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排序方式: 共有362条查询结果,搜索用时 15 毫秒
231.
Radiochemistry - Ascorbic acid plays a vital role in the extraction of uranium from hydrous oxide cake produced after alkali breakdown of Rosetta monazite mineral concentrate. The process involves... 相似文献
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Amer Jassim Al-Khafaji Fadhil Sadooni Mohammed Hadi Hindi 《Petroleum Science and Technology》2019,37(8):940-949
The huge quantities of oil and gas reserved in the fields of southern Iraq must be matched by enough source rocks that can generate and expel equivalent amounts of hydrocarbons. This study is an attempt to evaluate the potential and efficiency of the Zubair Formation strata as potential source rocks that contributed to the hydrocarbon budget. A Multiproxy investigation including TOC, pyrolysis, palynofacies, carbon isotope and biomarker analysis were used to investigate such possibility. Results indicate that Zubair rocks were ranging from poor to excellent source rocks, early to moderate maturity, and generated and expelled much hydrocarbons to the Cretaceous reservoirs of the Basin. 相似文献
234.
Precise Control of Lamellar Thickness in Highly Oriented Regioregular Poly(3‐Hexylthiophene) Thin Films Prepared by High‐Temperature Rubbing: Correlations with Optical Properties and Charge Transport 下载免费PDF全文
Amer Hamidi‐Sakr Laure Biniek Sadiara Fall Martin Brinkmann 《Advanced functional materials》2016,26(3):408-420
Precise control of orientation and crystallinity is achieved in regioregular poly(3‐hexylthiophene) (P3HT) thin films by using high‐temperature rubbing, a fast and effective alignment method. Rubbing P3HT films at temperatures TR ≥ 144 °C generates highly oriented crystalline films with a periodic lamellar morphology with a dichroic ratio reaching 25. The crystallinity and the average crystal size along the chain axis direction, lc, are determined by high‐resolution transmission electron microscopy and differential scanning calorimetry. The inverse of the lamellar period l scales with the supercooling and can accordingly be controlled by the rubbing temperature TR. Uniquely, the observed exciton coupling in P3HT crystals is correlated to the length of the average planarized chain segments lc in the crystals. The high alignment and crystallinity observed for TR > 200 °C cannot translate to high hole mobilities parallel to the rubbing because of the adverse effect of amorphous zones interrupting charge transport between crystalline lamellae. Although tie chains bridge successive P3HT crystals through amorphous zones, their twisted conformation restrains interlamellar charge transport. The evolution of charge transport anisotropy is correlated to the evolution of the dominant contact plane from mainly face‐on (TR ≤ 100 °C) to edge‐on (TR ≥ 170 °C). 相似文献
235.
This paper proposes a novel method for the detection of vandalism events in video sequences. The method is based on a proposed definition for common vandal behaviors recorded on surveillance video sequences. To do this, the method monitors changes inside a restricted site containing vandalism-prone objects such as a vending machine, a pay phone, or a street sign. When an object is detected as leaving such a site, the proposed method checks if the site contains temporally consistent and significant static changes, representing damage. If there are such changes and given that the site is normally unchanged after legal use, a vandalism event is declared and the vandals are tracked. The proposed method is tested on video sequences showing real and simulated vandal behaviors and it achieves a detection rate of 96%. It detects different forms of vandalism such as graffiti and theft, and can handle sudden illumination changes, occlusions, and segmentation errors. The proposed method operates at a frame rate of 13 frames per second. 相似文献
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本文对与干涉测距仪(IDM)测量不确定度有关的参数进行了讨论。采用一个简单、鲁棒装置测量了约12cm距离,扩展不确定性为±16.4,um,发现测量不确定度受波长测量精度制约。该设置可测量距离达56m,它也能够轻松确定测量臂和参考臂之间等光程差的点。LabVIEW程序用于条纹的计数,快速傅立叶变换(FFT)对噪声按频率进行选择性过滤。虽然本文对不确定性的测定不能代表同类测量距离的最高不确定度,但该测量方法提供了可溯源于长度单位为米的测量值。 相似文献
238.
