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   3436篇
  免费   270篇
  国内免费   103篇
耳鼻咽喉   10篇
儿科学   35篇
妇产科学   5篇
基础医学   441篇
口腔科学   31篇
临床医学   353篇
内科学   134篇
皮肤病学   3篇
神经病学   261篇
特种医学   280篇
外科学   1013篇
综合类   677篇
预防医学   53篇
眼科学   3篇
药学   150篇
  8篇
中国医学   293篇
肿瘤学   59篇
  2024年   12篇
  2023年   59篇
  2022年   112篇
  2021年   135篇
  2020年   154篇
  2019年   123篇
  2018年   99篇
  2017年   129篇
  2016年   172篇
  2015年   141篇
  2014年   250篇
  2013年   231篇
  2012年   272篇
  2011年   226篇
  2010年   175篇
  2009年   144篇
  2008年   143篇
  2007年   149篇
  2006年   128篇
  2005年   115篇
  2004年   111篇
  2003年   117篇
  2002年   88篇
  2001年   59篇
  2000年   47篇
  1999年   50篇
  1998年   58篇
  1997年   41篇
  1996年   35篇
  1995年   22篇
  1994年   34篇
  1993年   37篇
  1992年   15篇
  1991年   22篇
  1990年   12篇
  1989年   11篇
  1988年   8篇
  1987年   8篇
  1986年   8篇
  1985年   8篇
  1984年   8篇
  1983年   2篇
  1982年   13篇
  1981年   7篇
  1980年   7篇
  1979年   1篇
  1977年   5篇
  1976年   3篇
  1974年   2篇
  1971年   1篇
排序方式: 共有3809条查询结果,搜索用时 31 毫秒
31.
胸腰椎椎弓根的解剖学测量及其临床意义   总被引:13,自引:0,他引:13  
目的 观测胸腰椎椎弓根形态结构特征 ,为临床提供解剖学参数。方法 测量 31例成年男性椎骨T1~L5的横径、矢径、椎弓根间距及椎弓根通道长度。结果 横径 :T1~T6逐渐变小 ,T6~T12 逐渐增大 ,L1和L2 小于T12 ,L2 ~L5逐渐增大 ;矢径 :T1~T3 逐渐增大 ,T4~T7均小于T3 和T8,T7~T12 又逐渐增大 ,L1~L3 逐渐变小 ,L3 ~L5又逐渐增大 ,T1~L5均明显大于其横径 (P <0 0 1) ;模仿弓根通道长 :T1~T10 逐渐增长 ,T11和T12 均较T10 和L1短 ,L1~L4逐渐增长 ,L5较L4短 ;椎弓根间距 :T1~T4逐渐变窄 ,T5~L5逐渐增宽 ;左右侧比较无显著性差异 (P >0 0 5 )。结论 进行椎弓根螺钉固定时应根据不同节段椎弓根形态特点 ,结合影像学资料 ,选择相应的螺钉直径、长度、进钉部位及方向。  相似文献   
32.
脊柱侧凸患者椎弓根形态变化与椎弓根外固定术的应用   总被引:3,自引:2,他引:3  
目的:观测脊柱侧凸患者胸椎弓根等结构的形态变化,于脊柱侧凸矫形术中应用自行设计的胸椎椎弓根外内固定技术,探讨其临床意义。方法:对30例脊柱侧凸患者行术前CT扫描,观测椎弓根形态变化及椎体旋转程度,主动脉位置变化等;对过窄或变形严重的椎弓根行胸椎椎弓根根外内固定,观察效果。结果:CT扫描发现,侧凸患者凹侧椎弓根直径明显窄于凸侧椎弓根直径,差异具有显著统计学意义(P〈0.05)。凹侧及凸侧椎弓根直径都明显小于相应肋骨.椎弓根单元直径,差异具有显著统计学意义(P〈0.05)。椎体呈楔形变,主动脉位置相对向后外侧移位;临床选择5例侧凸病人共24个胸椎弓根过细(小于2mm)或变形严重不适合经椎弓根内固定,而对这部分椎弓根行椎弓根根外内固定取得满意效果,无神经血管并发症发生,经3,6及12个月随访无螺钉拔出或松动,无矫正度丢失。结论:脊柱侧凸病人椎弓根等结构的形态发生了改变;在脊柱侧凸病人中应用胸椎椎弓根根外内固定技术具有操作简单安全、固定牢固可靠等优点,具有临床实用价值。  相似文献   
33.
