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   36912篇
  免费   3058篇
  国内免费   1207篇
耳鼻咽喉   1032篇
儿科学   623篇
妇产科学   313篇
基础医学   3950篇
口腔科学   1171篇
临床医学   3580篇
内科学   4288篇
皮肤病学   593篇
神经病学   1698篇
特种医学   1588篇
外国民族医学   3篇
外科学   8509篇
综合类   5346篇
现状与发展   5篇
预防医学   1200篇
眼科学   654篇
药学   2835篇
  23篇
中国医学   1264篇
肿瘤学   2502篇
  2024年   69篇
  2023年   533篇
  2022年   1048篇
  2021年   1224篇
  2020年   1469篇
  2019年   1269篇
  2018年   1062篇
  2017年   1256篇
  2016年   1324篇
  2015年   1330篇
  2014年   2334篇
  2013年   2766篇
  2012年   2247篇
  2011年   2340篇
  2010年   1977篇
  2009年   2007篇
  2008年   1853篇
  2007年   1797篇
  2006年   1591篇
  2005年   1518篇
  2004年   1326篇
  2003年   1187篇
  2002年   936篇
  2001年   932篇
  2000年   795篇
  1999年   658篇
  1998年   623篇
  1997年   574篇
  1996年   471篇
  1995年   401篇
  1994年   356篇
  1993年   261篇
  1992年   229篇
  1991年   203篇
  1990年   155篇
  1989年   146篇
  1988年   120篇
  1987年   91篇
  1986年   84篇
  1985年   105篇
  1984年   85篇
  1983年   51篇
  1982年   72篇
  1981年   65篇
  1980年   64篇
  1979年   43篇
  1978年   36篇
  1977年   28篇
  1976年   20篇
  1975年   19篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
James H. Diaz  MD  DrPH 《Pain practice》2004,4(4):295-302
Abstract:   Spontaneous intracranial hypotension (SIH) is a postural headache syndrome unrelated to dural puncture. Because of the increasing failure of epidural blood patch (EBP) to relieve headache in SIH, we retrospectively investigated the epidemiological features and treatment outcomes in 55 cases of SIH. The study population was stratified by age and sex; continuous variables were compared for differences by t -tests; categorical variables were compared by Chi-squared analysis or Fisher exact tests. Significant differences were identified by P values of 0.05 or less. The mean age of the study population was 44 ± 12 years with a female to male ratio of 1.3:1.0. Men presented with subdural hematomas ( P  = 0.001) more often than women. Meningeal enhancement on contrast magnetic resonance imaging (MRI) was the most consistent radiographic finding. Radionuclide cisternography (RC) demonstrated thoracolumbar dural leaks in 16 of 22 patients. EBP failures were more common in patients aged 40 and younger than in older patients ( P  = 0.003). Postural headache from SIH was not uniformly responsive to EBP, and had significant comorbidities, especially in men. The management of postural headache in SIH by other techniques to restore brain position and cerebrospinal fluid dynamics should be investigated.  相似文献   
32.
A 13-year-old boy who had hemophilia A was reported with pain in the left thigh and hip on walking. He had no history of trauma. Severe hemophilia A is diagnosed with a Factor VIII level of <1 iu/dl. The presumptive diagnosis was that of a spontaneous bleed into the hip joint. Factor VIII mutational analysis revealed a C to G substitution at nucleotide 6683 which results in a cystine change at codon 2194. However, the symptoms persisted and an X-ray demonstrated the presence of an acute on chronic slip of the upper femoral epiphysis. The patient was transferred to the center treating his hemophilia where the hip was pinned in situ under cover with Factor VIII. This case demonstrates the need to be aware of a possible traumatic diagnosis of hip pain in a hemophiliac child with a longstanding history of spontaneous bleeding into joints.  相似文献   
33.
34.
小切口动力髋螺钉治疗高龄股骨转子间骨折   总被引:1,自引:0,他引:1  
[目的]探讨应用小切口动力髋螺钉(DHS)微创固定治疗高龄股骨转子间骨折的方法及临床效果.[方法]回顾性分析2001年8月~2006年1月应用闭合复位、小切口DHS固定治疗37例高龄股骨转子间骨折患者,其中男15例,女22例;年龄72~92岁,平均81.5岁.在C型臂X线机监视下,先将1~2枚克氏针经皮通过大转子打入股骨头上部.另将1枚导针按135°颈干角打入股骨头中央,在导针下做一长约4~5.5 cm纵切口,经导针拧入粗拉力螺纹钉.拔出导针将带套管接骨板沿肌层下插入,并将接骨板的套管套入螺纹钉的尾端.[结果]手术时间40~75 min,平均60 min.术中平均出血55 ml.术后与术前血红蛋白值比较无明显变化.37例均获11~18个月随访,骨折愈合时间10~15周.轻度髋内翻2例,无切口感染、内固定失效及旋转畸形.按董纪元疗效评定标准,优良率94.6%.[结论]小切口DHS微创技术具有手术时间短、出血少、创伤小、并发症少、康复快的特点,是治疗高龄股骨转子间骨折较理想的方法.  相似文献   
35.