Osman A Hassan Amer A AbuGhazaleh Salam A Ibrahim Omoanghe S Isikhuemhen Saddam S Awaisheh Reza Tahergorabi 《International Journal of Dairy Technology》2014,67(4):570-576
This study examined the impact of shiitake mushroom extract (ME) on the viability and α/β enzyme activity of Bifidobacterium breve ATCC 15701 and Lactobacillus reuteri DSM20016 in yoghurt during refrigerated storage. The presence of ME significantly enhanced the viability of both strains. L. reuteri DSM20016 exhibited better stability in yoghurt than B. breve ATCC 15701. L. reuteri DSM20016 showed the highest viability in yoghurt samples containing 4% ME, followed by B. breve ATCC 15701, and then control samples. Results suggest that ME can be used as a natural additive to dairy products to improve the growth and viability of L. reuteri DSM20016 and B. breve ATCC 15701 strains. 相似文献
239.
Feed efficiency (FE) is a complex phenotype made up of multiple traits for which there is potential for substantial genotype by environment interaction (G × E). The objective of this study is to evaluate the extent of G × E for FE traits with a simulation approach. We used a mechanistic model of the dairy cow that simulates trajectories of phenotypes throughout lifetime, depending on trajectories of resource acquisition and allocation, driven by 4 genetic scaling parameters, and depending on the nutritional environment (quantity and quality of feed resources). The cow model, calibrated for a grass-based farming system and seasonal calving, was combined with a genetic module. This simulated genetic variation in the 4 genetic scaling parameters related to resource acquisition and allocation, based on a simple balanced pedigree structure (200 paternal half-sib groups each of 100 daughters). The population of 20,000 cows generated was simulated in 4 nutritional environment scenarios, representing a gradient of feeding constraints. In each scenario, 6 traits derived from the model outputs were analyzed to obtain population genetic parameters. Genetic correlations between second-lactation production and FE were positive and high in all scenarios and increased as the nutritional environment became more constraining. A measure of lifetime FE was positively correlated with second-lactation production under a less constrained environment, but these correlations decreased as the environment became more constraining. The genetic correlation between body reserves at second calving, and lifetime FE was positive and low in the least constraining scenario and increased as the environment became more constraining. In addition to genetic parameters, we looked at the distributions of acquisition and allocation parameters among the best performing cows for lactation and life FE, in the 2 most contrasted scenarios. The 4 subpopulations of best cows had acquisition and allocation strategies different from the whole population. In conclusion, this simulation study identifies the potential underlying biological basis for important G × E in FE traits. This highlights the importance of having a balanced breeding goal when undertaking selection that should also be based on phenotypes relevant to the target performance environment. 相似文献
240.
A new selection index percent emphasis method using subindex weights and genetic evaluation accuracy
The current international standard methodology to quantify trait percent emphasis in selection indexes is based on a simple multiplication of the relative contribution of each trait's economic value (converted to absolute value) and its genetic standard deviation. This method does not reflect the actual selection emphasis applied when the index is used in practice. The economic value does not reflect selection effort when traits differ considerably in their accuracy of evaluation, and no account is taken for either favorable or antagonistic correlations among traits. A new emphasis method adjusted by both accuracy and genetic correlation is proposed. Genetically highly correlated traits are grouped into subindexes by applying a hierarchical clustering method to the genetic correlation matrix. Then each trait's subindex emphasis is calculated within its subindex group, with a weighting included for trait accuracy. Finally, each subindex emphasis is converted to a full index emphasis according to the conventional relative emphasis of its corresponding subgroup. The method can also be applied to sets of breeding values and their economic weights. When applied to a New Zealand sheep breeding selection index where trait genetic correlations are distinct across subindex groups, the new method shrank the emphasis on low-heritability traits, including survival, from 51% to 19%; and expanded that on growth traits from 30% to 49%, better reflecting the selection pressure applied in reality. When genetic correlations across traits were similar, clustering became difficult. Accounting for accuracy affected traits' within-subindex group rankings, whereas the clustering to account for correlations affected all traits within a subgroup equally. Accounting for differences in trait accuracy when describing percent emphasis within selection indexes gives a more practical indication of the likely outcome of selecting on the index. Accounting for correlations among traits when defining percent emphasis made a significant difference only in a subset of case study examples. 相似文献