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1.
三面固定槽形加压钢板内固定后股骨表面再造模拟   总被引:5,自引:5,他引:12  
采用骨再造理论和有限元相结合的方法,用计算机模拟钢板植入后骨的现地造行为,从而定量的分析了钢板对骨的应力遮挡效应。骨再造理论采用Cowin应变适应性弹性理论,有限单元采用狼节点六面全的等参数单元。  相似文献
2.
妇女骨质疏松过程及运动防治模拟   总被引:2,自引:0,他引:2  
应用带有力学调控系统的各向异性骨再造模型结合有限元法,进行妇女骨质疏松过程及运动防治的模拟。研究结果表明:在骨量下降初始阶段,下降平缓,绝经后骨量丢失加速,60岁时,骨量下降25.84%~28.63%,80岁时,骨量下降38.50%~40.44%,运动使外荷提高10%~20%后,可使骨量增加3.05%~10.26%,上述结果与临床观察结果基本一致。证明了肌力下降是妇女骨质疏松的主要因素,绝经则加快了妇女骨质疏松的过程。运动可减缓骨质疏松。  相似文献
3.
Osteosclerotic metastases account for 20% of breast cancer metastases with the remainder osteolytic or mixed. In mouse models, osteolytic metastases are dependent on bone resorption for their growth. However, whether the growth of osteosclerotic bone metastases depends on osteoclast or osteoblast actions is uncertain. In this study, we investigate the effects of high and low bone resorption on tumour growth in a mouse model of osteosclerotic metastasis. We implanted human breast cancer, MCF-7, cells into the tibiae of mice. Low and high levels of bone resorption were induced by osteoprotegerin (OPG) treatment or calcium deficient diet respectively. We demonstrate that OPG treatment significantly reduces tumour area compared to vehicle (0.42 +/- 0.06 vs. 1.27 +/- 0.16 mm2, P < 0.01) in association with complete inhibition of osteoclast differentiation. In contrast, low calcium diet increases tumour area compared to normal diet (0.90 +/- 0.30 vs. 0.58 +/- 0.20 mm2, P < 0.05) in association with increased osteoclast numbers (84.44 +/- 5.18 vs. 71.11 +/- 3.56 per mm2 bone lesion area, P < 0.05). Osteoblast surfaces and new woven bone formation were similarly increased within the tumour boundaries in all treatment groups. Tumour growth in this model of osteosclerotic metastasis is dependent on ongoing bone resorption, as has been observed in osteolytic models. Bone resorption, rather than bone formation, apparently mediates this effect as osteoblast surfaces in the tumour mass were unchanged by treatments. Treatment of breast cancer patients through correction of calcium deficiency and/or with anti-resorptive agents such as OPG, may improve patient outcomes in the adjuvant as well as palliative settings.  相似文献
4.
Advances in bone biology and new treatments for bone loss   总被引:1,自引:0,他引:1  
Gallagher JC 《Maturitas》2008,60(1):65-69
Recent advances in bone biology have led to a more detailed understanding of bone remodeling which is a process that leads to resorption of old bone and replacement by formation of new bone. The most important discoveries in this process of bone remodeling were those of the RANK Ligand/RANK/OPG system which is now recognized the dominant pathway regulating bone resorption. RANK Ligand (RANKL) is a cytokine belonging to the tumor necrosis factor family and is expressed by osteoblasts; it binds to membrane bound receptor RANK on osteoclasts and promotes differentiation of marrow cells through various stages to multinucleated osteoclasts which resorb bone. Several hormones such as parathyroid hormone, calcitriol and prostaglandins stimulate RANK Ligand expression by osteoblasts. Osteoblasts also secrete osteoprotegerin (OPG) which is a soluble receptor that is a potent antagonist of osteoclast formation by binding and inactivating RANKL and OPG is therefore an important regulator of bone resorption. OPG is stimulated by estrogen. OPG has been genetically engineered and in human subjects is a potent inhibitor of bone resorption. Another method for preventing bone resorption is to develope antibodies against RANKL and this has been shown to be a successful strategy. A single subcutaneous injection of this antibody (Denosumab) every 6 months proved to be a potent inhibitor of bone resorption and clinical fracture trials using this agent are now underway. These are novel developments that have risen from basic research in bone biology and other discoveries in the bone remodeling process can be expected to lead to further treatment options for various bone diseases.  相似文献
5.
正畸牙移动细胞生物力学研究进展   总被引:1,自引:0,他引:1       下载免费PDF全文
近年来,正畸牙移动细胞生物力学领域的研究蓬勃发展。牙周膜在正畸牙移动中的核心地位被广泛认识和接受。以牙周膜细胞为核心,包括骨髓基质干细胞、成骨细胞、成牙骨质细胞、成肌细胞等的体外研究成为揭示正畸牙移动生物学机制的重要手段。体外研究模型从通过基底形变、重物、液压、离心等方式对二维培养细胞进行应力加载的传统方式,发展到建立各种对细胞进行三维培养和应力加载的新型模型。骨改建循环中以成骨分化和破骨生成诱导为主的相关分子表达成为研究的热点。此外,牙周膜干细胞的细胞力学研究也是极具前景的崭新方向。  相似文献
6.
