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1.
基于有限元法的人类头部损伤生物力学的模拟分析   总被引:4,自引:1,他引:3  
根据正常头部螺旋CT扫描影像,通过对CT扫描影像的图像处理,利用计算机辅助工程技术,采用单元网格划分和三维重构技术,开发、建立了三维的人类头部有限元计算模型。应用本模型模拟颅脑在直接碰撞中的生物力学问题。计算模型比较真实地反映了头颅实际碰撞实验中的物理反应,比较忠实地再现了某些实验的结果,如头部撞击合力和脑压力/强等。同时,脑压力,强的分布再次证实了经典的撞击压-对撞压产生理论。本研究的计算模型可为进一步的头部损伤生物力学研究提供一种新的工具。  相似文献
2.
Examined direct and mediated relations between condition parametersand maternal mental health for 53 mothers of 2- to 11-year-oldchildren with juvenile rheumatoid arthritis (JRA). Multivariateanalyses revealed that when considered simultaneously, indicesof both biological severity and functional severity were associatedsignificantly with maternal mental health. Further, mother'sappraisals of the impact of the child's illness on the familypartially mediated the effects of medication type and child'sfunctional status on mother's mental health. Results providesupport for conceptual models that emphasize the cognitive mechanismsby which condition parameters such as biological and functionalseverity might affect maternal mental health. Explicating theprocesses by which a child's JRA might lead to psychologicaladjustment problems in the parent has implications for developingpreventive and treatment interventions.  相似文献
3.
This state of the art paper has been developed through EuroPrevall, a European multicentre research project funded by the European Union which aims to improve quality of life for food allergic individuals. Food allergy (whether clinically diagnosed or self-perceived) represents a major health issue in Western societies and may have a considerably greater impact on society than was previously believed. However, the social impact of food allergy has never been systematically investigated using validated instruments. Combining the information from studies on health-related quality of life (HRQoL) with epidemiological data on prevalence will ultimately give some indication of the magnitude of the social impact of food allergy in Europe. HRQoL can be assessed with disease-specific questionnaires, which are being developed in EuroPrevall. These instruments will be used to identify HRQoL problems associated with food allergy, and to assess the effectiveness of interventions and to guide the development of regulatory policies.  相似文献
4.
Investigated developmental and gender-related trends in 2nd,5th, and 8th graders', undergraduates', and adults' reactionsto simulated bicycle collisions. Recently, scientists have calledfor exploration of the developmental mechanisms that underliechildhood injury. Our laboratory has, in three separate studies,demonstrated age-related decreases in beliefs about the negativeconsequences of bicycle collision. These developmental decreasesin the expected seriousness of outcome parallel age-relatedincreases in injury risk. The present study examined two alternativeexplanations for cognitive differences that might be relatedto increased risk for bicycle injury with increasing age. Contraryto predictions, however, age and gender were unrelated to subjects'expectations for whether a collision would take place, be activelyavoided, or fail to take place. Similarly, age and gender wereunrelated to whether subjects believed they could remain safe,that safety equipment (e.g., helmets) would keep them safe,or that different behavior would keep them safe. Results failto support these expectations and beliefs as alternative explanationsto developmental and gender-related trends in bicycle injuries,and indirectly suggest the importance of children's beliefs,about the seriousness of injury as a contributer to injury riskbehavior.  相似文献
5.
New developments in the use of citation analysis in research evaluation   总被引:2,自引:0,他引:2  
This paper presents an overview of research assessment methodologies developed in the field of evaluative bibliometrics, a subfield of quantitative science and technology studies, aimed to construct indicators of research performance from a quantitative statistical analysis of scientific-scholarly documents. Citation analysis is one of its key methodologies. The paper illustrates the potentialities and limitations of the use of bibliometric indicators in research assessment. It discusses the relationship between metrics and peer review; databases used as sources of bibliometric analysis; the pros and cons of indicators often applied, including journal impact factors, Hirsch indices, and normalized indicators of citation impact; and approaches to the bibliometric measurement of institutional research performance.  相似文献
6.
AIM—To determine whether, following predictive genetic testing for familial adenomatous polyposis (FAP), children or adults receiving positive results experience clinically significant levels of anxiety or depression, and whether children receiving positive results experience higher levels of anxiety or depression than adults receiving positive results.
