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   2788篇
  免费   117篇
  国内免费   20篇
耳鼻咽喉   46篇
儿科学   74篇
妇产科学   74篇
基础医学   220篇
口腔科学   86篇
临床医学   293篇
内科学   592篇
皮肤病学   47篇
神经病学   180篇
特种医学   170篇
外科学   616篇
综合类   49篇
一般理论   1篇
预防医学   102篇
眼科学   58篇
药学   179篇
中国医学   16篇
肿瘤学   122篇
  2024年   3篇
  2023年   38篇
  2022年   83篇
  2021年   143篇
  2020年   74篇
  2019年   86篇
  2018年   123篇
  2017年   93篇
  2016年   92篇
  2015年   81篇
  2014年   143篇
  2013年   167篇
  2012年   199篇
  2011年   206篇
  2010年   162篇
  2009年   122篇
  2008年   170篇
  2007年   152篇
  2006年   152篇
  2005年   140篇
  2004年   105篇
  2003年   102篇
  2002年   82篇
  2001年   28篇
  2000年   26篇
  1999年   18篇
  1998年   12篇
  1997年   19篇
  1996年   12篇
  1995年   7篇
  1994年   7篇
  1993年   4篇
  1992年   18篇
  1991年   9篇
  1990年   3篇
  1989年   5篇
  1988年   8篇
  1987年   3篇
  1986年   8篇
  1985年   1篇
  1984年   5篇
  1983年   1篇
  1982年   1篇
  1981年   1篇
  1980年   3篇
  1979年   2篇
  1978年   2篇
  1973年   2篇
  1970年   1篇
  1964年   1篇
排序方式: 共有2925条查询结果,搜索用时 0 毫秒
1.
2.
3.
4.
Malignant thymomas are among the least common mediastinal tumors in the pediatric age group. Thymomas are considered malignant on the basis of macroscopic and microscopic invasiveness. As only 20 well-documented cases involving children have been reported in the literature, the pattern of responsiveness to therapy and the value of prognostic signs is obscure. Two cases of malignant pediatric thymomas are reported with pathognomonic histoimmunological features of aggressive thymoma. One was cured, with a follow-up of 70 months, and one died while on therapy. Analysis of the histological features and the immunoperoxidase staining displays the complexity of pediatric thymomas and the inability to prognosticate the outcome, respectively.  相似文献   
5.
A relationship between teething and fever was sought by examining mothers' reports of the 20 days before the eruption of the first tooth in 46 healthy infants. Twenty infants had a fever of greater than 37.5 degrees C on day 0 compared with seven infants (or fewer) from day 19 to day 4. The danger of attributing fever to teething is emphasised.  相似文献   
6.
SDD reduces ICU and in-hospital mortality, the length-of-stay in the ICU, the frequency of colonization with resistant GNB, and the total costs of antibiotic treatment. This supports the use of SDD in all patients expected to be on mechanical ventilation for at least two days in ICUs that have low prevalence of VRE and MRSA.  相似文献   
7.
2-[18F]Fluoro-3-(2(S)-azetidinylmethoxy)pyridine (2-[18F]F-A-85380) was among the first subtype selective radioligands to visualise the in vivo distribution of alpha4beta2-containing neuronal nicotinic acetylcholine receptors (nAChRs) in human brain. We developed a one-pot synthesis for the preparation of 2-[18F]F-A-85380 in a commercially available TRACERlab FXF-N synthesis module. The synthesis comprises a nucleophilic substitution followed by hydrolysis of a t-butyloxycarbonyl (BOC)-protected intermediate. After formulation for intravenous application up to 20 G Bq 2-[18F]F-A-85380 were produced from a starting activity of 100 G Bq [18F]fluoride in 60 min with a specific activity of about 4.10(5)GBq/mmol and a mean radiochemical purity of more than 99%.  相似文献   
8.
The reliability and accuracy of salivary theophylline levels as a predictor of serum theophylline levels was investigated in 28 hospitalized chronic asthmatics, free of other chronic diseases, on continuous aminophylline infusion for greater than 24 hours. Twenty paired blood and saliva theophylline levels from 12 patients (group 1) were used to develop a formula for predicting serum theophylline levels from salivary levels. Twenty-one paired blood and saliva theophylline levels from 16 patients (group 2) were used to test the formula obtained. The formula predicted the serum theophylline concentration within 1.51 microgram/mL in 76% of the samples and within 1.88 microgram/mL in 100% of the samples. There was an excellent correlation between the predicted and actual serum theophylline concentrations, r = .93; thus under controlled conditions of steady-state pharmacokinetics in patients free of other diseases, salivary theophylline levels can be used to accurately predict serum levels.  相似文献   
9.
Cholinergic deficits in Alzheimer's disease are accompanied by a number of alterations in other transmitter systems including glutamate, noradrenaline and serotonin, suggesting the involvement also of other neurotransmitter systems in the pathogenesis of the disease. To address the question whether beta-amyloid may contribute to these deficits, brain tissue from transgenic Tg2576 mice with Alzheimer plaque pathology at ages of 5 (still no significant plaque load) and 17 months (moderate to high cortical beta-amyloid plaque load) were examined for a number of cholinergic and non-cholinergic markers. Transgenic mice with no significant plaque load demonstrated reduced hemicholinium-3 (HCh-3) binding to choline uptake sites in anterior brain regions as compared to non-transgenic littermates, while in aged transgenic mice with high number of plaque deposits decreased HCh-3 binding levels were accompanied by increased vesicular acetylcholine transporter binding in selected cortical brain regions. In aged transgenic mice GABA(A), NMDA, AMPA, kainate, and beta-adrenergic as well 5-HT(1A)- and 5-HT(2A)-receptor binding levels were hardly affected, whereas alpha(1)- and alpha(2)-adrenoceptor binding was increased in selected cerebral cortical regions as compared to non-transgenic littermates. The development of changes in both cholinergic and non-cholinergic markers in transgenic Tg2576 mouse brain already before the onset of progressive plaque deposition provides in vivo evidence of a modulatory role of soluble beta-amyloid on cortical neurotransmission and may be referred to the deficits in learning and memory observed in these mice also before significant plaque load.  相似文献   
10.
AIMS--To evaluate a safe sputum processing method for detection of tuberculosis in developing countries. METHODS--A sample processing method was developed in which acid fast bacilli were killed with 1% sodium hypochlorite and concentrated by flotation on a layer of xylene before staining by the Ziehl Neelsen or auramine O methods. RESULTS--Best results were obtained by auramine O staining after flotation. Staining by the Ziehl Neelsen method after flotation gave better results than direct Ziehl Neelsen staining without flotation. CONCLUSIONS--The flotation method with Ziehl Neelsen staining offers advantages for smear preparation in the tuberculosis control programmes of developing countries.  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