以第四腰血管为蒂髂骨瓣转移修复腰椎缺损的应用解剖   总被引:2,自引:2,他引:2  
在40侧灌注红色乳胶和2侧灌注碳素墨汁的成年尸体上对第四腰血管进行了观察和测量.第四腰动脉外径为3.0mm;主干长5.7cm,腹侧支动脉外径为1.4mm;长6.7cm,背侧支外径为1.4mm;长1.4cm.依据解剖学观察结果,设计了以第四腰血管为蒂髂骨瓣移植修复腰段椎体缺损的新术式,并对术中有关应用解剖学要点进行了讨论.  相似文献   
34.
The clinical and radiological spectrum of spondylocostal dysostosis syndromes encompasses distinctive costo‐vertebral anomalies. RIPPLY2 biallelic pathogenic variants were described in two distinct cervical spine malformation syndromes: Klippel–Feil syndrome and posterior cervical spine malformation. RIPPLY2 is involved in the determination of rostro‐caudal polarity and somite patterning during development. To date, only four cases have been reported. The current report aims at further delineating the posterior malformation in three new patients. Three patients from two unrelated families underwent clinical and radiological examination through X‐ray, 3D computed tomography and brain magnetic resonance imaging. After informed consent was obtained, family‐based whole exome sequencing (WES) was performed. Complex vertebral segmentation defects in the cervico‐thoracic spine were observed in all patients. WES led to the identification of the homozygous splicing variant c.240‐4T>G in all subjects. This variant is predicted to result in aberrant splicing of Exon 4. The current report highlights a subtype of cervical spine malformation with major atlo‐axoidal malformation compromising spinal cord integrity. This distinctive mutation‐specific pattern of malformation differs from Klippel–Feil syndrome and broadens the current classification, defining a sub‐type of RIPPLY2‐related skeletal disorder. Of note, the phenotype of one patient overlaps with oculo‐auriculo‐vertebral spectrum disorder.  相似文献   
35.
目的直观立体地显示复杂胸椎骨折的图像,探讨螺旋CT医学图像三维重建在复杂胸椎骨折诊断中的价值及其对手术的指导意义。方法对92例胸椎骨折患者采用螺旋CT进行薄层扫描和三维重建进行诊断。CT扫描全部采用Siemens SOMATOM Sensation16型多排高速螺旋CT机,1.0mm层厚。扫猫所得断层资料通过网络传送至计算机工作站进行处理,采用Window.NT3.51平台上Insisht三维重建软件进行三维重建。结果三维CT图像能够围绕X轴和Z轴任意旋转、切割以从不同角度观察,能够清晰显示复杂的胸椎骨折和狭窄椎管的解剖形态特点。结论三维CT重建在胸椎骨折方面具有很大的临床应用价值,有助于提高脊柱骨折手术的安全性和精确性并对患者预后的估计提供帮助。  相似文献   
36.
颈椎钩突邻近结构薄层断面与MRI对照研究   总被引:1,自引:1,他引:1  
目的阐明颈椎钩突在薄层断面和MRI断面图像上与周围结构的毗邻关系,为颈椎退行性疾病提供影像学诊断依据。方法选取5例中国数字化可视人体(CVH)数据集中C3-C7椎体上缘清楚显示钩突的薄层断面图像,观察并测量钩突与邻近的椎动脉和颈神经的位置关系,选择对应平面的MRI断面图像对照分析。结果CVH数据集的薄层断面清晰显示颈椎钩突及其周围结构,在断面上测量并得出钩突与颈神经、钩突与椎动脉的距离的平均值,MRI清楚显示颈椎钩突及其邻近结构。结论将CVH数据集中的颈椎钩突平面的薄层断面与对应的MRI图像进行对照研究,可为颈椎病的影像学诊断和治疗提供形态学参考。  相似文献   
37.
