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Metallurgical and Materials Transactions A - This study involved laboratory unidirectional (UDR) and reverse (RR) cold rolling of steel, and corresponding direct (and indirect) observations of...  相似文献   
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In most metazoans, the glutathione S-transferases (GST) are encoded by gene families, and are used to detoxify xenobiotics. We describe the structure of genomic loci coding for the GSTs in the housefly that have been implicated, by both genetic and biochemical means, in mediating insecticide resistance. In earlier work, we showed that one of the theta-class enzymes, MdGST-3, is overproduced in resistant flies and degrades certain insecticides. We used a fragment from a cDNA clone of MdGST-3 as a probe to screen a housefly genomic DNA bank in phage lambda. This probe detected multiple gst loci. Genes for GSTs were found in five different, nonoverlapping lambda clones, three of which carry multiple, closely linked gsts. Multiple genes for both MdGST-3 and MdGST-4 were found; some of which have introns in their 5' untranslated regions. In adults, the only MdGST-3 enzymes that are expressed are encoded by the intron-free genes. A new theta-class GST (called MdGST-5) was also discovered. Fusion genes comprising 5' MdGST-3 sequences and either MdGST-4 or MdGST-5 sequences in their 3' halves were encountered at three separate loci. The genes described here are found in both the ancestral sensitive strain and the insecticide-resistant strains.  相似文献   
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The levels of the biologically important thiols in aqueous extracts of different spices were determined using a sensitive high performance liquid chromatography (HPLC) technique. The spices analysed: turmeric, ginger, cardamom, mustard, fenugreek, and coriander showed different levels of thiols. Biologically important thiols or biothiols measured in these spices included glutathione (GSH), cysteine (CYS), N-acetylcysteine (NAC), homocysteine (HCYS), and γ-glutamyl cysteine (GGC). Our results showed that thiol levels varied from 4 to 1089 nM/g weight (dry or wet). Furthermore, none of the biothiols analysed were found in cumin, nutmeg, clove or star anise. We also studied the antioxidant abilities of these aqueous extracts using various in vitro antioxidant methods to correlate between the levels of these thiols and their antioxidant effects. Our results suggested that antioxidant activities may be independent of thiol content and may be, in part the combination of all the phytochemicals present. These results may be useful in explaining the effect of spices on thiol levels in in vitro and in vivo studies.  相似文献   
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This paper presents the results of six large-scale centrifuge model tests that were performed to study the effect of relative density and thickness of sand layers on the amount of settlement and lateral spreading. The models included a “river” channel with clay flood banks underlain by layers of loose and dense sand of variable thickness, and a bridge abutment surcharge on one of the banks. The model container was tilted to provide an overall slope to the model. Each model was subjected to three or four significant ground motion events, which were obtained by scaling the amplitude of recordings of the Kobe (1995) and Loma Prieta (1989) earthquakes. Several measurements of acceleration, pore water pressure, settlement, and lateral movement are presented. The liquefaction potential index and a deformation index, which combine the influences of depth, density, and layer thickness, were found to correlate reasonably well with liquefaction induced settlements and lateral deformations for the range of models tested and indicate that centrifuge results are consistent with field observations.  相似文献   
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The design of novel compact two-element and eight-element lotus shaped multiple-input-multiple-output (MIMO) antenna system employing pattern diversity with enhanced isolation characteristics is presented. The proposed two-element antenna system is arranged rotationally on a square-hollow substrate resulting in an eight-element MIMO antenna system employing pattern diversity. The developed eight-element MIMO antenna system resonates in the frequency range 3.1 to 14.6 GHz housing the complete UWB band with triple band-notch characteristics at 3.7–4.5 GHz (C-band satellite down link [3.7–4.2 GHz]), 5.1–5.9 GHz (WLAN) and 6.8–8.25 GHz (X-band satellite down link (7.25–7.75 GHz) and up link (7.9–8.4 GHz)) bands. The antenna system gives element-to-element isolation of more than 25 dB in the majority of the operating band with a peak gain of 6.8 dBi and a maximum 90% efficiency. The important MIMO metrics like ECC (envelope correlation coefficient), DG (diversity gain), total active reflection coefficient (TARC), channel capacity losses (CCL) and MEG (mean effective gain) are presented for both two-element and eight-element to estimate the performance the proposed antennas in multi-antenna environments. The both two- and eight-element designs are fabricated and the measured results of those are well agreed with simulation results.  相似文献   
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The current study describes the aging characteristics and mechanical properties of a metastable β titanium alloy Ti-5Al-5Mo-5V-3Cr. The aged microstructures consist of fine α-phase precipitates (lath morphology) in equiaxed β grains. The sizes of the α-phase precipitates increase with the increasing aging temperature. The β ST WQ and 823 K (550 °C)-aged material exhibits maximum hardness due to precipitation hardening. The low- and high-temperature aging conditions result in strong c-type basal and prismatic textures in the α-phase, respectively. The β-phase of the alloy aged at low temperature reveals the presence of texture with moderate intensity. In contrast, high-temperature-aged material exhibits very strong β-phase texture. The strengths of the alloy under β ST WQ- and 923 K (650 °C)-aged conditions are the maximum and minimum along TD and RD, while the ductility values are the maximum and minimum along the RD and TD direction samples, respectively. The flow curves follow typical Holloman equation along three sample directions, and the work hardening rate curves display two distinctive regimes, namely, stage I and stage II. The yield locus plots of the β ST WQ and aged materials exhibit the presence of anisotropy.  相似文献   
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脑灌注显像剂^99mTc—MRP20的放化研究及初步药理实验   总被引:1,自引:0,他引:1  
方平  吴春英 《核技术》1996,19(5):318-320
报道了^99mTc-MRP20的最佳标记条件、小鼠脏器分布、兔血药清除动力学、血浆蛋白结合率、不同pH值时的分配系数、猴显像等结果。  相似文献   
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