全文获取类型
收费全文 | 1142篇 |
免费 | 92篇 |
国内免费 | 22篇 |
专业分类
儿科学 | 4篇 |
妇产科学 | 4篇 |
基础医学 | 169篇 |
口腔科学 | 190篇 |
临床医学 | 36篇 |
内科学 | 69篇 |
皮肤病学 | 2篇 |
神经病学 | 17篇 |
特种医学 | 18篇 |
外科学 | 441篇 |
综合类 | 124篇 |
预防医学 | 12篇 |
药学 | 93篇 |
中国医学 | 65篇 |
肿瘤学 | 12篇 |
出版年
2023年 | 12篇 |
2022年 | 8篇 |
2021年 | 19篇 |
2020年 | 5篇 |
2019年 | 5篇 |
2018年 | 19篇 |
2017年 | 31篇 |
2016年 | 30篇 |
2015年 | 42篇 |
2014年 | 56篇 |
2013年 | 56篇 |
2012年 | 71篇 |
2011年 | 75篇 |
2010年 | 55篇 |
2009年 | 64篇 |
2008年 | 78篇 |
2007年 | 76篇 |
2006年 | 98篇 |
2005年 | 80篇 |
2004年 | 74篇 |
2003年 | 56篇 |
2002年 | 36篇 |
2001年 | 34篇 |
2000年 | 21篇 |
1999年 | 20篇 |
1998年 | 26篇 |
1997年 | 6篇 |
1996年 | 13篇 |
1995年 | 8篇 |
1994年 | 10篇 |
1993年 | 5篇 |
1992年 | 14篇 |
1991年 | 13篇 |
1990年 | 10篇 |
1989年 | 7篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有1256条查询结果,搜索用时 10 毫秒
41.
目的 探索乳铁蛋白促进大鼠成骨细胞增殖的最佳浓度及1000μg/mL乳铁蛋白对促进成骨细胞分化的最佳时间。方法 用混合酶消化法分离大鼠颅盖骨成骨细胞进行原代培养;不同浓度乳铁蛋白干预成骨细胞,浓度分别为0、0.1、1、10、100、200、400、600、800和1000μg/mL,在1、3、5、7d后分别采用CCK-8法测定细胞增殖;用1000μg/mL的乳铁蛋白干预成骨细胞7、14、21d后,采用碱性磷酸酶染色法检测细胞内碱性磷酸酶的活性。结果 1.CCK-8法测定细胞增殖结果显示,低于100μg/mL浓度乳铁蛋白组其OD值随着浓度的增高而增高,而高于100μg/mL浓度乳铁蛋白组其OD值随着乳铁蛋白浓度的增高而递减;2.碱性磷酸酶染色法结果显示,1000μg/mL的乳铁蛋白在干预第21天时碱性磷酸酶活性最高。结论 100μg/mL乳铁蛋白是促进大鼠成骨细胞增殖的最佳浓度;1000μg/mL的乳铁蛋白促进成骨细胞分化作用呈时间依赖性。 相似文献
42.
目的 探讨α-玉米赤霉醇(α-zearalanol,α-ZAL)对小鼠骨髓间充质干细胞(Bone marrow-derived mesenchymal stem cells, BMSCs)向成骨细胞增殖、分化的影响。方法 采用全骨髓培养差速贴壁法体外分离培养小鼠骨髓间充质干细胞,取第3代细胞分为空白对照组、雌二醇阳性对照组、低浓度α-ZAL组、中浓度α-ZAL组,高浓度α-ZAL组。镜下每天观察细胞形态变化,碱性磷酸酶染色鉴定成骨细胞纯度,MTT实验测定细胞增殖活性绘制细胞生长曲线,采用酶联免疫吸附法(ELISΑ)测定碱性磷酸酶(alkaline phosphatase,ALP)、骨形态发生蛋白2( Bone morphogenetic protein-2,BMP-2),运用蛋白免疫印迹法(Western blotting,WB)检测护钙素(Osteoprotegerin,OPG)和NF-KB受体活化配体(Receptor actiator of nuclear factor-KB ligand, RANKL)的蛋白水平表达变化。结果 不同浓度的α-玉米赤霉醇可显著的促进小鼠骨髓间充质干细胞向成骨细胞增殖、分化,增加细胞活性(P<0.05),明显提高小鼠骨髓间充质干细胞向成骨细胞分化后ALP和BMP-2的表达(P<0.05),并且显著的上调了成骨细胞内OPG/ RANKL的表达率(P<0.05)。结论 不同浓度的α-玉米赤霉醇可以促进骨髓间充质干细胞向成骨细胞增殖、分化,并且通过上调OPG/ RANKL的表达率抑制成骨细胞细胞向破骨细胞分化,有望成为临床骨折疏松症治疗的激素替代药物。 相似文献
43.
