil and thin-oil reservoirs, based on the principle of capillarity and breakthrough time. A time half the initial breakthrough times was preset for the electromagnetic valve to close. The valve closed almost immediately at the set time thereby shutting oil production temporarily, causing the water and gas height levels to recede by gravity and capillarity with receding reservoir pressure. The efficiency of this technique was compared with an uncontrolled simulation case, in terms of cumulative oil, oil recovery and water produced at the same overall production time. From the results obtained, higher percentages in oil produced and water reduction were observed in the cases controlled proactively, with a 3.6% increase in oil produced and water reduction of 10.0% for thick-oil rim reservoirs, whereas only a small increment in oil produced (0.7%) and a lower water reduction of 1.03% were observed for the thin-oil rim reservoirs. Hence, the effectiveness of the cresting control procedure depends on the oil column height of the reservoir. 相似文献
47.
Ahmed M.A. Nasr 《International Journal of Pavement Engineering》2014,15(10):889-905
This article investigates the strength behaviour of oil-contaminated sand stabilised with cement kiln dust (CKD) in order to assess the engineering properties of the stabilised soil for its application in the construction of rural road. Tests including pH measurement, compaction, unconfined compressive strength (UCS) and California bearing ratio (CBR) were conducted. The investigations were carried out by varying the percentage of CKD, the percentage of oil content, the type of oil, the ageing of stabilised samples and the ambient temperature. Depending on the pH response, the CKD content from 5% to 15% represents a practical limit for cost-effective stabilisation. Results revealed that an increase in the UCS and CBR values of oil-contaminated sand occurred with the addition of CKD. The strength of stabilised contaminated sand decreases as the percentage of oil increases. The addition of 10% CKD to the sand contaminated with 6% oil content is found to give the optimum UCS and CBR values. Furthermore, a series of two-dimensional finite-element model was developed using PLAXIS software package. 相似文献
48.
Hamid Montazerolghaem Mohsen Badrossamay Alireza Fadaie Tehrani Saeed Ziaie Rad Morteza Shamanian Esfahani 《Materials and Manufacturing Processes》2015,30(9):1109-1114
Implementing differential rotation speeds of pin and shoulder in the friction stir welding process is considered. Experimental investigations were carried out using a newly designed and fabricated apparatus for dual-rotation speed friction stir welding. Metallographic studies demonstrated that appropriate selection of separate pin and the shoulder rotation speeds not only results in defect-free joints, but also affects the weld zone by controlling the heat input delivered. An energy model for predicting maximum temperature was extended to the dual-rotation speed friction stir process. The model was verified using the previous experimental results reported in the literature. 相似文献
49.
El-Ridy MS Abdelbary A Nasr EA Khalil RM Mostafa DM El-Batal AI Abd El-Alim SH 《Drug development and industrial pharmacy》2011,37(9):1110-1118
It is estimated that more than one-third of the world population is infected with Mycobacterium tuberculosis. Pyrazinamide (PZA) plays a unique role in shortening therapy because it kills a population of semilatent tubercle bacilli residing in an acidic environment. Niosomes are vesicles made up of non-ionic surfactant and exhibit behavior similar to liposomes in vivo. Preparation of PZA niosomes took place using different molar ratios of Span 60 and Span 85, with cholesterol (CH) i.e. Span: CH (1:1) and (4:2). Dicetyl phosphate and stearyl amine were used in preparation of negative and positively charged niosomes, respectively. Free PZA was separated by cooling centrifugation and estimated spectrophotometrically at 268.4 nm. Niosomes were characterized by electron microscopy and differential scanning calorimetry. The highest percentage PZA entrapped was obtained using Span 60 and the molar ratio (4:2:1) negatively charged niosomes. This was followed by the neutral PZA neutral (4:2) Span 60 niosomes. Biological evaluation of selected PZA niosomal formulations took place on guinea pigs infected with M. tuberculosis. The present work is an attempt to target maximum concentration of PZA to the affected site (lungs) and to exclude undesirable side effects and decrease toxicity. Macrophage targeting and overcoming drug resistance is our final goal. 相似文献
50.