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   899765篇
  免费   62442篇
  国内免费   2334篇
耳鼻咽喉   12474篇
儿科学   28677篇
妇产科学   26148篇
基础医学   126584篇
口腔科学   24686篇
临床医学   74753篇
内科学   183164篇
皮肤病学   18984篇
神经病学   71386篇
特种医学   36445篇
外国民族医学   336篇
外科学   142219篇
综合类   19030篇
一般理论   247篇
预防医学   64558篇
眼科学   20083篇
药学   63857篇
中国医学   1806篇
肿瘤学   49104篇
  2018年   9059篇
  2017年   7163篇
  2016年   7680篇
  2015年   8727篇
  2014年   12381篇
  2013年   19224篇
  2012年   25663篇
  2011年   27281篇
  2010年   16580篇
  2009年   15788篇
  2008年   26131篇
  2007年   27744篇
  2006年   27926篇
  2005年   27455篇
  2004年   26301篇
  2003年   25467篇
  2002年   25056篇
  2001年   41361篇
  2000年   42554篇
  1999年   36267篇
  1998年   9967篇
  1997年   9148篇
  1996年   9082篇
  1995年   8446篇
  1994年   8082篇
  1993年   7586篇
  1992年   28200篇
  1991年   26980篇
  1990年   26412篇
  1989年   25347篇
  1988年   23553篇
  1987年   23172篇
  1986年   22256篇
  1985年   21153篇
  1984年   15807篇
  1983年   13478篇
  1982年   8089篇
  1979年   14589篇
  1978年   10208篇
  1977年   8628篇
  1976年   8147篇
  1975年   8959篇
  1974年   10697篇
  1973年   10182篇
  1972年   9661篇
  1971年   8918篇
  1970年   8585篇
  1969年   8025篇
  1968年   7684篇
  1967年   7086篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Epidermolysis bullosa acquisita (EBA) is an acquired subepidermal bullous disease characterized by IgG autoantibodies directed against type VII collagen, the major component of anchoring fibrils. The classical phenotype of EBA is a non-inflammatory, mechanobullous disease resembling the dystrophic forms of inherited epidermolysis bullosa. Mucous membrane involvement is frequent but usually mild. We report a 1-year-old girl suffering from IgA-EBA, who presented with an initial eruption of disseminated urticarial lesions and tense blisters of the skin but subsequently developed severe oral and ocular lesions reminiscent of cicatricial pemphigoid. Direct immunofluorescence of the skin and buccal mucosa revealed linear IgA and C3 at the basement membrane zone (BMZ). IgA anti-BMZ autoantibodies stained the dermal side of salt-split skin by indirect immunofluorescence and recognized a dermal protein of 290 kDa co-migrating with type VII collagen by immunoblotting. Direct and indirect immunoelectron microscopy revealed IgA deposits overlying the anchoring fibrils. The ocular involvement led to total blindness in spite of intense treatment. This case of childhood IgA-EBA is particularly striking because of the cicatricial pemphigoid phenotype with severe ocular involvement which resulted in blindness. It reinforces the necessity to use modern immunological methods to classify autoimmune bullous diseases in order to allow early and appropriate treatment.  相似文献   
992.
993.
994.
Abstract Several previous studies have evaluated the effects of 0.12% chlorhexidine digluconate (ChD) mouthrinses on plaque and gingival inflammation. However, previously, none have been based in general dental practices. The aim of this study was to evaluate the potential to conduct controlled periodontal clinical trials in co-operation with general dental practitioners (gdps). The project took place in 5 general dental practices in the South of England. 121 healthy subjects (24 at 4 sites and 25 at the 5th). aged 18-65 years, mean 35 ± 12) years participated in a double-blind, randomised study during which they received full mouth assessments for plaque and gingival bleeding at baseline, 6 and 12 weeks. 60 subjects were randomly asigned to use the 0.12% ChD mouth wash and 6i the placebo. The assessments were carried out by 5 gpds, who had previously achieved inter-examiner κ scores of 0.78–0.85 (mean 0.81) for the plaque index (PlI), and of 0.73–0.94 (mean 0.87) for a modified gingival index (mGI), and who maintained κ scores of 0.51–0.90 for PII and of 0.73–1.00 for mGI during the 12 months required to complete the study. 98 subjects (48 ChD and 50 placebo) completed the study. Even though the baseline levels of plaque and gingivitis were low, by week 12, mean whole mouth piaque score of the ChD mouthwash users had fallen from 1.33 at baseline to 0.96 and was significantly lower (p < 0.001) than for the placebo users, 1.31 at baseline to 1.13. Whole-mouth gingival bleeding score fell from 0.56 to 0.42 in the ChD mouthwash group but was unchanged (0.54–0.55) in the placebo group. A subsidiary data analysis which considered the effects at sites indicated that within these overall differences, the ChD users experienced almost 2× the reduction from plaque score 2 at baseline at proximal molar sites over a 12-week period (50.6% ChD versus 27.6% placebo). It was concluded that 0.12% ChD mouthwash reduced plaque accumulation fay 28% and gingival inflammation by 25% over a 12–week period, that it is feasible for a group of gdps to maintain high levels of inter–examiner consistency in the use of PlI and mGI, that it is also feasible to carry out such a multicentre study in general dental practice, and that the use of mean mouth scores per subject to analyse the effects of mouthrinses may well mask variations in response throughout the mouth.  相似文献   
995.
