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   713篇
  免费   21篇
  国内免费   8篇
耳鼻咽喉   13篇
儿科学   53篇
妇产科学   33篇
基础医学   49篇
口腔科学   36篇
临床医学   43篇
内科学   163篇
皮肤病学   25篇
神经病学   35篇
特种医学   20篇
外科学   150篇
综合类   14篇
预防医学   6篇
眼科学   30篇
药学   26篇
肿瘤学   46篇
  2023年   2篇
  2022年   11篇
  2021年   23篇
  2020年   14篇
  2019年   13篇
  2018年   22篇
  2017年   21篇
  2016年   24篇
  2015年   32篇
  2014年   38篇
  2013年   41篇
  2012年   48篇
  2011年   46篇
  2010年   31篇
  2009年   29篇
  2008年   43篇
  2007年   49篇
  2006年   43篇
  2005年   57篇
  2004年   35篇
  2003年   14篇
  2002年   19篇
  2001年   16篇
  2000年   18篇
  1999年   5篇
  1998年   4篇
  1997年   6篇
  1996年   5篇
  1995年   3篇
  1994年   2篇
  1993年   1篇
  1991年   1篇
  1990年   2篇
  1989年   1篇
  1985年   1篇
  1979年   1篇
  1977年   1篇
  1974年   4篇
  1973年   1篇
  1972年   2篇
  1971年   4篇
  1970年   4篇
  1969年   3篇
  1968年   1篇
  1967年   1篇
排序方式: 共有742条查询结果,搜索用时 15 毫秒
1.
Gastroesophageal reflux is the most common benign disorder of the esophagus and laparoscopic Nissen fundoplication has become the standard surgical treatment for its treatment. In our area, where the use of bougie calibration is debatable, postoperative dysphagia is encountered often after this surgery although it is usually not permanent. The aim of this study was to investigate the effect of using a soft silicone tube 39 F in diameter for esophageal calibration during laparoscopic Nissen fundoplication on the incidence of postoperative dysphagia. We divided cases scheduled to undergo laparoscopic Nissen fundoplication between January 2009 and November 2010 into two groups, each consisting 25 patients. Esophageal calibration with a 39 F silicone orogastric tube was used for the first group while there was no operative calibration in the second group. The surgical duration was recorded; the presence and severity of the postoperative dysphagia was calculated by using a dysphagia severity scoring system during the 1-year postoperative follow-up. The dysphagia severity scores were significantly lower in group 1 than group 2 on the postoperative second day and at the end of the first week and first month. We did not find a significant difference at the end of the 6-month and first year. There was also no significant difference regarding surgery duration. The use of a soft orogastric tube 39 F in diameter for esophagus calibration during laparoscopic Nissen fundoplication has significantly decreased the incidence of postoperative transient dysphagia without affecting the duration of surgery. Although dysphagia gradually resolves in the majority of patients, a safe and easy calibration method for its prevention is worth developing, and we believe that the use of our method in larger series could be beneficial.  相似文献   
2.
3.
Since it covers the lateral wall of the mastoid air system, the suprameatal triangle is of importance to otologic surgeons during mastoidectomy. Because of this clinical importance, topographic anatomy of the suprameatal spine and depression was studied on Anatolian skulls. In all, 363 male and 231 female skulls were studied. The most prevalent type of suprameatal spine resembled a crest and was found in both sexes on the right (77.6%) and left (80%) sides. The absence of a suprameatal depression was significantly higher in females (right 9.1%; left 8.7%) than in males (right 1.7%; left 2.5%). Suprameatal depressions were mostly shallow in female subjects, but were mostly observed in males to be at a medium depth or deep. Received: 5 January 1998 / Accepted: 19 March 1998  相似文献   
4.
Congenital epulis is a very rare lesion found only in newborn infants. This tumor is multiple in about 10% of reported cases, rarely with the simultaneous involvement of the maxilla and mandibula, as in this article. In the presented case, light microscopy demonstrated large eosinophilic granular cells arranged in solid nests that are separated by thin fibrovascular areas. The tumors In the maxilla and mandibula were investigated with a panel of polyclonal and monoclonal antibodies, and using immunoperoxidase methods on formalin-fixed, paraffin-embedded sections. Immunohistochemical studies revealed strong and diffuse cytoplasmic staining for neuron specific enolase and vimentin. However, all other reactions were negative. These results suggest that the congenital epulis may be derived from uncommitted nerve-related mesenchymal cells.  相似文献   
5.
