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   602篇
  免费   49篇
  国内免费   18篇
耳鼻咽喉   5篇
儿科学   4篇
妇产科学   2篇
基础医学   55篇
口腔科学   42篇
临床医学   61篇
内科学   100篇
皮肤病学   29篇
神经病学   3篇
特种医学   26篇
外科学   53篇
综合类   136篇
预防医学   30篇
眼科学   2篇
药学   76篇
中国医学   39篇
肿瘤学   6篇
  2024年   1篇
  2023年   18篇
  2022年   9篇
  2021年   67篇
  2020年   39篇
  2019年   21篇
  2018年   21篇
  2017年   29篇
  2016年   24篇
  2015年   34篇
  2014年   41篇
  2013年   44篇
  2012年   26篇
  2011年   42篇
  2010年   15篇
  2009年   24篇
  2008年   31篇
  2007年   21篇
  2006年   19篇
  2005年   13篇
  2004年   18篇
  2003年   9篇
  2002年   12篇
  2001年   8篇
  2000年   2篇
  1999年   6篇
  1998年   9篇
  1997年   10篇
  1996年   4篇
  1995年   2篇
  1994年   4篇
  1993年   6篇
  1992年   6篇
  1991年   4篇
  1990年   2篇
  1989年   2篇
  1988年   8篇
  1987年   4篇
  1986年   1篇
  1985年   4篇
  1984年   2篇
  1983年   1篇
  1981年   1篇
  1980年   2篇
  1977年   2篇
  1976年   1篇
排序方式: 共有669条查询结果,搜索用时 15 毫秒
1.
目的 通过临床与实验研究选择合适的皮片游离移植手术包扎材料.方法 实验分别以软质聚氨酯泡沫塑料、层叠干纱布、松散干沙团和干棉花团为测试包扎材料.分别在测试包扎材料上加压,记录血浆袋所受到的压力和包扎材料厚度压缩比例的变化;临床常规方法片皮移植,以软质聚氨酯泡沫塑料块加压包扎皮片.结果 软质聚氨酯泡沫塑料当外加压力使其压缩至原厚度的90%~34%时,可使皮片受到25 cmH2O~54.4 cmH2O的压力;此压力范围足以使皮片与创面密切接触,保证皮片成活,又避免过大的压力影响皮片血供重建.以软质聚氨酯泡沫塑料为包扎材料植皮,皮片成活率明显提高.结论 软质聚氨酯泡沫塑料是一种良好的植皮包装材料.  相似文献   
2.
泡沫分离法用于蜣螂蛋白质分离的研究   总被引:2,自引:1,他引:1       下载免费PDF全文
马家骅  谭承佳  韩丽  张艳艳  李文丽  杨明 《中草药》2009,40(8):1223-1225
目的 优选蜣螂提取液中蛋白质类成分泡沫分离的最佳工艺条件.方法 采用单因素试验法,以富集比、回收率、泡沫液中蛋白的质量分数为评价指标,对影响泡沫分离的几个关键因素进行考察.结果 泡沫分离蜣螂提取液蛋白类成分的较佳工艺为:气流速度600 mL/min,进料液质量浓度为含药材0.050 g/mL,pH4,进料体积1 000 mL,室温;在此条件下,富集比为1.56,回收率为85.6%,泡沫液质量分数为20.37%.结论 采用泡沫分离法浓缩和分离蜣螂蛋白质类成分回收率较高,能提高产品中蛋白质的质量分数,浓缩和分离蜣螂提取液中蛋白类物质有一定的可行性.  相似文献   
3.
考察了各类添加剂在不同浓度、温度及不同基础油中的泡沫倾向,并测定了这些条件下体系的表面张力。从表面化学角度解释了添加剂对泡沫性质的影响,并通过对抗泡剂配伍性能的研究,验证了消泡机制:抗泡剂须具备高的表面活性才能吸附于泡膜表面,降低泡膜的表面粘弹性,改变膜的流变性能,从而起消泡作用。  相似文献   
4.
One of the advantages of polyurethane foam-covered prostheses has been that in the first 5 to 10 years after their use, the amount of capsular contraction was found much less than when similar ``slick' prostheses were used. Another advance was their fixation to the surrounding tissue thus giving a more natural appearance and movement with the muscles when the arms were moved in any direction. The formation of a thick capsule also acted as a protection against gel granuloma due to rupture of the prosthesis and has been thought to be a factor in the lower capsule contraction rate. The greatest disadvantage has been that its removal was extremely difficult and this has continued up until the technique described in this paper has been introduced.  相似文献   
5.
The role of human spumaretrovirus (HSRV) infections in the pathogenesis of multiple sclerosis (MS) was investigated with recombinant HSRV env-specific enzyme-linked immunosorbent assay. The presence of HSRV antibodies was determined in pairs of serum and cerebrospinal fluid (CSF) samples from 60 MS patients. In 7 of these patients serial serum and CSF samples were obtained in relation to the clinical activity of the disease during a period of 2 years. No increased antibody reactivity was demonstrable in the MS population compared with 14 aseptic meningitis patients, 50 blood donors and 16 healthy controls. Slightly elevated levels of antibodies were demonstrable in serum and/or CSF in 4 MS patients but also in 1 patient with aseptic meningitis, 1 blood donor and 1 child. No marked serum or CSF HSRV antibody fluctuation was observed in the MS patients followed longitudinally. Thus, this study does not support the involvement of HSRV in the pathogenesis of MS.  相似文献   
6.
