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   86549篇
  免费   8613篇
  国内免费   1893篇
耳鼻咽喉   669篇
儿科学   1240篇
妇产科学   617篇
基础医学   5091篇
口腔科学   1324篇
临床医学   16453篇
内科学   9814篇
皮肤病学   488篇
神经病学   10419篇
特种医学   25583篇
外国民族医学   20篇
外科学   6380篇
综合类   8733篇
现状与发展   2篇
一般理论   1篇
预防医学   1661篇
眼科学   1275篇
药学   3108篇
  59篇
中国医学   531篇
肿瘤学   3587篇
  2024年   98篇
  2023年   1426篇
  2022年   2224篇
  2021年   3610篇
  2020年   3631篇
  2019年   3434篇
  2018年   3320篇
  2017年   3577篇
  2016年   3769篇
  2015年   3757篇
  2014年   6369篇
  2013年   5564篇
  2012年   5254篇
  2011年   5731篇
  2010年   4832篇
  2009年   4942篇
  2008年   4889篇
  2007年   4593篇
  2006年   4091篇
  2005年   3592篇
  2004年   2996篇
  2003年   2380篇
  2002年   1885篇
  2001年   1757篇
  2000年   1467篇
  1999年   1119篇
  1998年   1092篇
  1997年   1024篇
  1996年   847篇
  1995年   792篇
  1994年   660篇
  1993年   540篇
  1992年   411篇
  1991年   309篇
  1990年   235篇
  1989年   176篇
  1988年   152篇
  1987年   131篇
  1986年   89篇
  1985年   71篇
  1984年   58篇
  1983年   42篇
  1982年   32篇
  1981年   23篇
  1980年   27篇
  1979年   15篇
  1978年   9篇
  1977年   4篇
  1976年   5篇
  1971年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
PurposeTo create a nonsurgical animal model of osteoarthritis (OA) to evaluate the effects of embolotherapy during geniculate artery embolization (GAE).Materials and MethodsFluoroscopy-guided injections of 700 mg of sodium monoiodoacetate were performed into the left stifle in 6 rams. Kinematic data were collected before and after induction. At 10 weeks after induction, Subjects 1 and 4–6 underwent magnetic resonance (MR) imaging with dynamic contrast enhancement (DCE) and Subjects 1, 3, and 4–6 underwent angiography with angiographic scoring to identify regions with greatest disease severity for superselective embolization (75–250-μm microspheres). Target vessel size was measured. At 24 weeks after angiography, DCE-MR imaging, angiography, and euthanasia were performed, and bilateral stifles were harvested. Medial/lateral tibial and femoral condylar, patellar, and synovial samples were cut, preserved, decalcified, and scored using the Osteoarthritis Research Society International criteria. The stifle and synovium Whole-Organ Magnetic Resonance Imaging Score and Multicenter Osteoarthritis Study score were determined. The volume transfer constant (Ktrans) and extracellular volume fraction (ve) were calculated from DCE-MR imaging along the lateral synovial regions of interest.ResultsThe mean gross and microscopic pathological scores were elevated at 38 and 61, respectively. Mean synovitis score was elevated at 9.2. Mean pre-embolization and postembolization angiographic scores were 5 and 3.8, respectively. Mean superior, transverse, and inferior geniculate artery diameters were 3.1 mm ± 1.21, 2.0 mm ± 0.50, and 1.6 mm ± 0.41 mm, respectively. Mean pre-embolization and postembolization cartilage and synovitis scores were elevated at 35.13 and 73.3 and 5.5 and 9.2, respectively. The Ktrans/ve values of Subjects 4, 5, and 6 were elevated at 0.049/0.38, 0.074/0.53, and 0.065/0.51, respectively. Altered gait of the hind limb was observed in all subjects after induction, with reduced joint mobility. No skin necrosis or osteonecrosis was observed.ConclusionsA nonsurgical ovine animal knee OA model was created, which allowed the collection of angiographic, histopathological, MR imaging, and kinematic data to study the effects of GAE.  相似文献   
6.
IntroductionVascularized fibular autografts (VFA) are used in the oncologic skeletal reconstructions of long bones, alone or combined with massive bone allografts (MBA). Data regarding the role of imaging in assessing these complex skeletal reconstructions are lacking, and have mainly focused on Computed Tomography (CT). Our aim was to evaluate if early conventional radiography (CR) findings are correlated with the outcome of these skeletal reconstructions.Materials and methodsAll consecutive patients who underwent oncologic resection of lower limbs long bones followed by VFA reconstruction were included in this single-center retrospective study. We compared the CR obtained immediately after surgery with the CR at the 6-month control, as well as the CR at 6 months with the CT at 6 months when available. The following scores were assigned to the VFA: 0 (unchanged), 1 (osteopenia-cortical bone thinning), 2 (increase in bone density-cortical thickening). We then investigated whether this score correlated with the implant outcome within 12 months (optimal integration, suboptimal integration, integration requiring further surgery or lack of integration) using Kaplan-Meier and Cox regression analyses, considering the occurrence of integration and the duration time before the surgical removal of the whole bone reconstruction.ResultsForty-five patients were included (32 men [71.1%], mean age 14.6 years), 26 affected by osteosarcoma, 14 by Ewing sarcoma, 3 by adamantinoma and 2 operated for the failure of previous reconstructions for bone sarcoma. VFA changes on 6-month CR were significantly associated with optimal integration of the implants (log-rank P = 0.0137, multivariate Hazard ratio = 7.62, 95% confidence interval = 1.13–51.25). None of the other clinical and surgical features were associated with the implant outcome. The findings on 6-month CR and CT follow-up were not significantly different. CT at 6 months was available in 36 patients (80.0%).ConclusionThe assessment of VFA morphological changes on CR performed at 6 months can predict the outcome of the skeletal implant. This data should be considered for clinical decision-making, selecting patients requiring additional images (CT), and possible subsequent revision surgical procedures.  相似文献   
7.
