Results 21 to 30 of about 7,467 (211)

Flexible reduced field of view imaging and distortion correction via single-shot spatiotemporally encoded MRI [PDF]

, 2015
在众多的超快速成像方法中，单扫描平面回波成像(echoplanarimaging,EPI)，因其在速度和分辨率方面的突出表现，成为最受欢迎的成像方法之一。然而，EPI图像容易受到B0场不均匀和单次k空间采样中相位误差累积的影响而出现严重的几何形状畸变。最近以色列威兹曼研究所的Frydman小组提出了一种基于线性扫频激发的时空编码(spatiotemporallyencoded,SPEN)磁共振成像方法，该方法可以减弱EPI因非均匀场引起的伪影与图像畸变。本文首先基于SPEN成像方法的特点提出了两种小视野(
李敬
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Adaptive Chemical Strain Boundary in Freestanding BiSmFe2O6 Double‐Perovskite Membranes

Rare Metals, Volume 45, Issue 1, January 2026.
ABSTRACT Double‐perovskite multiferroic systems have attracted increasing attention due to their highly tunable structures and chemical adaptability. The uncontrollable performance changes caused by the release of boundary conditions are an important factor hindering the development of freestanding membranes.
Jie Tu, Hangren Li, Xudong Liu, Jiaqi Ding, Siyuan Du, Longyuan Shi, Menglin Li, Yonghui Wu, Pengfei Song, Guoqiang Xi, Yuzhe Yang, Dongxing Zheng, Xiaolong Li, Jianjun Tian, Linxing Zhang   +14 more
wiley   +1 more source

The foraminiferal taxa in surface sediment and its environmental implication in Sansha Bay [PDF]

, 2016
有孔虫对所生存的环境变化较敏感。对于不同的水深、温度、盐度、pH、沉积速率等环境因子的变化，有孔虫群落特征会发生相应变化。故有孔虫群落特征能较好地反映海洋环境变化。由于季节的变化，夏季和冬季所对应的环境因子条件不同，其有孔虫群落特征也会发生相应变化。本论文根据福建三沙湾的夏冬季24个站位表层沉积物样品，进行有孔虫鉴定和沉积物粒度分析。在广泛收集前人资料及室内分析的基础上，结合表层沉积物中七种重金属含量平面分布特征，通过研究分析有孔虫种群的空间分布及其与环境因子间相互关系 ...
龚凌
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Study on the Polysaccharides from Phellinus Linteus on Sperm Abnormal- ity and Chromosome Aberration in Testicle Cell of Mice [PDF]

, 2017
目的通过小鼠精子畸变和睾丸细胞染色体畸变试验，探讨桑黄多糖对雄性小鼠的生殖毒性。方法试验设三个剂量组为2．5g．kg^-1、5．Og·kg^-1、10．Og·kg^-1Bw，经口灌胃进行试验，取小鼠睾丸制备标本，分别观察并计算各剂量组小鼠的精予畸变和睾丸细胞染色体畸变率。结果桑黄多糖各剂量组小鼠的精子和睾丸细胞染色体畸变率与空白对照均无显著性差异（P〉0．05），而环磷酰胺与空白对照组比较有显著性差异（P〈O．01）。结论桑黄多糖各剂量组对雄性小鼠无生殖毒性作用。OBJECTIVE To explore
林惠武, 林燕琼
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Performance of non‐invasive prenatal testing in vanishing‐twin and multiple pregnancies: results of TRIDENT‐2 study

