首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 234 毫秒
1.
目的在不同钻型和钻削参数下对骨骼进行钻削力学和热学分析,降低钻骨过程中的钻削力和钻削温度,减小对周围骨组织的损伤。方法通过有限元仿真软件Advant Edge建立骨骼钻削模型并与猪股骨钻削实验对比,分析标准麻花钻与3种标准群钻在不同转速和进给速度下的仿真与实验结果。结果仿真与实验对比发现,钻头刃型、钻头转速和进给速度对钻削力和钻削温度的影响趋势一致,建立的仿真模型可信。结论相同钻削条件下,钻橡胶群钻比标准麻花钻的钻削力和钻削温度更低。研究结果为群钻在骨折手术中的应用提供理论依据。  相似文献   

2.
赵杰 《医学信息》2018,(11):138-139
目的 建立高效液相色谱(HPLC)法测定注射用泮托拉唑钠中EDTA-2Na的含量。方法 选择固定相为十八烷基硅烷键合硅胶(直径为5 μm),尺寸为250 mm×4.6 mm色谱柱,以乙腈-磷酸盐缓冲液(15∶85,v/v,用磷酸调节pH至2.5±0.1)为流动相,流速为1.0 ml/min,检测波长为255 nm,柱温为35 ℃。结果 EDTA-2Na浓度在2.0~32.0 μg/ml范围内线性方程为A=2.317×104C-1.235×103(r=0.9998),EDTA-2Na的平均回收率为100.40%,RSD 为0.92%(n=9)。结论 本方法简便、可靠、准确度高、重复性好,可用于测定注射用泮托拉唑钠中EDTA-2Na的含量。  相似文献   

3.
吴玮 《医学信息》2018,(18):127-128,131
目的 建立HPLC法测定对乙酰氨基酚片的含量。方法 色谱柱为Agilent Eclipse XDB-C18柱(4.6 mm×150 mm,5 μm);流动相为甲醇-水(20∶80),流速为1.0 ml/min,检测波长为244 nm,柱温30 ℃。结果 对乙酰氨基酚浓度在10.16~30.48 μg/ml范围内线性关系良好,r=0.9998(n=5);平均加样回收率为100.04%,RSD=0.95%(n=6)。结论 HPLC法操作简便、结果准确、重复性好、专属性强,适用于测定对乙酰氨基酚片中对乙酰氨基酚的含量。  相似文献   

4.
目的 评价不同变牙厚椎弓根螺钉(transitional thread pedicle screw, TTPS)对螺钉拔出力的影响。 方法 取新鲜小牛胸腰椎标本(T11~L4)5具,共30个椎体(60侧椎弓根),剔除周围肌肉、筋膜,注意保持骨结构完整,解离成单个椎骨。平均骨密度为(1.186±0.182)g/cm2。TTPS规格有6种:A0(牙厚保持不变)、A1(逐牙加厚0.01mm)、A2(逐牙加厚0.02 mm)、A3(逐牙加厚0.03 mm)、A4(逐牙加厚0.04  mm)、A5(逐牙加厚0.05 mm)。每种螺钉随机置入10侧椎弓根,将标本包埋好并用夹具固定在材料试验机上,设置椎弓根螺钉长轴与拔出力轴线方向重合。设置材料试验机加载速率为0.08 mm/s进行拔出实验,结果输出拔出力-位移曲线、最大轴向拔出力(Fmax)。计算拔出刚度。 结果 A0至A5 6种螺钉的最大轴向拔出力分别为(983.99±324.19)、(1119.84±362.47)、(1067.67±398.00)、(900.04±255.89)、(799.07±406.79)、(850.71±408.11)N。6种不同规格TTPS轴向拔出力间无显著差异(组间差异P=0.216)。6种不同规格的TTPS的拔出刚度间无显著差异(组间差异P=0.07)。 结论 小范围增加螺纹牙厚,对椎弓根螺钉抗拔出力没有显著影响。  相似文献   