Summary A pathologic study was undertaken of seven encephalic arteriovenous malformations, including five resected from one to seven days after balloon embolization, one resected 10 days after embolization with polyvinyl alcohol foam (PVA), and a large mesencephalic AVM in a patient who died eight weeks after a series of embolization procedures with PVA and silicone spheres. AVM's resected 6–7 days following balloon embolization showed focal mural and adventitial inflammatory infiltrates and parenchymal (i.e. non-vascular) necrosis of a large portion of one AVM. The AVM examined 7 days post-balloon embolization showed an intraluminal thrombus containing refractile particles surrounded by foreign body giant cells (FBGC's). The AVM removed 10 days after PVA embolotherapy showed mural and perivascular necrosis with infiltration by polymorphonuclear leukocytes. The single autopsy case showed FBGC's surrounding residual PVA, refractile particles deep within vascular walls, and marked mural thickening of AVM channel walls, changes that may represent a response to previous angionecrosis and inflammation at the time of embolization. These findings, the pathogenesis of which is discussed in detail, may help to explain some of the rare complications of iatrogenic embolotherapy with these materials, as well as providing evidence for the basis of their efficacy.Presented in part at the 63rd Annual meeting of the American Association of Neuropathologists, Seattle, Washington, June, 1987  相似文献   
7.
In order to investigate the role of monocyte/macrophages and their relationship to the expression of macrophage colony-stimulating factor (MCSF) in pulmonary atherosclerosis, lungs were excised from rabbits that had been fed for 60 and 90 days on a diet containing 0.5% cholesterol. In the lungs, fatty streaks and elevated foam cell lesions predominated in the large or medium-sized elastic pulmonary arteries, while massive accumulation of foam cells in the intima of muscular arteries produced marked luminal narrowing and nearly complete occlusion. In these lesions, most of the foam cells were reactive with RbM2, a monoclonal antibody (mAb) against rabbit macrophages, while smooth muscle cell-derived foam cells were detected by mAb against smooth muscle actin in the deeper area of elevated foam cell lesions of elastic arteries. Ultrastructural observation confirmed the presence of monocytes in the intima, their differentiation into macrophages, and their transformation into foam cells in the atherosclerotic lesions. lmmunohistochemical expression of MCSF was demonstrated in the endothelial cells, smooth muscle cells and foam cells. A minor macrophagederived foam cell population was demonstrated to possess a prolif-erative capacity. These data suggest that MCSF is involved in the differentiation of monocytes into macrophages, their transformation into foam cells, and their proliferation during pulmonary atherogenesis.  相似文献   
8.
目的:探讨肺炎衣原体( Cpn) 促进 C57 B L/6 J 小鼠腹膜巨噬细胞泡沫化的机制。方法:取 C57 B L/6 J小鼠腹膜巨噬细胞培养24 h 让其贴壁后分为对照组、 L D L 组和 L D L 加 Cpn 组3 组培养,然后测反应液中自由基、 M D A 及 S O D 含量。结果:反应液中自由基、 M D A、 S O D 含量 L D L 加 Cpn 组比 L D L 组高,存在显著性差异。结论:脂质过氧化是肺炎衣原体促进巨噬细胞泡沫化的机制之一。  相似文献   
9.
马齿苋抗家兔主动脉泡沫细胞形成机制的探讨   总被引:5,自引:0,他引:5  
目的 探讨马齿苋抗家兔主动脉泡沫细胞形成的作用机制 ,研究影响动脉粥样硬化 (AS)形成的有关因素。方法 动物分为 4组 ,A、B、C 3组建立动物高脂模型 ,B、C组分别喂饲马齿苋干粉 8或 12g/ (d·只 ) ,实验 11周末 ,采血测定血脂、丙二醛、血液粘度等指标并观察透射电镜下主动脉内膜病理改变。用多元逐步回归分析 ,筛选影响AS形成的主要因素。结果 B、C组与A组相比 ,血清总胆固醇 (TC)、甘油三脂 (TG)、丙二醛 (MDA)、全血低切表观粘度、血浆中切表观粘度水平明显下降 (P <0 0 1) ;高密度脂蛋白胆固醇 (HDL -C)明显上升 (P <0 0 1) ,C组TC、全血低切表观粘度数值较B组明显降低 (P <0 0 1)。多元方程显示α =0 0 5,0 0 1时对Y有显著影响的是TC(X1) ,血浆中切表观粘度 (X6 )。结论 马齿苋可明显阻止或降低血清TC、TG、MDA、全血低切及血浆中切表观粘度的升高 ,并升高HDL -C ,随着剂量的增加 ,马齿苋作用增强。电镜观察显示马齿苋能使主动脉内膜泡沫细胞数目减少 ,脂质沉积减轻 ,抑制AS斑块形成。多元分析表明 ,影响主动脉AS形成的主要因素是TC及血浆中切表观粘度 ,二者皆为正向影响 ,且TC影响最大。试验显示 ,马齿苋降低该两项因素的作用最为明显  相似文献   
10.
胆固醇酯蓄积的巨噬细胞(泡沫细胞)是早期动脉粥样硬化斑块的主要组成和特征。它通过其细胞表面的多种受体无限制地摄取氧化型低密度脂蛋白(ox-LDL)颗粒及其他配体,结果在巨噬细胞内有大量的胆固醇酯和三酰甘油蓄积,使巨噬细胞发展成为泡沫细胞。因此,通过各种途径抑制这种在巨噬细胞的过量脂质蓄积,可以起到预防和治疗动脉粥样硬化的作用。  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