全文获取类型
收费全文 | 1660篇 |
免费 | 216篇 |
国内免费 | 2篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 133篇 |
妇产科学 | 5篇 |
基础医学 | 225篇 |
口腔科学 | 7篇 |
临床医学 | 158篇 |
内科学 | 368篇 |
皮肤病学 | 156篇 |
神经病学 | 103篇 |
特种医学 | 68篇 |
外科学 | 166篇 |
综合类 | 66篇 |
一般理论 | 1篇 |
预防医学 | 129篇 |
眼科学 | 24篇 |
药学 | 119篇 |
中国医学 | 1篇 |
肿瘤学 | 148篇 |
出版年
2023年 | 10篇 |
2022年 | 8篇 |
2021年 | 35篇 |
2020年 | 25篇 |
2019年 | 35篇 |
2018年 | 44篇 |
2017年 | 34篇 |
2016年 | 29篇 |
2015年 | 33篇 |
2014年 | 43篇 |
2013年 | 48篇 |
2012年 | 70篇 |
2011年 | 107篇 |
2010年 | 61篇 |
2009年 | 38篇 |
2008年 | 101篇 |
2007年 | 95篇 |
2006年 | 111篇 |
2005年 | 90篇 |
2004年 | 64篇 |
2003年 | 79篇 |
2002年 | 80篇 |
2001年 | 67篇 |
2000年 | 57篇 |
1999年 | 62篇 |
1998年 | 28篇 |
1997年 | 20篇 |
1996年 | 27篇 |
1995年 | 14篇 |
1994年 | 16篇 |
1993年 | 13篇 |
1992年 | 40篇 |
1991年 | 28篇 |
1990年 | 27篇 |
1989年 | 28篇 |
1988年 | 25篇 |
1987年 | 37篇 |
1986年 | 28篇 |
1985年 | 14篇 |
1984年 | 12篇 |
1983年 | 13篇 |
1982年 | 10篇 |
1981年 | 8篇 |
1979年 | 9篇 |
1978年 | 6篇 |
1976年 | 7篇 |
1975年 | 6篇 |
1973年 | 4篇 |
1971年 | 5篇 |
1967年 | 6篇 |
排序方式: 共有1878条查询结果,搜索用时 31 毫秒
61.
62.
Susan Hoe James W. Ivey Mohammed A. Boraey Abouzar Shamsaddini-Shahrbabak Emadeddin Javaheri Sadaf Matinkhoo Warren H. Finlay Reinhard Vehring 《Pharmaceutical research》2014,31(2):449-465
Purpose
A fundamental approach incorporating current theoretical models into aerosol formulation design potentially reduces experimental work for complex formulations. A D-amino acid mixture containing D-Leucine (D-Leu), D-Methionine, D-Tryptophan, and D-Tyrosine was selected as a model formulation for this approach.Methods
Formulation design targets were set, with the aim of producing a highly dispersible D-amino acid aerosol. Particle formation theory and a spray dryer process model were applied with boundary conditions to the design targets, resulting in a priori predictions of particle morphology and necessary spray dryer process parameters. Two formulations containing 60% w/w trehalose, 30% w/w D-Leu, and 10% w/w remaining D-amino acids were manufactured.Results
The design targets were met. The formulations had rugose and hollow particles, caused by deformation of a crystalline D-Leu shell while trehalose remained amorphous, as predicted by particle formation theory. D-Leu acts as a dispersibility enhancer, ensuring that both formulations: 1) delivered over 40% of the loaded dose into the in vitro lung region, and 2) achieved desired values of lung airway surface liquid concentrations based on lung deposition simulations.Conclusions
Theoretical models were applied to successfully achieve complex formulations with design challenges a priori. No further iterations to the design process were required. 相似文献63.
A novel technique for performing transseptal puncture guided by a non‐fluoroscopic 3D mapping system
64.
Dissecting virulence: systematic and functional analyses of a pathogenicity island 总被引:32,自引:0,他引:32 下载免费PDF全文
Deng W Puente JL Gruenheid S Li Y Vallance BA Vázquez A Barba J Ibarra JA O'Donnell P Metalnikov P Ashman K Lee S Goode D Pawson T Finlay BB 《Proceedings of the National Academy of Sciences of the United States of America》2004,101(10):3597-3602
Bacterial pathogenicity islands (PAI) often encode both effector molecules responsible for disease and secretion systems that deliver these effectors to host cells. Human enterohemorrhagic Escherichia coli (EHEC), enteropathogenic E. coli, and the mouse pathogen Citrobacter rodentium (CR) possess the locus of enterocyte effacement (LEE) PAI. We systematically mutagenized all 41 CR LEE genes and functionally characterized these mutants in vitro and in a murine infection model. We identified 33 virulence factors, including two virulence regulators and a hierarchical switch for type III secretion. In addition, 7 potential type III effectors encoded outside the LEE were identified by using a proteomics approach. These non-LEE effectors are encoded by three uncharacterized PAIs in EHEC O157, suggesting that these PAIs act cooperatively with the LEE in pathogenesis. Our findings provide significant insights into bacterial virulence mechanisms and disease. 相似文献
65.