5.
目的 建立癌痛消方及其拆方中松脂醇二葡萄糖苷和芍药苷的测定方法。方法 采用十八烷基硅烷键合硅胶柱(Inertsil ODS-3柱 250×4.6 mm,5 μm);流动相:乙腈-0.1%磷酸(15∶85)为流动相,进行梯度洗脱;检测波长:230 nm(0~16 min,松脂醇二葡萄糖苷),277 nm(16~30 min,芍药苷);流速:1.0 ml/min;柱温:30oC。结果 癌痛消-补虚组中松脂醇二葡萄糖苷在1.0~5.0 μg范围内呈现良好的线性关系,r=0.9992,平均回收率为97.23%(RSD=1.31%,n=6);癌痛消-抑癌组中芍药苷在1.0~5.0 μg范围内呈现良好的线性关系,r=0.9993,平均回收率为97.08%(RSD=1.38%,n=6);癌痛消-全方中松脂醇二葡萄糖苷在1.0~5.0 μg范围内呈现良好的线性关系,r=0.9992,平均回收率为98.01%(RSD=1.30%,n=6);癌痛消-全方中芍药苷在1.0~5.0μg范围内呈现良好的线性关系,r=0.9993,平均回收率为96.97%(RSD=1.54%,n=6);结论 本方法专属性强,准确度高,重现性良好,可用于癌痛消方的质量控制。  相似文献   

6.
唐昌莉 《医学信息》2010,23(14):2459-2460
目的建立高效液相色谱法测定珍珠菜提取物中芦丁含量。方法色谱柱为Diamonsil C18(4.6mm×250mm);流动相为甲醇-0.4%冰醋酸-四氢呋喃(30:60:10);流速1.0ml/min;检测波长355nm。结果提取物中芦丁的保留时间为25.4min,色谱峰分离良好,对照品芦丁线性范围为1.0312~30.936μg/ml(r=0.9994,n=5),方法回收率为100.1%,RSD为1.03%。结论该法可用于珍珠菜提取物中芦丁的含量测定,可以用来对提取物进行质量控制。  相似文献   

7.
目的:探讨大鼠心脏缺血预处理(IPC)中金属硫蛋白(MT)的变化。方法:采用经典的IPC模型,与I/R心肌损伤比较。实验动物分为3组:假手术组(n=6),开胸旷置2 h 20 min;缺血/再灌注组(n=12),结扎左冠状动脉前降支40 min,再灌注1 h 40 min;经典IPC组(n=12),按经典的Murry法复制。以心肌MT的含量,心肌梗塞范围,心肌组织丙二醛(MDA)含量和超氧化物歧化酶(SOD)活性为观察指标。结果:IPC组心肌MT含量明显高于I/R组(P<0.01),心肌MDA含量明显低于I/R组(P<0.01),心肌SOD活性明显高于I/R组(P<0.01)。经直线相关分析,IPC组心肌MT含量与SOD活性呈正相关(r=0.91, P<0.01),与MDA含量呈负相关(r=-0.92, P<0.01),IPC组心肌梗塞范围明显小于I/R组(P<0.05)。结论:缺血预处理能促进大鼠心肌MT合成,MT可能参与IPC的保护效应。  相似文献   

8.
目的 测量人体多部位松质骨矿质密度、轴向弹性模量,建立矿质密度与轴向弹性模量相关关系的本构方程,为国人有限元材料属性赋值提供依据。方法 采取10例成人新鲜尸体作为样本源,选取胫骨近端、大转子、股骨颈、肱骨头和椎体5个部位的松质骨,加工成直径约6 mm、长约30或40 mm的准试样。测量尺寸并计算体积,CT扫描试样骨矿质密度。对松质骨试样进行力学性能测试,分析不同部位松质骨弹性模量。对矿质密度与轴向弹性模量关系进行线性与幂次回归分析。结果 测试成功的试样来自5个部位,共169枚,其中胫骨近端52枚,大转子31枚,股骨颈15枚,肱骨头17枚,椎体54枚;5个部位松质骨矿质密度、轴向弹性模量均有所差异,线性相关性均较好(0.850>r2>0.785),3个部位(胫骨近端、大转子、椎体)的幂次相关性较好(0.871>r2>0.825),2个部位(肱骨头、股骨颈)的幂次相关性较弱(0.671>r2>0.643)。结论 各个部位骨矿质密度与轴向弹性模量的线性和幂次回归的相关性均较高,且同部位两种回归的r2值之间无明显差异;可应用于体外检测患者的骨骼质量,准确分辨骨质变化的部位,配合有限元建模能够预测骨折的风险。  相似文献   

