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   2642篇
  免费   315篇
  国内免费   1篇
耳鼻咽喉   34篇
儿科学   138篇
妇产科学   76篇
基础医学   414篇
口腔科学   63篇
临床医学   367篇
内科学   539篇
皮肤病学   12篇
神经病学   277篇
特种医学   92篇
外科学   163篇
综合类   67篇
预防医学   411篇
眼科学   31篇
药学   199篇
中国医学   4篇
肿瘤学   71篇
  2022年   20篇
  2021年   30篇
  2020年   27篇
  2019年   42篇
  2018年   29篇
  2017年   24篇
  2016年   27篇
  2015年   40篇
  2014年   84篇
  2013年   92篇
  2012年   118篇
  2011年   117篇
  2010年   66篇
  2009年   66篇
  2008年   76篇
  2007年   115篇
  2006年   119篇
  2005年   111篇
  2004年   78篇
  2003年   121篇
  2002年   86篇
  2001年   89篇
  2000年   90篇
  1999年   62篇
  1998年   42篇
  1997年   41篇
  1996年   37篇
  1995年   27篇
  1994年   42篇
  1993年   37篇
  1992年   57篇
  1991年   60篇
  1990年   65篇
  1989年   54篇
  1988年   51篇
  1987年   52篇
  1986年   39篇
  1985年   54篇
  1984年   42篇
  1983年   30篇
  1982年   23篇
  1981年   19篇
  1979年   37篇
  1978年   37篇
  1977年   26篇
  1976年   25篇
  1975年   26篇
  1974年   39篇
  1973年   33篇
  1951年   23篇
排序方式: 共有2958条查询结果,搜索用时 15 毫秒
1.
2.
用体外培养的人的伪表皮作为模型,进行药物毒理学作用的研究,观察了二甲亚砜(DMSO)在不同浓度和不同接触时间条件下,对人的伪表皮细胞脱氧核糖核酸(DNA)、核糖核酸(RNA)和蛋白质合成的影响:随着接触时间的延长,DNA、RNA和蛋白质合成均受抑制。低浓度条件下(1%),DNA、RNA和蛋白质合成增加;在15~50%浓度下,DNA和蛋白质合成抑制,而RNA合成仍增加;在高浓度条件下(70%~100%),DNA、RNA和蛋白质合成均明显抑制。  相似文献   
3.
In recent trials in The Gambia, mass chemoprophylaxis with Maloprim administered over several years by primary health care workers to children aged 3-59 months has reduced both mortality and morbidity without inducing impairment of natural immunity or significant development of drug resistance. Taking expenditure of both time and money, by both public authorities and village volunteers, into account, the costs and the cost effectiveness of such mass chemoprophylaxis are estimated here. The cost per child protected per season was (1990 US) $2.84; the cost per childhood death averted was $143. Both costs compare favourably with those of permethrin bed net impregnation. So in some circumstances where malaria is holoendemic, control of childhood malaria by chemoprophylaxis may be more economically efficient than provision of impregnated bed nets.  相似文献   
4.
5.
The current WHO recommendations for the case management of acute respiratory infections (ARI) in children aged 2 months to 5 years in developing countries use fast breathing (respiratory rate of > or = 50 per minute in children under 12 months and > or = 40 in children aged 12 months to 5 years) and lower chest wall indrawing to determine which child is likely to have pneumonia and should therefore receive antibiotics. We have evaluated these and other physical signs in 487 malnourished children and 255 well nourished children who presented with a cough or breathing difficulty. Pneumonia, defined as definite radiological pneumonia or probable radiological pneumonia associated with crackles on auscultation, was present in 145 (30%) of the malnourished children and 68 (26%) of the well nourished children. The respiratory rate predicted pneumonia equally well in the two groups, but to achieve an appropriate sensitivity and specificity the respiratory rate cut-off required in malnourished children was approximately 5 breaths per minute less than that in well nourished children. Intercostal indrawing was more common and lower chest wall indrawing was less common in the malnourished children, with or without pneumonia. These results suggest that fast breathing, as defined at present by WHO, and lower chest wall indrawing are not sufficiently sensistive as predictors of pneumonia in malnourished children. As the latter are a high-risk group, we should like to recommend that children with malnutrition who present with a cough, fast breathing or difficult breathing should be treated with antibiotics.  相似文献   
6.
Methsuximide for intractable childhood seizures   总被引:1,自引:0,他引:1  
Methsuximide was added to the therapeutic regimens of 25 children with intractable epilepsy. In 15 patients the drug was well tolerated and resulted in a 50% or greater reduction in seizure frequency. No serious or irreversible adverse effects were seen. Methsuximide is frequently overlooked and may be an effective adjunctive antiepileptic for children with intractable seizures.  相似文献   
7.
8.
OBJECTIVE: To explore the effects of a single session of repetitive Transcranial Magnetic Stimulation, given as Theta Burst Stimulation, on behavioural and physiological measures of hand function in chronic stroke patients. METHODS: Six chronic stroke patients with incomplete recovery of the hand were tested under three conditions: excitatory TBS over the stroke hemisphere (iTBS(SH)), inhibitory TBS (cTBS(IH)) over the intact hemisphere and sham stimulation. Behavioural outcomes included simple and choice reaction time paradigms. Physiological effects were assessed using single pulse TMS on both sides. Changes were sought for up to 40min after TBS. RESULTS: Immediately after iTBS(SH) simple reaction times in the paretic hands were decreased and, compared to sham stimulation, remained significantly shorter throughout the testing period. The amplitude of the MEPs at rest and during background contraction and the area under the Input-Output curves were also increased on the stroke side after iTBS(SH). cTBS(IH) suppressed the MEPs evoked in the healthy hands but did not change motor behaviour or the electrophysiology of the paretic hands. No side effects were encountered. CONCLUSIONS: TBS seems safe in chronic stroke patients. iTBS over the stroke hemisphere transiently improved motor behaviour and corticospinal output in the paretic hands. SIGNIFICANCE: Excitatory TBS may represent a useful rTMS protocol to apply to the stroke hemisphere in future longer term therapy trials.  相似文献   
9.
10.
BACKGROUND. Previous investigations of the psychological consequences of having breast cancer have usually involved quantitative analysis within medical models. AIM. This qualitative study set out to identify key events which had caused distress to women with breast cancer and to compare the frequency of these events with doctors' beliefs about their relative frequency. METHOD. The causes of distress in 26 women with breast cancer were identified by qualitative analysis of unstructured interviews. Subsequently, all hospital doctors and general practitioners in the Exeter health district were sent a list in random order of the eight events which had most commonly caused distress and were asked to rank them in order of frequency for patients with breast cancer. RESULTS. The responses suggest a mismatch between the doctors' expectations and the experience of the patients. CONCLUSION. Patients may suffer distress in areas of management doctors do not suspect are important; qualitative analysis can identify these areas.  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