首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3710篇
  免费   357篇
  国内免费   108篇
  2024年   12篇
  2023年   59篇
  2022年   76篇
  2021年   177篇
  2020年   162篇
  2019年   242篇
  2018年   214篇
  2017年   136篇
  2016年   89篇
  2015年   147篇
  2014年   271篇
  2013年   363篇
  2012年   166篇
  2011年   187篇
  2010年   165篇
  2009年   141篇
  2008年   162篇
  2007年   165篇
  2006年   144篇
  2005年   126篇
  2004年   103篇
  2003年   100篇
  2002年   99篇
  2001年   81篇
  2000年   52篇
  1999年   55篇
  1998年   47篇
  1997年   53篇
  1996年   39篇
  1995年   28篇
  1994年   56篇
  1993年   31篇
  1992年   28篇
  1991年   27篇
  1990年   9篇
  1989年   12篇
  1988年   14篇
  1987年   12篇
  1986年   14篇
  1985年   22篇
  1984年   21篇
  1983年   11篇
  1982年   9篇
  1981年   4篇
  1980年   8篇
  1979年   8篇
  1978年   7篇
  1976年   6篇
  1975年   4篇
  1974年   4篇
排序方式: 共有4175条查询结果,搜索用时 15 毫秒
131.
132.
The objective of the present study was to systematically explore the effects of 32K Da protein (32KP) on postmenopausal osteoporosis. Eighty 3-mo-old female Sprague-Dawley rats were employed and randomly divided into one sham-operated group (SHAM) and five ovariectomy (OVX) subgroups as OVX (control), OVX with 17-ethinylestradiol (E2, 25 g/kg/day), OVX with 32KP of graded doses (50, 50, or 150 mg/kg/day). 32KP or E2 diet was fed on week 4 after operation, for 16 weeks. Bone mass, bone turnover and strength were evaluated by dual-energy X-ray absorptiometry (DEXA), biochemical markers and three-point bending test, respectively. Femur marrow cavity was observed by light microscopy via hematoxylin-eosin staining. It is observed that different dosage treatment of 32KP increased the body weight and prevented the loss of bone mass induced by OVX. The prevention effect against bone loss was presumably due to the altering of the rate of bone remodeling. The bone mineral density and bone calcium content in OVX rats were lower than that in the control group, suggesting that 32KP was able to prevent significant bone loss. In addition, the data from three point bending test and femur sections showed that 32KP treatment enhanced bone strength and reduced the marrow cavity of the femur in OVX rats. In the serum and urine assay, 32KP decreased urinary deoxypyridinoline and calcium concentrations; however, serum alkaline phosphatase activities were not inhibited. It suggested that amelioration of bone loss was changed via inhibition of bone reabsorption. Our findings indicated that 32KP might be a potential alternative drug for the prevention and treatment of postmenopausal osteoporosis.  相似文献   
133.
134.
The treatment of osteochondral articular defects has been challenging physicians for many years. The better understanding of interactions of articular cartilage and subchondral bone in recent years led to increased attention to restoration of the entire osteochondral unit. In comparison to chondral lesions the regeneration of osteochondral defects is much more complex and a far greater surgical and therapeutic challenge. The damaged tissue does not only include the superficial cartilage layer but also the subchondral bone. For deep, osteochondral damage, as it occurs for example with osteochondrosis dissecans, the full thickness of the defect needs to be replaced to restore the joint surface 1. Eligible therapeutic procedures have to consider these two different tissues with their different intrinsic healing potential 2. In the last decades, several surgical treatment options have emerged and have already been clinically established 3-6.Autologous or allogeneic osteochondral transplants consist of articular cartilage and subchondral bone and allow the replacement of the entire osteochondral unit. The defects are filled with cylindrical osteochondral grafts that aim to provide a congruent hyaline cartilage covered surface 3,7,8. Disadvantages are the limited amount of available grafts, donor site morbidity (for autologous transplants) and the incongruence of the surface; thereby the application of this method is especially limited for large defects.New approaches in the field of tissue engineering opened up promising possibilities for regenerative osteochondral therapy. The implantation of autologous chondrocytes marked the first cell based biological approach for the treatment of full-thickness cartilage lesions and is now worldwide established with good clinical results even 10 to 20 years after implantation 9,10. However, to date, this technique is not suitable for the treatment of all types of lesions such as deep defects involving the subchondral bone 11.The sandwich-technique combines bone grafting with current approaches in Tissue Engineering 5,6. This combination seems to be able to overcome the limitations seen in osteochondral grafts alone. After autologous bone grafting to the subchondral defect area, a membrane seeded with autologous chondrocytes