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   2676篇
  免费   107篇
  国内免费   7篇
耳鼻咽喉   122篇
儿科学   40篇
妇产科学   179篇
基础医学   333篇
口腔科学   10篇
临床医学   152篇
内科学   953篇
皮肤病学   9篇
神经病学   190篇
特种医学   87篇
外科学   200篇
综合类   13篇
预防医学   95篇
眼科学   21篇
药学   230篇
中国医学   3篇
肿瘤学   153篇
  2024年   3篇
  2023年   17篇
  2022年   121篇
  2021年   191篇
  2020年   59篇
  2019年   60篇
  2018年   93篇
  2017年   56篇
  2016年   58篇
  2015年   74篇
  2014年   79篇
  2013年   134篇
  2012年   209篇
  2011年   202篇
  2010年   100篇
  2009年   75篇
  2008年   160篇
  2007年   204篇
  2006年   164篇
  2005年   181篇
  2004年   166篇
  2003年   173篇
  2002年   127篇
  2001年   17篇
  2000年   3篇
  1999年   6篇
  1998年   9篇
  1997年   7篇
  1996年   9篇
  1995年   3篇
  1993年   1篇
  1992年   3篇
  1991年   4篇
  1989年   1篇
  1988年   3篇
  1987年   2篇
  1986年   2篇
  1985年   2篇
  1983年   3篇
  1982年   3篇
  1981年   2篇
  1980年   2篇
  1977年   1篇
  1976年   1篇
排序方式: 共有2790条查询结果,搜索用时 15 毫秒
21.
22.
23.
The aim of this study was to determine the existence of cosmic spherules in oceanic sediments. Two cores recovered from the Clarion-Clipperton fault zone (northeastern Pacific Basin) contain magnetic spherules of extraterrestrial origin. Their chemical compositions and morphological features show the degree of heterogeneity of cosmic material reaching the earth??s surface. The diverse origins of spherules from the Pacific Ocean explains their diverse composition and does not allow for the classification of the material into a single group. In addition, the time interval over which sediments accumulated extends for an estimated period of approximately 200 000 years to the present.  相似文献   
24.
25.
There are no previous studies of the association between prediagnostic serum vitamin D concentration and glioma. Vitamin D has immunosuppressive properties; as does glioma. It was, therefore, our hypothesis that elevated vitamin D concentration would increase glioma risk. We conducted a nested case-control study using specimens from the Janus Serum Bank cohort in Norway. Blood donors who were subsequently diagnosed with glioma (n = 592), between 1974 and 2007, were matched to donors without glioma (n = 1112) on date and age at blood collection and sex. We measured 25-hydroxyvitamin D [25(OH)D], an indicator of vitamin D availability, using liquid chromatography coupled with mass spectrometry. Seasonally adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs) were estimated for each control quintile of 25(OH)D using conditional logistic regression. Among men diagnosed with high grade glioma >56, we found a negative trend (P = .04). Men diagnosed ≤ 56 showed a borderline positive trend (P = .08). High levels (>66 nmol/L) of 25(OH)D in men >56 were inversely related to high grade glioma from ≥2 yr before diagnosis (OR = 0.59; 95% CI = 0.38, 0.91) to ≥15 yr before diagnosis (OR = 0.61; 95% CI = 0.38,0.96). Our findings are consistent long before glioma diagnosis and are therefore unlikely to reflect preclinical disease.  相似文献   
26.
Life‐threatening arrhythmia is an unusual complication of endomyocardial biopsy in transplanted heart. Herein we described a case of VF during endomyocardial biopsy. The possibility of VF during a biopsy necessitates immediate access to defibrillation during endomyocardial biopsy.  相似文献   
27.
Empyema is a severe complication of different diseases and traumas. Management of this complication is difficult and should comprise general and local procedures. The general procedure is mainly based on administering wide-spectrum antibiotics. Local management depends on patient general condition, but in all cases the essential procedure is to insert a drain into the pleural cavity and to evacuate the pus. Sometimes pus is very thick and its evacuation and following re-expansion of the lung is rather impossible. In these patients surgical intervention is needed. The use of intrapleural enzymes to support the drainage was first described in 1949 by Tillett and Sherry using a mixture of streptokinase and streptococcal deoxyribonuclease. Nowadays, purified streptokinase has come into widespread use, but recent studies reported no streptokinase effect on pus viscosity. On the other side, deoxyribonuclease reduces pus viscosity and may be more useful in treatment. We report two cases of intrapleural administration of Pulmozyme (alfa dornase – deoxyribonuclease (HOFFMANN-LA ROCHE AG) in dosage 2 × 2.5 mg with a significant improvement caused by changes in pus viscosity.  相似文献   
28.
29.
30.
An abnormal serum immunoglobulin free light chain (FLC) ratio at diagnosis may identify risk of progression to myeloma in patients with solitary bone plasmacytoma (SBP). In the cohort of 116 patients, 43 have progressed to myeloma, with a median time to progression of 1.8 years. The FLC ratio was determined in all 116 patients on serum collected at time of diagnosis and was abnormal in 54 patients (47%). An abnormal FLC ratio was associated with a higher risk of progression to myeloma (P = .039). The risk of progression at 5 years was 44% in patients with an abnormal serum FLC ratio at diagnosis compared with 26% in those with a normal FLC ratio. One to 2 years following diagnosis, a persistent serum M protein level of 5 g/L (0.5 g/dL) or higher was an additional risk factor for progression. A risk stratification model was constructed using the 2 variables of FLC ratio and M protein level: patients with a normal FLC ratio at baseline and M protein level less than 5 g/L (0.5 g/dL) at 1 to 2 years following diagnosis (low risk, n = 31); with either risk factor abnormal (intermediate risk, n = 26); and with both an abnormal FLC ratio and M protein level of 5 g/L (0.5 g/dL) or higher (high risk, n = 18). The corresponding progression rates at 5 years were significantly different in the low, intermediate, and high groups: 13%, 26%, and 62%, respectively (P < .001).  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