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   6753篇
  免费   366篇
  国内免费   17篇
耳鼻咽喉   79篇
儿科学   419篇
妇产科学   66篇
基础医学   707篇
口腔科学   319篇
临床医学   486篇
内科学   1331篇
皮肤病学   182篇
神经病学   545篇
特种医学   285篇
外科学   973篇
综合类   105篇
一般理论   2篇
预防医学   264篇
眼科学   319篇
药学   501篇
中国医学   32篇
肿瘤学   521篇
  2023年   42篇
  2022年   92篇
  2021年   252篇
  2020年   120篇
  2019年   192篇
  2018年   196篇
  2017年   173篇
  2016年   202篇
  2015年   229篇
  2014年   330篇
  2013年   383篇
  2012年   592篇
  2011年   605篇
  2010年   324篇
  2009年   268篇
  2008年   400篇
  2007年   407篇
  2006年   340篇
  2005年   359篇
  2004年   309篇
  2003年   232篇
  2002年   231篇
  2001年   60篇
  2000年   71篇
  1999年   68篇
  1998年   42篇
  1997年   30篇
  1996年   29篇
  1995年   23篇
  1994年   20篇
  1993年   26篇
  1992年   43篇
  1991年   35篇
  1990年   29篇
  1989年   37篇
  1988年   28篇
  1987年   34篇
  1986年   28篇
  1985年   28篇
  1984年   21篇
  1983年   15篇
  1982年   26篇
  1981年   14篇
  1980年   15篇
  1979年   13篇
  1978年   16篇
  1977年   13篇
  1976年   15篇
  1972年   12篇
  1970年   12篇
排序方式: 共有7136条查询结果,搜索用时 15 毫秒
1.
2.
3.
Coronavirus disease 2019 (COVID-19) is associated with a high risk of mortality and complications in patients with diabetes mellitus. Achieving good glycemic control is very important in diabetic patients to reduce complications and mortality due to COVID-19. Recent studies have shown the mortality benefit and anti-inflammatory effects of Dipeptidyl-peptidase-4 inhibitors (DPP-4i) in diabetic patients with COVID-19. DPP-4i may have a beneficial role in halting the severity of infection primarily by three routes, namely viral entry inhibition, anti-inflammatory and anti-fibrotic effects and glycemic control. This has raised the pro-mising hypothesis that DPP-4i might be an optimal strategy for treating COVID-19 in patients with diabetes. This review aims to summarise the possible therapeutic non-glycemic effects of DPP-4i in diabetic patients diagnosed with COVID-19 in the light of available evidence.  相似文献   
4.
5.
Acute renal failure (ARF) developed in a 7-week-old infant due to bilateral candidal bezoars (fungal balls) causing obstruction at the pelviureteric junction. The baby was born at term with an appropriate birthweight, and had been treated with broad-spectrum antibiotics for respiratory distress and septicemia during the 1st week of life. Recovery from ARF followed renal decompression with bilateral nephrostomy tube placement and parenteral administration of amphotericin B and 5-flucytosine. Received August 21, 1996; received in revised form and accepted January 3, 1997  相似文献   
6.
We report an unusual case of sporadic adult onset cerebellar ataxia with hypogonadism. A 40-year-old unmarried man presented with progressive ataxia and dysarthria along with complaints of non-development of secondary sexual characteristics and erectile dysfunction. There were complaints of intermittent diarrhea. Clinical examination revealed a pan-cerebellar syndrome with features of hypoandrogenism. No eye movement abnormalities were evident. There were signs of malabsorption. Investigations confirmed the presence of auto-antibodies found in celiac disease, and a duodenal biopsy confirmed the same. Hypoandrogenism was postulated to be due to hypergonadotropic hypogonadism which has been mentioned in a few patients of celiac disease. However, the pattern seen in our patient was of a hypogonadotropic hypogonadism. This is probably secondary to an autoimmune hypophysitis seen in some patients in the absence of other clinical manifestations. Autoantibody testing should be a diagnostic necessity in any adult with a sporadic cerebellar ataxia.  相似文献   
7.
