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991.
ABSTRACT: Using a Rapid Visco Analyzer (RVA), it was revealed that 2 alkalizing agents (Na2CO3 and NaOH) had a far larger effect on pasting properties of nonwaxy starches (wheat, corn, rice) compared with their effect on waxy starches (waxy corn and waxy rice). It was hypothesized that the alkalizing agents have a greater propensity to attack the amorphous regions of the nonwaxy starch granules, thereby causing increased leaching of amylose molecules and possibly also some hydrolysis of starch chains. As a result, the RVA pasting profile of a nonwaxy starch, in the presence of alkali, was drastically altered to one that more closely resembled that of its waxy counterpart without added alkali. 相似文献
992.
In this paper, we present a robust image alignment algorithm based on matching of relative gradient maps. This algorithm consists of two stages; namely, a learning-based approximate pattern search and an iterative energy-minimization procedure for matching relative image gradient. The first stage finds some candidate poses of the pattern from the image through a fast nearest-neighbor search of the best match of the relative gradient features computed from training database of feature vectors, which are obtained from the synthesis of the geometrically transformed template image with the transformation parameters uniformly sampled from a given transformation parameter space. Subsequently, the candidate poses are further verified and refined by matching the relative gradient images through an iterative energy- minimization procedure. This approach based on the matching of relative gradients is robust against nonuniform illumination variations. Experimental results on both simulated and real images are shown to demonstrate superior efficiency and robustness of the proposed algorithm over the conventional normalized correlation method. 相似文献
993.
为了改进HDT-55转台过滤机使用中暴露出的布料布水槽角度不合理、栈桥及支架腐蚀严重、滤布冲洗水喷头易堵、钢衬胶真空环形管易起泡等问题,采取了如下措施:将布水、布料槽顺时针转10~15°,增加吸气室空间,改进滤布冲洗喷头总成,改进环形管材质等.实施后,磷石膏达到含水质量分数<30%,过滤现场气雾下降,滤布冲洗喷头使用时间延长,消除了环形管腐蚀和堵管现象. 相似文献
994.
995.
Chia-Hsun Tu Yi-Sheng Lai Dim-Lee Kwong 《Electron Device Letters, IEEE》2006,27(5):354-356
This letter investigated the reproducible bistable resistance switching characteristics of a single-layer organic device based on 8-hydroquinoline aluminum (Alq3) fabricated by spin coating. By controlling the ON-state current through the Alq3 films, it has been possible to achieve various resistance states of the films. In addition, the resistance of the ON-state Alq3 films also affects the threshold current and voltage to switch off the device. The independence of the current-injected direction to erase the ON state implies that the filament theory could elucidate the observed phenomenon. The ratio between low- and high-resistance states can reach five orders of magnitude, which will be a potential material for nonvolatile memory application. 相似文献
996.
P Verdier-Pinard JY Lai HD Yoo J Yu B Marquez DG Nagle M Nambu JD White JR Falck WH Gerwick BW Day E Hamel 《Canadian Metallurgical Quarterly》1998,53(1):62-76
Originally purified as a major lipid component of a strain of the cyanobacterium Lyngbya majuscula isolated in Cura?ao, curacin A is a potent inhibitor of cell growth and mitosis, binding rapidly and tightly at the colchicine site of tubulin. Because its molecular structure differs so greatly from that of colchicine and other colchicine site inhibitors, we prepared a series of curacin A analogs to determine the important structural features of the molecule. These modifications include reduction and E-to-Z transitions of the olefinic bonds in the 14-carbon side chain of the molecule; disruption of and configurational changes in the cyclopropyl moiety; disruption, oxidation, and configurational reversal in the thiazoline moiety; configurational reversal and substituent modifications at C13; and demethylation at C10. Inhibitory effects on tubulin assembly, the binding of colchicine to tubulin, and the growth of MCF-7 human breast carcinoma cells were examined. The most important portions of curacin A required for its interaction with tubulin seem to be the thiazoline ring and the side chain at least through C4, the portion of the side chain including the C9-C10 olefinic bond, and the C10 methyl group. Only two modifications totally eliminated the tubulin-drug interaction. The inactive compounds were a segment containing most of the side chain, including its two substituents, and analogs in which the methyl group at the C13 oxygen atom was replaced by a benzoate residue. Antiproliferative activity comparable with that observed with curacin A was only reproduced in compounds that were potent inhibitors of the binding of colchicine to tubulin. Molecular modeling and quantitative structure-activity relationship studies demonstrated that most active analogs overlapped extensively with curacin A but failed to provide an explanation for the apparent structural analogy between curacin A and colchicine. 相似文献
997.
A discrete replacement model for a repairable system which is subject to shocks and minimal repairs is discussed. Such shocks can be classified, depending on its effect to the system, into two types: Type I and Type II shocks. Whenever a type II shock occurs causes the system to go into failure, such a failure is called type II failure and can be corrected by a minimal repair. A type I shock does damage to the system in the sense that it increases the failure rate by a certain amount and the failure rate also increases with age due to aging process without external shocks; furthermore, the failure occurred in this condition is called type I failure. The system is replaced at the time of the first type I failure or the n-th type Il failure, whichever occurs first. Introducing costs due to replacement and mininal repairs, the long-run expected cost per unit time is derived as a criterion of optimality and the optimal number n∗ found by minimizing that cost. It is shown that, under certain conditions, there exists a finite and unique optimal number n∗. 相似文献
998.
999.
1000.
介绍了灯饰横梁零件成形工作过程及工艺过程,对灯饰横梁零件压形整形复合模作了较详细介绍,对生产类似产品的厂家有一定的参考应用价值。 相似文献