Ultrasound in Obstetrics &Gynecology, Volume 66, Issue 6, Page 738-746, December 2025.
ABSTRACT Objective To evaluate the performance of non‐invasive prenatal testing (NIPT) in vanishing‐twin and multiple pregnancies. Methods This study was conducted as part of the TRIDENT‐2 study, in which NIPT was offered as a first‐tier screening test to women with a multiple pregnancy or vanishing‐twin pregnancy between 1 June 2020 and 31 March 2023 ...
J. C. A. van Eekhout, C. J. Bax, L. van Prooyen Schuurman, E. C. Becking, A. J. E. M. van der Ven, D. Van Opstal, E. M. J. Boon, M. V. E. Macville, M. N. Bekker, R. J. H. Galjaard, on behalf of the Dutch NIPT Consortium, E.A. Sistermans, L. Henneman, A. Polstra, E. Voorhoeve, S.L. Zelderen‐Bhola, E.M.J. Boon, M.P.R. Lombardi, M.C. Bakker, E.J. Bradley, E.M.J. Boon, C. Louwerens‐Zintel, M. Smit, M.C. van Maarle, M.B. Tan‐Sindhunata, K. van der Meij, H. Meij, C.J. Bax, E. Pajkrt, I.H. Linskens, L. Martin, J.T. Gitsels‐van der Wal, R. J. H. Galjaard, D. van Opstal, M.I. Srebniak, F.M. Sarquis Jehee, I.H.I.M. Hollink, F. Sleutels, W. de Valk, W.H. Deelen, A.M.S. Joosten, K.E.M. Diderich, M.E. Redeker, A.T.J.I. Go, M.F.C.M. Knapen, S. Galjaard, A.K.E. Prinsen, A.P.G. Braat, M.J.V. Hoffer, N.S. den Hollander, E.J.T. Verweij, M.C. Haak, M.V.E. Macville, S.J.C. Stevens, A. van der Wijngaard, L.H. Houben, M.A.A. van Esch‐Lennarts, L. Hamers, A.G.P. Jetten, S.A.I. Ghesquiere, B. de Koning, M. Zamani Esteki, C.J. Heesterbeek, C.E.M. de Die‐Smulders, H. Brunner, M.J. Pieters, A.B.C. Coumans, D.F.C.M. Smeets, B.H.W. Faas, D. Westra, M.M. Weiss, I. Derks‐Prinsen, I. Feenstra, M. van Rij, E. Sikkel, R.F. Suijkerbuijk, B. Sikkema‐Raddatz, I.M. van Langen, K. Bouman, L.K. Duin, G.H. Schuring‐Blom, K.D. Lichtenbelt, M.N. Bekker, E. van Vliet‐Lachotzki, J. Pot, A. J. E. M. van der Ven, S van 't Padje   +86 more
wiley   +1 more source

Research on current tracking methods of single-phase inverter based on observer [PDF]

, 2016
近年来，逆变技术作为电力电子技术的一个重要分支，在交流驱动、有源滤波器、静止无功补偿器、电网互联等方面得到了广泛的应用。逆变器作为电网中的重要接口设备，其性能的优劣决定了电能的质量。因此，吸引了大量学者致力于逆变控制技术的研究。 逆变器控制的核心问题是电流跟踪控制。模型预测控制算法具有控制效果好、鲁棒性强等优点，可有效地克服过程的不确定性、非线性和耦合性，因此，在电力电子领域得到了广泛的应用。然而，模型预测控制是一类基于模型的控制方法。在实际应用中，系统模型与真实被控系统之间总存在着偏差 ...
吴扬波
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Combined first‐trimester screening and invasive diagnostics for atypical chromosomal aberrations: Danish nationwide study of prenatal profiles and detection compared with NIPT

Ultrasound in Obstetrics &Gynecology, Volume 64, Issue 4, Page 470-479, October 2024.
ABSTRACT Objectives Our aim was to examine the prenatal profiles of pregnancies affected by an atypical chromosomal aberration, focusing on pathogenic copy‐number variants (pCNVs). We also wanted to quantify the performance of combined first‐trimester screening (cFTS) and a second‐trimester anomaly scan in detecting these aberrations. Finally, we aimed
K. Gadsbøll, I. Vogel, S. E. Kristensen, L. H. Pedersen, J. Hyett, O. B. Petersen, The Danish Cytogenetic Central Register study group   +6 more
wiley   +1 more source

Technology development in nano-sized photocatalyst powder preparation technologies [PDF]

, 2006
Nano-sized semiconductor powders for use as photocatalysts have great potential in environmental and energy engineering applications. The photocatalytic activity of photocatalyst is significantly affected by preparation process since the crystalline ...
Leung, DYC, Leung, MKH, Ni, M
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Indexable Insert Grinding Error Measurement and Compesation Technique [PDF]

, 2016
可转位刀片作为可转位刀具的关键切削元件，其制造精度对刀具的加工精度和切削效率有着重要影响。随着先进制造技术的发展，涌现出大量新工艺、新材料的可转位刀片，推动了精密制造的发展进程。目前高档可转位刀片周边数控磨床被国外产品垄断，国内可转位刀片制造技术落后于国外。因此，开展高精、高效可转位刀片刃磨工艺技术研究具有重要意义。 基于以上背景，本论文在项目组前期研究基础上，围绕“可转位刀片磨削误差测量与补偿技术”课题，从以下几个方面展开研究： 1.基于可转位刀片周边磨床特点，重新设计了一种V型块底座 ...
罗琪
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Study on the Optimization of Internal Control and Camera Distortion Parameters Method Based on Matlab [PDF]

, 2017
为了提高相机标定结果的准确度,文中就相机内参和畸变参数的优化方法进行了研究。在建立准确的相机成像及标定模型基础上,根据模型参数估计的具体推导步骤,利用最大似然估计法对得到的参数进行结果优化,然后通过修改镜头畸变模型重新计算参数得到最终结果。实验证明,应用文中提出的流程求解相机内参和畸变参数,简单快速、准确度高且实用性强。Study on the optimization method of camera internal and distortion parameters is conducted in
张世超, 李超
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