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   1022篇
  免费   72篇
耳鼻咽喉   5篇
儿科学   22篇
妇产科学   15篇
基础医学   115篇
口腔科学   14篇
临床医学   56篇
内科学   172篇
皮肤病学   16篇
神经病学   47篇
特种医学   74篇
外科学   130篇
综合类   41篇
预防医学   55篇
眼科学   208篇
药学   43篇
中国医学   1篇
肿瘤学   80篇
  2024年   1篇
  2023年   3篇
  2022年   10篇
  2021年   30篇
  2020年   13篇
  2019年   20篇
  2018年   28篇
  2017年   17篇
  2016年   22篇
  2015年   25篇
  2014年   28篇
  2013年   29篇
  2012年   83篇
  2011年   87篇
  2010年   29篇
  2009年   36篇
  2008年   104篇
  2007年   85篇
  2006年   67篇
  2005年   56篇
  2004年   59篇
  2003年   44篇
  2002年   44篇
  2001年   37篇
  2000年   25篇
  1999年   16篇
  1998年   4篇
  1997年   2篇
  1996年   2篇
  1995年   3篇
  1994年   1篇
  1993年   6篇
  1992年   8篇
  1991年   5篇
  1990年   6篇
  1989年   5篇
  1988年   4篇
  1987年   9篇
  1986年   11篇
  1985年   5篇
  1982年   1篇
  1980年   2篇
  1979年   7篇
  1978年   3篇
  1977年   2篇
  1976年   1篇
  1975年   1篇
  1974年   4篇
  1973年   3篇
  1970年   1篇
排序方式: 共有1094条查询结果,搜索用时 46 毫秒
1.
2.
3.
Arteriovenous (AV) fistulas are common in renal cell carcinoma. These are usually small and asymptomatic. Case reports have previously described symptomatic fistulas in primary renal cell tumour or, less commonly, bone metastases. The current study describes a patient with lung metastases from renal cell carcinoma who developed a symptomatic pulmonary AV fistula. The patient presented with debilitating progressive shortness of breath, which resolved after coiling of the pulmonary AV fistula. Supporting radiographs include a unique ventilation-perfusion finding of perfusion tracer in the kidney that is diagnostic of a pulmonary shunt. This is the first report of a pulmonary fistula from renal cell carcinoma. This rare complication of renal cell carcinoma reflects its diverse clinical presentations and unique tumour biology.  相似文献   
4.
5.
6.
The recognition of high-risk human papillomaviruses (HPVs) as etiological agents of cervical cancer has increased the demands to use testing for HPV for the detection of abnormal cervical smears and for cervical cancer screening. The present study compared the performance of the Hybrid Capture 2 (HC2) assay with that of PCR for the detection of significant cervical lesions in 1,511 women with different risks for HPV infections in three New Independent States of the former Soviet Union. The results showed that the level of agreement between the HC2 assay and PCR was substantial, with a kappa (Cohen) value of 0.669 (95% confidence interval [CI], 0.629 to 0.709). Of the 228 samples with discrepant results, 92 were positive by the HC2 assay but negative by PCR, whereas 136 samples were PCR positive but HC2 assay negative. The positive predictive values (PPVs) of the HC2 assay and PCR in detecting high-grade intraepithelial lesions (HSILs) were 4.5% (95% CI, 3.5 to 5.5%) and 3.6% (95% CI, 2.7 to 4.5%), respectively, and the negative predictive values (NPVs) were 99.6% (95% CI, 99.3 to 99.9%) and 99.3% (95% CI, 98.9 to 99.7%), respectively. The sensitivities of the HC2 assay and PCR for the detection of HSILs were 85.2 and 74.0%, respectively, and the specificities were 67.2 and 64.1%, respectively. In receiver operating characteristic (ROC) analysis, the performance of the HC2 assay for the detection of HSILs was excellent (P = 0.0001); the area under the ROC analysis curve was 0.858 (95% CI, 0.811 to 0.905), and the optimal balance between sensitivity (86.5%) and specificity (80%) was obtained with an HC2 assay cutoff level of 15.6 relative light units/positive control. Use of this cutoff would increase the specificity of the HC2 assay to 80.0% without compromising sensitivity. In conclusion, the results of PCR and the HC2 assay were concordant for 85% of samples, resulting in substantial reproducibility. Both tests had low PPVs, equal specificities, and equal (almost 100%) NPVs for the detection of HSILs; but the sensitivity of the HC2 assay was slightly better.  相似文献   
7.
