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   65509篇
  免费   5967篇
  国内免费   4895篇
耳鼻咽喉   639篇
儿科学   701篇
妇产科学   618篇
基础医学   7756篇
口腔科学   1114篇
临床医学   8622篇
内科学   9754篇
皮肤病学   600篇
神经病学   3593篇
特种医学   2525篇
外国民族医学   34篇
外科学   6894篇
综合类   11130篇
现状与发展   16篇
一般理论   1篇
预防医学   4478篇
眼科学   1881篇
药学   6849篇
  54篇
中国医学   3335篇
肿瘤学   5777篇
  2024年   211篇
  2023年   1080篇
  2022年   2728篇
  2021年   3415篇
  2020年   2515篇
  2019年   2175篇
  2018年   2311篇
  2017年   2039篇
  2016年   1946篇
  2015年   3100篇
  2014年   3723篇
  2013年   3160篇
  2012年   4957篇
  2011年   5475篇
  2010年   3524篇
  2009年   2589篇
  2008年   3295篇
  2007年   3448篇
  2006年   3351篇
  2005年   3465篇
  2004年   2208篇
  2003年   2102篇
  2002年   1759篇
  2001年   1399篇
  2000年   1576篇
  1999年   1617篇
  1998年   1079篇
  1997年   1010篇
  1996年   759篇
  1995年   707篇
  1994年   675篇
  1993年   394篇
  1992年   473篇
  1991年   426篇
  1990年   365篇
  1989年   312篇
  1988年   232篇
  1987年   227篇
  1986年   170篇
  1985年   114篇
  1984年   66篇
  1983年   59篇
  1982年   43篇
  1981年   31篇
  1980年   14篇
  1979年   23篇
  1978年   4篇
  1977年   3篇
  1975年   4篇
  1973年   8篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
目的:探讨波及黄斑区的孔源性视网膜脱离(RRD)行巩膜扣带手术前后黄斑区三维光学相干断层扫描图像(3D-OCT)特征,分析其与视力的相关性。方法:回顾性系列病例,30例30眼波及黄斑区的RRD行巩膜扣带术治疗的临床资料,在术后2d,2wk,1、3、6mo随诊时双眼均行3D-OCT检查,观察椭圆体带(EZ)、外界膜(ELM)、黄斑区视网膜下液高度(SRFH)、黄斑中心凹视网膜厚度(CRT)的变化,分析其与术后最佳矫正视力(BCVA)的关系。结果:术前,术后2d,2wk,1、3、6mo SRFH、CRT、BCVA均有差异(P<0.01),术后SRFH、CRT都有不同程度降低,术后BCVA都有不同程度升高,组内两两对比:除SRFH(2wk vs 1mo,P>0.05)、CRT(2d vs 2wk,P>0.05)、BCVA(2d vs术前,2wk vs术前,P>0.05)无统计学意义外,其余各项间的比较均有统计学意义(P<0.05)。EZ、ELM形态可分为:A:EZ和ELM均连续(EZ+ELM+),9眼;B:EZ断裂和ELM连续(EZ-ELM+),7眼;C:EZ连续和ELM断裂:EZ+ELM-,6眼;D:EZ和ELM均断裂(EZ-ELM-),8眼,术后6mo上述4种类型的BCVA分别为0.15±0.04、0.50±0.06、0.54±0.05、0.59±0.09(F=87.210,P<0.05),两两比较:除C vs B和C vs D差异无统计学意义(P>0.05)外,其余各组间的比较差异均有统计学意义(P<0.05)。术后2d的SRF发生率为87%,术后6mo仍有46.6%患者存在持续性SRF。术后CRT与术后SRFH具有正相关关系。结论:巩膜扣带术后黄斑微结构呈动态改变,SRF影响可能表现为BCVA延迟恢复,随着SRF缓慢吸收,CRT逐渐降低,BCVA逐渐升高;ELM或EZ连续提示有较好的BCVA,而ELM断裂可能提示视觉质量更差。  相似文献   
993.
蒋伟鹏  卢珊珊  金益 《国际眼科杂志》2015,15(10):1763-1765
目的:探讨视网膜激光光凝术联合雷珠单抗(ranibizumab)治疗新生血管青光眼(neovascular glaucoma, NVG)对视功能的改善及不良反应,为临床治疗提供依据。

方法:选择本院2012-01/2014-06 NVG患者100例129眼,随机分为观察组和对照组,对照组50例67眼,应用视网膜激光光凝术治疗; 观察组50例62眼,应用视网膜激光光凝术联合雷珠单抗进行治疗。评估治疗后虹膜新生血管消退情况、视力恢复、眼压及眼底状况,评估患者不良反应。并应用光学相干断层扫描(OCT)检测视网膜神经纤维层(retinal nerve fiber layer,RNFL)厚度及视野缺损值。