DESIGN—Two studies, one cross sectional and one prospective.
SAMPLE—208 unaffected subjects (148 adults and 60 children) at risk for FAP who have undergone genetic testing since 1990.
MAIN MEASURES—Dependent variables: anxiety, depression; independent variables: test results, demographic measures, psychological resources (optimism, self-esteem).
RESULTS—Study 1. In children receiving positive results, mean scores for anxiety and depression were within the normal range. There was a trend for children receiving positive results to be more anxious and depressed than those receiving negative results. In adults, mean scores for anxiety were within the normal range for those receiving negative results, but were in the clinical range for those receiving positive results, with 43% (95% CI 23-65) of the latter having scores in this range. Regardless of test result, adults were more likely to be clinically anxious if they were low in optimism or self-esteem. Children receiving positive or negative results did not experience greater anxiety or depression than adults. Study 2. For children receiving a positive test result, mean scores for anxiety, depression, and self-esteem were unchanged over the year following the result, while mean anxiety scores decreased and self-esteem increased after receipt of a negative test result over the same period of time.
CONCLUSION—Children, as a group, did not show clinically significant distress over the first year following predictive genetic testing. Adults were more likely to be clinically anxious if they received a positive result or were low in optimism or self-esteem, with interacting effects. The association between anxiety, self-esteem, and optimism suggests that counselling should be targeted, not only at those with positive test results, but also at those low in psychological resources.


Keywords: genetic testing; children; familial adenomatous polyposis; emotional impact  相似文献
7.
骨盆垂直不稳定性骨折的生物力学研究   总被引:1,自引:0,他引:1  
目的 利用人体骨盆标本制作骶髂关节骨折脱位模型,研究垂直不稳定性骨盆骨折中骶髂复合体生物力学损伤特点。 方法 成年男性冰冻骨盆标本6具,固定于MTS生物材料试验机上以2 m/s速度进行动态撞击,记录骶髂关节出现完全骨折脱位所需的最大撞击力及响应时间,用步态分析仪的动作捕捉系统测量骶髂复合体中韧带完全破坏时骶髂关节空间三维位移,解剖学方法观察骶髂复合体损伤特点。 结果 成功制备出骶髂关节骨折、脱位损伤模型,单侧骶髂复合体完全损伤所需的撞击力峰值平均值(4.05±0.42)kN,标本响应时间平均值为(22.99±1.89)ms,骶髂关节最大垂直位移平均为(8.15±1.34) mm;骶髂复合体损伤以经骶髂关节骨折并脱位为多,髂腰韧带均表现为连同第四、五腰椎横突骨折,骶髂腹侧韧带相对薄弱易于髂骨止点处撕裂,骶髂后短韧带易发生髂骨侧的撕脱骨折,骶棘韧带骶结节韧带及盆底肌肉损伤不明显。  结论    骨盆垂直不稳定性骨折中骶髂复合体损伤具有一定的规律和特点,当骶髂关节垂直位移超过0.9 cm时提示后方骶髂复合体的韧带结构已全部破坏,骨盆环处于绝对不稳状态。  相似文献
8.
老龄对腰椎松质骨冲击力学特性的影响   总被引:1,自引:0,他引:1  
目的 腰椎松质骨的冲击力学特性对治疗骨质疏松、骨重建、骨再造以及人工关节置换术等具有重要的临床意义,本文对正常国人青年和老年新鲜尸体腰椎松质骨进行冲击试验,通过分析确定老年腰椎松质骨和青年尸体腰椎松质骨是否具有不同的冲击力学特性.方法 死后1h之内解剖取出青年和老年死者腰椎L1-L5标本,并将标本沿纵向切成长30mm、宽5mm、高5mm的试样共40个,按年龄分青年和老年组各20个样本.以能量释放方法对2组样本进行冲击实验,根据试验机显示出的样本承受的冲击功,利用材料力学中的数学公式计算出每个样本的冲击韧性.结果 青年组腰椎松质骨承受的冲击功为(35.92±3.26)N·mm,冲击韧性为(1.44±0.13)N·cm/mm^2;老年组的冲击功为(28.2±2 94)N·mm,冲击韧性为(1.14±0.11)N·cm/mm^2.结论 老年组腰椎松质骨的冲击力学特性因老年性骨质疏松发生一定变化,其冲击力学性能显著降低.  相似文献
9.