Summary Induction of microtubulin paracrystals (Pc) by Kunjin (KUN) virus occurred after 15 hours post-infection and were often associated with convoluted membranes (cm) and virus particles. Vinblastine sulphate which disrupts microtubulin, had an inhibitory effect on the virus production when added during the viral latent period. When infected samples were extracted with Triton X-100 and analysed by SDS-PAGE, four viral proteins were observed.  相似文献   
8.
Patients with retinoblastoma have an increased risk of developing second primary tumors. Only a few examples of sinonasal small cell neoplasms developing after radiation therapy for retinoblastoma have been reported. We report one such case that developed 18 years after treatment for retinoblastoma. Histologic examination revealed a small, blue, round cell tumor without rosettes or cytoplasmic glycogen. Immunohistochemically, the tumor cells were positive for neuron-specific enolase, synaptophysin, and S-100 protein, but negative for epithelial and mesenchymal markers, suggesting that this was a primitive neuroectodermal tumor. Cytogenetic studies of this tumor failed to reveal the chromosome 13 abnormality typical of retinoblastoma and the t(11:22) translocation typical of the group of peripheral neuroepitheliomas.  相似文献   
9.
Previous retrospective studies have demonstrated improved outcome in patients whose donors were matched for non-HLA markers in the MHC as well as for HLA genes. Forty patients receiving transplants from unrelated donors were typed prospectively for HLA and non-HLA markers. Non-HLA markers near HLA-B (beta-block markers) and in the DRB1 introns (delta-block markers) were used to assess MHC match between donors and recipient. Patients whose donors were matched at the beta- and delta-blocks had improved event free survival (63%) compared to patients whose donors were mismatched at one or both blocks (25%) (p < 0.05). Patients whose donors were matched at the beta-block had significantly less severe acute graft versus host disease (p < 0.05). In order to investigate the basis for improved outcome block matching was correlated with HLA matching as determined by DNA sequencing. Beta-block matching was highly correlated with matching for exons 2 and 3 of HLA-B but less so for HLA-C. Delta-block matching was highly correlated with matching for exon 2 of HLA DRB1. It is concluded that matching for non-HLA markers in the MHC improves matching for HLA genes. Further studies are required to determine whether matching for non-HLA markers improves outcome to a greater extent than matching for the HLA genes alone.  相似文献   
10.
BACKGROUND: Severe acute respiratory syndrome (SARS) became a worldwide outbreak with a mortality of 9.2%. This new human emergent infectious disease is dominated by severe lower respiratory illness and is aetiologically linked to a new coronavirus (SARS-CoV). METHODS: Pulmonary pathology and clinical correlates were investigated in seven patients who died of SARS in whom there was a strong epidemiological link. Investigations include a review of clinical features, morphological assessment, histochemical and immunohistochemical stainings, ultrastructural study, and virological investigations in postmortem tissue. RESULTS: Positive viral culture for coronavirus was detected in most premortem nasopharyngeal aspirate specimens (five of six) and postmortem lung tissues (two of seven). Viral particles, consistent with coronavirus, could be detected in lung pneumocytes in most of the patients. These features suggested that pneumocytes are probably the primary target of infection. The pathological features were dominated by diffuse alveolar damage, with the presence of multinucleated pneumocytes. Fibrogranulation tissue proliferation in small airways and airspaces (bronchiolitis obliterans organising pneumonia-like lesions) in subpleural locations was also seen in some patients. CONCLUSIONS: Viable SARS-CoV could be isolated from postmortem tissues. Postmortem examination allows tissue to be sampled for virological investigations and ultrastructural examination, and when coupled with the appropriate lung morphological changes, is valuable to confirm the diagnosis of SARS-CoV, particularly in clinically unapparent or suspicious but unconfirmed cases.  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