is sutured above and facilitates to match the topology of the graft with the injured site. Of course, the previous bone reconstruction needs additional surgical time and often even an additional surgery. Moreover, to date, long-term data is missing 12.Tissue Engineering without additional bone grafting aims to restore the complex structure and properties of native articular cartilage by chondrogenic and osteogenic potential of the transplanted cells. However, again, it is usually only the cartilage tissue that is more or less regenerated. Additional osteochondral damage needs a specific further treatment. In order to achieve a regeneration of the multilayered structure of osteochondral defects, three-dimensional tissue engineered products seeded with autologous/allogeneic cells might provide a good regeneration capacity 11.Beside autologous chondrocytes, mesenchymal stem cells (MSC) seem to be an attractive alternative for the development of a full-thickness cartilage tissue. In numerous preclinical in vitro and in vivo studies, mesenchymal stem cells have displayed excellent tissue regeneration potential 13,14. The important advantage of mesenchymal stem cells especially for the treatment of osteochondral defects is that they have the capacity to differentiate in osteocytes as well as chondrocytes. Therefore, they potentially allow a multilayered regeneration of the defect.In recent years, several scaffolds with osteochondral regenerative potential have therefore been developed and evaluated with promising preliminary results 1,15-18. Furthermore, fibrin glue as a cell carrier became one of the preferred techniques in experimental cartilage repair and has already successfully been used in several animal studies 19-21 and even first human trials 22.The following protocol will demonstrate an experimental technique for isolating mesenchymal stem cells from a rabbit''s bone marrow, for subsequent proliferation in cell culture and for preparing a standardized in vitro-model for fibrin-cell-clots. Finally, a technique for the implantation of pre-established fibrin-cell-clots into artificial osteochondral defects of the rabbit''s knee joint will be described.  相似文献   
135.
目的:对闭孔沟进行解剖学观察和测量,为相关应用提供临床解剖学依据和丰富人类学数据。方法:选取结构完整、解剖标志清晰的髋骨108例,其中男性髋骨59例(左侧36例,右侧23例),女性髋骨49例(其中左侧20例,右侧29例),对闭孔沟进行观察并测量其长度和闭孔沟中点宽度。结果:试验测得男性左、右侧闭孔沟长度分别为31.4±3.4mm、32.1±2.4min,女性左、右侧闭孔沟长度分别为19.4±2.2mm、20.8±2.7mm;统计学分析显示同性别左、右侧差异无统计学意义(P〉0.05),男、女性之间差异有统计学意义(P〈0.05)。男性左、右侧闭孔沟中点宽度分别为9.7±1.6mm、10.7±1.5mm,女性左、右侧闭孔沟中点宽度分别为12.1±1.7mm、11.6±2.0mm;同性别左、右侧及男、女间差异均无统计学意义(P〉0.05)。结论:男、女性闭孔沟测量数据可为闭孔处疾病的诊断和治疗提供应用解剖学的考虑依据并丰富人类学数据。  相似文献   
136.
Multiple myeloma (MM) comprises 1% of all malignancies and 10% of all hematological malignancies. MM is a malignancy of plasma cells in the bone marrow where complex and dynamic interactions with the bone marrow microenvironment lead to tumor progression, skeletal destruction and angiogenesis. Despite the discovery of several novel treatments against MM, including the proteasome inhibitor bortezomib, it is considered to be an incurable disease with an average 4–5 years overall survival.  相似文献   
137.
We have identified in plasma cells a novel ATG5-dependent selective negative control on the secretory pathway, which restricts antibody production, sustaining energy metabolism. Revealing new immune functions, autophagy is required in vivo for antibody responses and to maintain the memory plasma cell compartment.  相似文献   
138.
139.
140.
Some human observational studies have suggested an anti-inflammatory role of osteocalcin (OCN). An inflammatory protocol using interferon-γ and tumor necrosis factor-α (10 ng/ml) was employed to examine the acute (24 hr) and chronic (144 hr) effects of uncarboxylated OCN (ucOCN) in commercial, primary, subcultured human aortic endothelial cells (HAEC), and human smooth muscle cells (HASMCs). The inflammatory protocol increased phosphorylation of intracellular signaling proteins (CREB, JNK, p38, ERK, AKT, STAT3, STAT5) and increased secretion of adhesion markers (vascular cell adhesion molecule-1, intracellular adhesion molecule-1, monocyte chemoattractant protein-1) and proinflammatory cytokines (interleukin-6 [IL-6], IL-8). After acute inflammation, there were no additive or reductive effects of ucOCN in either cell type. Following chronic inflammation, ucOCN did not affect cell responses, nor did it appear to have any pro- or anti-inflammatory effects when administered acutely or chronically on its own in either cell type. Additionally, ucOCN did not affect lipopolysaccharide (LPS)-induced acute inflammation in HAECs or HASMCs. The findings of this study do not support a causal role for OCN within the models of vascular inflammation chosen. Further confirmatory studies are warranted.  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