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1.
目的:阐述老年新鲜股骨颈骨折的手术治疗方法及疗效评价.方法:通过C型臂X光机透视下牵引复位后空心加压螺纹钉内固定术治疗老年新鲜股骨颈骨折的结果及随访记录.结果:26例手术,疗效优良.结论:空心加压螺纹钉内固定术是治疗老年新鲜股骨颈骨折的首选方法之一,手术适应证,疗效佳. 相似文献
2.
试验测试了建立在相关解剖学数据测量基础上、自行设计的H型、T型、X型和工字型4种腰骶部前路内固定器的抗压缩和扭转结构力学性能。试验结果表明,T型内固定器具有最大的结构屈服载荷和抗压载荷,并且结构稳定性和抗压缩刚度也最优;H型内固定器的结构屈服扭矩和扭转刚度较高。综合压缩和扭转试验结果,T型内固定器具有最优的综合生物力学性能。 相似文献
3.
以股骨干骨折的接骨板内固定方式为研究对象,开发了一个综合性的生物力学实验。在传统静态应变仪采集应变片数据的基础上,结合三维数字散斑动态应变测量系统分析接骨板固定骨折的股骨在压力载荷的作用下发生的变形、接骨板及骨上的应力分布特点。实验结果显示:当螺钉数量较少时,接骨板的弯曲变形增大,增加了接骨板塑性变形及疲劳断裂的可能性;骨折断口下侧的螺钉的应力明显高于上侧的螺钉,因过载导致塑性变形及疲劳断裂的可能性大。该实验有利于提高学生分析处理问题能力,激发了学生的科研积极性。 相似文献
4.
为了寻找利用小波散射网络进行彩色图像处理的最佳彩色空间,用小波散射网络对KTH_TIPS_COL彩色图像数据库进行了图像纹理分类研究.采用将彩色图像从RGB彩色空间转换到其他各种彩色空间的方法,研究了彩色空间的选择对于小波散射网络用于彩色图像纹理分类的影响.实验结果表明:在不同的彩色空间对彩色图像纹理进行分类,分类成功率往往差别较大;在基于竞争机制的红绿蓝彩色空间中进行小波散射变换比其他彩色空间具有更好的分类性能.考虑到彩色空间可以互相转换,对于彩色纹理图像的分类,推荐将彩色空间转化到基于竞争机制的红绿蓝彩色空间后再输入小波散射网络. 相似文献
5.
"平面与平面垂直"是空间垂直关系的重难点内容,也是高考的考查热点,是"转化""降维"思想,以及"直观想象""数学抽象""逻辑推理"三大核心素养的重要体现.本节课主要通过两名学生活动突出教学重点,突破教学难点:一是用折纸实验探究二面角的平面角的作法的合理性;二是通过小组讨论发现面面垂直判定定理的实例和原理. 相似文献
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为降低路面和冰雪之间的黏结力,用有机硅憎水材料作为道路表面涂层.有机硅憎水涂层技术的除冰效果用接触角实验和剪切实验来表征,其耐久性用加速加载磨耗实验来评价,而其抗滑性能则用摆式摩擦法和铺砂法来评价.接触角实验结果表明,有机硅憎水涂层材料与水的接触角为100.2°,具有很好的憎水性能.其次,通过剪切实验可以得出:在涂有有机硅憎水材料的情况下,冰层与试件表面的最大剪切应力仅为0.06 MPa,低于没有进行表面涂层处理的最大剪切力3.5 MPa;剪切之后,冰层能够很完整地从试件表面脱落.加速加载磨耗实验表明,在经过一定时间的磨耗之后,残留在沥青路面构造深度里的有机硅涂层材料仍然具有除冰雪的效果.表面涂层后的道路表面的BPN值和构造深度值均有所降低,但是其仍然远远大于规范的要求,确保了安全性.研究表明,沥青道路表面涂层技术能有效地降低沥青路面与冰层的黏结,从而解决冬季道路结冰影响行车安全的问题. 相似文献
7.
