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排序方式: 共有1531条查询结果,搜索用时 218 毫秒
101.
Justesen J. Andersen J.D. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》1998,44(4):1608-1611
If the calculation of the critical length is based on the expurgated exponent, the length becomes nonzero for low error probabilities. This result applies to typical long codes, but it may also be useful for modeling error events in specific codes 相似文献
102.
C Kristensen T Kjeldsen FC Wiberg L Sch?ffer M Hach S Havelund J Bass DF Steiner AS Andersen 《Canadian Metallurgical Quarterly》1997,272(20):12978-12983
Alanine scanning mutagenesis has been used to identify specific side chains of insulin which strongly influence binding to the insulin receptor. A total of 21 new insulin analog constructs were made, and in addition 7 high pressure liquid chromatography-purified analogs were tested, covering alanine substitutions in positions B1, B2, B3, B4, B8, B9, B10, B11, B12, B13, B16, B17, B18, B20, B21, B22, B26, A4, A8, A9, A12, A13, A14, A15, A16, A17, A19, and A21. Binding data on the analogs revealed that the alanine mutations that were most disruptive for binding were at positions TyrA19, GlyB8, LeuB11, and GluB13, resulting in decreases in affinity of 1,000-, 33-, 14-, and 8-fold, respectively, relative to wild-type insulin. In contrast, alanine substitutions at positions GlyB20, ArgB22, and SerA9 resulted in an increase in affinity for the insulin receptor. The most striking finding is that B20Ala insulin retains high affinity binding to the receptor. GlyB20 is conserved in insulins from different species, and in the structure of the B-chain it appears to be essential for the shift from the alpha-helix B8-B19 to the beta-turn B20-B22. Thus, replacing GlyB20 with alanine most likely modifies the structure of the B-chain in this region, but this structural change appears to enhance binding to the insulin receptor. 相似文献
103.
HU Andersen PM Larsen SJ Fey AE Karlsen T Mandrup-Poulsen J Nerup 《Canadian Metallurgical Quarterly》1995,44(4):400-407
Interleukin (IL)-1 beta-mediated damage to beta-cells in isolated islets of Langerhans depends upon de novo synthesis of proteins that have not been fully identified. Further, IL-1 beta-induced and tumor necrosis factor alpha-induced islet damage partly depends on the intracellular production of the nitric oxide (NO) radical. IL-1 beta has also been reported to induce the synthesis of cellular defense proteins, e.g., heme-oxygenase and heat shock proteins 70 and 90. Nicotinamide, while in itself inactive, inhibited IL-1 beta-induced NO production in a time- and dose-dependent manner. To enable the identification of IL-1 beta-induced proteins with possible protective and deleterious effects, we characterized the effects of IL-1 beta, nicotinamide, and NO synthesis inhibition by L-arginine depletion on rat islet protein expression detected by high-resolution two-dimensional gel electrophoresis. More than 1,600 proteins were reproducibly detected in control rat islets. Incubation with IL-1 beta-, nicotinamide-, or L-arginine-depleted control medium upregulated 29, 3, and 1 protein, respectively, and downregulated 4, 0, and 1 protein, respectively. Addition of nicotinamide and L-arginine depletion reduced the upregulation of 16 and 20 IL-1 beta-induced proteins, respectively. The identity of these proteins is under study. The demonstrated changes in protein expression caused by IL-1 beta +/- nicotinamide and L-arginine depletion may form the basis for identification of proteins with possible protective and deleterious roles in the initial beta-cell destruction in insulin-dependent diabetes mellitus. 相似文献
104.
A case of digoxin intoxication and hyperkalaemia causing cardiac arrest in a 63-year-old female who had undergone cardiac surgery is presented. Symptomatic treatment was given. However, as the patient continued to be unstable we introduced digoxin Fab-antibody in the treatment. The patient changed her heart rhythm from atrioventricular conduction block to atrial fibrillation within a few minutes and recovered later on. The pharmacology and the indications for treatment with digoxin Fab-antibody fragments are discussed. 相似文献
105.
106.