前列腺癌(prostate cancer, PCa)是中老年男性常见恶性肿瘤之一,目前尚缺乏有效的晚期癌症治疗方法,因此早期诊断对于降低PCa死亡率至关重要。近年来,较多研究开发出多种新型诊断方法以改善对PCa诊断的准确性,同时避免过度诊疗,但其有效性及实用性尚需进一步验证。本文对目前新型生物标志物、联合成像技术及风险预测模型等的早期诊断技术进行总结,以期为临床研究提供指导作用。  相似文献   
8.
9.
目的 基于红外热成像技术探讨“扶正温阳法”对阳虚质的影响,探讨阳虚质者红外热图的共性规律,分析判断“扶正温阳法”干预阳虚质人群的疗效。方法 纳入30例阳虚质患者给予益气温阳药物在大椎、肾俞(双侧)、命门等进行穴位贴敷,分别在干预前后运用红外热成像技术测定督脉、腰部、腹部、双手及双足局部温度的变化。结果 干预后阳虚体质患者的督脉、腰部、腹部、双手、双足温度均升高(P<0.05),阳虚体质局部温度得以改善。结论 本研究发现“扶正温阳法”可诱发循经热传导现象,通过调节热能代谢而起到调治阳虚体质的作用,红外热成像技术可用来辅助评价阳虚质的治疗效果,对临床指导制定阳虚质人群的干预方案疗效判定具有指导意义。  相似文献   
10.
目的利用多体素氢质子磁共振波谱成像(hydrogen proton magnetic resonance spectroscopy,1H-MRS)探讨慢性高原病(chronic mountain sickness,CMS)长期缺氧状态下脑部代谢物的特点,并比较各代谢物与血液指标之间的相关性。材料与方法前瞻性纳入青海大学附属医院经临床确诊为CMS的17例男性患者作为实验组,年龄(53.29±9.03)岁,居住海拔(3989.12±937.45)m,血红蛋白(hemoglobin,HGB)(224.35±11.81)g/mL,并招募与实验组年龄及居住海拔相匹配的18名健康男性志愿者作为对照组,年龄(48.61±8.76)岁,居住海拔(3674.94±634.27)m,HGB(156.67±9.46)g/mL。采用Siemens Prisma 3.0 T MR扫描仪20通道头颅线圈对所有受试者行常规头颅MRI及多体素;H-MRS检查,通过Syngo.via后处理软件获得;H-MRS图,ROI选取双侧额叶及海马区,并获得相应脑区N-乙酰天门冬氨酸/肌酸(NAA/Cr)、胆碱/肌酸CHo/Cr、乙酰天门冬氨酸/胆碱(NAA/CHo)、乳酸/肌酸(Lac/Cr)的比值。结合独立样本t检验及非参数曼-惠特尼U检验以比较两组间代谢物相对浓度差异,然后将CMS组双侧额叶及海马区各代谢物比值与血液生化指标作相关性分析。结果(1)两组受试者年龄、长期居住海拔差异均无统计学意义(P>0.05),而与对照组相比,CMS组HGB、红细胞计数(red blood cell count,RBC)、血细胞比容(hematocrit,HCT)增高,血小板(blood platelet,简称PLT)减低,差异均有统计学意义(P<0.01);(2)与对照组相比,CMS组双侧额叶及海马区NAA/Cr及NAA/CHo均减低(P<0.05),Lac/Cr增高(P<0.05),差异均具有统计学意义;(3)与对照组相比,CMS组双侧额叶及双侧海马区CHo/Cr均增高(P>0.05),差异无统计学意义;(4)CMS组右侧额叶及左侧海马CHo/Cr与RBC明显正相关,左侧额叶CHo/Cr与HCT低度正相关,右侧额叶及左侧海马Lac/Cr与HCT低度正相关。结论CMS长期缺氧状态下脑组织局部代谢物改变,神经元受损,无氧代谢增加,且这些代谢物的改变与血液指标呈一定的相关性,可为临床后续进一步预防或干预CMS患者脑损害提供影像学证据及监测指标。  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