9.
目的探讨老年股骨颈骨折病人的股骨头样本各个区域的结构和生物力学性能差异,研究不同区域显微结构和生物力学特征及其对内固定物的影响。方法收集20个老年股骨颈骨折病人关节置换术后股骨头标本,以股骨头表面解剖标志点为参照,将股骨头按平分方法分为外侧、内侧、中间三部分。确定环钻的位置和钻取方向,用环钻于不同区域钻取直径10 mm、高10 mm圆柱形松质骨柱。通过Micro-CT系统扫描分析,分析不同区域内松质骨柱数据,包括骨体积分数(BVF)、骨小梁间隙(Tb.Sp)、骨小梁厚度(Tb.Th)、骨小梁数目(Tb.N)、骨表面积体积比(BS/BV)、结构模型指数(SMI)。应用微有限元计算不同区域骨组织的力学差异。结果老年股骨头颈内骨质含量下降,显微结构和生物力学性能区域变化明显,中间区域的骨结构和力学性能明显优于内侧和外侧。结论股骨头中间部位骨骼结构和力学强度明显优于内侧和外侧,在临床治疗骨质疏松股骨颈骨折的时候需要充分考虑内固定的部位。  相似文献   

10.
研制出一台采用永磁轴承的左心室辅助装置(LVAD)。该装置包括一个定子和一个转子,采用径向驱动方式;转子包括驱动磁钢和叶轮,电机定子线圈和泵壳组成定子。装置设计采用了一种特殊结构的永磁轴承。转子的位置测量表明,转子稳定悬浮的前提条件是必须有较高的转速(大于3250r/min)且流量大于1L/min。用猪血为介质所做的液动力测试表明,当转速达到3500r/min~4000r/min时,血泵输出流量达到4L/min~6L/min,输出压力达到100mmHg。该装置重200g,最大处直径为40mm。  相似文献   

11.
Over 200 schizophrenic patients belonging to three major and interrelated pedigree complexes have been investigated over the past 30 years in a North Swedish geographically isolated population, presently numbering about 6,000. An intensive investigation of a number of biochemical correlates and genetic markers in a few selected families belonging to one of the major pedigrees has indicated new strategies for the current research program.
Schizophrenia, as defined operationally, is significantly associated with decreased activities of two enzymes (1) blood platelet monoamine oxidase, (2) plasma dopamine-β-hydroxylase, and (3) with the genetic marker Gc2 (group specific antigen). Both enzymes are subject to genetic variation. A positive score for linkage between schizophrenia and low plasma DBH activity has been calculated, but, so far, available data are insufficient for discrimination between linkage and partial contribution of genetically controlled low plasma DBH to the pathogenesis of the disease. Alternatively, both mechanisms could be involved.
As a model for continued research, schizophrenia is explained as based on a double dominant-recessive genotype (Aabb), representing a vulnerability which in about 50 % of cases develops into clinical schizophrenia. It is suggested that the dominant mutation (A) operates on or affects MAO activity, and that the recessive genotype (bb) is instrumental in low variates of DBH activity and very likely such variates within the normal range of physiological variation. Moreover, it is suggested that the combined effects of MAO- and DBH-reduced efficiency on the metabolism of e.g. dopamine could be an essential pathogenic mechanism for the schizophrenic illness which is segregating in this population.  相似文献   

12.
Most bodily functions require the coordinated actions of complementary and supplementary paired muscle groups. Where this essential muscular cooperation is lacking, hollow organs may burst and others become literally screwed up, giving rise to many similar spastic diseases such as Torticollis, Twisted ovarian cyst, Torsion of the Testis, Volvulus of the intestines, Varicose Veins, Megacolon, Aortamegaly, Scoliosis, Erb's Palsy, Peyronie's Disease, Main-en-Griffe, Undescended Foot (Pes Cavus), Talipes, Strabismus. Spasm is “panenepidemic” and unclassified examples of Torsion Dystonia and Dyskinesia really are as common as debt and taxes.  相似文献   

13.
About 1900, modern food selection and processing caused widespread epidemics of the B vitamin deficiency diseases of beriberi and pellagra which, for genetic reasons, often expressed as different diseases ranging from bowel and heart disease to dermatoses and psychoses. But the B vitamins merely help convert essential fatty acids (EFA) into the prostaglandin (PG) tissue regulators and it now turns out that, through hydrogenation, milling and selection of w3-poor southern foods, we have also been systematically depleting, by as much as 90%, a newly discovered trace Nordic EFA (w3) of special importance to primates and sole precursor of the PG3(4) series, even as a concurrent fiber deficiency increases body demand for EFA. Since substrate EFA is processed by many B vitamin catalysts, an EFA deficiency will mimic a panhypovitaminosis B, i.e., a mixture of substrate beriberi and substrate pellagra resembling vitamin beriberi and pellagra but exhibiting as even more diverse endemic disease. This would consitute a second stage of the Modern Malnutrition and explain why some workers now hold the dominant diseases of modermized societies to be new, nutritionally based, pellagraform yet lipid-related and to range, once again, from heart disease to psychosis. It is an assumption that our dominant diseases are unrelated to each other or are merely revealed by our diagnostic acumen and therapeutic success; and that hydrogenating millions of tons of food oils annually, to destroy the rancidity producing w3-EFA, is safe for primates. Extensive beriberiform disease is reported here in 32 typical cases taken from medical practice which responds strikingly to linseed oil supplements (60% w3-EFA) in confirmation of identical results in Capuchins.  相似文献   