Visual guidance of landing behaviour when stepping down to a new level   总被引:1,自引:0,他引:1  
When stepping down from one level to another, the leading limb has to arrest downward momentum of the body and subsequently receive and safely support bodyweight before level walking can begin. Such step downs are performed over a wide range of heights and predicting when and where contact between the landing limb and the lower level will be made is likely a critical factor. To determine if visual feedback obtained after movement initiation is habitually used in guiding landing behaviour, the present study determined whether pre-landing kinematics and the mechanics of landing would be modulated according to the type of visual feedback available during the stepping down phase. Ten healthy participants (32.3 ± 7.9 years) stepped, from a standing position, down from three different heights onto a forceplatform, either coming immediately to rest or proceeding directly to walking across the laboratory. Repeated trials were undertaken under habitual vision conditions or with vision blurred or occluded 2–3 s prior to movement initiation. Pre-landing kinematics were assessed by determining, for the instant of landing, lead-limb knee and ankle angle, stepping distance, forwards positioning of the body CM within the base of support and the forwards and downwards body CM velocity. Landing mechanics for the initial contact period were characterized using lead limb vertical loading and stiffness, and trail limb un-weighting. When vision was occluded movement time, ankle plantarflexion and knee flexion were significantly increased compared to that determined for habitual vision, whereas forwards body CM positioning and velocity, vertical loading and stiffness, and trail limb un-weighting, were significantly reduced (p < 0.05). Similar adaptations were observed under blurred conditions, although to a lesser extent. Most variables were significantly affected by stepping task and step height. Subjects likely reduced forwards CM position and velocity at instant of landing, in order to keep the CM well away from the anterior border of the base of support, presumably to ensure boundary margins of safety were high should landing occur sooner or later than expected. The accompanying increase in ankle plantarflexion at instant of landing, and increase in single limb support time, suggests that subjects tended to probe for the ground with their lead limb under modified vision conditions. They also had more bodyweight on the trail limb at the end of the initial contact period and as a consequence had a prolonged weight transfer time. These findings indicate that under blurred or occluded vision conditions subjects adopted a cautious strategy where by they ‘sat back’ on their trail limb and used their lead limb to probe for the ground. Hence, they did not fully commit to weight transfer until somatosensory feedback from the lead limb confirmed they had safely made contact. The effect of blurring vision was not identical to occluding vision, and led to several important differences between these conditions consistent with the use of impoverished visual information on depth. These findings indicate that online vision is customarily used to regulate landing behaviour when stepping down.
John G. BuckleyEmail:
  相似文献
10.
Biomechanical studies using postmortem human subjects (PMHS) in lateral impact have focused primarily on chest and pelvis injuries, mechanisms, tolerances, and comparison with side impact dummies. A paucity of data exists on the head–neck junction, i.e., forces and moments, and cranial angular accelerations. The objective of this study was to determine lateral impact-induced three-dimensional temporal forces and moments at the head–neck junction and cranial linear and angular accelerations from sled tests using PMHS and compare with responses obtained from an anthropomorphic test device (dummy) designed for lateral impact. Following initial evaluations, PMHS were seated on a sled, restrained using belts, and lateral acceleration was applied. Specimens were instrumented with a pyramid-shaped nine-accelerometer package to record cranial accelerations. A sled accelerometer was used to record the input acceleration. Radiographs and computed tomography scans were obtained to identify pathology. A similar testing protocol was adopted for dummy tests. Results indicated that profiles of forces and moments at the head–neck junction and cranial accelerations were similar between the two models. However, peak forces and moments at the head–neck junction were lower in the dummy than PMHS. Peak cranial linear and angular accelerations were also lower in the dummy than in the PMHS. Fractures to the head–neck complex were not identified in PMHS tests. Peak cranial angular accelerations were suggestive of mild traumatic brain injury with potential for loss of consciousness. Findings from this study with a limited dataset are valuable in establishing response corridors for side impacts and evaluating side impact dummies used in crashworthiness and safety-engineering studies.  相似文献
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