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   2056篇
  免费   134篇
  国内免费   45篇
耳鼻咽喉   16篇
儿科学   96篇
妇产科学   26篇
基础医学   140篇
口腔科学   42篇
临床医学   287篇
内科学   342篇
皮肤病学   44篇
神经病学   61篇
特种医学   288篇
外科学   292篇
综合类   205篇
预防医学   139篇
眼科学   16篇
药学   120篇
  2篇
中国医学   32篇
肿瘤学   87篇
  2022年   30篇
  2021年   34篇
  2020年   33篇
  2018年   22篇
  2017年   22篇
  2016年   18篇
  2015年   34篇
  2014年   48篇
  2013年   74篇
  2012年   77篇
  2011年   87篇
  2010年   90篇
  2009年   107篇
  2008年   70篇
  2007年   79篇
  2006年   82篇
  2005年   52篇
  2004年   51篇
  2003年   50篇
  2002年   47篇
  2001年   36篇
  2000年   29篇
  1999年   28篇
  1998年   82篇
  1997年   74篇
  1996年   72篇
  1995年   67篇
  1994年   41篇
  1993年   50篇
  1991年   19篇
  1990年   14篇
  1989年   30篇
  1988年   43篇
  1987年   39篇
  1986年   29篇
  1985年   33篇
  1984年   19篇
  1983年   24篇
  1982年   16篇
  1980年   16篇
  1977年   15篇
  1976年   14篇
  1963年   17篇
  1960年   14篇
  1959年   22篇
  1958年   29篇
  1957年   19篇
  1956年   30篇
  1955年   42篇
  1954年   35篇
排序方式: 共有2235条查询结果,搜索用时 0 毫秒
101.
102.
The authors describe a simple technique for diagnosis of tricuspid regurgitation. Red blood cells were labeled in vivo with 99mTc and 22 patients were studied with ECG-gated blood-pool imaging of the liver. A single region of interest was manually drawn around the liver and a time-activity curve obtained. The per cent change in liver counts during the cardiac cycle was found to be significantly higher in the 12 patients with tricuspid regurgitation (Group I) (mean, 4.04 +/- 1.6%; range, 1.3-21.4%) compared with the 10 controls (Group II) (mean, 0.35 +/- 0.16%; range, 0.013-1.3%) (p less than 0.05). Using a 1% change in liver counts as the criterion of a positive study, all 12 cases in Group I were diagnosed correctly, but there was one false positive in Group II; thus the sensitivity was 100% and the specificity 90%.  相似文献   
103.
We have investigated the possible hepatic microsomal enzymeinduction effect of enflurane, administered by inhalation inanaesthetic doses for periods of 1 h a day. In 15 experimentalgroups, differing from one another in anaesthetic concentration(1,2 and 3% enflurane) and in the number of days of treatment(3,7, 10,14,21 and 24) we found (1) no alteration either inthe ratio of liver to body weight or in the microsomal proteincontent; (2) no modifications in aniline hydroxylase activity;(3) a decrease in the aminopynne demethylase activity aftera number of exposures, varying with the dose.  相似文献   
104.
Ultrasound diagnosis of hydrocolpos and hydrometrocolpos   总被引:1,自引:0,他引:1  
Wilson  DA; Stacy  TM; Smith  EI 《Radiology》1978,128(2):451
  相似文献   
105.
106.
107.

OBJECTIVE:

Inflammation plays an important role in the development of chronic lung disease (CLD), which has become a major cause of morbidity in surviving infants less than 1250 g at birth. The authors hypothesized that the progression of this inflammation and, therefore, the establishment of CLD would be decreased with the use of early prophylactic inhaled corticosteroids. Short, and long term respiratory and neurodevelopmental outcomes were also examined.

DESIGN:

A double-blind, randomized placebo controlled trial.

SETTING:

Level-III neonatal intensive care unit.

POPULATION STUDIED:

Sixty infants less than 1250 g at birth, diagnosed with respiratory distress syndrome and requiring ventilatory support at 72 h of age were enrolled in the study.

INTERVENTION:

Infants enrolled received either placebo or beclomethasone diproprionate by a metered dose inhaler, which was used in-line with the ventilator circuit while the infant was ventilated and then via a spacer until 28 days of age.

RESULTS:

Thirty infants were given beclomethasone and 30 were given placebo. There were two deaths in each group. Among the surviving infants, the frequency of moderate-to-severe CLD was 17% in each study group. Mean time to extubation was not different for beclomethasone compared with placebo at 16.4 and 12.5 days (P=0.12), respectively. The requirement for intravenous corticosteroids was lower in the beclomethasone-treated group (RR 0.67, 95% CI 0.43 to 1.04), although this difference was not statistically significant. The incidence of growth failure, infection and intraventricular hemmorhage did not differ between the two groups. Long term outcomes were not different with respect to the incidence of respiratory re-admissions, cerebral palsy, developmental delay, blindness or deafness.

CONCLUSIONS:

Early treatment with inhaled beclomethasone diproprionate did not reduce the incidence of CLD or decrease the duration of mechanical ventilation. The decrease in intravenous corticosteroid use was not statistically significant. Long term outcome was not affected.  相似文献   
108.
Background The contribution of dysmotility to dysphagia in oesophageal cancer is unclear. Aim To examine oesophageal motility in patients with oesophageal carcinoma and to assess the effect of chemoradiotherapy on motility. Methods Stationary manometry and 24-hour pH-metry were performed in 12 patients with oesophageal carcinoma and one week following completion of chemoradiotherapy using 5-fluorouracil (5-FU), cisplatin and 40Gy radiotherapy. Results All patients had abnormal motility prior to treatment. Peristalsis was impaired in 11 patients with a mean (SD) of 25% (9) of waves normally propagated. Eight patients had 20% or more simultaneous waves. Following chemoradiotherapy, the percentage of waves normally propagated increased from 25% (9) to 52% (10) (p < 0.03) and normal peristalsis was restored in four patients. The percentage of simultaneous waves decreased from 38% (11) to 21.6% (10) (p=0.129) while the percentage of dropped or increased waves decreased from 20% (11) to 8.3% (4) (p=0.264). Conclusions Oesophageal motility is disturbed in oesophageal cancer. Dysphagia in oesophageal cancer may be partly explained by oesophageal dysmotility. This is improved by chemotherapy.  相似文献   
109.
Background Hydatid disease is rare in Ireland and its incidence and prevalence are unknown. Most cases are diagnosed by a combination of clinical findings, morphological features on imaging and by serological testing. Aims We describe an Irish case of pulmonary hydatid disease detected at bronchoscopy by bronchoalveolar lavage, and discuss the diagnosis and treatment of the disorder.  相似文献   
110.
近年来,国内有大量中药新药申请,大多集中在消化系统领域,如消化性溃疡或慢性胃炎;但是几乎所有的新药试验均设计相同、结果类似。实际上,物质基础的不同,必然会带来治疗效应上的差异。因此,新药审评机构专门召集国内部分知名专家就此问题进行讨论,希望能给业界一点建议,同时也鼓励研究者应根据研究目的的不同,选择采用不同的试验设计。  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