14.
Zusammenfassung Eine Reihe pathologischer Zustände bedingen Magnesiummangel. Zustände mit Hypermagnesämie sind ebenfalls bekannt, doch wesentlich seltener. Für den Kardiologen beachtenswert ist, daß unter Therapie mit bestimmten Diuretica bei Herzinsuffizienz, bei Herzinfarkt, Kardiomyopathie, Digitalisintoxikation und bestimmten Herzrhythmusstörungen Hypomagnesämie beobachtet wurde. Leider kann in der klinischen Routine nur ein extracelluläres Magnesiumdefizit durch Serumbestimmungen gemessen werden; über Magnesiummangel einzelner Organe kann nichts ausgesagt werden. Hinweise für Magnesiummangel geben aber neben der Messung des Serumspiegels Anamnese, klinischer Befund, bestimmte EKG-Veränderungen wie auch evtl. Hypokalämie, ein Zustand, bei dem sich oft — besonders bei Aldosteronismus — parallele Veränderungen zeigten.Tierexperimente deuten darauf hin, daß infarktähnliche Läsionen unter Magnesiummangel entstehen, doch ob Herzinfarkt beim Menschen durch Magnesiummangel ausgelöst werden kann, ist noch ungeklärt. In Leichenherzen zeigte sich im Infarktgebiet neben Calciumakkumulation signifikanter Magnesiumverlust, wobei unklar blieb, ob sich Ursache oder Folge des Infarktes widerspiegelten. Falls ein ursächlicher Zusammenhang besteht, ist er im Myokardstoffwechsel selbst zu suchen, wie bei der Alkoholkardiomyopathie, wo myokardialer Magnesiummangel zumindest als pathogenetischer Teilfaktor anerkannt wird. Andererseits versucht man aber auch Beziehungen zwischen Atherosklerose, Blutgerinnung und Hypomagnesämie herzustellen, in der Meinung, daß Magnesiummangel auch über den coronaren Pathomechanismus des Herzinfarktes wirken könnte. Sicher scheint, daß gewisse EKG-Veränderungen und Herzrhythmusstörungen durch einen irritierten Magnesiumhaushalt bedingt sein können, da sie bei Gabe bzw. Entzug von Magnesium verschwinden. Daß Magnesiummangel die Glykosidtoleranz verringert, wird tierexperimentell bestätigt. Unter Hypomagnesämie bewirkt Acetylstrophanthidin eher und länger Rhythmusstörungen als ohne, außerdem lassen diese sich durch Magnesiumgaben eliminieren. Da in gewissen Fällen spontane und digitalisinduzierte Herzrythmusstörungen durch Magnesiuminjektionen beseitigt wurden, scheint Magnesium als Therapeuticum angebracht. Einsatz verschiedener Magnesiumsalze bei Angina pectoris, degenerativen Herzerkrankungen und Herzinsuffizienz ohne geprüften und offensichtlich gestörten Magnesiumhaushalt ist fragwürdig, weil keine eindeutigen klinischen Erfolgsbeweise vorliegen. Immerhin mag es aber larvierte, durch Serumbestimmungen nicht erfaßbare Mangelzustände geben. Allgemein erscheint es aus kardiologischer Sicht ratsam, den Magnesiumhaushalt zu überwachen und in entsprechenden Fällen auszugleichen, um möglichen Myokardläsionen oder fatalen Herzrhythmusstörungen entgegenzuwirken.  相似文献   

15.
16.
Introduction: The etiology of atopic dermatitis (AD) is multifactorial with interaction between genetics, immune and environmental factors.

Areas covered: We review the role of prenatal exposures, irritants and pruritogens, pathogens, climate factors, including temperature, humidity, ultraviolet radiation, outdoor and indoor air pollutants, tobacco smoke exposure, water hardness, urban vs. rural living, diet, breastfeeding, probiotics and prebiotics on AD.

