全文获取类型
收费全文 | 13450篇 |
免费 | 895篇 |
国内免费 | 37篇 |
专业分类
耳鼻咽喉 | 139篇 |
儿科学 | 509篇 |
妇产科学 | 363篇 |
基础医学 | 2009篇 |
口腔科学 | 200篇 |
临床医学 | 1620篇 |
内科学 | 2443篇 |
皮肤病学 | 323篇 |
神经病学 | 1637篇 |
特种医学 | 312篇 |
外科学 | 1320篇 |
综合类 | 67篇 |
一般理论 | 13篇 |
预防医学 | 1091篇 |
眼科学 | 234篇 |
药学 | 861篇 |
中国医学 | 17篇 |
肿瘤学 | 1224篇 |
出版年
2023年 | 99篇 |
2022年 | 182篇 |
2021年 | 301篇 |
2020年 | 246篇 |
2019年 | 323篇 |
2018年 | 365篇 |
2017年 | 306篇 |
2016年 | 372篇 |
2015年 | 407篇 |
2014年 | 502篇 |
2013年 | 706篇 |
2012年 | 1056篇 |
2011年 | 1024篇 |
2010年 | 624篇 |
2009年 | 553篇 |
2008年 | 858篇 |
2007年 | 890篇 |
2006年 | 875篇 |
2005年 | 832篇 |
2004年 | 762篇 |
2003年 | 705篇 |
2002年 | 673篇 |
2001年 | 84篇 |
2000年 | 47篇 |
1999年 | 106篇 |
1998年 | 159篇 |
1997年 | 126篇 |
1996年 | 98篇 |
1995年 | 103篇 |
1994年 | 63篇 |
1993年 | 76篇 |
1992年 | 45篇 |
1991年 | 54篇 |
1990年 | 46篇 |
1989年 | 25篇 |
1988年 | 37篇 |
1987年 | 25篇 |
1986年 | 28篇 |
1985年 | 28篇 |
1984年 | 28篇 |
1983年 | 34篇 |
1982年 | 42篇 |
1981年 | 23篇 |
1980年 | 33篇 |
1979年 | 28篇 |
1978年 | 15篇 |
1977年 | 20篇 |
1976年 | 27篇 |
1974年 | 20篇 |
1969年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
The purpose of this study was to examine the effect of exacerbations on mild to moderate asthmatic patients' preference-based, health-related, quality of life scores and also to describe the effect of these exacerbations on daily life. In a survey, 100 mild to moderate asthmatic patients in the United Kingdom were asked to rate three different health marker states on a scale between 0 (death) and 100 (perfect health), defined as: your asthma of today, a mild exacerbation, and a severe exacerbation of asthma. They were also asked to describe their symptoms and what they did when experiencing an exacerbation. During exacerbations the vast majority of asthmatic patients have significant symptoms and consume a considerable amount of health care resources, which often overlap. The health marker state “your asthma of today” was given a mean score of 81.0, a mild exacerbation a score of 62.1, and a severe exacerbation a score of 25.6, indicating a large impact on patients' daily life and their health-related quality of life. In conclusion, asthmatic patients are severely affected in their health and daily living by mild and severe exacerbations. Considerable effort should be made to reduce the number and severity of exacerbations. 相似文献
12.
13.
14.
Dardo G Tomasi Elisabeth C Caparelli 《Journal of cerebral blood flow and metabolism》2007,27(1):33-42
Brain activation maps of blood oxygenation level dependent (BOLD) signals during functional magnetic resonance imaging (fMRI) are sensitive to unwanted contributions from large vessels. Most BOLD-fMRI studies are based on a stimulus-correlated modulation of the MRI signal amplitude that is sensitive to desired microvascular effects and unwanted macrovascular effects. Aiming to suppress macrovascular effects in activation patterns, this BOLD-fMRI study evaluates brain activation during a verbal working memory task (2-back) in healthy volunteers (n=18) using the amplitude and phase components of the MRI signal. The use of the first time point as a phase reference allowed us to eliminate phase wrapping artifacts and increase the statistical power of 'phase' activation, and this information was used to filter out voxels with significant macrovascular (i.e., draining and pial veins) contribution in 'amplitude' activation patterns. Across subjects, the task produced large modulations of the relative phase in the occipital, dorsolateral prefrontal, and parietal cortices, suggesting a common distribution of draining veins in these regions across subjects, and in the rostral frontal cortex, probably associated to stimulus-correlated motion of the head. The phase filtering method partially suppressed BOLD responses in the superior and lateral prefrontal, parietal, and occipital cortices; therefore the commonly reported brain activation in these cortices during working memory tasks may include significant macrovascular contributions. This study suggests that the phase information embedded in the MRI signal can be used to suppress unwanted macrovascular contributions in fMRI studies. 相似文献
15.
