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   742篇
  免费   59篇
  国内免费   22篇
耳鼻咽喉   4篇
儿科学   53篇
妇产科学   6篇
基础医学   72篇
口腔科学   42篇
临床医学   72篇
内科学   126篇
皮肤病学   27篇
神经病学   21篇
特种医学   222篇
外科学   35篇
综合类   34篇
预防医学   35篇
眼科学   4篇
药学   22篇
肿瘤学   48篇
  2019年   3篇
  2018年   11篇
  2017年   7篇
  2016年   10篇
  2015年   9篇
  2014年   15篇
  2013年   11篇
  2012年   10篇
  2011年   8篇
  2010年   19篇
  2009年   21篇
  2008年   19篇
  2007年   13篇
  2006年   14篇
  2005年   7篇
  2004年   12篇
  2003年   8篇
  2002年   3篇
  2001年   11篇
  2000年   9篇
  1999年   12篇
  1998年   42篇
  1997年   45篇
  1996年   41篇
  1995年   37篇
  1994年   23篇
  1993年   31篇
  1992年   20篇
  1991年   21篇
  1990年   14篇
  1989年   25篇
  1988年   28篇
  1987年   45篇
  1986年   25篇
  1985年   16篇
  1984年   8篇
  1983年   12篇
  1982年   14篇
  1981年   20篇
  1980年   17篇
  1979年   8篇
  1978年   7篇
  1977年   9篇
  1976年   21篇
  1975年   10篇
  1934年   4篇
  1933年   3篇
  1930年   3篇
  1927年   4篇
  1926年   4篇
排序方式: 共有823条查询结果,搜索用时 15 毫秒
1.
2.
3.
FM sonography - a signal-processing technique that uses frequency and phase information as well as amplitude data - shows promise in evaluation of patients with diffuse liver disease. In a prospective blinded review of 37 patients with biopsy-proved liver disease and 42 healthy volunteers, FM sonography was clearly superior to traditional amplitude-based (AM) sonography in distinguishing healthy from diseased subjects. Statistically significant differences were seen in accuracy (FM, 98.7%; AM, 84.8%), sensitivity (FM, 97.3%; AM, 70.3%), and negative predictive value (FM, 97.7%; AM, 78.8%). Our data also suggest that current FM sonographic techniques cannot differentiate among histologic findings associated with different hepatic parenchymal abnormalities. It is unclear, therefore, whether FM imaging can reduce the numbers of patients who require biopsy for diagnosis or the frequency of biopsy procedures in patients with known disease.  相似文献   
4.
Anaerobic threshold and performance in middle and long distance running.   总被引:2,自引:0,他引:2  
A total of 112 endurance athletes, divided in three groups according to their age, were selected considered in this study. Thirtythree randomly subjects (11 per each age group) were both laboratory--and field--tested for anaerobic threshold (AT) determination. The running speed (RS) and heart rate (HR) at which AT occurred were highly correlated in the two conditions, with R ranging from 0.82 to 0.90, with the highest correlation for the oldest group. All the athletes participated a series of competition races at various distances, and the correlation between RS at AT and actual racing RS was calculated. It was found that RS at AT is highly correlated with racing RS for distances from 5 km and above, with the highest correlation found in the 10 km race for the 12-18 years and the 19-30 years age groups, and for the one hour race for the oldest group. Shorter distances (e.g. 800 m) did not show significant correlation with RS at AT, and this was particularly evident for the oldest group (R = 0.30).  相似文献   
5.
6.
7.
Development of a new wound dressing with antimicrobial delivery capability   总被引:1,自引:0,他引:1  
A bilaminar wound dressing composed of an outer membrane and an inner three-dimensional matrix of a fabric or a sponge may be considered to constitute an ideal structure that promotes wound healing: the outer membrane prevents body fluid loss, controls water evaporation, and protects the wound surface from bacterial invasion, and the inner matrix encourages adherence by tissue growth into the matrix. Using this concept, we developed a biosynthetic wound dressing with a drug delivery capability. This medicated wound dressing is composed of a spongy sheet of a chitosane derivative and collagen mixture that is laminated to an antimicrobial-impregnated polyurethane membrane. In this study, a gentamycin sulfate-impregnated wound dressing was prepared and evaluated. The antimicrobial efficacy of this wound dressing was examined on an agar plate seeded with Pseudomonas aeruginosa. Also, the cytotoxicity of an antimicrobial released from this wound dressing was examined in an in vitro system with cultured skin substitutes. Both in vitro tests have shown that this wound dressing is capable of suppressing bacterial growth and minimizing cellular damage. In addition, in the treatment of wounds inflicted on rats and rabbits, this wound dressing was shown to be efficacious in covering full-thickness and split-thickness skin defects. Finally, the efficacy of this wound dressing was evaluated in a nonrandomized open-label study of 31 clinical cases. In 31 cases treated with this wound dressing, good or excellent wound healing was achieved.  相似文献   
8.
The use of self-expanding prostheses in the management of malignant oesophageal strictures has become well established. The majority of benign peptic oesophageal strictures can be successfully managed using endoscopic or fluoroscopically guided balloon oesophageal dilatation combined with long-term drug therapy, particularly using proton pumper inhibitors. Although endoscopic oesophageal dilatation can be performed on an outpatient basis, it requires repeated hospital visits. There is a small risk of oesophageal perforation whilst cardio-respiratory complications may be encountered during the use of intravenous sedation in an elderly population. The use of a self-expanding Strecker stent in a 98 year old woman with a benign oesophageal stricture is described.  相似文献   
9.
Lynch  DA; Gamsu  G; Ray  CS; Aberle  DR 《Radiology》1988,169(3):603-607
In 260 asbestos-exposed individuals evaluated by means of computed tomography (CT), 43 unsuspected pulmonary masses were found in 27 individuals. The masses included fissural pleural plaques (n = 10), dense fibrotic bands (n = 3), round atelectasis (n = 11), carcinomas (n = 3), and other presumed benign masses (n = 16). The most helpful features in the diagnosis of rounded atelectasis with CT were (a) contiguity to areas of diffuse pleural thickening, (b) a lentiform or wedge-shaped outline, (c) evidence of volume loss in the adjacent lung, and (d) a characteristic "comet tail" of vessels and bronchi sweeping into the margins of the mass. Less advanced areas of focal atelectasis had fewer classic features. Intrafissural pleural plaques were readily identified with high-resolution CT. In asbestos-related masses, the demonstration of stability over time is necessary. Careful interpretation of CT and high-resolution CT features and close surveillance can obviate the need for biopsy in the majority of instances.  相似文献   
10.
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