Expert commentary: The increased global prevalence of AD cannot be attributed to genetics alone, suggesting that evolving environmental exposures may trigger and/or flare disease in predisposed individuals. There is a complex interplay between different environmental factors, including individual use of personal care products and exposure to climate, pollution, food and other exogenous factors. Understanding these complex risk factors is crucial to developing targeted interventions to prevent the disease in millions. Moreover, patients require counseling on optimal regimens for minimization of exposure to irritants and pruritogens and other harmful exposures.  相似文献   


17.
《Human immunology》2020,81(5):193-194
Huastecos or Teenek Amerindians are presently living at North East Mexico (San Luis Potosi State). They have probably one of the most ancient culture of Mexico and Central America together with Mayas and Olmec groups with which also show close relationships. Proximity to Atlantic Ocean/Mexican Gulf originated that Spaniards had very early contact with them at about 1519 CE or before. In the present paper we have aimed to study HLA gene profile which may be useful for HLA and disease epidemiology and transplant programs in Teeneks. HLA-DRB1*04:07, -DRB1*14:06 and -DRB1*04:11 have been found in high frequency like in other Amerindian groups. High frequency typical Amerindians HLA extended haplotypes have been found, such as A*02-B*35-DRB1*04:07-DQB1*03:02; A*68-B*39-DRB1*04:07-DQB1*03:02 and A*02-B*39-DRB1*04:07-DQB1*03:02; also new haplotypes have been described, like A*02-B*52-DRB1*04:11-DQB1*03:02, A*68-B*35-DRB1*14:02-DQB1*03:01 and A*68-B*40-DRB1*16:02-DQB1*03:01. Genetic proximity is observed not only to linguistically close Mayans, but also to Mazatecans, Mixtecans and Zapotecans, who speak an altogether different languages; it shows once more that genes and languages do not correlate. This population was greatly diminished after European contact between 1500 and 1600 years CE; in fact, North and South America First Inhabitants population was brought from 80 down to 8 million people because of diseases (i.e.: measles, smallpox or influenza), slavery and war.  相似文献   

18.
Newton H 《Medical history》2011,55(2):153-182
Sick children were ubiquitous in early modern England, and yet they have received very little attention from historians. Taking the elusive perspective of the child, this article explores the physical, emotional, and spiritual experience of illness in England between approximately 1580 and 1720. What was it like being ill and suffering pain? How did the young respond emotionally to the anticipation of death? It is argued that children’s experiences were characterised by profound ambivalence: illness could be terrifying and distressing, but also a source of emotional and spiritual fulfilment and joy. This interpretation challenges the common assumption amongst medical historians that the experiences of early modern patients were utterly miserable. It also sheds light on children’s emotional feelings for their parents, a subject often overlooked in the historiography of childhood. The primary sources used in this article include diaries, autobiographies, letters, the biographies of pious children, printed possession cases, doctors’ casebooks, and theological treatises concerning the afterlife.  相似文献   

19.
Recent advancements in agricultural biotechnology have created a need for analytical techniques to determine introduced proteins in crops enhanced through modern biotechnology techniques. These proteins are expressed in plant tissues and may be present in food ingredients. Immunoassays are ideally suited for protein detection and may be used as both quantitative and threshold methods. Microplate ELISA and lateral flow devices are two of the most commonly used immunoassay formats for agricultural biotechnology applications. This paper provides general background information and a discussion of criteria for the validation and application of immunochemical methods to the analysis of proteins introduced into plants and food ingredients using biotechnology methods. It is the result of a collaborative effort of members of the Analytical Environmental Immunochemical Consortium. This collaborative effort represents the combined expertise of several organizations to reach consensus on establishing guidelines for the validation and use of immunoassays. Further, the paper offers developers and users a consistent approach to adopting the technology as well as aid in producing accurate and meaningful results.  相似文献   

20.
The preparation steps usually necessary for obtaining ultrathin frozen sections of biological material (chemical prefixation, enclosing, cryoprotective treatment, freezing, sectioning, and post-staining the sections for transmission electron microscopy) are submitted to a critical analysis. The application of cryo-ultramicrotomy, in particularly for cytochemical purposes, is reviewed. Fundamental considerations of chemical prefixation and poststaining are supported by examples from yeast cytology. Furthermore, the efficiency of the cryo-ultramicrotomy (electron optical resolution of ultrastructural details) is demonstrated on yeast cells and protoplasts.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号