目的 应用有限元方法研究不同加载强度和偏轴角对股骨头内松质骨空间分布和力学性能变化的影响。方法 基于断层磨削后扫描、计算机三维重建的方法建立得到股骨近端骨结构三维模型,按照与主压力小梁方向成0°、15°、45°分别选取相同大小的松质骨试件。计算试件的三维空间结构参数,应用有限元分析方法模拟单轴压缩试验,观察松质骨试件应力、应变分布,探讨不同加载强度和离轴角度对松质骨生物力学性质的影响。结果 基于建立的人股骨头内松质骨三维有限元模型,模拟了松质骨试件单轴压缩试验,发现不同加载强度和偏轴角度在松质骨试件中≥5 000 με(微应变)的松质骨比例存在统计学差异(P<0.05)。结论 股骨头内松质骨小梁空间分布与力学适应性密切相关。结构与功能的不相适应降低了股骨头内部松质骨的生物力学性能,反复不良刺激引起的骨重塑、改建可能在股骨头坏死中起着重要的作用。  相似文献
7.
Zusammenfassung In einer Langzeitstudie wurde mit quantitativen histologischen Methoden die Wirkung von Calcitonin an der Spongiosa und Corticalis der Ratte untersucht. Neben den Veränderungen des Serumcalciums wurden Art und Ausmaß der Hemmwirkung auf die Knochenresorption, sowie die Beeinflussung der Knochenneubildung und der Knochenmineralisation durch das Hormon beurteilt.In Übereinstimmung mit den bisherigen Ergebnissen anderer Autoren wird die Knochenresorption bei sonst unbehandelten Ratten durch Calcitonin gehemmt. Diese Hemmung ist jedoch nicht durch eine Reduktion der Osteoklastenzahl, sondern durch eine Verminderung der zellulären Resorptionsleistung bedingt. Unter den gewählten Bedingungen beeinflußt Calcitonin nicht die Matrixsynthese der Osteoblasten. Calcitonin fördert aber die Mineralisationsleistung der Osteoblasten bei parathyreoidektomierten Ratten, bei denen eine erhebliche Mineralisationsstörung ausgebildet ist. Als Ursache für die verbesserte Mineralisation wird eine direkte hormonale Beeinflussung des Mineraltransportes im Osteoblasten angenommen.
The effect of long-term calcitonin administration on bone cells and bone mineralization in the rat
Summary The effect of calcitonin on bone tissue was studied in rat cortical and trabecular bone after long-term treatment. The aim of this study was to get exact data on calcitonin action on bone tissue by histomorphometry.Histomorphometric analysis of bone alterations was performed using undecalcified longitudinal as well as grounded cross sections of the tibial metaphysis and diaphysis.In agreement with other authors our experimental results show that calcitonin inhibits bone resorption. This inhibitory effect is not caused by a reduction of the number of osteoclasts but by a reduced cellular resorption activity of osteoclasts. Bone formation is not affected by calcitonin in intact as well as in parathyroidectomized animals. On the contrary bone mineralization is clearly improved under calcitonin administration in parathyroidectomized rats. This favourable effect is probably caused by a direct hormonal influence on calcium transport in the osteoblast.
Mit Unterstützung der Deutschen Forschungsgemeinschaft SFB 34-Endokrinologie, Hamburg.  相似文献
8.
The cellular relationship between the substantia spongiosa of bone (cancellous or trabecular bone) and the haematopoietic bone marrow in the femoral metaphysis of C57BL/6NJCL mice was studied by transmission electron microscopy (TEM). Special attention was directed to intercellular junctions between osteocytes, osteoblasts, and bone marrow reticular cells. These were gap junctions and adhesive devices of simple architecture referred to as primitive junctions or zonula adherens-like junctions. Gap junctions were observed between osteocytes (within the trabeculae) and osteoblasts (at the trabecular surface) and between osteoblasts and marrow reticular cells. Gap junctions were also observed between the same cell type within each of these categories. These junctions involved the plasmalemmal membranes of adjacent cell bodies and of processes. Primitive cell junctions had a similar cellular distribution. Quantitative analysis of the cell types covering or positioned around the trabecular bones and of gap junctions between these and other cells was carried out by TEM. It was found that osteoblasts were the most numerous cell type, occupying 31% of the total of each cell type positively identified around the trabeculae (31%), while pre-osteoblasts, (flattened bone marrow reticular cells) took up 26%. These data emphasise the intimate relationship of the various mesenchymal cells based on processes and intercellular junctions, and point to an anatomical and probably functional integration of trabeculae and marrow. The functional significance and putative regulatory activity of this unit are discussed.  相似文献
9.
骨重建是指骨骼成熟后。在人的一生中仍存在骨的不断更新和改造,这个过程包括骨吸收,骨形成和和静止期。影响骨重建的因素有多种,本文只涉及力学环境,对应力影响骨重建作一理论性阐述。  相似文献
10.
Remodelling of bone occurs in response to physical stress. Habitual squatting is associated with modifications of the neck of the talus (squatting facets) and its trochlear/malleolar surfaces (trochlear extensions), and individual populations exhibit different incidences of these modifications that reflect their lifestyle. The occurrence of talar modifications was therefore investigated in a population of late Byzantine (13th century AD) adult male skeletons. Lateral squatting facets occurred most frequently (37.7%), but medial (0.6%), combined (0.6%) and continuous (gutter-like) facets (0.6%) were also observed. Lateral (8.0%), medial (10.9%) and continuous (lateral/central/medial) extensions (4.6%) of the trochlear surface were all present in the late Byzantine population. There was no evidence of side dimorphism. The occurrence of lateral squatting facets in the late Byzantine population was greater than that reported for modern Europeans, but similar to that reported for some populations of modern Indians. The frequency of occurrence of trochlear extensions in the late Byzantine population was substantially less than in modern Indian populations, but similar to modern Europeans. Therefore, it is unlikely that precisely the same factors determine the expression of squatting facets and trochlear extensions.  相似文献
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