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   835篇
  免费   43篇
  国内免费   2篇
耳鼻咽喉   7篇
儿科学   75篇
妇产科学   52篇
基础医学   74篇
口腔科学   44篇
临床医学   77篇
内科学   173篇
皮肤病学   25篇
神经病学   61篇
特种医学   78篇
外科学   141篇
综合类   6篇
预防医学   12篇
眼科学   29篇
药学   12篇
肿瘤学   14篇
  2023年   5篇
  2022年   12篇
  2021年   16篇
  2020年   13篇
  2019年   15篇
  2018年   22篇
  2017年   18篇
  2016年   28篇
  2015年   18篇
  2014年   33篇
  2013年   27篇
  2012年   47篇
  2011年   58篇
  2010年   28篇
  2009年   43篇
  2008年   73篇
  2007年   71篇
  2006年   51篇
  2005年   57篇
  2004年   59篇
  2003年   38篇
  2002年   38篇
  2001年   24篇
  2000年   16篇
  1999年   25篇
  1998年   3篇
  1997年   3篇
  1996年   4篇
  1995年   1篇
  1994年   1篇
  1993年   1篇
  1992年   3篇
  1991年   1篇
  1989年   2篇
  1987年   3篇
  1983年   1篇
  1980年   1篇
  1976年   1篇
  1975年   1篇
  1974年   4篇
  1973年   3篇
  1971年   4篇
  1970年   3篇
  1969年   3篇
  1968年   2篇
排序方式: 共有880条查询结果,搜索用时 0 毫秒
71.
Living donor liver transplantation (LDLT) has become a viable alternative for end-stage liver disease. The shortage of brain-dead donors has led to development of advanced surgical approaches. Dual lobe LDLT has been performed successfully in the recent years. The major indication for this complex procedure has been insufficient graft size from a single donor or insufficient remnant in the donor. We performed a dual left lobe LDLT using 2 donors who were unacceptable for right lobe donation.  相似文献   
72.
73.
The aim of this study was to investigate possible correlations of the cognitive impairment with abnormalities of regional cerebral blood flow and electroencephalogram in children with (Down's Syndrome) DS. Nine patients with DS were evaluated by single photon emission computed tomography (SPECT) in combination with clinical findings, electroencephalography (EEG), and magnetic resonance imaging (MRI). In cases with IQs below 40, there were one or more findings of abnormal EEG/MRI and brain perfusion SPECT. In 6 cases (66.7%) EEG findings were normal, but 3 (33.3%) had abnormal EEG findings. Perfusion abnormalities were most pronounced in the fronto-parieto-temporal region in the form of hypoperfusion (n = 5) and in the right hemisphere (n = 5) than the left hemisphere (n = 1). These findings suggest that the children with DS had varying levels of structural, perfusion, and electrophysiological abnormalities in the brain and these abnormalities were reflected by measurable alterations of the cognitive functions.  相似文献   
74.
Recently it has emerged that hippocampal long-term depression (LTD) may play an important role in the acquisition and storage of spatial memories. This form of synaptic plasticity is tightly regulated by metabotropic glutamate receptors (mGluRs) that negatively couple to adenylyl cyclase. Activation of group III mGluRs is necessary for persistent hippocampal LTD, but is not required for depotentiation or long-term potentiation (LTP) in the dentate gyrus in vivo. In the CA1 region antagonism of group III mGluRs prevents LTD in vivo. Effects on LTP in vivo are as yet unknown. We investigated the effects of group III mGluR antagonism on LTP and LTD at Schaffer collateral-CA1 synapses, and on spatial learning in the eight-arm radial maze. Daily application of the group III mGluR antagonist (R,S)-alpha-cyclopropyl-4-phosphonophenylglycine (CPPG) resulted in impairment of long-term (reference) memory, with effects becoming apparent 4 days after training and drug treatment began. Short-term (working) memory was unaffected throughout the 10-day study. Application of CPPG prevented LTD, but not LTP, in the CA1 region. These data suggest that activation of group III mGluRs is required for the establishment of spatial long-term memory. Their exclusive role in mediating hippocampal LTD provides correlational evidence for a role for LTD in the type of spatial learning studied.  相似文献   
75.
Symptomatic interhemispheric arachnoid cysts (ACs) are extremely rare lesions seen more frequently in the elderly. Only 13 cases of symptomatic interhemispheric ACs in the elderly have previously been reported. Herein, we describe a 70-year-old female with symptoms of vertigo, memory and behavior disturbances. Magnetic resonance imaging (MRI) revealed a giant arachnoid cyst (AC) on the interhemispheric fissure, which was exerting a mass effect and displacement on the corpus callosum and anterior cerebral vessels, with a massive midline shift. The patient was treated with a cysto-peritoneal shunt. Reports to date have reviewed the pathology, clinical presentation, radiology and surgical management of interhemispheric symptomatic arachnoid cysts in elderly patients.  相似文献   
76.
