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   868851篇
  免费   71203篇
  国内免费   1854篇
耳鼻咽喉   12840篇
儿科学   24782篇
妇产科学   25208篇
基础医学   124936篇
口腔科学   25647篇
临床医学   75986篇
内科学   166475篇
皮肤病学   17131篇
神经病学   70790篇
特种医学   35431篇
外国民族医学   171篇
外科学   137068篇
综合类   24726篇
现状与发展   2篇
一般理论   290篇
预防医学   67453篇
眼科学   20759篇
药学   65074篇
中国医学   1615篇
肿瘤学   45524篇
  2018年   7495篇
  2015年   7839篇
  2014年   11254篇
  2013年   17024篇
  2012年   23026篇
  2011年   24186篇
  2010年   14071篇
  2009年   13234篇
  2008年   22892篇
  2007年   24943篇
  2006年   24837篇
  2005年   24449篇
  2004年   23953篇
  2003年   23114篇
  2002年   22145篇
  2001年   35964篇
  2000年   36623篇
  1999年   31038篇
  1998年   9281篇
  1997年   8597篇
  1996年   8525篇
  1995年   8067篇
  1994年   7777篇
  1992年   26793篇
  1991年   26214篇
  1990年   25724篇
  1989年   24787篇
  1988年   23325篇
  1987年   23003篇
  1986年   21854篇
  1985年   21197篇
  1984年   16480篇
  1983年   14053篇
  1982年   8895篇
  1981年   8233篇
  1980年   7704篇
  1979年   16811篇
  1978年   12187篇
  1977年   10232篇
  1976年   9368篇
  1975年   10190篇
  1974年   12703篇
  1973年   12194篇
  1972年   11593篇
  1971年   10739篇
  1970年   10254篇
  1969年   9945篇
  1968年   8945篇
  1967年   8270篇
  1966年   7702篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
Health and access to health care vary strikingly across the globe, and debates about this have been pervasive and controversial. Some comparative data in Canada and South Africa illustrate the complexity of achieving greater equity anywhere, even in a wealthy country like Canada. Potential bi-directional lessons relevant both to local and global public health are identified. Both countries should consider the implications of lost opportunity costs associated with lack of explicit resource allocation policies. While National Health Insurance is attractive politically, Canada's example cannot be fully emulated in South Africa. Short- and medium-term attempts to improve equity in middle-income countries should focus on equitable access to insurance to cover primary health care and on making more use of nurse practitioners and community health workers. In the longer-term, attention is needed to the economic and political power structures that influence health and health care and that ignore the social and societal determinants of sustainable good health locally and globally. This long-term vision of health is needed globally to achieve improvements in individual and population health in a century characterised by limits to economic growth, widening disparities, continuing conflict and migration on a large scale and multiple adverse impacts of climate change.  相似文献   
52.
53.
54.
55.
56.
57.

Purpose

This article describes preclinical development of cell-based medicinal products for European markets and discusses European regulatory mechanisms open to developers to aid successful product development. Cell-based medicinal products are diverse, including cells that are autologous or allogeneic, have been genetically modified, or not, or expanded ex vivo, and applied systemically or to an anatomical site different to that of their origin; comments applicable to one product may not be applicable to others, so bespoke development is needed, for all elements - quality, preclinical and clinical.

Methods

After establishing how the product is produced, proof of potential for therapeutic efficacy, and then safety, of the product need to be determined. This includes understanding biodistribution, persistence and toxicity, including potential for malignant transformation. These elements need to be considered in the context of the intended clinical development.

Results

This article describes regulatory mechanisms available to developers to support product development that aim to resolve scientific issues prior to marketing authorization application, to enable patients to have faster access to the product than would otherwise be the case.

Conclusions

Developers are encouraged to be aware of both the scientific issues and regulatory mechanisms to ensure patients can be supplied with these products.
  相似文献   
58.
The spread of antimicrobial resistance challenges the empirical treatment of urinary tract infections (UTIs). Among others, nitrofurantoin is recommended for first-line treatment, but acceptance among clinicians is limited due to chronic nitrofurantoin-induced lung toxicity and insufficient coverage of Enterobacteriaceae other than Escherichia coli. Nitroxoline appears to be an alternative to nitrofurantoin owing to its favourable safety profile, however data on its current in vitro susceptibility are sparse. In this study, susceptibility to nitroxoline was tested against 3012 urinary clinical isolates (including multidrug-resistant bacteria and Candida spp.) by disk diffusion test and/or broth microdilution. At least 91% of all Gram-negatives (n?=?2000), Gram-positives (n?=?403) and yeasts (n?=?132) had inhibition zone diameters for nitroxoline ≥18?mm. Except for Pseudomonas aeruginosa, nitroxoline MIC90 values were ≤16?mg/L and were 2- to >16-fold lower compared with nitrofurantoin. In extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae and methicillin-resistant Staphylococcus aureus (MRSA), MIC90 values of nitroxoline were two-fold higher compared with non-ESBL-producing enterobacteria and methicillin-susceptible S. aureus (MSSA). The in vitro efficacies of nitroxoline and nitrofurantoin against ATCC strains of E. coli, Enterococcus faecalis and Proteus mirabilis were compared by time–kill curves in Mueller–Hinton broth and artificial urine. Nitroxoline was non-inferior against E. coli, P. mirabilis and E. faecalis in artificial urine. In conclusion, nitroxoline showed a broad antimicrobial spectrum, with inhibition zone diameters and MICs of nitroxoline well below the EUCAST breakpoint for E. coli for most organisms, and thus may also be a target for therapy of uncomplicated UTIs.  相似文献   
59.
Increased functional brain response towards alcohol-associated stimuli is a neural hallmark of alcohol dependence and a promising target for pharmacotherapy. For the first time, we assessed the effects of individually titrated high-dose baclofen on cue reactivity and functional connectivity in alcohol-dependent (AD) patients in a randomized controlled trial (RCT).We investigated 23 recently detoxified AD patients and 23 matched healthy controls (HC) with a cue reactivity functional magnetic resonance imaging task. Patients were further scanned at baseline without medication and during treatment with high-dose baclofen/placebo (30–270 mg/d). Analyses were conducted for alcohol cue-elicited brain response, alcohol cue-modulated and stimulus-independent functional connectivity with left ventral tegmental area (VTA) as seed region.At baseline, AD patients (N?=?23) showed increased cue-elicited brain activation in the ventral striatum (VS) compared to HC (N?=?23), which was decreased at the second scanning session compared to baseline. Patients receiving baclofen (N?=?10) showed a significant stronger decrease in cue-elicited brain activation in left orbitofrontal cortex (OFC), bilateral amygdala and left VTA than patients receiving placebo (N?=?13). Treatment with baclofen further led to a decrease in alcohol cue-modulated functional connectivity between left VTA and left anterior cingulate cortex (ACC) as well as left medial prefrontal cortex (MPFC). Regarding clinical outcome, significantly more patients of the baclofen group remained abstinent during the high-dose period.Baclofen specifically decreased cue-elicited brain responses in areas known to be involved in the processing of salient (appetitive and aversive) stimuli. Treatment with high-dose baclofen seems to provide a pharmacological relief of this neural “warning signal” evoked by alcohol-related cues, thereby possibly supporting patients in remaining abstinent.Trial Registration Identifier of the main trial [BACLAD study] at clinicaltrials.gov: NCT01266655.  相似文献   
60.
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