结果:观察组患者虹膜新生血管消失率为95.2%(59/62),高于对照组83.6%(56/67); 观察组视力4.3~4.7为62.9%(39/62),高于对照组49.3%(33/67),观察组视力≤4.3为25.8%(16/62),低于对照组43.3%(29/67)(P<0.05); 观察组治疗后视网膜静脉循环时间和眼压分别为8.20±0.41s和18.50±0.48mmHg,低于对照组9.42±0.30s和23.94±0.52mmHg(P<0.05); 观察组虹膜新生血管消退时间6.19±0.27d,低于对照组8.37±0.31d(P<0.05); 观察组治疗后RNFL厚度为91.12±2.05μm,高于对照组治疗后85.06±2.19μm,观察组治疗后视野缺损值为13.44±0.59dB,低于对照组治疗后15.92±0.56dB(P<0.05)。两组患者不良反应结果比较,差异无统计学意义(P>0.05)。

结论:视网膜激光光凝术联合雷珠单抗治疗NVG具有较好的临床疗效,能够显著改善患者视力及视网膜结构和功能,具有较高的安全性。  相似文献   

994.
庆大霉素玻璃体腔注射对兔视网膜血管的影响   总被引:2,自引:0,他引:2  
目的:通过观察不同浓度庆大霉素对青紫蓝兔视网膜及血管的损伤探讨其作用机制,为研究视网膜血管性疾病尤其是视网膜血管炎提供新的思路和方法。方法:将100,500,1000以及3000μg庆大霉素注入青紫蓝兔玻璃体腔,观察不同时间兔眼眼底彩照、眼底荧光血管造影、视网膜血管消化铺片、光镜及电镜、免疫组织化学检测细胞间黏附分子-1含量的变化。结果:青紫蓝兔眼底出现不同程度视网膜血管栓塞、出血,出血面积与时间及剂量相关(P=0.048<0.05);荧光血管造影显示视网膜大面积无灌注,视网膜血管部分管壁着染及荧光素渗漏;光学显微镜观察视网膜血管炎性细胞浸润和视网膜色素上皮细胞排列紊乱出现最早,炎性细胞数量与剂量相关(P=0.004<0.01,P=0.007<0.01);透射电镜下视网膜色素上皮细胞线粒体肿胀、嵴断裂最早出现;免疫组织化学检测细胞间黏附分子-1的表达也略有变化。结论:庆大霉素对青紫蓝兔玻璃体腔注射后视网膜的损伤主要表现为急性栓塞出血,视网膜色素上皮细胞最先受累,线粒体损伤最为敏感。视网膜血管的变化机制为白细胞栓塞,节段状血管阻塞和出血、白细胞聚集和渗漏。  相似文献   
995.
AIM: To characterize spectral-domain optical coherence tomography (SD-OCT) features of chorioretinal folds in orbital mass imaged using enhanced depth imaging (EDI). METHODS: Prospective observational case-control study was conducted in 20 eyes of 20 patients, the uninvolved eye served as a control. All the patients underwent clinical fundus photography, computed tomography, EDI SD-OCT imaging before and after surgery. Two patients with cavernous hemangiomas underwent intratumoral injection of bleomycin A5; the remaining patients underwent tumor excision. Patients were followed 1 to 14mo following surgery (average follow up, 5.8mo). RESULTS: Visual acuity prior to surgery ranged from 20/20 to 20/200. Following surgery, 5 patients’ visual acuity remained unchanged while the remaining 15 patients had a mean letter improvement of 10 (range 4 to 26 letters). Photoreceptor inner/outer segment defects were found in 10 of 15 patients prior to surgery. Following surgical excision, photoreceptor inner/outer segment defects fully resolved in 8 of these 10 patients. CONCLUSION: Persistence of photoreceptor inner/outer segment defects caused by compression of the globe by an orbital mass can be associated with reduced visual prognosis. Our findings suggest that photoreceptor inner/outer segment defects on EDI SD-OCT could be an indicator for immediate surgical excision of an orbital mass causing choroidal compression.  相似文献   
996.
AIM: To evaluate the efficacy of intralesional radiofrequency ablation in the treatment of periorbital syringomas. METHODS: We tried the intralesional radiofrequency ablation for 64 patients with periorbital syringomas from 2007 to 2011. The operation was performed under 2.5 loupe magnifications. The handpiece was assembled with a needle electrode and connected to the radiofrequency ablation apparatus. The electrode was then inserted into the target lesions in dermis and delivering injury to the base of these tumors. Results were assessed clinically by comparing pre- and post-treatment photographs and patient satisfaction rates. RESULTS: Clinical improvement increased with each subsequent treatment session. The percent of patients whose clinic improvement grade were≥3 after each session was respectively 71.9%(Session1), 83.3%(Session2), and 100%(Session3). The statistical results indicated the concordance of the clinical assessment and the satisfaction level of patients (kappa=0.78 of the session1; kappa=0.82 of the session2). The majority of patients had good or excellent cosmetic results. Postoperatively, there were no permanent side effects or recurrences. CONCLUSION: As a new technique of minimally invasion, the intralesional radiofrequency ablation was found to be an effective, inexpensive, highly precise and safe way of treating periorbital syringomas.  相似文献   
997.
老年性白内障与正常晶状体蛋白质双向电泳的差异   总被引:2,自引:1,他引:2  
目的:应用双向电泳技术对比研究老年性白内障与正常晶状体,寻找差异表达的蛋白质。方法:分别收集老年性白内障和正常晶状体,采用固相pH梯度(IPG)等电聚焦双向电泳技术进行蛋白质分离,使用ImageMaster图像分析软件分析电泳图像,对比分析蛋白质表达的差异。结果:大部分晶状体蛋白质分布在Mr14000~97000,等电点(pI)5~9的范围内;高丰度蛋白质斑点分布在Mr20000~31000、等电点(pI)6~8的区域内。经软件分析正常组共识别出133±7个蛋白质斑点,白内障组共识别出136±8个斑点,两组之间的匹配率为87%(115个),其中有8个点蛋白质表达量增加了300%以上,其中44号增加了480%,有6个点蛋白质表达量减少了300%以上,其中125号减少了336%。结论:老年性白内障与正常晶状体存在差异表达的蛋白质。  相似文献   
998.
PURPOSE: To detect the abnormalities of gray matter in children with amblyopia by voxel-based morphometry (VBM). DESIGN: Prospective, nonrandomized clinical trial. METHODS: Thirteen children with amblyopia and 14 normally sighted children underwent magnetic resonance (MR) examination. The two groups were age-matched with a mean age of 5.8 years. In the amblyopia group, five children had strabismus amblyopia, and eight had anisometropic amblyopia. We analyzed the original 3-dimensional T1 brain images using the VBM module within the widely used analysis software package SPM2 (Welcome Department of Cognitive Neurology, London, United Kingdom). After normalization, segmentation, and smoothing of the images, comparison between amblyopic and control groups was derived for the gray matter of the entire brain using parametric statistics. RESULTS: The results of VBM analysis indicated that the amblyopic group had decreased gray matter density in the middle frontal gyrus, parahippocampal gyrus, fusiform gyrus, inferior temporal gyrus of the left hemisphere, and the bilateral calcarine cortices. The radii of these regions ranged from 12 to 36 voxels. These abnormalities were consistent with morphologic changes in brain regions related to visual function. CONCLUSIONS: Using MR and VBM analysis, we detected morphologic changes in the visual cortex of children with amblyopia, which may indicate developmental abnormalities of visual cortex during the critical growth period.  相似文献   
999.
目的探讨标记大鼠全角膜新生血管和淋巴管的方法。方法应用心脏灌注荧光联合全角膜免疫荧光法.共焦显微镜下区分并标记全角膜的新生血管和淋巴管。结果适度的抗体浓度和灌注时间下可标记出全角膜新生血管和淋巴管。血管呈黄绿色,淋巴管呈红色。结论心脏灌注荧光联合全角膜免疫荧光法可用于标记大鼠全角膜新生血管和淋巴管。  相似文献   
1000.

