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   427篇
  免费   17篇
耳鼻咽喉   14篇
儿科学   10篇
妇产科学   6篇
基础医学   26篇
口腔科学   15篇
临床医学   32篇
内科学   131篇
皮肤病学   3篇
神经病学   24篇
特种医学   12篇
外科学   42篇
综合类   3篇
预防医学   21篇
眼科学   7篇
药学   61篇
中国医学   4篇
肿瘤学   33篇
  2023年   1篇
  2022年   6篇
  2021年   14篇
  2020年   8篇
  2019年   12篇
  2018年   17篇
  2017年   14篇
  2016年   4篇
  2015年   8篇
  2014年   16篇
  2013年   13篇
  2012年   36篇
  2011年   25篇
  2010年   22篇
  2009年   19篇
  2008年   32篇
  2007年   21篇
  2006年   30篇
  2005年   14篇
  2004年   18篇
  2003年   17篇
  2002年   14篇
  2001年   6篇
  2000年   8篇
  1999年   7篇
  1998年   4篇
  1997年   2篇
  1996年   1篇
  1994年   1篇
  1993年   1篇
  1992年   5篇
  1991年   5篇
  1990年   2篇
  1989年   4篇
  1988年   5篇
  1987年   5篇
  1986年   2篇
  1985年   1篇
  1984年   3篇
  1983年   2篇
  1982年   1篇
  1979年   3篇
  1974年   3篇
  1973年   1篇
  1972年   2篇
  1971年   2篇
  1970年   1篇
  1968年   4篇
  1966年   1篇
  1923年   1篇
排序方式: 共有444条查询结果,搜索用时 15 毫秒
21.
Purpose:To compare multicolor imaging (MCI) with Optos color fundus photography (OCFP) for the evaluation of morphology and extent of preretinal membranes in diabetic tractional retinal detachments (TRD).Methods:In this retrospective study, 30 eyes with diabetic TRDs were imaged using the MCI feature of the Heidelberg Spectralis Spectral-domain optical coherence tomography (SD-OCT) and color photo using the Optos Daytona ultra-widefield fundus camera. Two investigators independently graded and determined the agreeability between the two modalities with respect to the extent of the TRD and preretinal membranes on the SD-OCT B-scan images.Results:The MCI provided better visualization of the attachments and traction points of the posterior hyaloid face and preretinal membranes and is comparable to the SD-OCT B-scan images. The inter-rater agreeability rates for OCFP had a Kappa (κ) value of 0.37, while the MCI had a κ value of 0.46. When comparing between images of different wavelengths, grading using infrared reflectance (IR) had a poor agreement (−0.04 ± 0.04) while green reflectance (GR) (0.46 ± 0.32) and blue reflectance (BR) (0.53 ± 0.19) had a moderate agreement. The composite MCI and GR images also had comparatively higher intraclass coefficient when compared to the OCFP (0.25 [−0.09–0.55]) and IR (−0.03 [−0.39–0.34]) images.Conclusion:MCI is more sensitive for determining the extent of TRDs and for the detection of secondary membranes when compared to OCFP, thus, aiding in better surgical planning.  相似文献   
22.
BackgroundFluid dynamics is a majorly neglected aspect to be studied in root canal irrigation. The fundamental rule to understand mechanics is to observe patterns of flow during the process. Thus, this work is conducted to do a systemic assessment of the in-vitro and ex-vivo based studies to evaluate the effect of various parameters on the irrigant flow and apical pressure on using a manual syringe needle for root canal irrigation.MethodsThe literature search was conducted through libraries such as PubMed (Medline), CINAHL, Embase, Scopus and other hand literature from Google Scholar, the British medical library etc. The systematic review was reported following the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. As they include studies that were in-vitro and ex-vivo based, the risk of bias of the selected articles was assessed using a customized tool based on the previous literature and parameters evaluated in the studies included.ResultsThe literature search resulted in 101 items of which 19 records were included in this review. Results reported that multiple factors and parameters were assessed to evaluate the flow and apical pressures on using manual syringe needle irrigation.ConclusionsPresent systematic review gives insights in-depth about the irrigation dynamics of manual syringe needle irrigation. Besides, it is inconclusive to compile a single factor or a single parameter contributing to the enhanced irrigant flow and least apical pressures.  相似文献   
23.