PURPOSE: To retrospectively determine the sensitivity and specificity of magnetic resonance (MR) imaging for differentiation between acute and chronic cholecystitis, with histopathologic analysis as the reference standard. MATERIALS AND METHODS: Institutional review board approval with waived informed consent was obtained for this HIPAA-compliant study. Four reviewers blinded to the cholecystitis type but aware that cholecystitis was present retrospectively evaluated MR images for predetermined findings in 32 patients (15 male, 17 female; mean age +/- standard deviation, 55 years +/- 20) with histopathologically proved acute or chronic cholecystitis. The final MR diagnoses and MR findings in both groups were compared with each other and with the histopathologic diagnoses to determine the sensitivity and specificity of MR imaging. Chi(2) tests were used to detect differences in MR findings between the acute and chronic cholecystitis groups. RESULTS: MR imaging sensitivity and specificity for detection of acute cholecystitis were 95% (18 of 19 patients) and 69% (nine of 13 patients), respectively. The sensitivities of increased gallbladder wall enhancement and increased transient pericholecystic hepatic enhancement were 74% (14 of 19 patients) and 62% (10 of 16 patients), respectively. Both findings had 92% (12 of 13 patients) specificity. Sensitivities of increased wall thickness, pericholecystic fluid, and adjacent fat signal intensity changes were 100% (19 of 19 patients), 95% (18 of 19 patients), and 95% (18 of 19 patients), respectively; specificities were 54% (seven of 13 patients), 38% (five of 13 patients), and 54% (seven of 13 patients), respectively. Pericholecystic abscess, intraluminal membranes, and wall irregularity or defect each had 100% (13 of 13 patients) specificity; sensitivities were 11% (two of 19 patients), 26% (five of 19 patients), and 21% (four of 19 patients), respectively. Increased gallbladder wall enhancement (P<.001) and increased transient pericholecystic hepatic enhancement (P=.003) were the most significantly different between acute and chronic cholecystitis. CONCLUSION: Increased gallbladder wall enhancement and increased transient pericholecystic hepatic enhancement had the highest combination of sensitivity and specificity for the diagnosis and differentiation of acute and chronic cholecystitis.  相似文献   
77.
Anovaginal fistulae (AVF) are frequently seen in patients with inflammatory bowel disease, especially in Crohn disease with active colonic inflammation. Herein, we report a 21-year-old woman with Crohn disease suffering from vaginal discharge and anal pain. Although clinical presentation was very suggestive of AVF, physical examination and colonoscopy were inconclusive. We used an alternative technique and performed magnetic resonance fistulography by applying rectal contrast for the demonstration of AVF.  相似文献   
78.
Simultaneous sudden infant death syndrome   总被引:1,自引:0,他引:1  
The simultaneous sudden deaths of twins rarely occur and therefore it has received limited attention in the medical literature. When the deaths of the twins meet the defined criteria for sudden infant death syndrome (SIDS) independently and take place within the same 24 h range it can be called as simultaneous SIDS (SSIDS). The case(s): Twin girls (3.5-month-old) were found dead by their mother in their crib, both in supine position. The infants were identical twins and delivered at a hospital by cesarean section. Both infants were healthy and did not have any serious medical history. Two days prior to the incident, the twins had received the second dose of oral polio, DPT and the first dose of hepatitis B vaccines and they had fever on the first day of the vaccination and been given teaspoonful of acetaminophen. Death scene investigation, judicial investigation, parental assessment, macroscopic and microscopic autopsy findings and the toxicological analysis did not yield any specific cause of death. The case(s) were referred to a supreme board composed of multidisciplinary medical professionals at the Institute of Forensic Medicine, Ministry of Justice, in Istanbul. The Board decided that the available data was consistent with SIDS. These SIDS case(s) are presented because twin SIDS are rare and this is the first time that a simultaneous twin SIDS have been reported in Turkey. Simultaneous SIDS cases have many implications regarding definition, diagnosis and medico-legal approach.  相似文献   
79.
80.
PURPOSE: To investigate the long-term effect of varicocele repair on ipsilateral intratesticular arterial resistance index (RI) using color Doppler sonography (CDS). METHODS: A total of 26 infertile patients with left varicocele who underwent a testicular artery and lymphatic-sparing subinguinal varicocelectomy were examined with CDS for intratesticular flow parameters before and at least 6 months after surgery. We also evaluated preoperative and postoperative semen parameters. RESULTS: The mean values of RI, end-diastolic velocity and pulsatility index decreased significantly after surgery, whereas no significant change was observed in peak systolic velocity. Repair of the varicocele resulted in a statistically significant increase in the total sperm count, motility, morphology, and total motile sperm count. However, no significant correlation was found between sperm parameters and RI values (p > 0.05). CONCLUSIONS: Our data show that a significant improvement occurs in testicular blood supply and sperm parameters after surgical varicocele repair, without significant correlation between these 2 changes.  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