目的:评价钛表面纳米管和纳米颗粒形貌对MG63成骨细胞的增殖、分化能力的影响。方法:通过磁控溅射和阳极氧化技术制备纳米颗粒和纳米管形貌。采用扫描电镜和轮廓仪表征材料表面形貌以及粗糙度,并将MG63成骨细胞株与不同形貌的钛材料进行复合培养,检测1d、4d、7d的MTT值及4d、7d的碱性磷酸酶活性。结果:培养1d、4d、7d后,纳米管和纳米颗粒组MTT值高于对照组,7d时,纳米管组MTT值高于纳米颗粒组;培养7d后,纳米形貌实验组碱性磷酸酶活性明显高于对照组。结论:纳米管和纳米颗粒形貌均有利于成骨细胞的增殖和分化。相对于纳米颗粒,表面的纳米管形貌更有利于促进成骨细胞的增殖。 相似文献
44.
成骨细胞与破骨细胞共培养及其应用研究进展 总被引:1,自引:1,他引:0
成骨细胞与破骨细胞并非孤立存在,两种细胞存在直接接触、分泌旁分泌因子、细胞与骨基质3种相互作用.成骨细胞与破骨细胞共培养技术有直接接触式、间接接触式2类方式,它能最大程度地模拟体内微环境,有利于研究两细胞间的相互作用,探讨两者失衡在骨质疏松症等骨代谢疾病形成中的作用;细胞共培养应根据病理状态下两细胞的比例选用种属来源一致的细胞.目前该技术主要用于探讨药物防治骨质疏松症的作用机制,已有淫羊藿、三七、补骨脂、雷奈酸锶等既促进成骨细胞骨形成,又抑制破骨细胞骨吸收活性的双重药理作用研究等报道.成骨细胞与破骨细胞共培养的一个新的应用方向,将是应用于软骨下骨重建功能活动的探讨以及中西药干预骨性关节炎的研究. 相似文献
45.
Colombo JS Satoshi S Okazaki J Crean SJ Sloan AJ Waddington RJ 《Journal of dentistry》2012,40(4):338-346
Objectives
Increasing surface roughness and coating with tricalcium phosphate of titanium and titanium alloy implants has been proposed to provide better rates of osseointegration. However, how these changes in surface topography and chemistry influence the osseointegration process of immediate implants placed in fresh extraction sockets is unclear. This study investigated the influence of three clinically employed implant surfaces on the early bone healing events in vivo.Methods
Machined smooth implants were milled from grade 5 Ti6Al4V titanium. Surfaces were moderately roughened by grit blasting, which were then coated with tricalcium phosphate. Implants were placed into freshly extracted incisor sockets of mandibles of normal Wistar rats and left for 1, 3 and 9 weeks. Healing bone tissue around the implants was examined by histochemistry and immunocytochemistry to localise PCNA proliferative cells, and osteoblast differentiation markers osteopontin and osteocalcin. Positive synthesising cells were counted using image analysis.Results
Histology indicated no differences in the amount or pattern of bone formation within the healing tissue surrounding the different implant surfaces. Bone healing occurred predominantly on exposed bone surfaces (distance osteogenesis) and not on the implant surface (contact osteogenesis). No differences were observed in the number or timing of PCNA, osteopontin and osteocalcin positive cells within the bone healing tissue around each of the implant analysed.Conclusion
For immediately placed implants, the surface modifications investigated appeared to have little influence on the activity of bone forming cells surrounding the implant, probably due to the high level of distance osteogenesis seen within this scenario.Clinical significance
For immediate placement of implants into fresh extraction sockets, titanium implants with roughened surfaces and coating with tricalcium phosphate have negligible influence in accelerating the early bone healing events of osseointegration. 相似文献46.
47.