P Pfeiffer E Nex? SM Bentzen PP Clausen K Andersen C Rose 《Canadian Metallurgical Quarterly》1998,78(1):96-99
PURPOSE: Cyclosporine-A (CSA) combined with corticosteroid therapy was administered to 12 patients with severe Beh?et's uveitis who were resistant to colchicine or cytotoxic therapy. METHODS: Previous colchicine or cytotoxic therapies were tapered off one month before CSA therapy. All patients were started on an initial oral dose of 5 mg/kg/day of CSA. After the first three months, the CSA dose was reduced to a maintenance dose according to the intraocular inflammatory response. RESULTS: The average follow-up period was 20 (12-36) months. Visual acuity remained the same in 12 (%54.5) and improved in 8 (%36.4) eyes. There was a decrease in the frequency (p<0.01) and severity (p<0.01) of ocular attacks and in the maintenance steroid dose (p<0.01) when compared with conventional therapy. The frequent side effects were paraesthesia-hyperesthesia, fatigue, nausea, hirsutism and dose-related nephrotoxicity in one patient. CONCLUSION: The results of the study suggest that low dose CSA combined with low dose corticosteroid may be an effective therapeutic alternative in the treatment of severe refractory Beh?et's uveitis. 相似文献
107.
Helle Lindberg Madsen Lotte Andersen Luise Christiansen Per Brockhoff Grete Bertelsen 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1996,203(4):333-338
The sensory intensity measured as theabsolute threshold value of spice andrecognition of spice was evaluated for summer savory and rosemary in meat balls. The values forabsolute threshold value of spice were found to be significantly lower for rosemary than for summer savory. The antioxidative activity of the spices was analysed in two accelerated model systems and in a storage experiment. In one of the model systems, oxidation was accelerated by heat and by an elevated pressure of oxygen. Both spices significantly improved the oxidative stability of the meat balls in this model system. In the second model system metal catalyst oxidation in a meat slurry was used and a reduction in the oxidative processes in samples containing the spices was again shown. In both model systems a slightly higher antioxidative activity was seen for rosemary compared to summer savory. In the storage experiment, the spices were added at a sensorially acceptable level and the heat-treated meat balls were stored at 5°C. A significant reduction in the development of warmed-over flavour (WOF) caused by the addition of spices was measured by a reduction in 2-thiobarbituricacid-reactivesubstances (TBARS) and in hexanal. A reduction in TBARS of approximately 30% in meat balls containing added spices was seen independently of packaging in 1% oxygen or in atmospheric air and the reduction (30%) was constant throughout the storage period. 相似文献
108.
109.
Simon I. Andersen 《Petroleum Science and Technology》1994,12(1):51-74
Petroleum asphaltenes were separated from Boscan and Kuwait crude oils by n-heptane at constant temperatures ranging from -2 to 80 ° C. A decreased yield with increase in temperature was observed. The precipitated material was characterized using infrared spectroscopic functional group analysis, HPLC-size exclusion chromatography, vapor pressure osmometry, and elemental analysis. The change in vanadium porphyrin content was estimated for Boscan using UV-Vis. With elevated temperature the asphaltenes are more aromatic (lower H/C) and have higher apparent molecular weight, whereas the pattern of changes in functional groups and heteroatoms (NSO) are more complex and apparently dependent on the crude oil. Porphyrins and low molecular weight types were seen to stay in solution at increased temperature, and a specific extraction of these takes place above 40 ° C. Asphaltene solubility is seen to approximate the Flory-Huggins theory as small molecules go into solution before large molecules. Several other mechanisms may, however, be involved in the phase separation. The molecular size distribution curves obtained by HPLC-SEC were found to explain the trends found in the molecular weights by VPO. 相似文献
110.
J. S. Forster G. C. Ball W. G. Davies J. S. GeigerJ. U. Andersen J. ChevallierJ. A. DaviesH. Geissel 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》1994,90(1-4)
Dielectronic recombination for He-like 79Br has been measured for channeling along a 110 axis in Ni. The KLL resonance has a FWHM of 14% of the beam energy and an area corresponding to a density of about 6 electrons per atom. 相似文献