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   950篇
  免费   27篇
  国内免费   31篇
耳鼻咽喉   2篇
儿科学   31篇
妇产科学   15篇
基础医学   84篇
口腔科学   17篇
临床医学   89篇
内科学   112篇
皮肤病学   17篇
神经病学   55篇
特种医学   224篇
外科学   95篇
综合类   38篇
预防医学   68篇
眼科学   13篇
药学   66篇
中国医学   12篇
肿瘤学   70篇
  2022年   11篇
  2021年   19篇
  2020年   14篇
  2019年   10篇
  2018年   24篇
  2017年   18篇
  2016年   21篇
  2015年   23篇
  2014年   33篇
  2013年   41篇
  2012年   66篇
  2011年   66篇
  2010年   34篇
  2009年   28篇
  2008年   48篇
  2007年   47篇
  2006年   38篇
  2005年   29篇
  2004年   28篇
  2003年   32篇
  2002年   26篇
  2001年   16篇
  2000年   17篇
  1999年   12篇
  1998年   19篇
  1997年   32篇
  1996年   22篇
  1995年   10篇
  1994年   15篇
  1993年   11篇
  1992年   10篇
  1991年   10篇
  1990年   11篇
  1989年   26篇
  1988年   8篇
  1987年   9篇
  1986年   14篇
  1985年   10篇
  1984年   8篇
  1982年   8篇
  1980年   11篇
  1975年   6篇
  1974年   4篇
  1971年   5篇
  1970年   3篇
  1969年   3篇
  1968年   9篇
  1967年   4篇
  1966年   7篇
  1965年   4篇
排序方式: 共有1008条查询结果,搜索用时 0 毫秒
101.
Journal of Assisted Reproduction and Genetics - What is the trend in sperm parameters in a group of men attending a single reproductive center, over a 10-year period? A retrospective study was...  相似文献   
102.
103.
Echocardiography may miss prosthetic heart valve (PHV) endocarditis which advocates for novel imaging techniques to improve diagnostic accuracy and patient outcome. The purpose of this study was to determine the complementary diagnostic value of cardiac computed tomography angiography (CTA) to the clinical routine workup including transthoracic and transesophageal echocardiography (TTE/TEE) in patients with suspected PHV endocarditis and its impact on patient treatment. A diagnostic prospective cross-sectional study was chosen as design. Besides clinical routine workup (including TTE/TEE), CTA was performed to assess its diagnostic accuracy and complementary diagnostic/therapeutic value. For the diagnostic accuracy, the reference standard was surgical findings or clinical follow-up. To determine the complementary diagnostic/therapeutic value an expert-panel was used as reference standard. Twenty-eight patients were included. CTA resulted in a major diagnostic change in six patients (21 %) mainly driven by novel detection of mycotic aneurysms by CTA. Furthermore, treatment changes occurred in seven patients (25 %) compared to clinical routine workup. Diagnostic accuracy of routine clinical workup plus CTA was superior to clinical routine workup alone for the detection of PHV endocarditis in general, vegetations and peri-annular extension. This study demonstrates that CTA and clinical workup including TTE and TEE are complementary in patients with PHV endocarditis. Therefore, CTA imaging has to be considered after clinical routine workup in patients with a high suspicion on PHV endocarditis.  相似文献   
104.
105.
Aims: The aim of this study was to develop and refine a decision rule on when to undertake brain imaging (BI) in neurologically normal children with headaches. Methods: From the literature and a questionnaire study, a list of red flags (RFs) was drawn‐up. During the prospective 4‐year period, consecutive children with headache were classified according to RFs and the headache diagnosis. Result: Three of 709 (0.4%) neurologically normal children had significant brain abnormalities. BI was carried out in 389 of 498 (78%) children with RFs. Significant abnormalities were found in three of 389 children (0.8%), all had unclassified headache (UH). BI was not arranged for the 211 children with no RFs. None of these developed RFs or abnormal signs on follow‐up for a mean of 13 months. Conclusion: In addition to BI for those with neurological signs, we think BI should be considered for neurologically normal patients with UH and RFs. This would have saved imaging children needlessly: only 101 of 709 (14%) would have had scans arranged, instead of 389 of 709.  相似文献   
106.
Jolles  PR; Shin  MS; Jones  WP 《Radiology》1986,159(3):647-651
A retrospective morphologic study of 80 cases was undertaken to determine factors affecting detectability of computed tomographically (CT) proved aortopulmonary (AP) window lesions on conventional posteroanterior (PA) and lateral chest radiographs. Criteria used for determining abnormality were: solitary lymph node enlargement over 1.5 cm or three or more 1-cm nodes and obvious large masses or vascular anomalies. CT scans and corresponding PA and lateral radiographs were analyzed for lesion detectability, size, and location. In 49% of cases there was no detectable lesion in the AP window on radiographs; a definite AP window lesion was seen in 41%, and 10% were equivocal. Major contributing factors to low detectability of AP window lesions on radiographs include size and, more important, location of the lesion. An additional 45 cases of CT-proved normal AP windows were retrospectively reviewed to determine the false-positive rate of PA and lateral radiographs in detection of AP window lesions: 43 (96%) were classified as negative, the remaining two (4%) as equivocal. Although the AP window is a small space, it is the site of many pathologic conditions; the study results indicate that CT may be an essential procedure for its evaluation.  相似文献   
107.
Six normal and 16 neoplastic colorectal specimens were examined with 8.5-MHz ultrasound (US). An articulated system facilitated precise spatial correlation between US and histologic sections. Images were blindly interpreted and then compared with histologic results. All six normal specimen showed five distinct echo layers and were distinguished from neoplastic specimens by all the observers. The central echogenic layer, corresponding to the submucosa, is useful in determining the depth of origin of a neoplasm and the presence of submucosal invasion. US had an accuracy of 92.5% in demonstrating invasion of the submucosa and 77% for invasion of the muscularis externa. For mucosal neoplasms with invasion through the muscularis externa and extension into the subserosal tissues, nearly 90% of US interpretations were correct. High-frequency US may be useful in determining the depth of invasion of mucosal tumors with respect to the submucosa and in differentiating mucosal from extramural masses.  相似文献   
108.
109.
Phosphorus-31 MR spectroscopy of the human testis was performed on healthy volunteers (n = 17) and oligospermic (n = 7) and azoospermic patients (n = 4). All patients in the latter group had the Sertoli-cell-only syndrome. Determination of the ratios of phosphomonoesters (PMs) to adenosine triphosphate (ATP), phosphodiesters (PDs) to ATP, and inorganic phosphate (Pi) to ATP made it possible to discriminate among these three groups. The testicular PM/ATP ratio was 1.71 +/- 0.03 (mean +/- standard deviation) in the healthy volunteers and dropped to 1.41 +/- 0.06 (P less than .001 in comparison with healthy volunteers) in the oligospermic patients and to 1.22 +/- 0.07 (P less than .001) in the azoospermic patients. The testicular PD/ATP ratio did show a slight increase from 0.52 +/- 0.10 in healthy volunteers to 0.68 +/- 0.09 (not significant) for oligospermic patients and to 0.83 +/- 0.10 (P less than .01) for azoospermic patients. The Pi/ATP ratio did not show significant differences between healthy volunteers (0.12 +/- 0.07) and oligospermic patients (0.23 +/- 0.08) but was elevated in the azoospermic patients (0.79 +/- 0.12) (P less than .001).  相似文献   
110.
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