996.
Retroperitoneal fibrosis, either idiopathic or associated with aortic inflammatory aneurysm, is a chronic fibrotic disease that causes progressive obstruction of ureters and vessels around the lower abdominal aorta. Treatment is often difficult (surgery) or hazardous (steroids). We report a case of a woman with retroperitoneal fibrosis associated with aortic inflammatory aneurysm, who was successfully treated with oral tamoxifen.  相似文献   
997.
998.
The MR imaging features of a paraganglioma of the cauda equina with associated spinal cord cysts are presented. MR imaging showed the tumor to be isointense with the spinal cord on all pulse sequences and to enhance homogeneously. The intramedullary cysts had increased signal intensity on proton density- and T2-weighted images, and involved the cervical and thoracic regions.  相似文献   
999.
蓖麻油引产餐对妊娠大鼠分娩的影响   总被引:5,自引:0,他引:5  
目的蓖麻油引产餐用于妊娠晚期引产效果明显,但其作用机制不清楚。本研究通过引产餐灌服妊娠大鼠建立动物引产模型,以期了解引产餐对妊娠大鼠分娩启动和产程的影响,并初步探讨蓖麻油引产餐活性成份。方法于大鼠妊娠第18~20天灌服引产餐,观察大鼠分娩启动和分娩产程变化。利用高压液相分析蓖麻油和蓖麻油引产餐中脂肪酸成份。结果引产餐可提前妊娠大鼠分娩启动时间,缩短分娩产程。蓖麻油引产餐和蓖麻油两者脂肪酸对比结果显示,成份相同,蓖麻酸均占90%,未见花生四烯酸成份。结论引产餐对妊娠晚期大鼠具有引产、催产作用,可以利用引产餐灌服妊娠大鼠建立动物引产模型。推测蓖麻酸是引产餐启动分娩和缩短产程的活性物质。  相似文献   
1000.
1 The present study examined the role of muscarinic receptors in the modulation of noradrenaline (NA) release in the guinea-pig isolated distal colon. The spontaneous endogenous NA overflow assayed by HPLC-ED was taken as an index of NA release from enteric noradrenergic nerve terminals. 2 Physostigmine (10 μm ) significantly enhanced spontaneous endogenous NA overflow. Hyoscine (muscarinic antagonist), (R)-(-)-trihexyphenidyl and telenzepine (M1-selective antagonists), and 11[[2-[(diethylamino)methyl]-1-piperydil]acetyl]-5,11-dihydro-6H-pyrido[2,3-b][1,4]benzodiazepine-6-one (AF-DX 116, M2-selective antagonist) inhibited NA overflow in a concentration dependent manner, with the following EC50 values: 131.74 (18.19–953.96), 101.62 (58.83–175.60), 150 (60–330), 30 (5–170) nm , respectively. 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP, M1- and M3- selective antagonist) had no significant effect up to 100 μm . 3 The muscarinic agonist oxotremorine inhibited NA overflow in a concentration dependent manner, with an EC50 value of 0.67 (0.30–1.51) μm . The response to oxotremorine was inhibited by muscarinic antagonists with the following order of potency: hyoscine = (R)-(-)-trihexyphenidyl = telenzepine > 4-DAMP >> AF-DX 116. 4 In the presence of 3 μm tetrodotoxin (TTX), the effect of oxotremorine and 4-DAMP was unchanged, while hyoscine, (R)-(-)-trihexyphenidyl, telenzepine and AF-DX 116, instead of inhibiting, significantly enhanced NA overflow. 5 The present results indicate that, in the guinea-pig colon, endogenous acetylcholine sustains spontaneous NA release by activating muscarinic receptors possibly located on interneurones. In addition, inhibitory muscarinic receptors may exist on adrenergic terminals.  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