目的以股骨头骨坏死样本的Micro-CT断层图像为基础,对其进行空间结构评估。方法2003年11月~2005年6月,收集股骨头骨坏死患者行全髋关节置换术时取出的股骨头样本6个,对样本进行Micro-CT断层扫描,获取股骨头骨坏死样本的计算机三维图像,图像空间分辨率为36μm×36μm×36μm。手工选取兴趣区,随后采用骨体积分数(BV/TV)、骨小梁间隙(Tb.Sp)、骨小梁厚度(Tb,Th)、骨小梁数目(Tb.N)、骨表面积体积比(BS/BV)、结构模型指数(SMI)、骨小梁模型因子(Tb.Pf)等三维空间参数分别对股骨头骨坏死标本的正常区域、硬化带和塌陷区进行评价。结果晚期股骨头骨坏死硬化区和塌陷区的骨小梁空间结构明显改变:硬化区Bv/Tv明显增加,Tb.Th明显增厚,Tb,Sp变窄,SMI与正常区域的骨小梁无差别;而塌陷区Bv/Tv明显减少,BS/BV增大,Tb.N和Tb.Pf增加,Tb,Th改变不明显。结论Micro-CT作为一种新的检测手段,能够在不损伤样本的条件下快速获取股骨头骨坏死样本断层图像,具有精度高、检测快、可进行三维重建分析的优点。晚期股骨头骨坏死不同区域的骨三维结构呈现出不同的空间结构特征。  相似文献   
36.
37.
Focal full-thickness cartilage lesions of the human medial femoral condyle (MFC) can cause pain and functional impairment. Affected middle-aged patients respond unpredictably to existing treatments and knee arthroplasty may be required, prompting risk of revision. This study assesses the safety of, and biological and functional response to, a metallic resurfacing implant which may delay or obviate the need for traditional arthroplasty. The anatomic contour of the surgically exposed MFC of six adult goats was digitally mapped and an 11 mm diameter full-thickness osteochondral defect was created. An anchor-based Co-Cr resurfacing implant, matching the mapped articular contour, was implanted. Each goat's contralateral unoperated femorotibial joint was used as a control. Postoperative outcome was assessed by lameness examination, radiography, arthroscopy, synoviocentesis, necropsy, and histology up to 26 (n = 3) or 52 (n = 3) weeks. By postoperative week (POW) 4, goats demonstrated normal range of motion, no joint effusion, and only mild lameness in the operated limb. By POW 26 the animals were sound with only occasional very mild lameness. Arthroscopy at POW 14 revealed moderate synovial inflammation and a chondral membrane extending centrally across the implant surface. Radiographs at POWs 14 to 52 implied implant stability in the operated joints, as well as subchondral bone remodeling and mild exostosis formation in the operated and contralateral unoperated joints of some goats. By POW 26, histology revealed new trabecular bone abutting the implant. At POWs 26 and 52 MFC cartilage was metachromatic and intact in the operated and unoperated femorotibial joints. Proximal tibiae of some operated and unoperated limbs demonstrated limited subchondral bone remodeling and foci of articular cartilage fibrillation and thinning. The chondral membrane crossing the prosthesis possessed a metachromatic matrix containing singular and clustered chondrocytes. Our data imply the safety, biocompatibility, and functionality of the implant. Focal articular damage was documented in the operated joints at POWs 26 and 52, but lesions were much reduced over those previously reported in untreated defects. Expanded animal or preclinical human studies are justified.  相似文献   
38.
We describe a case of type B aortic dissection with large ascending aortic aneurysm occurring 12.8 years after aortic root replacement (Cabrol procedure) in a non-Marfan patient with cystic medial necrosis of the aorta. We have successfully performed an extended total aortic arch replacement using a four-branched graft through the “L-indsion” approach (a combination of a left anterior thoracotomy and upper half median sternotomy). Of note, a histological specimen from the aneurysmal ascending aortic wall revealed “healed aortic dissection” with fibrous tissue replacing the media and intima in addition to multiple foci of cystic medial necrosis.  相似文献   
39.
Catastrophic failure of two zirconia—ceramic modular femoral heads occurred, despite the theoretical improved toughness of zirconia—ceramic relative to alumina—ceramic. This experience led the authors to return to cobalt—chromium as the metal of choice for articulation against polyethylene in total hip arthroplasty.  相似文献   
40.
Summary Acute cerebrovascular congestion after a closed head injury is significantly related to intracranial hypertension. As an indirect method of cerebral blood flow measurement, transcranial doppler sonography (TCD) provides a rapid and noninvasive assessment of cerebral haemodynamics, including hyperaemic conditions.TCD examinations was serially performed in 35 patients with severe head injury with intact cerebral circulation; i.e. the mean flow velocity (MFV) patterns of the middle cerebral artery (MCA) did not show signs of cerebral circulatory arrest such as systolic spike, to and fro, or no flow. The results showed that the MFV of the MCAs and ipsilateral extracranial internal carotid arteries (ICAs) in 9 of these patients increased sharply and pulsatility index (PI) decreased during 48–96 hours after the injury. This was soon followed by patterns of high intracranial resistance, consistent with elevated intracranial pressure (ICP) in monitored patients and acute brain swelling on repeated computed tomographic (CT) scans. The correlation between increased MFVs, decreased PIs, and cerebral haemodynamic changes leading to acute brain swelling is discussed.The number of patients who ended with severe disability, vegetative state, or death was 66% in this group of 9 patients, compared to only 34% for the 35 patients overall with severe head injury. Though the morbidity and mortality rates largely depend on the primary injury, the presence of acute cerebral swelling aggravate the grave course in these patients. And the ability of TCD to monitor the hyperaemic state prior to oedema should lead us to adjust the therapy in order to minimize the secondary insult related to intracranial hypertension.  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