Giant or huge colloid cysts of the third ventricle up to of more than 3 cm in diameter are extremely rare. The patient presented with symptoms of increased intracranial pressure, including headache, vomiting, and papilledema. Computerized tomographic (CT) scan revealed a hypodense, huge colloid cyst of the third ventricle associated with calcification in the cyst wall. Both hypodensity and calcification are uncommon roentgenological findings for colloid cysts of the third ventricle. The patient was operated on by the transcortical/transventricular approach and the colloid cyst was completely excised.  相似文献   
6.
PURPOSENonalcoholic fatty liver disease (NAFLD) can progress to liver cirrhosis and is predicted to become the most frequent indication for liver transplantation in the near future. Noninvasive assessment of NAFLD is important for diagnosis and patient management. This study aims to prospectively determine the liver stiffness and T1 and T2 values in patients with NAFLD and to compare the diagnostic performance of magnetic resonance elastography (MRE) and mapping techniques in relation to the proton density fat fraction (PDFF).METHODSEighty-three patients with NAFLD and 26 participants with normal livers were imaged with a 1.5 T scanner. PDFF measurements obtained from the multiecho Dixon technique were used to quantify the liver fat. MRE, native T1 mapping (modified Look-Locker inversion recovery [MOLLI] schemes 5(3)3, 3(3)3(3)5, and 3(2)3(2)5 and the B1-corrected variable flip angle [VFA] method), and T2 mapping values were correlated with PDFF. The diagnostic performance of MRE and the mapping techniques were analyzed and compared.RESULTST1 values measured with the MOLLI schemes and the B1-corrected VFA (p < 0.001), and the stiffness values from MRE (p = 0.047) were significantly higher in the NAFLD group. No significant difference was found between the groups in terms of T2 values (p = 0.127). In differentiation of the NAFLD and control groups, the B1-corrected VFA technique had slightly higher accuracy and area under the curve (AUC) than the MOLLI schemes. In the NAFLD group, there was a good correlation between the PDFF, MOLLI 3(3)3(3)5 and 3(2)3(2)5, and VFA T1 measurements (r=0.732; r=0.735; r=0.716, p < 0.001, respectively).CONCLUSIONLiver T1 mapping techniques have the potential to distinguish steatotic from nonsteatotic livers, and T1 values seem to have a strong correlation with the liver fat content.

Nonalcoholic fatty liver disease (NAFLD) is one of the most common causes of chronic liver disease, with an estimated worldwide prevalence of around 25% (1). It may range from simple steatosis, which is considered a benign condition, to nonalcoholic steatohepatitis (NASH), which can progress to fibrosis, cirrhosis, liver failure, and hepatocellular carcinoma. NAFLD is also known to be associated with metabolic syndrome, which is a risk factor for cardiovascular disease and type II diabetes mellitus (24).The gold standard method for diagnosing NAFLD and distinguishing its different patterns is a liver biopsy which has considerable limitations, including sampling errors, its invasive nature and associated complication risks, small sample size, and inter- and intraobserver variability (5, 6). These drawbacks constrain its utility for clinical monitoring and make it unsuitable as a screening method. Therefore, there is an urgent clinical need for an accurate noninvasive approach in the assessment of NAFLD. Accordingly, both the European Association for the Study of the Liver and the American Association for the Study of Liver Disease propose magnetic resonance imaging (MRI) as a noninvasive diagnostic tool for NAFLD (7, 8). Proton density fat fraction (PDFF)-based MRI and magnetic resonance spectroscopy (MRS) techniques are considered the most accurate noninvasive methods for the quantification of liver fat (912). The PDFF is accepted as a standardized biomarker of hepatic steatosis. Studies suggest that this biomarker is equivalent to the hepatic “signal fat fraction” (FF) after correcting all the confounding factors (13). However, PDFF measurement is not suitable for the assessment of any inflammation or fibrosis in NAFLD (13). On the other hand, recent studies have shown that other quantitative MRI techniques such as magnetic resonance elastography (MRE) and T1–T2 mapping can be useful in detecting hepatic inflammatory and fibrotic changes (14, 1521). Thus, the application of a multiparametric MRI protocol might be helpful in liver tissue characterization and thereby in the risk stratification and therapeutic management of patients with NAFLD.In this prospective study, we aimed to determine liver stiffness and T1 and T2 values in patients with NAFLD and nonsteatotic subjects and compare the diagnostic performance of MRE and mapping techniques in relation to the FF.  相似文献   
7.