Nitrite anion has been demonstrated to be a prodrug of nitric oxide (NO) with positive effects on tissue ischemia/reperfusion injury, cytoprotection, and vasodilation. However, effects of nitrite anion therapy for ischemic tissue vascular remodeling during diabetes remain unknown. We examined whether sodium nitrite therapy altered ischemic revascularization in BKS-Leprdb/db mice subjected to permanent unilateral femoral artery ligation. Sodium nitrite therapy completely restored ischemic hind limb blood flow compared with nitrate or PBS therapy. Importantly, delayed nitrite therapy 5 days after ischemia restored ischemic limb blood flow in aged diabetic mice. Restoration of blood flow was associated with increases in ischemic tissue angiogenesis activity and cell proliferation. Moreover, nitrite but not nitrate therapy significantly prevented ischemia-mediated tissue necrosis in aged mice. Nitrite therapy significantly increased ischemic tissue vascular endothelial growth factor (VEGF) protein expression that was essential for nitrite-mediated reperfusion of ischemic hind limbs. Nitrite significantly increased ischemic tissue NO bioavailability along with concomitant reduction of superoxide formation. Lastly, nitrite treatment also significantly stimulated hypoxic endothelial cell proliferation and migration in the presence of high glucose in an NO/VEGF-dependent manner. These results demonstrate that nitrite therapy effectively stimulates ischemic tissue vascular remodeling in the setting of metabolic dysfunction that may be clinically useful.  相似文献   
24.
BackgroundDuring the initial wave of COVID-19 hospitalizations, care delivery and workforce adaptations were rapidly implemented. In response to subsequent surges of patients, institutions have deployed, modified, and/or discontinued their workforce plans.ObjectiveUsing rapid qualitative methods, we sought to explore hospitalists’ experiences with workforce deployment, types of clinicians deployed, and challenges encountered with subsequent iterations of surge planning during the COVID-19 pandemic across a collaborative of hospital medicine groups.ApproachUsing rapid qualitative methods, focus groups were conducted in partnership with the Hospital Medicine Reengineering Network (HOMERuN). We interviewed physicians, advanced practice providers (APP), and physician researchers about (1) ongoing adaptations to the workforce as a result of the COVID-19 pandemic, (2) current struggles with workforce planning, and (3) evolution of workforce planning.Key ResultsWe conducted five focus groups with 33 individuals from 24 institutions, representing 52% of HOMERuN sites. A variety of adaptations was described by participants, some common across institutions and others specific to the institution’s location and context. Adaptations implemented shifted from the first waves of COVID patients to subsequent waves. Three global themes also emerged: (1) adaptability and comfort with dynamic change, (2) the importance of the unique hospitalist skillset for effective surge planning and redeployment, and (3) the lack of universal solutions.ConclusionsHospital workforce adaptations to the COVID pandemic continued to evolve. While few approaches were universally effective in managing surges of patients, and successful adaptations were highly context dependent, the ability to navigate a complex system, adaptability, and comfort in a chaotic, dynamic environment were themes considered most critical to successful surge management. However, resource constraints and sustained high workload levels raised issues of burnout.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11606-022-07480-x.KEY WORDS: COVID-19, hospital medicine, workforce planning, surge planning, focus groups, qualitative  相似文献   
25.
Tryptophan is metabolized through serotonin, indole, and kynurenine (KN) pathways. Uptake of an excess amount of tryptophan accompanied with vitamin B6 deficiency may result in the accumulation of higher concentrations of metabolites mainly from the KN pathways in the bladder. These metabolites could interact with nitrite to become mutagenic nitrosamines. They could be a promoter in the initiator–promoter model of carcinogenesis. They produced bladder cancer when implanted in the bladder. They also interact with transition metals copper or iron to form reactive radicals or reactive oxygen species (ROS). Some metabolites, 3‐hydroxy‐anthranilic acid, were autooxidized to mutagenic cinnabarinic and anthranilyl radical intermediates. These radical intermediates could also be ligands that interact with aryl hydrocarbon receptor (AhR) and induce xenobiotic metabolizing enzymes (XMEs) to metabolize contaminated carcinogens. When tryptophan is exposed to either visible or UV light, a photoproduct of 6‐formylindolo[3,2b]‐carbazole is formed, which has a very high affinity for the AhR that plays a role in carcinogenesis. This review gives an insight into various mechanisms through which tryptophan metabolites cause carcinogenesis. It could be concluded that tryptophan metabolites play a complementary role in promoting carcinogenesis along with carcinogens like aflatoxin, CCl4, 2‐acetylaminofluorene, 4‐aminobiphenyl, 2‐naphthylamine, or N‐[4‐(5‐nitro‐2‐furyl)?2‐thiazolyl] formamide. The underlying mechanisms could be their autoxidation, exposure to either visible or UV light, interaction with nitrite or transition metals to form reactive intermediates, serving as ligands to interact with an AhR that is known to play a role in carcinogenesis through induction of XMEs. Further research is warranted.Environ. Mol. Mutagen. 52:81–104, 2011. © 2010 Wiley‐Liss, Inc.  相似文献   
26.