Xun Li Parm Naidoo Paul Guy Paul Finlay Soo-Wei Foo Kais Hamza 《The Journal of asthma》2014,51(3):282-287
Objective: It is not known how airway structure is altered during real-life acute asthma exacerbations. The aim of this study was to examine changes in airway structure during acute asthma exacerbations and at convalescence by using lung-volume controlled high resolution computerised tomography (HRCT). Methods: Eight subjects with acute asthma exacerbation admitted to hospital were recruited. HRCT was performed within 72?h of admission (n?=?8) and repeated after 8 weeks of convalescence (n?=?7). Individual airways were carefully matched on acute and convalescent CT data sets for comparisons of airway parameters. A novel methodology was employed for standardisation of lung volumes to permit valid comparisons of lung imaging. Measurements of bronchial cross sectional airway area (Aa) and bronchial luminal area (Ai)?for each matched airway were obtained using a validated program. Results: The airway wall thickness was analysed as wall area (WA) calculated as a percentage: WA%?=?WA/Aa?×?100. Wilcoxon signed-rank testing was used to compare acute and convalescent asthma and Spearman’s correlation to examine associations. Airway lumen (Ai) areas were similar in both acute and stable asthma phases (6.6?±?3.1?mm2 versus 7.2?±?3.8?mm2 p?=?0.8). However, the airway wall was significantly thickened during acute asthma exacerbations compared to convalescence (62?±?4% versus 55?±?7%; p?=?0.01). There was no correlation between airway structure dimensions and lung function measurements. Conclusions: This is the first study to demonstrate an increase in airway wall thickness during real-life acute asthma exacerbation. However, narrowing of the airway lumen area was variable and will require larger studies able to detect small differences. These results suggest that airway wall thickening linked to mucosal inflammation is likely to characterise acute asthma in vivo but that changes in the airway lumen accompanying bronchoconstriction may be more heterogeneous. 相似文献
66.
Sodium valproate is one of the most commonly used drugs to treat epilepsy. However, there is growing evidence that valproate can cause renal tubular injury in children, and there are increasing reports of valproate-induced Fanconi’s syndrome where the renal tubules lose their ability to reabsorb electrolytes, urea, glucose and protein. In this review article we attempt to bring together all of the studies conducted to date on the effects of valproate on renal function in epileptic children. The research is generally considered in two themes; the first comprises studies which indicate subclinical tubular injury measured by renal enzymes such as N-acetyl-β-D-glucosaminidase (NAG), and the second comprises clinical reports where Fanconi’s syndrome has occurred. This article goes on to analyse the current data and draws on recurring patterns to suggest that a specific subpopulation of severely disabled epileptic children may benefit hugely from the close monitoring of enzymes which are indicative of renal tubular injury, particularly NAG or in the very least periodical urinalysis. 相似文献
67.
Helminth parasites are highly successful pathogens, chronically infecting a quarter of the world's population, causing significant morbidity but rarely causing death. Protective immunity and expulsion of helminths is mediated by T-helper 2 (Th2) cells, type 2 (M2) macrophages, type 2 innate lymphoid cells, and eosinophils. Failure to mount these type 2 immune responses can result in immunopathology mediated by Th1 or Th17 cells. Helminths have evolved a wide variety of approaches for immune suppression, especially the generation of regulatory T cells and anti-inflammatory cytokines interleukin-10 and transforming growth factor-β. This is a very effective strategy for subverting protective immune responses to prolong their survival in the host but has the bystander effect of modulating immune responses to unrelated antigens. Epidemiological studies in humans have shown that infection with helminth parasites is associated with a low incidence of allergy/asthma and autoimmunity in developing countries. Experimental studies in mice have demonstrated that regulatory immune responses induced by helminth can suppress Th2 and Th1/Th17 responses that mediate allergy and autoimmunity, respectively. This has provided a rational explanation of the ‘hygiene hypothesis’ and has also led to the exploitation of helminths or their immunomodulatory products in the development of new immunosuppressive therapies for inflammatory diseases in humans. 相似文献
68.
69.
Samir Gupta MD MDCS AGAF Balambal Bharti MBBS MPH PhD Dennis J. Ahnen MD Daniel D. Buchanan PhD Iona C. Cheng PhD MPH Michelle Cotterchio PhD Jane C. Figueiredo PhD Steven J. Gallinger MD MSc Robert W. Haile DrPH MPH Mark A. Jenkins PhD Noralane M. Lindor MD Finlay A. Macrae MD AGAF Loïc Le Marchand MD PhD Polly A. Newcomb PhD MPH Stephen N. Thibodeau PhD Aung Ko Win MBBS MPH PhD Maria Elena Martinez PhD 《Cancer》2020,126(13):3013-3020
70.
Jennifer L. Beebe-Dimmer MPH PhD Julie J. Ruterbusch MPH Felicity W. K. Harper PhD Tara M. Baird MS David G. Finlay BS Andrew G. Rundle MPH DrPH Stephanie S. Pandolfi PhD Theresa A. Hastert PhD Kendra L. Schwartz MD Gerold Bepler MD Michael S. Simon MD Julia Mantey MPH Judy Abrams PhD Teri L. Albrecht PhD Ann G. Schwartz MPH PhD 《Cancer》2020,126(9):1987-1994