大规模多源异构数据的产生为多视角学习算法提出了新的挑战。文中系统回顾了三类基于子空间学习的多视角聚类算法:最大相关子空间、低维子空间潜入和隐子空间,归纳了不同多视角学习算法的优缺点和适用范围,并在两个真实的多视角数据集上执行了大量对比实验,结果显示:用鲁棒的关联矩阵来刻画具有非线性、复杂结构关系的数据,有助于带来算法性能的显著提升;最后,总结了多视角学习领域出现的问题并展望了未来可以深入研究的方向。 相似文献
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用紫外光谱研究了合成的系列磷酰化肽酯（DPP）与几种不同价态的常见金属离子——K＋、Ag＋、Mg2＋、Cu2＋、Fe3＋和Al3＋的相互作用,讨论了不同结构的磷酰化肽酯与金属离子相互作用的规律.结果表明,系列磷酰化肽酯与6种金属离子的相互作用没有差别,均表现为与K＋、Fe3＋和Al3＋几乎没有相互作用,与Mg2＋和Cu2＋有弱的相互作用,与Ag＋有较强的相互作用.相互作用的结果使磷酰化肽酯在190 nm左右的吸收峰强度下降、最大吸收波长红移.主要的作用位点应是系列磷酰化肽酯分子中不饱和基团的杂原子.它们的相互作用主要受金属离子的离子半径、电荷数、电子构型、水解性能和浓度的影响. 相似文献
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对2根外包钢-混凝土连续梁试件进行了静力加载实验研究与承栽力分析.测量并分析了试件的荷栽-挠度及荷载-应变关系曲线.结果表明:外包钢-混凝土组合梁负弯矩区钢筋和外包钢梁通过抗剪连接措施能有效地共同工作,整体工作性能良好.在承栽能力极限状态,负弯矩和正弯矩最大截面的塑性应变均充分发展,并形成比较理想的塑性铰.随着配筋率的提高,组合梁受弯承栽力明显提高,而延性和转动能力相应降低.在试验数据基础上,给出了外包钢-混凝土组合梁在负弯矩区极限受弯承载力的计算公式,计算结果与实验结果吻合良好. 相似文献
10.
阿司匹林肠溶片是一种抗血小板药物,应用于心血管疾病的预防和治疗,由于近年来百姓对药品的安全性越来越重视,所以对于药品的检测也就越来越严谨,本文将用多种溶剂溶解药物,利用紫外光度法对其进行实验,该法较其他方法操作简单,且灵敏度高,适用于含量的测定.实验表明:当选用丙酮作为溶解溶剂时,三价铁离子与水杨酸反应产物在530 nm处有最大吸收,药物及对照品溶解的程度也较好,稳定性实验的数据变化幅度也较小. 相似文献
11.
夏桂芳 《乌鲁木齐成人教育学院学报》2004,12(3):79-81
四面体是立体几何中最重要的几何体，它的地位相当于平面几何中的三角形。对四面体的研究，很有实用价值，通过对特殊四面体——直角四面体、正四面体、等腰四面体的性质进行梳理来说明它在高考解题中的作用。 相似文献
12.
Edward S. Redhead Derek A. Hamilton Matthew O. Parker Wai Chan Craig Allison 《Learning & behavior》2013,41(2):179-191
In three experiments, we examined whether overshadowing of geometric cues by a discrete landmark (beacon) is due to the relative saliences of the cues. Using a virtual water maze task, human participants were required to locate a platform marked by a beacon in a distinctively shaped pool. In Experiment 1, the beacon overshadowed geometric cues in a trapezium, but not in an isosceles triangle. The longer escape latencies during acquisition in the trapezium control group with no beacon suggest that the geometric cues in the trapezium were less salient than those in the triangle. In Experiment 2, we evaluated whether generalization decrement, caused by the removal of the beacon at test, could account for overshadowing. An additional beacon was placed in an alternative corner. For the control groups, the beacons were identical; for the overshadow groups, they were visually unique. Overshadowing was again found in the trapezium. In Experiment 3, we tested whether the absence of overshadowing in the triangle was due to the geometric cues being more salient than the beacon. Following training, the beacon was relocated to a different corner. Participants approached the beacon rather than the trained platform corner, suggesting that the beacon was more salient. These results suggest that associative processes do not fully explain cue competition in the spatial domain. 相似文献
13.
