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排序方式: 共有247条查询结果,搜索用时 15 毫秒
1.
M Agelli P Dello Sbarba ED Halay RA Faris DE Hixson LM Reid 《Canadian Metallurgical Quarterly》1997,29(3):205-217
BACKGROUND AND OBJECTIVES: We operated on three patients with leiomyosarcoma of the inferior vena cava. METHODS: Complete excision was possible in all three patients. RESULTS: One patient developed widespread metastasis at 23 months, one patient is alive with no evidence of disease at 70 months, and one patient is alive at 15 months. The third patient had subcutaneous and pulmonary metastases at the time of presentation, which are radiologically nondetectable at present following postoperative chemotherapy. CONCLUSIONS: The clinicopathologic features, prognostic factors, and treatment of 130 cases found in a comprehensive literature search and our three cases are reported. 相似文献
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针对当前大型互联网站提升用户体验的需求,本研究创造性地提出基于本体的用户行为分析引擎的思想,它通过上下文感知技术,实时获取用户访问页面时的上下文信息(以下也称为动态行为),基于本体对用户行为建模,建立基于规则的上下文推理算法,对监测到的动态用户行为进行实时推理,及时反馈结果信息给用户。实验表明:本研究理论上独辟蹊径,设计实现上结合了云存储技术,能够一定程度改善用户体验效果。 相似文献
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In this paper, the effect of mass diffusion in a thermoelastic nanoscale beam in context Lord and Shulman theory is studied. The analytical solution in the Laplace domain is obtained for lateral deflection, temperature, displacement, concentration, stress and chemical potential. The both ends of the nanoscale beam are simply supported. The basic equations have been written in the form of a vector-matrix differential equation in the Laplace transform domain, which is then solved by an eigenvalue approach. The results obtained are presented graphically for the effect of time and mass diffusion to display the phenomena physical meaning. 相似文献
5.
Zi-Hang Wang Xiao-Yuan Wu Wen-Xuan Yu Faris Alzahrani Aatef Hobiny Fu-Guo Deng 《Quantum Information Processing》2017,16(5):141
We present some different hyperentanglement concentration protocols (hyper-ECPs) for nonlocal N-photon systems in partially polarization-spatial hyperentangled states with known parameters, resorting to linear optical elements only, including those for hyperentangled Greenberger–Horne–Zeilinger-class states and the ones for hyperentangled cluster-class states. Our hyper-ECPs have some interesting features. First, they require only one copy of nonlocal N-photon systems and do not resort to ancillary photons. Second, they work with linear optical elements, neither Bell-state measurement nor two-qubit entangling gates. Third, they have the maximal success probability with only a round of entanglement concentration, not repeating the concentration process some times. Fourth, they resort to some polarizing beam splitters and wave plates, not unbalanced beam splitters, which make them more convenient in experiment. 相似文献
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Hydrogenation of p‐Nitrophenol to p‐Aminophenol as a Test Reaction for the Catalytic Activity of Supported Pt Catalysts 下载免费PDF全文
Michael Goepel Majd Al‐Naji Patrick With Gerald Wagner Oliver Oeckler Dirk Enke Roger Gläser 《化学工程与技术》2014,37(3):551-554
Hydrogenation of p‐nitrophenol (PNP) to p‐aminophenol (PAP) using NaBH4 as a reducing agent was studied as a test reaction for determining the catalytic activity of supported Pt catalysts. The initial reaction rate, which is accessible within less than 10 min via online UV‐vis spectroscopy at room temperature, ambient pressure, and in water as solvent, was applied as measure for catalytic activity. For three Pt catalysts supported on porous SiO2, porous glass, and Al2O3, respectively, significant differences in the catalytic activity by almost one order of magnitude were observed. However, especially in the case of very active catalysts, limitations of the reaction by internal or external mass transfer have to be considered. 相似文献
8.
This article attempts to increase the crashworthiness characteristics of energy absorbers. It is found that the effect of the bi-tubular arrangement on the energy absorption and peak force is nonlinear. This nonlinearity is somewhat related to friction but is mostly related to the changing of buckling modes. Therefore, it is possible to reach higher Specific Absorbed Energy (SAE) in the bi-tubular case than with two tubes since the weight is the same in both arrangements while the energy absorption is higher in the bi-tubular case. To exploit this, multi-objective optimization of bi-thin walled cylindrical aluminium tubes under axial impact loading is performed. The absorbed energy and the SAE are considered as the objective functions while the maximum crush load is regarded as a constraint. Finally, the optimal dimensions of tubes are found in order to maximize the SAE and energy absorption for a specified maximum crushing force. 相似文献
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In the present paper, we plan to introduce a new procedure for learner’s assessment in the learning environment in a way true to reality by using fuzzy logic. In this evaluation, learner’s responses are accompanied by a degree of certainty expressed by him. This method allows detection of problems encountered by the learner and also to fix the concepts mastered and those that are not. It is a diagnostic procedure that improves the process of content adaptation and self-adjustment on the one hand and makes the knowledge model clearly interpretable and more understandable to learner and tutor/teacher/head teacher on the other hand. 相似文献
10.
This work is a seminal attempt to address the drawbacks of the recently proposed monarch butterfly optimization (MBO) algorithm. This algorithm suffers from premature convergence, which makes it less suitable for solving real-world problems. The position updating of MBO is modified to involve previous solutions in addition to the best solution obtained thus far. To prove the efficiency of the Improved MBO (IMBO), a set of 23 well-known test functions is employed. The statistical results show that IMBO benefits from high local optima avoidance and fast convergence speed which helps this algorithm to outperform basic MBO and another recent variant of this algorithm called greedy strategy and self-adaptive crossover operator MBO (GCMBO). The results of the proposed algorithm are compared with nine other approaches in the literature for verification. The comparative analysis shows that IMBO provides very competitive results and tends to outperform current algorithms. To demonstrate the applicability of IMBO at solving challenging practical problems, it is also employed to train neural networks as well. The IMBO-based trainer is tested on 15 popular classification datasets obtained from the University of California at Irvine (UCI) Machine Learning Repository. The results are compared to a variety of techniques in the literature including the original MBO and GCMBO. It is observed that IMBO improves the learning of neural networks significantly, proving the merits of this algorithm for solving challenging problems. 相似文献