Although seasonal trends in incidence and diagnosis of pediatric cancers have been widely investigated, the results have been inconclusive. A consistent seasonal trend may possibly provide etiological insights into pediatric cancers. This study aims to determine if there is a seasonal variation in cancer diagnoses in the pediatric population at the IWK Health Centre, a tertiary care center serving three Canadian provinces: Nova Scotia, New Brunswick, and Prince Edward Island. All pediatric cancer patients aged 0–20 y diagnosed from 1995 to 2015 at the center were included in this study. The annual data was divided into four seasonal periods (December to February, March to May, June to August, and September to November). The cancer diagnoses were categorized as leukemia, lymphoma, sarcoma, brain tumors, and miscellaneous. Seasonal variation was assessed by a harmonic function in a Poisson regression model. The amplitude of multiplicative change in the incidence rate caused by the seasonal variation is expressed as the incidence rate ratio (IRR). For all cancer diagnoses for the entire cohort of 1200 patients, the IRR was 1.03 [95% confidence interval (CI) 0.96–1.13]. None of the IRRs for the cancer groups indicated a statistically significant seasonality of cancer diagnosis: Leukemia 1.11 (95% CI 0.96–1.28); Lymphoma 1.17 (95% CI 0.93–1.47); Sarcoma 1.29 (95% CI 0.99–1.69); Brain tumors 1.16 (95% CI 0.97–1.38); Miscellaneous 1.09 (95% CI 0.93–1.27). The present study did not show a seasonal variation in the various cancer types in the pediatric population at the IWK.  相似文献   
8.
Therapy related acute lymphoblastic leukemia (t‐ALL) of B cell origin is rare and constitutes approximately 2% of all ALL. Previously compiled data on the complete cytogenetic analysis of 48 t‐B‐ALL cases suggested that MLL rearrangement at 11q23 gene locus is the most common abnormality. Philadelphia chromosome (Ph) and a normal karyotype were reported as the second and third most common karyotypes, respectively. We investigated cytogenetic karyotypes of six t‐B‐ALL cases with a pre‐B cell immunophenotype. Ph + t‐B‐ALL was noted in four of six patients previously treated with radiation and/or chemotherapy. In addition, one case demonstrated MLL rearrangement at 11q23 locus while one case demonstrated normal cytogenetic karyotype. Five of the six t‐B‐ALL patients had persistent leukemia following initiation of chemotherapy for secondary leukemia with survival ranging from 10 to 21 months. To our knowledge, only fourteen patients with Ph + t‐B‐ALL have been described in the literature. In the current study, three of four cases with Ph + t‐B‐ALL were associated with treated breast carcinoma while one patient was treated for Hodgkin lymphoma. All four patients had undergone radiation therapy. The results may indicate a plausible association between Ph+t‐B‐ALL and prior radiation exposure.  相似文献   
9.
Objective: The aim of present study was to evaluate the indications and the complications associated with neonatal exchange transfusion (ET) performed for hyperbilirubinemia.

Methods: This study included overall 306 neonates who underwent ET between 2005 and 2012. The demographic characteristics of patients, causes of jaundice and adverse events occurred during or within 1 week after ET were recorded from their medical files. Those newborns that underwent ET were classified as either “otherwise healthy” or “sick” group.

Results: Of the 306 patients who underwent ET, 244 were otherwise healthy and had no medical problems other than jaundice. The remaining 62 patients were classified as sick that had medical problems other than jaundice ranging from mild to severe. The mean gestational age was 37.6?±?2.5 weeks and the mean peak total bilirubin levels was 25.8?±?6.6?mg/dl. The mean age at presentation was 5.4?±?3.8?d for all infants. The most common cause of hyperbilirubinemia was ABO isoimmunization (27.8%). None of newborns died secondary to ET. Three infants had had necrotizing enterocolitis, and also three infants had had acute renal failure. The most common encountered complications of ET procedure were hyperglycemia (56.5%), hypocalcaemia (22.5%) and thrombocytopenia (16%).

Conclusions: Our data showed that ABO isoimmunization was the most common cause of hyperbilirubinemia. Even mortality was not seen, very rare but major gastrointestinal and renal complications were associated with ET. The majority of adverse events associated with ET were laboratory abnormalities mainly hyperglycemia, hypocalcaemia and thrombocytopenia which were asymptomatic and treatable.  相似文献   
10.
Clinical Rheumatology - This study aims to assess rheumatologists’ perceptions, utilization patterns, and attitudes towards the modified New York (mNY) criteria for ankylosing spondylitis...  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