Purpose

To investigate the concentrations of transforming growth factor (TGF)-β2, matrix metalloproteinase (MMP)-2, and tissue inhibitor of metalloproteinase (TIMP)-2 in the vitreous of patients with high myopia.

Methods

Twenty-six patients with high myopia (HM) who received vitrectomy for macular retinoschisis or macular hole were enrolled in this prospective study. Twenty-six patients with idiopathic macular hole or macular epiretinal membrane were chosen as a control group. Vitreous samples were obtained during the vitrectomy surgery. The levels of TGF-β2、MMP-2TIMP-2 in the vitreous samples were measured by enzyme-linked immunosorbent assay. The MMP activity was determined by a fluorometric assay.

Results

There was no significant difference in the vitreous level of TGF-β2 between HM (1.64?±?0.38 ng/ml) and the control group (1.56?±?0.32 ng/ml, p?=?0.56). The vitreous levels of MMP-2 in HM (32.40?±?14.90 ng/ml) were significantly higher than in the control group (21.42?±?6.74 ng/ml, p?MMP-2/TIMP-2 was significantly elevated in the vitreous samples from HM (0.61?±?0.19), compared to the control group (0.48?±?0.11, p?p?Conclusions The elevated MMP/TIMP ratio and MMP activity may play a role in the pathogenesis of human high myopia. Large prospective studies are needed to further investigate the effect of MMPs in the pathogenesis of human high myopia.  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