BACKGROUND: Past receiver operating characteristic (ROC) studies have demonstrated that single photon emission computed tomography (SPECT) perfusion imaging by use of iterative reconstruction with combined compensation for attenuation, scatter, and detector response leads to higher area under the ROC curve (A(z)) values for detection of coronary artery disease (CAD) in comparison to the use of filtered backprojection (FBP) with no compensations. A new ROC study was conducted to investigate whether this improvement still holds for iterative reconstruction when observers have available all of the imaging information normally presented to clinical interpreters when reading FBP SPECT perfusion slices. METHODS AND RESULTS: A total of 87 patient studies including 50 patients referred for angiography and 37 patients with a lower than 5% likelihood for CAD were included in the ROC study. The images from the two methods were read by 4 cardiology fellows and 3 attending nuclear cardiologists. Presented for the FBP readings were the short-axis, horizontal long-axis, and vertical long-axis slices for both the stress and rest images; cine images of both the stress and rest projection data; cine images of selected cardiac-gated slices; the CEQUAL-generated stress and rest polar maps; and an indication of patient gender. This was compared with reading solely the iterative reconstructed stress slices with combined compensation for attenuation, scatter, and resolution. With A(z) as the criterion, a 2-way analysis of variance showed a significant improvement in detection accuracy for CAD for the 7 observers (P = .018) for iterative reconstruction with combined compensation (A(z) of 0.895 +/- 0.016) over FBP even with the additional imaging information provided to the observers when scoring the FBP slices (A(z) of 0.869 +/- 0.030). When the groups of 3 attending physicians or 4 cardiology fellows were compared separately, the iterative technique was not statistically significantly better; however, the A(z) for each of the 7 observers individually was larger for iterative reconstruction than for FBP. Compared with results from our previous studies, the additional imaging information did increase the diagnostic accuracy of FBP for CAD but not enough to undo the statistically significantly higher diagnostic accuracy of iterative reconstruction with combined compensation. CONCLUSIONS: We have determined through an ROC investigation that included two classes of observers (experienced attending physicians and cardiology fellows in training) that iterative reconstruction with combined compensation provides statistically significantly better detection accuracy (larger A(z)) for CAD than FBP reconstructions even when the FBP studies were read with all of the extra clinical nuclear imaging information normally available.  相似文献   
8.
9.
BACKGROUND: Dynamic single photon emission computed tomography (SPECT) acquisition and reconstruction of early poststress technetium 99m teboroxime washout images has been shown to be useful in the detection of coronary disease. Assessment of poststress regional wall motion may offer additional use in assessing coronary disease. Our goal was to investigate the feasibility of simultaneously imaging myocardial ischemia and transient poststress akinesis using gated-dynamic SPECT. METHODS AND RESULTS: A gated-dynamic mathematical cardiac torso (MCAT) phantom was developed to model both teboroxime kinetics and cardiac regional wall motion. A lesion was simulated as having delayed poststress teboroxime washout together with a transient poststress wall motion abnormality. Gated projection data were created to represent a 3-headed SPECT system undergoing a total rotation of 480 degrees . The dynamic expectation-maximization reconstruction algorithm with postsmoothing across gating intervals by Wiener filtering, and the ordered-subset expectation maximization reconstruction algorithm with 3-point smoothing across gating intervals were compared. Compared with the ordered-subset expectation maximization with 3-point smoothing, the dynamic expectation-maximization algorithm with Wiener filtering was able to produce visually higher-quality images and more accurate left ventricular ejection fraction estimates. CONCLUSION: From simulations, we conclude that changing cardiac function and tracer localization possibly can be assessed by using a gated-dynamic acquisition protocol combined with a 5-dimensional reconstruction strategy.  相似文献   
10.
We report a 40-year-old man with rheumatic heart disease who presented with abdominal pain for three weeks and hematemesis for 24 hours. CT scan showed a large splenic artery aneurysm without evidence of pancreatitis. Mycotic aneurysm due to infective endocarditis was considered and confirmed by echocardiogram, which showed aortic and mitral valve regurgitation and vegetations. He was managed successfully with coil embolization of the aneurysm and antibiotics.  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