Distal radius fractures are the most common upper extremity fracture, representing one-sixth of all fractures treated in emergency departments nationwide. Beyond the initial reduction and immobilization of these fractures, providing proper followup to ensure maintenance of the reduction and identify complications is necessary for optimal recovery of forearm and wrist functions. We sought to identify the clinical and demographic factors that characterize patients with distal radius fractures who do not return for followup and to assess the underlying causes for their poor followup rates. Compared with patients who were compliant with followup, those lost to followup had lower Physical and Mental Health scores on the SF-36 forms, more often were treated nonoperatively, and more likely had not surpassed secondary education. However, we found no difference between these two groups based on age, gender, mechanism of injury, marital status, or hand dominance. Early identification of patients who potentially are noncompliant can result in additional measures being taken to ensure the patient’s return to the treating hospital and physicians. This in turn will prevent complications attributable to lack of followup and allow more accurate assessment of results, thereby improving patient outcomes.  相似文献   
27.
Introgen, under license from Corixa (formerly GenQuest), is developing INGN-241, a gene therapy based on the mda-7 gene in combination with the company's adenoviral delivery system, for the potential treatment of cancer. A phase I trial for the treatment of solid tumors was initiated at the end of November 2000.  相似文献   
28.
The incidence of peripheral pulmonary adenocarcinoma has increased in recent years. Clara cell has been known as target for carcinogens and source of pulmonary tumors. One of the presumed roles of the bronchiolar Clara cell is the secretion of pulmonary surfactant into the bronchiolar lumen. To establish the secretory morphology of Clara cell, a well-defined secretory agonist, isoproterenol (500 mg/kg) and the antagonist, propranolol (20 mg/kg), were administered into five-week old mice. The secretory response was examined at 1 hour and 4 hours after injection. Ultrastructural morphometry was used to quantitate the secretory response by measuring area of apical cap of the Clara cells. Isoproterenol caused a significant increase in area of apical cap of Clara cells 1 and 4 hours after injection (p < 0.0001), while pretreatment with propranolol prevented this effect at 4 hours. Propranolol alone significantly decreased the area of Clara cells (p < 0.0001). Clara cells secretory granules disappeared 1 hour after propranolol plus isoproterenol administration, and the granules reappeared at 4 hours. The accelerated secretion of Clara cells by isoproterenol provides evidence of their secretory mechanism controlled by beta-adrenergic agonists. The study has confirmed the secretory role of Clara cells. The secretion is both apocrine and merocrine type.  相似文献   
29.
Tobacco smoking and pulmonary tuberculosis   总被引:12,自引:1,他引:11  
Kolappan C  Gopi PG 《Thorax》2002,57(11):964-966
BACKGROUND: The prevalence of tuberculosis in adult men in India is 2-4 times higher than in women. Tobacco smoking is prevalent almost exclusively among men, so it is possible that tobacco smoking may be a risk factor for developing pulmonary tuberculosis. A nested case control study was carried out to study the association between tobacco smoking and pulmonary tuberculosis. METHODS: A tuberculosis disease survey was carried out in two Panchayat unions in the Tiruvallur district of Tamil Nadu in India. Eighty five men aged 20-50 years with bacteriological tuberculosis (smear and/or culture positive) were selected as cases and 459 age matched men without tuberculosis were selected randomly as controls. Information on smoking status, type of tobacco smoked, quantity of tobacco smoked, and duration of tobacco smoking was collected from cases and controls using a questionnaire. RESULTS: The estimated crude odds ratio (OR) of the association between tobacco smoking and bacillary tuberculosis was 2.48 (95% confidence interval (CI) 1.42 to 4.37), p<0.001.The age adjusted OR (Mantel-Hanszel estimate) was 2.24.(95% CI 1.27 to 3.94), p<0.05. The ORs for mild (1-10 cigarettes/day), moderate (11-20/day), and heavy (>20/day) smokers were 1.75, 3.17, and 3.68, respectively (p<0.0001 test for linear trend). The ORs for smokers with <10 years, 11-20 years, and >20 years of smoking were 1.72, 2.45, and 3.23, respectively (p<0.0001 test for linear trend). CONCLUSION: There is a positive association between tobacco smoking and pulmonary (bacillary) tuberculosis (OR 2.5). The association also shows a strong dose-response relationship.  相似文献   
30.
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