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931.
《Palaeoworld》2014,23(3-4):276-284
Five new species are described from the Middle–Upper Jurassic Daohugou Beds of Inner Mongolia, China, and assigned to the genus Karataus Rasnitsyn, 1977 in the subfamily Symphytopterinae of Ephialtitidae. They are illustrated as Karataus daohugouensis n. sp., K. strenuus n. sp., K. vigoratus n. sp., K. exilis n. sp., and K. orientalis n. sp., and a key to species of Karataus is presented.  相似文献   
932.
933.
Elbow joint stiffness is critical to positioning the hand. Abnormal elbow joint stiffness may affect a person's ability to participate in activities of daily living. In this work, elbow joint stiffness was measured in ten healthy young adults with a device adapted from one previously used to measure stiffness in other joints. Measurements of elbow stiffness involved applying a constant-velocity rotational movement to the elbow and measuring the resultant displacement, torque, and acceleration. Elbow stiffness was then computed using a previously-established model for joint stiffness. Measurements were made at two unique elbow joint angles, two speeds, and two forearm muscle contraction levels. The results indicate that the elbow joint stiffness is significantly affected by both rotational speed and forearm muscle contraction level.  相似文献   
934.
浙江天台盆地上白垩统赤城山组长形蛋科一新蛋属   总被引:2,自引:0,他引:2  
浙江天台盆地上白垩统赤城山组发现一新的恐龙蛋类型。依据蛋化石形态、大小和蛋壳柱状层生长纹呈波浪形等特征,将其归入长形蛋科(Elongatoolithidae)。这枚恐龙蛋的蛋壳外表面具网状纹饰,蛋壳锥体层与柱状层界线明显,二者厚度之比近1:2,气孔道细而直,这些特征区别于其他长形蛋科的成员,因此,建立一新的蛋属、蛋种:网纹副长形蛋(Paraelonga-toolithus reticulatus oogen.et oosp.nov.),代表晚白垩世早期长形蛋科的新成员。  相似文献   
935.
Chronic ethanol consumption is a strong risk factor for the development of certain types of cancer including those of the upper aerodigestive tract, the liver, the large intestine and the female breast. Multiple mechanisms are involved in alcohol-mediated carcinogenesis. Among those the action of acetaldehyde (AA), the first metabolite of ethanol oxidation is of particular interest. AA is toxic, mutagenic and carcinogenic in animal experiments. AA binds to DNA and forms carcinogenic adducts. Direct evidence of the role of AA in alcohol-associated carcinogenesis derived from genetic linkage studies in alcoholics. Polymorphisms or mutations of genes coding for AA generation or detoxifying enzymes resulting in elevated AA concentrations are associated with increased cancer risk. Approximately 40% of Japanese, Koreans or Chinese carry the AA dehydrogenase 2*2 (ALDH2*2) allele in its heterozygous form. This allele codes for an ALDH2 enzyme with little activity leading to high AA concentrations after the consumption of even small amounts of alcohol. When individuals with this allele consume ethanol chronically, a significant increased risk for upper alimentary tract and colorectal cancer is noted. In Caucasians, alcohol dehydrogenase 1C*1 (ADH1C*1) allele encodes for an ADH isoenzyme which produces 2.5 times more AA than the corresponding allele ADH1C*2. In studies with moderate to high alcohol intake, ADH1C*1 allele frequency and rate of homozygosity was found to be significantly associated with an increased risk for cancer of the upper aerodigestive tract, the liver, the colon and the female breast. These studies underline the important role of acetaldehyde in ethanol-mediated carcinogenesis.  相似文献   
936.
白龙江上游地区森林植物群落物种多样性的研究   总被引:71,自引:3,他引:68       下载免费PDF全文
 白龙江上游地区属长江防护林工程重点地区之一。根据36个样地的调查资料,分析了该地区森林植物群落物种多样性的特征:群落内各层物种丰富度指数的大小顺序为“灌木层>草本层>乔木层”;均匀度指数变化比较复杂,在杜鹃巴山冷杉(Rhododendron fastigiatum-Abies fargesii)林中为“草本层>灌木层>乔木层”,在苔藓巴山冷杉林中为“乔木层>灌木层>草本层”,其余群落中为“灌木层>草本层>乔木层”;多样性指数的大小顺序为“乔木层<灌木层和草本层”,而灌木层与草本层的多样性指数随林分郁闭度变化而变化,在郁闭度30%的杜鹃巴山冷杉林中,草本层大于灌木层,在郁闭度47%的箭竹巴山冷杉林中,草本层和灌木层相当,在郁闭度55%以上的各个群落内,灌木层大于草本层。同一海拔不同坡向群落的物种多样性表现为分布于阳坡的油松(Pinus tabulaeformis)林大于分布于阴坡的草类云杉(Picea asperata)林。物种多样性沿海拔梯度的变化表现为随海拔升高先降低后增加,从海拔2 400 m的栎类阔叶林,2 600 m的草类云杉林,2 800 m的箭竹(Sinarundinaria nitida)巴山冷杉林,到3 000 m的苔藓巴山冷杉林和3 200 m的杜鹃巴山冷杉林,物种多样性依次下降,到海拔3 400 m的高山杜鹃(Rhododendron fastigiatum)灌丛,物种多样性增加。物种多样性在紫果云杉(Picea purpurea)林的演替系列中表现为随群落演替发展而增加,后降低,在针阔混交林阶段达到最大。  相似文献   
937.