AIMS: Although intracranial dissecting aneurysm (IDA) is a newly described variant of the brain aneurysms that affects mainly the vertebrobasilar arterial system, its pathogenesis remains obscure. We aimed to clarify the role of arteriosclerosis in the pathogenesis of IDA based on histopathological findings in seven autopsy cases of IDA. METHODS AND RESULTS: All cases exhibited systemic hypertension or left ventricular hypertrophy. Macroscopically, all cases exhibited subarachnoid haemorrhage. Two types of dissection were recognized in the vertebral artery. Six of seven IDA cases showed a widespread disruption of the entire thickness of the arterial wall with the formation of a dilated pseudoaneurysm, which consisted of thin adventitia (arterial wall disruption type). Medial disruption of the arterial wall and subadventitial dissecting haemorrhage were also found, resulting in the formation of a false lumen and stenosis of the 'true' lumen of the artery. However, these lesions were connected to the site of rupture of the entire arterial wall. Within 1 day after onset of IDA, the autopsy cases showed formation of fibrin thrombus, marked leucocyte infiltration and necrosis of the arterial wall at the site of the lesion. Cases that survived more than 1 week showed smooth muscle cell proliferation, macrophage accumulation and lymphocytic infiltration in the lesions. These cases showed no atherosclerotic plaque, but non-atherosclerotic fibrocellular intima. The thickness of intima and media was significantly less in the vertebral artery of IDA patients than that of non-IDA patients with systemic hypertension. On the other hand, the remaining case showed severe atherosclerosis with haemorrhage into the lipid core without connection to the arterial lumen (intra-atheromatous plaque haemorrhage type). However, unusual arterioles and neovascularization of the intra-and peri-arterial walls were observed. CONCLUSIONS: Our results suggest that disruption of the entire arterial wall may be a critical event in the development of IDA and result in the medial disruption and subadventitial haemorrhage. Non-atheromatous intima might function as a protective factor in arterial wall disruption. On the other hand, atherosclerosis may predispose to intra-atheromatous plaque haemorrhage type of IDA through intramural haemorrhage originating from the newly formed vessels.  相似文献   
38.
Linear microcracks and diffuse damage (staining over a broad region) are two types of microscopic damage known to occur in vivo in human vertebral trabecular bone. These damage types might be associated with vertebral failure. Using microcomputed tomography and finite element analysis for specimens of cancellous bone, we estimated the stresses in the trabeculae of human vertebral tissue for inferosuperior loading. Microdamage was quantified histologically. The density of in vivo linear microcracks was, but the diffuse damage area was not, related to the estimates of von Mises stress distribution in the tissue. In vivo linear microcrack density increased with increasing coefficient of variation of the trabecular von Mises stress and with increasing average trabecular von Mises stress generated per superoinferior apparent axial stress. Nonlinear increase in linear crack density, similar to the increase of the coefficient of variation of trabecular shear stresses, with decreasing bone stiffness and bone volume fraction suggests that damage may accumulate rather rapidly in diseases associated with low bone density due to the dramatic increase of shear stresses in the tissue. © 2003 Biomedical Engineering Society. PAC2003: 8719Rr, 8719Xx, 8759Ls, 8759Fm, 8710+e  相似文献   
39.
Aspergillus infection of the central nervous system (CNS) is an uncommon disease. Most of the reported cases are of sinocranial spread and cases with contiguous spread to spinal cord from lung and other organs are uncommon. A case of pulmonary aspergillosis with extension to thoracic vertebrae forming a paraspinal mass resulting in neurological deficit due to Aspergillus flavus, is reported. The 43 year old patient did not have any obvious predisposing condition. He presented with loss of motor function and succumbed to the infection despite operative intervention and antifungal therapy. A brief update on CNS aspergillosis is presented along with detailed clinical, radiological and laboratory work up of the patient.  相似文献   
40.
选择腰椎椎弓根螺钉长度的放射解剖学研究   总被引:7,自引:2,他引:7  
目的 :探讨在腰椎侧位片及CT片上推算椎弓根螺钉长度的方法 ,为临床提供参考。方法 :随机在 3 0个腰椎骨标本上用 1mm软钢丝在椎弓根最狭窄处缠绕 ,按人字嵴进钉方法打入椎弓根直钢丝 ,拍正侧位片、横断面片及椎弓根CT扫描 ,分别在标本、CT及侧位片上测量椎弓根螺钉长度 ,三组数据比较。结果 :腰椎侧位片上测量的自关节突关节间隙下缘至椎体前缘距离乘以 0 .83即是螺钉长度 ,椎弓根CT扫描测量其长度更为准确。结论 :正常拍照条件下 ,用腰椎侧位片和椎弓根CT片可准确地推算螺钉长度 ,具有临床实用意义。  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