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   335篇
  免费   12篇
  国内免费   52篇
耳鼻咽喉   48篇
儿科学   12篇
基础医学   28篇
口腔科学   7篇
临床医学   58篇
内科学   60篇
皮肤病学   4篇
神经病学   4篇
特种医学   70篇
外科学   51篇
综合类   9篇
预防医学   9篇
药学   27篇
肿瘤学   12篇
  2020年   2篇
  2018年   3篇
  2017年   2篇
  2016年   3篇
  2015年   3篇
  2014年   5篇
  2013年   8篇
  2012年   7篇
  2011年   5篇
  2010年   11篇
  2009年   11篇
  2008年   7篇
  2007年   49篇
  2006年   15篇
  2005年   19篇
  2004年   6篇
  2003年   2篇
  2002年   7篇
  2001年   6篇
  2000年   9篇
  1999年   7篇
  1998年   24篇
  1997年   12篇
  1996年   23篇
  1995年   15篇
  1994年   21篇
  1993年   10篇
  1992年   3篇
  1991年   8篇
  1990年   6篇
  1989年   11篇
  1988年   8篇
  1987年   7篇
  1986年   14篇
  1985年   6篇
  1984年   3篇
  1981年   4篇
  1980年   3篇
  1979年   1篇
  1978年   3篇
  1977年   6篇
  1976年   5篇
  1975年   4篇
  1973年   2篇
  1972年   3篇
  1971年   2篇
  1970年   1篇
  1968年   1篇
  1962年   1篇
  1959年   1篇
排序方式: 共有399条查询结果,搜索用时 15 毫秒
1.
2.
The treatment of pediatric laryngotracheal stenosis using open surgery to expand the airway has become a widely accepted and effective method. Stents and cartilage grafts represent the main features of expansion laryngotracheal surgery, which is indicated after failure of endoscopic treatment and/or in the presence of severe stenosis. Stenting is needed in all situations with the exception of using a single cartilage graft in the anterior subglottic lumen. There are several options available for stenting. The most valuable and commonly used stents are the Aboulker stent and the Silastic sheet roll. In looking for the features of an ideal stent, I analyzed 51 procedures using the Aboulker stent on 48 patients. The purpose of this report is to discuss these features and relate them to the Aboulker stent.  相似文献   
3.
Uroscopy in the 21st century: high-field NMR spectroscopy   总被引:1,自引:1,他引:0  
From the experiments described, it can be seen that there are different research approaches that can be taken and these are summarized in Table 1. Whereas much scientific research is principally hypothesis led, there remains, nevertheless, an important place for exploratory research. High resolution NMR can measure, directly and simultaneously, a wide range of endogenous metabolites in biological fluids and has the unique capability of providing structural information on the metabolites detected. It has proved to be a powerful research tool with which to study inherited metabolic diseases, renal disease, drug metabolism, and toxicity, and can be used to monitor the effects of drug therapy. For instance, by using a library of experimental toxins one can map the metabolic profile of site-specific nephron injury. With this approach in man one could eventually take an unknown disease such as Balkan nephropathy and predict the initial site of tubular injury, the mode of injury and therefore the kind of toxin capable of producing that injury. NMR spectroscopic techniques are still advancing rapidly, with ever increasing sensitivity and sophistication of NMR pulse sequences to enhance structural elucidation in complex mixtures. Given the advances in directly coupled HPLC-NMR and even HPLC-NMR-mass spectroscopy it is likely that these technologies in conjunction with pattern recognition will make major contribution to our understanding of renal processes and provide new diagnostic insights in the 21st century.   相似文献   
4.
5.

Background  

Correct diagnosis in psychiatry may be improved by novel diagnostic procedures. Computerized Decision Support Systems (CDSS) are suggested to be able to improve diagnostic procedures, but some studies indicate possible problems. Therefore, it could be important to investigate CDSS systems with regard to their feasibility to improve diagnostic procedures as well as to save time.  相似文献   
6.
Cystic hypersecretory carcinoma (CHC) is a rare variant of intraductal carcinoma. A CHC in a 50-year-old woman was excised and processed for light and electron microscopy and immunohistochemistry. The tumor had a marked cystic appearance. The walls of the cysts consisted of epithelial and myoepithelial cells and a well-developed basement membrane. The epithelial cells contained well-developed rough-surfaced endoplasmatic reticulum and Golgi apparatus. Secretory granules were not detected, with the exception of a few mucus-producing cells. The secretion was predominantly homogenous, reminiscent of thyroid colloid, and demonstrated distinct PAS positivity. The cells displayed a strong labeling with epithelial membrane antigen (EMA) and EMA-positive structures were observed within the intraluminal secretion, too. Some of these were stained by alcian blue. In addition, the colloid-like material was admixed with mucus showing a filamentous internal structure and lipid droplets resulting in some heterogenity of the secretion. Intraductal micropapillary proliferation in some of the cysts and adjacent nondistended ducts was a further defining feature of the tumor. Steroid hormone receptor and Ki-67 proliferation marker immuno his Tochemistry showed scattered positivity among the tumor cells. These results are in agreement with previous observations and further clarify the nature of this low-grade in situ cancer.  相似文献   
7.
The diagnosis of laryngotracheal stenosis should be suspected in children with stridor, feeding difficulties, or atypical croup. Only half of the children with congenital laryngotracheal stenosis require tracheotomy, and many of these children can be decannulated following uncomplicated surgical therapy. In contrast, tracheotomy-dependent patients with acquired laryngotracheal stenosis require more extensive surgical intervention, which should be carried out as early as possible to provide the best opportunity for developing normal oral communication. Received: 8 March 1977 / Accepted: 31 July 1997  相似文献   
8.

BACKGROUND:

Flavonoids are polyphenolic substances with antioxidant properties, and they are found in different vegetables and fruits. Epidemiological studies have shown that the consumption of flavonoids reduces the prevalence of cardiovascular diseases. The use of synthetic antioxidants, however, has been limited because of their toxicity. Therefore, medical researchers have intensified their quest to find natural antioxidants.

OBJECTIVES:

To investigate the effect of several pure flavonoids, such as kaempferol, quercetin, morin and rutin, on red blood cell hemolysis and evaluate their -SH capacity as an indicator of membrane protection.

METHODS:

The rate of hemolysis and cell membrane -SH capacity were determined by spectrophotometry. Red blood cell peroxidation was induced using 2,2′-azo-bis-(2-amidinopropane) dihydrochloride. The effect of each flavonoid on hemolysis was examined at three concentrations (0.5 μg/mL, 5 μg/mL and 10 μg/mL), however, only the greatest concentration (10 μg/mL) of each flavonoid was used to study the effect on -SH groups.

RESULTS:

In all cases, the antioxidant activity was dose-dependent. Rutin showed the highest inhibitory effect on hemolysis among flavonoids (42.5%). The protective effect of kaempferol, rutin and morin against -SH group oxidation measured 7.7%, 23.3% and 26.4%, respectively.

CONCLUSIONS:

Results showed that flavonoids and flavonoid-containing plants can be used as natural antioxidants for the treatment and prevention of disease conditions, the pathogenesis of which is mediated by lipid peroxidation.  相似文献   
9.
10.

Background  

Canadian trauma units have relatively little experience with major cardiac trauma (disruption of a cardiac chamber) so injury outcome may not be comparable to that reported from other countries. We compared our outcomes to those of other centers.  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