Denitrification in floodplains is a major issue for river- and groundwater quality. In the Upper Rhine valley, floodplain forests are about to be restored to serve as flood retention areas (polders). Besides flood attenuation in downstream areas, improvement of water quality became recently a major goal for polder construction. Redox potential monitoring was suggested as a means to support assessment of nitrogen elimination in future floodplains by denitrification during controlled flooding. To elucidate the relationship between redox potential and denitrification, experiments with floodplain soils and in situ measurements were done. Floodplain soil of two depth profiles from a hardwood forest of the Upper Rhine valley was incubated anaerobically with continuous nitrate supply. Reduction of nitrate was followed and compared with redox potential and organic matter content. The redox potential under denitrifying conditions ranged from 10 to 300 mV. Redox potential values decreased with increasing nitrate reduction rates and increasing organic matter content. Furthermore, a narrow correlation between organic matter and nitrate reduction was observed. Experiments were intended to help interpreting redox potentials generated under in situ conditions as exemplified by in situ observations for the year 1999. Results obtained by experiments and in situ observations showed that monitoring of redox potential could support management of the flooding regime to optimize nitrogen retention by denitrification in future flood retention areas.  相似文献   
938.
Obstructive sleep apnoea syndrome (OSAS) is a breathing disorder with a multifactorial etiology. The respiratory epithelium is lined with a thin layer of airway surface liquid preventing interactions between the airflow and epithelium. The effect of the liquid lining in OSAS pathogenesis remains poorly understood despite clinical research. Previous studies have shown that the physical properties of the airway surface liquid or altered stimulation of the airway mechanoreceptors could alleviate or intensify OSAS; however, these studies do not provide a clear physical interpretation. To study the forces transmitted from the airflow to the liquid-lined compliant wall and to discuss the effects of the airway surface liquid properties on the stimulation of the mechanoreceptors, a novel and simplified experimental system mimicking the upper airway fundamental characteristics (i.e., liquid-lined compliant wall and complex unsteady airflow features) was constructed. The fluctuating force on the compliant wall was reduced through a damping mechanism when the liquid film thickness and/or the viscosity were increased. Conversely, the liquid film damping was reduced when the surface tension decreased. Based on the experimental data, empirical correlations were developed to predict the damping potential of the liquid film. In the future, this will enable us to extend the existing computational fluid–structure interaction simulations of airflow in the human upper airway by incorporating the airway surface liquid effect without adopting two-phase flow interface tracking methods. Furthermore, the experimental system developed in this study could be used to investigate the fundamental principles of the complex once/twice-coupled physical phenomena.  相似文献   
939.
目的:分析A型肉毒毒素与肌电生物反馈联合用于治疗脑卒中后上肢肌痉挛的临床疗效。方法:选择2014年10月至2016年12月辽宁本溪市中心医院和北京博爱医院收治的84例脑卒中后上肢肌痉挛患者,并将其随机分为观察组和对照组,每组42例。两组患者均首先接受常规康复训练,随后对照组加用肌电生物反馈治疗,观察组患者在对照组的基础之上注射A型肉毒毒素。采用改良Ashworth痉挛量表(MAS)比较两组治疗前后的上肢肌痉挛改善情况,采用Fugl-Meyer评定量表评价患者上肢运动功能,采用量角器测量治疗前后患者的腕关节主动活动范围,采用改良的Barthel指数评价患者治疗前后的日常生活能力。结果:治疗后,观察组的上肢痉挛改善总有效率显著高于对照组(P0.05);治疗2周和4周时,两组的Fugl-Meyer评分、腕关节主动活动范围、改良的Barthel指数(MBI)均较治疗前显著升高(P0.05),且观察组治疗后2周和4周的Fugl-Meyer评分、腕关节主动活动范围、改良的Barthel指数(MBI)均显著高于对照组(P0.05)。结论:A型肉毒毒素与肌电生物反馈联合用于治疗脑卒中后上肢肌痉挛的临床疗效显著,可有效降低患者上肢痉挛状态,改善上肢和腕部运动能力,提高患者的日常生活能力。  相似文献   
940.
Galve (Teruel, Spain) is a town in the interior of a synclinal fold with Upper Jurassic marine limestones along its flanks, and, in its core, Upper Jurassic–Lower Cretaceous continental and shoreline sediments crop out. The core sediments cover an area about 8 km2, and contain a concentration of sites with footprints, bones, and eggshells of dinosaurs. The footprints are both shafts and natural casts. Some casts are attributed to stegosaurs (Deltapodus). The Deltapodus casts are characterized by features that allow us to make direct observations on the skin formed by polygonal scales, and ellipsoidal “hooves,” as well as deductions on the movement of the limbs during walking. According to the opinion of some authors, dinosaur footprints are indicators of the motion of their limbs and sometimes of the whole body. So far, results have been deduced from theropod, ornithopod, and sauropod footprints. This article shows the results obtained from analis of the aforementioned Deltapodus casts, i.e., forelimb movement similar to that of the forelimbs of sauropods, and the rigid structure of the autopodial part of the hind limb.  相似文献   
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