选择32例骨母细胞性肿瘤,包括14例良性骨母细胞瘤、2例侵袭性骨母细胞瘤和16例骨母细胞型骨肉瘤,用ABC法作多种抗血清标记(vimentin、S-100、α-AT、lysozyme、Leu-7、K12和CEA)。结果显示:32例肿瘤性骨母细胞vimentin均呈不同程度的阳性反应;在6例骨母细胞型骨肉瘤和1例侵袭性骨母细胞瘤中散在的单个细胞S-100蛋白呈阳性反应,表明肿瘤性的骨母细胞具有软骨分化的潜能124例肿瘤中的多核巨细胞α-AT和15例肿瘤中的多核巨细胞lysozyme均呈不同程度的阳性反应,进一步证实这些细胞可能是组织细胞起源;6例骨母细胞型骨肉瘤和4例良性骨母细胞瘤中的骨样基质Leu-7呈阳性反应。 相似文献
48.
Kangchu Li Shirong Ma Yurong Li Guirong Ding Zenghui Teng Junye Liu Dongqing Ren Yao Guo Lei Ma Guozhen Guo 《Archives of oral biology》2014
Objective
Pulsed electromagnetic fields (PEMFs) were considered to be a factor which may affect osteogenesis of osteoblasts, but the effects were diverse with different PEMF parameters. The aim of the current study is to explore the effects of exposure to PEMFs at different pulse number on osteogenesis of osteoblasts.Design
The mouse osteoblast-like MC3T3-E1 cells were exposed to 0, 400 or 2800 pulses 400 kV/m PEMF and the proliferation, differentiation and mineralization of cells were observed after PEMF exposure by the methods of MTT, biochemical measurement, real-time PCR and Alizarin Red assay.Results
Compared with 0 pulses groups, the growth curve, alkaline phosphatase (ALP) activity, mRNA level of osteocalcin (OCN) and mineralized nodule formation of MC3T3-E1 cells did not change after 400 pulses PEMF exposure, but decreased after 2800 pulses PEMF exposure. It suggested that under our experimental conditions, only 2800 pulses 400 kV/m PEMF exposure can suppress the proliferation, differentiation and mineralization of MC3T3-E1 cells, but 400 pulses 400 kV/m PEMF exposure cannot.Conclusions
Pulse number is another involved parameter which may influence the effects of PEMF on osteogenesis of osteoblasts. 相似文献49.
《Pediatric Dental Journal》2014,24(2):83-88
Background and objectiveAlveolar bone defects in aggressive periodontitis are generally caused by Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) through osteoclast differentiation facilitated by the interaction between the host's immune system, stimulated by the bacterial outer components of A. actinomycetemcomitans, and osteoblasts. Recently, some reports on the direct effects of A. actinomycetemcomitans on osteoblast differentiation have been published. However, the mechanisms in detail have still remained unknown. We herein demonstrated that A. actinomycetemcomitans might inhibit differentiation of osteoblasts and identified a causative substance.Materials and methodsThe following culture supernatants of A. actinomycetemcomitans were added to mouse osteoblasts, MC3T3-E1: supernatants fractionated by the molecular weight, supernatant supplemented with proteinase K and then heated, and supernatant supplemented with polymyxin B. Subsequently, RNA was extracted to determine the expressions of bone differentiation markers, alkaline phosphatase (ALP), osteocalcin (OCN), and bone sialoprotein (BSP). Additionally, lipopolysaccharide (LPS) was added to MC3T3-E1 culture to measure the markers.ResultsA. actinomycetemcomitans culture supernatant, added to the MC3T3-E1, inhibited the expressions of bone differentiation markers at all concentrations. Only the fraction with a molecular weight of >100 kDa inhibited the bone differentiation. Neither proteinase K nor heating had an effect. However, polymyxin B completely abrogated the differentiation inhibitory activity. A. actinomycetemcomitans LPS concentration dependently inhibited the expressions of the bone differentiation markers.ConclusionsA. actinomycetemcomitans LPS suppressed osteoblast differentiation. This suggests that suppressed bone differentiation is involved in the alveolar bone destruction. 相似文献
50.
目的探讨bFGF-明胶海绵复合物作为骨组织工程支架的可行性,为进一步的体内实验提供基础研究。方法取第二代培养的成骨细胞分别与bFGF-明胶海绵复合物及明胶海绵复合培养,进行一般与超微形态学观察,观察细胞生长情况并做成骨细胞碱性磷酸酶(ALP)及微量蛋白含量的测定,比较细胞的粘附能力、增殖活力及成骨活性。结果bFGF-明胶海绵复合物、明胶海绵均可与成骨细胞复合生长,前者的细胞粘附能力、增殖活力及成骨活性均明显优于后者。结论bFGF-明胶海绵复合物能较好的发挥bF- GF作为信号因子的作用,并能提高明胶海绵的相容性,是构建组织工程骨的一种理想的支架材材。 相似文献