针对二值图像的几何相似性,本文提出一种基于等腰直角三角形的压缩算法。该算法以四叉树为数据结构,以达到减小中间结点的开销;同时该算法的时间复杂度和空间复杂度均低于采用JBIG标准来压缩二值图像。其压缩比可提高15%;同时适用于复杂图像。 相似文献
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对三种玻璃纤维土工格栅在不同的加载速率下的断裂强力进行了大量的试验研究,得到了断裂强力与加载速率的关系曲线。结果表明,加载速率对断裂强力的影响明显,速率越大,断裂强力越高。 相似文献
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Sheng-yong Wu Hui-hui Jia Didier Hans Jing Lan Li-ying Wang Jing-xue Li Yue-zeng Cai 《Journal of Zhejiang University. Science. B》2009,10(7):499-504
Objective: To demonstrate the validity and reliability of volumetric quantitative computed tomography (vQCT) with multi-slice computed tomography (MSCT) and dual energy X-ray absorptiometry (DXA) for hip bone mineral density (BMD) measurements, and to compare the differences between the two techniques in discriminating postmenopausal women with osteoporosis-related vertebral fractures from those without. Methods: Ninety subjects were enrolled and divided into three groups based on the BMD values of the lumbar spine and/or the femoral neck by DXA. Groups 1 and 2 consisted of postmenopausal women with BMD changes ＜-2SD, with and without radiographically confirmed vertebral fracture (n=11 and 33, respectively).Group 3 comprised normal controls with BMD changes ≥-1SD (n=46). Post-MSCT (GE, LightSpeed16) scan reconstructed images of the abdominal-pelvic region, 1.25 mm thick per slice, were processed by OsteoCAD software to calculate the following parameters: volumetric BMD values of trabecular bone (TRAB), cortical bone (CORT), and integral bone (INTGL) of the left femoral neck, femoral neck axis length (NAL), and minimum cross-section area (mCSA). DXA BMD measurements of the lumbar spine (AP-SPINE) and the left femoral neck (NECK) also were performed for each subject. Results: The values of all seven parameters were significantly lower in subjects of Groups 1 and 2 than in normal postmenopausal women (P＜0.05, respectively).Comparing Groups 1 and 2, 3D-TRAB and 3D-INTGL were significantly lower in postmenopausal women with vertebral fracture(s) [(109.8±9.61) and (243.3±33.0) mg/cm3, respectively] than in those without [(148.9±7.47) and (285.4±17.8) mg/cm3,respectively] (P＜0.05, respectively), but no significant differences were evident in AP-SPINE or NECK BMD. Conclusion: the femoral neck-derived volumetric BMD parameters using vQCT appeared better than the DXA-derived ones in discriminating osteoporotic postmenopausal women with vertebral fractures from those without, vQCT might be useful to evaluate the effect of osteoporotic vertebral fracture status on changes in bone mass in the femoral neck. 相似文献
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目的:探讨颈前入路C2-3椎体螺钉钢板内固定融合术治疗Hangman骨折的方法、临床效果和安全性.方法:9例Hangman骨折经颅骨牵引复位后,在仰卧位采取右侧颌下斜切口,在颈动脉鞘和内脏鞘之间进入椎前间隙,切除C2-3椎间盘,取自体髂骨移植,枢法模带锁钢板螺钉内固定.术后费城颈托外固定6～8周.术后所有患者随访6～30月,平均18个月.结果:本组9例病例均获得骨性融合,无假关节形成,颈部活动度正常,无神经功能受损症状.结论:经颈前入路C2-3椎体螺钉钢板内固定融合术治疗Hangman骨折可获得良好的即时稳定性,防止假关节形成和鹅颈畸形,有利于患者早期下床活动,且不影响颈椎活动度,是一种安全、效果良好的治疗方法. 相似文献
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本文给出等腰三角形两腰上具有某些特性的顶边线的相等关系及其逆命题 ,由此不难推出著名的Lehmus -Steiner定理。 相似文献
18.
研究股骨近端空心钉锁定板内固定微创治疗青壮年股骨近端骨折的临床疗效及优点。采用透视下闭合复位应用股骨近端空心钉锁定板内固定治疗41例青壮年股骨颈基底部GardenⅠ～Ⅲ型骨折或股骨转子间EvansⅠ～Ⅱ型骨折。观察术后骨折愈合情况、髋关节功能恢复情况及股骨头坏死情况。结果显示,41例患者骨折愈合率为100%,无髋内翻及内固定失败;髋关节功能优良率90%(Harris评分标准);股骨头坏死率7.3%。结果表明,该方法具有创伤小、操作简单、固定可靠和并发症少等优点。 相似文献
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The purpose of this article is to introduce ‘a new analysis’ to students of mathematics at the undergraduate and postgraduate levels, which in turn introduces a geometry very different from our Euclidean geometry and Riemannian geometry. Some strange things happen: for instance, ‘every triangle becomes isosceles!’. 相似文献
20.
In three experiments, a new reference memory procedure was used to examine how male rats search for consistently located food in a cue-controlled spatial environment. The animals searched the tops of 24 poles for six hidden baits in an enclosed circular arena containing a fixed configuration of six object landmarks. In Experiment 1, acquisition was faster and overall performance better for theconsistent group (10 rats), in which the six baited poles were fixed relative to the landmarks for each session, than for therandom group (4 rats), in which baited poles were randomly configured. Cue-control tests and computer simulations suggested that the consistent group relied on the landmarks to directly go to the baited poles, whereas the random group used them to employ a response strategy for searching the arena. Experiments 2 and 3 revealed that the number, identity, and geometric configuration of the landmarks were important to the consistent group’s search performance. Overall, these results are most consistent with the use of a geometric representation by male rats which includes information about both the identity and the relative geometry of discrete landmarks in the surrounding spatial environment. 相似文献