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   986篇
  免费   53篇
  国内免费   15篇
耳鼻咽喉   4篇
儿科学   47篇
妇产科学   6篇
基础医学   111篇
口腔科学   16篇
临床医学   127篇
内科学   210篇
皮肤病学   21篇
神经病学   23篇
特种医学   152篇
外科学   46篇
综合类   106篇
预防医学   61篇
眼科学   3篇
药学   69篇
中国医学   4篇
肿瘤学   48篇
  2022年   10篇
  2021年   10篇
  2020年   5篇
  2019年   7篇
  2018年   10篇
  2017年   10篇
  2016年   13篇
  2015年   22篇
  2014年   38篇
  2013年   30篇
  2012年   33篇
  2011年   43篇
  2010年   40篇
  2009年   40篇
  2008年   46篇
  2007年   37篇
  2006年   28篇
  2005年   23篇
  2004年   17篇
  2003年   28篇
  2002年   24篇
  2001年   19篇
  2000年   16篇
  1999年   22篇
  1998年   51篇
  1997年   43篇
  1996年   32篇
  1995年   20篇
  1994年   28篇
  1993年   24篇
  1992年   10篇
  1991年   19篇
  1990年   14篇
  1989年   21篇
  1988年   25篇
  1987年   40篇
  1986年   14篇
  1985年   20篇
  1984年   11篇
  1983年   9篇
  1982年   15篇
  1981年   9篇
  1980年   7篇
  1978年   11篇
  1977年   4篇
  1976年   13篇
  1975年   10篇
  1973年   4篇
  1972年   4篇
  1970年   5篇
排序方式: 共有1054条查询结果,搜索用时 15 毫秒
1.
Background: Gastrointestinal stromal tumors (GIST) are one of the most common mesenchymal tumors of the gastrointestinal tract. GIST are defined by positive immunohistochemical staining for KIT or CD34 and thus are generally diagnosed after surgery. Because small GIST are rarely diagnosed before surgery, the clinical course of these small tumors is not clear. The aim of the present study was to follow changes in size and configuration of small GIST that were pathologically confirmed using endoscopic ultrasonography‐guided fine‐needle aspiration biopsy (EUS‐FNAB). Methods: Between July 1997 and December 2003, 16 tumors in 16 patients (10 men and 6 women) with an immunohistochemical diagnosis of GIST were regularly followed in our hospital. The median patient age when EUS‐FNAB was performed was 62 years (range 26–82 years) and the median follow‐up period was 4.9 years (range 0.5–9.6 years). Results: Fourteen tumors showed no remarkable changes in size and shape during follow up compared with the initial diagnosis. Two tumors enlarged: one tumor approximately doubled its diameter in 8 years and the other tumor increased from 1.8 cm at diagnosis to up to 10 cm after only 2 years. Doubling time of the latter tumor was calculated as 3.1 months. Conclusions: We conclude that EUS‐FNAB might be a good modality for final diagnosis of GIST without surgery, and that GIST without rapid growth on follow up can be endoscopically followed.  相似文献   
2.
The activity of LCAT (the controlling enzyme for cholesterol esterification in plasma) is known to be reduced in alcoholic cirrhosis, while little is known about early stage (liver steatosis) alcoholics. In this study, LCAT activity was assayed by Stokke and Norum's method, before and after a 15-day sobriety period, in liver steatosis and in cirrhosis alcoholics. Before alcohol withdrawal, LCAT activity was depressed in both groups. After the sobriety period, LCAT activity was significantly raised in liver steatosis patients, but was still lower than in controls; in cirrhosis patients, it was increased, but not significantly. According to our results, LCAT activity impairment in alcoholic liver disease is sustained by both the hypothesized mechanisms, alcohol-related metabolic disorders and lowered LCAT-enzyme production, but to different degrees, depending on the stage of the disease. In liver steatosis, metabolic disorders play a major role, as a liver-impairment-induced decrease in LCAT production seems rather unlikely, and increased LCAT activity is more likely to be sustained by metabolic normalisation than by any recovery of the damaged liver. However, the lack of improvement in about 20% of patients, and the fairly wide scattering of individual data, suggest a minor LCAT production impairment in liver steatosis too. In cirrhosis, the major role seems to be played by a permanent decrease in LCAT production, as no significant rise in LCAT activity was observed after alcohol withdrawal. However the restored LCAT activity observed in some patients could be related to improvement in the metabolic disorder, thus confirming the effectiveness of this mechnism in cirrhosis too.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
3.
Coronary artery bypass grafts: visualization with MR imaging   总被引:1,自引:0,他引:1  
Gomes  AS; Lois  JF; Drinkwater  DC  Jr; Corday  SR 《Radiology》1987,162(1):175
  相似文献   
4.
5.
6.
7.
The purpose of the study was to identify maxim allowable concentrations of urea in reclaimed potable water. The urea concentration equal to 80 mg/l is the threshold dose influencing the taste and flavor of water. Urea is a low toxicity substance (LD50 = 14,300 mg/kg), the effect of which is not cumulative. However, when used in high doses it affects bioenergetic and cholinergic processes and causes changes in ECG, higher nervous activity and visceral structure. It has been shown that when applied to warm-blooded animals the acting dose of urea is 14.3 and 1.43 mg/kg (1/1000 and 1/10000 LD50), the threshold dose is 0.72 mg/kg (1/20000 LD50), and the ineffective dose is 0.36 mg/kg (1/40000 LD50) which amounts to the concentration of 10 mg/l. In terms of toxic effects the dose equal to 10 mg/l is taken to be the maximally allowable concentration of urea. It is recommended to use the Laham biotest for measuring urea in water.  相似文献   
8.
9.
10.
A new commercial test for the diagnosis of rotavirus gastroenteritis was assessed. With some modifications it compared favourably with electron microscopy and immunofluorescence.  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