Elisabeth U. Dexter M.D. John M. Snider M.D. Ellen E.I. Gordon M.D. Wayne E. Richenbacher M.D. 《Journal of cardiac surgery》1997,12(6):412-415
A bstract One etiology of unilateral lobar pulmonary edema is mitral regurgitation. Echocardiography is able to demonstrate the retrograde flow of blood into the pulmonary veins and allows timely diagnosis and treatment planning. Correction of mitral regurgitation is followed by resolution of the radiographic abnormality. 相似文献
16.
Hans Brunner Thomas C Wetter Birgit Hogl Alexander Yassouridis Claudia Trenkwalder Elisabeth Friess 《Movement disorders》2002,17(5):928-933
We investigated non-rapid eye movement (non-REM) sleep in patients with newly diagnosed Parkinson's disease (PD) who had never previously received dopaminergic medication. There were no significant differences in the conventional sleep parameters between de novo patients with PD and a healthy control group, but the length of stage 1 sleep and the number of awakenings increased significantly upon administration of dopaminergic drugs. Analyzing the quantitative electroencephalogram (EEG), we observed a significant reduction in the low-delta frequency range and a nonsignificant increase in the sigma frequency range in de novo patients with PD. The dopaminergic medication also nonsignificantly reduced the low-delta and sigma frequencies, the latter to the level of the controls. Possible mechanisms that may account for the observed differences are discussed. It is suggested that Parkinson's disease as well as the application of dopaminergic drugs exerts a desynchronizing effect on the sleep EEG that is reflected in a disruption of sleep continuity. 相似文献
17.
18.
Elisabeth Rodier Hubert Lochard Martial Sauceau Jean-Jacques Letourneau Bernard Freiss Jacques Fages 《European journal of pharmaceutical sciences》2005,26(2):184-193
The aim of this study is to improve the dissolution properties of a poorly-soluble active substance, Eflucimibe by associating it with gamma-cyclodextrin. To achieve this objective, a new three-step process based on supercritical fluid technology has been proposed. First, Eflucimibe and cyclodextrin are co-crystallized using an anti-solvent process, dimethylsulfoxide being the solvent and supercritical carbon dioxide being the anti-solvent. Second, the co-crystallized powder is held in a static mode under supercritical conditions for several hours. This is the maturing step. Third, in a final stripping step, supercritical CO(2) is flowed through the matured powder to extract the residual solvent. The coupling of the first two steps brings about a significant synergistic effect to improve the dissolution rate of the drug. The nature of the entity obtained at the end of each step is discussed and some suggestions are made as to what happens in these operations. It is shown the co-crystallization ensures a good dispersion of both compounds and is rather insensitive to the operating parameters tested. The maturing step allows some dissolution-recrystallization to occur thus intensifying the intimate contact between the two compounds. Addition of water is necessary to make maturing effective as this is governed by the transfer properties of the medium. The stripping step allows extraction of the residual solvent but also removes some of the Eflucimibe which is the main drawback of this final stage. 相似文献
19.
Demetrius Moskophidis Elisabeth Laine Rolf M. Zinkernagel 《European journal of immunology》1993,23(12):3306-3311
Antiviral cytotoxic memory CD8+ T cells adoptively transferred to mice which are persistently infected with lymphocytic choriomeningitis virus WE or DOCILE initially proliferated extensively; they either caused the death of the recipient or, alternatively, disappeared within a few days. Apparently, the complete and coordinated induction and stimulation by widely distributed viral antigen caused these memory T cells to die before virus had been eliminated from the host. Thus memory T cells are as susceptible to peripheral exhaustion/deletion as unprimed T cells. These results indicate possible limitations of exclusively CD8+ T cell-mediated adoptive immunotherapy against viral infections or tumors. 相似文献
20.