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   13340篇
  免费   1419篇
  国内免费   333篇
耳鼻咽喉   162篇
儿科学   378篇
妇产科学   247篇
基础医学   752篇
口腔科学   137篇
临床医学   1656篇
内科学   2903篇
皮肤病学   171篇
神经病学   612篇
特种医学   444篇
外国民族医学   2篇
外科学   1916篇
综合类   1635篇
现状与发展   2篇
预防医学   1210篇
眼科学   143篇
药学   1316篇
  66篇
中国医学   702篇
肿瘤学   638篇
  2024年   120篇
  2023年   580篇
  2022年   1004篇
  2021年   1378篇
  2020年   1260篇
  2019年   1032篇
  2018年   973篇
  2017年   791篇
  2016年   647篇
  2015年   559篇
  2014年   1120篇
  2013年   1039篇
  2012年   677篇
  2011年   643篇
  2010年   469篇
  2009年   439篇
  2008年   407篇
  2007年   370篇
  2006年   312篇
  2005年   234篇
  2004年   188篇
  2003年   126篇
  2002年   112篇
  2001年   77篇
  2000年   58篇
  1999年   49篇
  1998年   54篇
  1997年   56篇
  1996年   45篇
  1995年   33篇
  1994年   24篇
  1993年   33篇
  1992年   23篇
  1991年   22篇
  1990年   19篇
  1989年   18篇
  1988年   14篇
  1987年   12篇
  1986年   9篇
  1985年   17篇
  1984年   15篇
  1983年   7篇
  1982年   9篇
  1981年   5篇
  1980年   2篇
  1978年   3篇
  1977年   3篇
  1975年   1篇
  1972年   1篇
  1971年   1篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
动态脑电图对缺血缺氧性昏迷病人的预后评估   总被引:4,自引:0,他引:4  
目的:观察动态脑电图和临床检测指标对缺血缺氧性昏迷病人预后的评估价值。方法:在45例缺血缺氧性昏迷病人急性期进行动态脑电图检测和Glasgow评分、瞳孔对光反应、脑干反应检查,随访3个月时病人的预后,将动态脑电图检测和各项临床检查结果与病人的预后结果进行相关分析。结果:动态脑电图对昏迷病人预后的评估在敏感性(83.3%)、特异性(100%)和对预后评估的准确率(91.7%)方面均比临床检测结果高,临床指标Glasgow评分、瞳孔对光反射、脑干反射的敏感性、特异性及准确率分别为73.1%、84.2%及77.9%;76.9%、73.7%及75.6%;76.0%、68.4%及68.9%。结论:动态脑电图检测对急性缺血缺氧性昏迷病人预后的评估有确定的价值。  相似文献   
82.
Evolution of sleep and sleep EEG after hemispheric stroke   总被引:3,自引:0,他引:3  
The evolution of subjective sleep and sleep electroencephalogram (EEG) after hemispheric stroke have been rarely studied and the relationship of sleep variables to stroke outcome is essentially unknown. We studied 27 patients with first hemispheric ischaemic stroke and no sleep apnoea in the acute (1-8 days), subacute (9-35 days), and chronic phase (5-24 months) after stroke. Clinical assessment included estimated sleep time per 24 h (EST) and Epworth sleepiness score (ESS) before stroke, as well as EST, ESS and clinical outcome after stroke. Sleep EEG data from stroke patients were compared with data from 11 hospitalized controls and published norms. Changes in EST (>2 h, 38% of patients) and ESS (>3 points, 26%) were frequent but correlated poorly with sleep EEG changes. In the chronic phase no significant differences in sleep EEG between controls and patients were found. High sleep efficiency and low wakefulness after sleep onset in the acute phase were associated with a good long-term outcome. These two sleep EEG variables improved significantly from the acute to the subacute and chronic phase. In conclusion, hemispheric strokes can cause insomnia, hypersomnia or changes in sleep needs but only rarely persisting sleep EEG abnormalities. High sleep EEG continuity in the acute phase of stroke heralds a good clinical outcome.  相似文献   
83.
In order to achieve a clinical pregnancy rate higher than that achieved following initial adoption of in-vitro fertilization embryo transfers, more than one embryo is transferred. This has led to a substantial increase in unwanted multiple pregnancy rates with IVF as compared with natural conception. What is therefore required is a simple, clinically useful embryo scoring system, to reflect embryo developmental potential, which will enable the selection of the optimal number of embryos to transfer in order to achieve the maximum pregnancy rate with a low incidence of high order multiple pregnancies. We believe that the Cumulative Embryo Score (CES) achieves these aims. On the day of embryo transfer the grade of each embryo transferred was multiplied by the number of blastomeres to produce a score for each embryo, and summation of the scores obtained for all the embryos transferred gave the CES. The grouped pregnancy rates obtained rose as the CES increased to maximum of 42. A continued increase in the CES above 42 did not result in any further rise in the pregnancy rate. However, an analysis of all our IVF pregnancies showed that the multiple pregnancy rate continued to rise above a CES of 42. By restricting the CES per embryo transfer to 42, 78% of triplet pregnancies and 100% of the quadruplet IVF pregnancies could have been predicted and potentially avoided.  相似文献   
84.
Xia J  Deng H  Feng Y  Zhang H  Pan Q  Dai H  Long Z  Tang B  Deng H  Chen Y  Zhang R  Zheng D  He Y  Xia K 《Journal of human genetics》2002,47(12):0635-0640
 Hearing impairment is an extremely heterogeneous disorder. A total of 35 loci and 17 related genes for autosomal dominant nonsyndromic hearing loss have been identified. In a Chinese pedigree characterized by autosomal dominant inheritance with bilateral, postlingual, progressive, and sensorineural nonsyndromic hearing impairment, the putative disease gene locus was localized to chromosome 5q31.1-32 by a genome-wide scan. Fine mapping indicated that the disease gene was located within an 8.8-cM region between markers D5S2056 and D5S638, with a maximum two-point logarithm of differences (LOD) score of 6.89 (θ = 0) at D5S2017. By the candidate gene approach, mutation screening of the DIAPH1 and POU4F3 genes at 5q31 was performed. No mutation was found, suggesting that this is a novel deafness locus, which has been named DFNA42. Received: May 8, 2002 / Accepted: October 1, 2002  相似文献   
85.
《Value in health》2022,25(5):824-834
ObjectivesThe Patient-Reported Outcome Measurement Information System (PROMIS) Preference score (PROPr) can be used to assess health state utility (HSU) and estimate quality-adjusted life-years in cost-effectiveness analyses. It is based on item response theory and promises to overcome limitations of existing HSU scores such as ceiling effects. The PROPr contains 7 PROMIS domains: cognitive abilities, depression, fatigue, pain, physical function, sleep disturbance, and ability to participate in social roles and activities. We aimed to compare the PROPr with the 5-level EQ-5D (EQ-5D-5L) in terms of psychometric properties using data from 3 countries.MethodsWe collected PROMIS-29 profile and EQ-5D-5L data from 3 general population samples (United Kingdom = 1509, France = 1501, Germany = 1502). Given that cognition is not assessed by the PROMIS-29, it was predicted by the recommended linear regression model. We compared the convergent validity, known-groups construct validity, and ceiling and floor effects of the PROPr and EQ-5D-5L.ResultsThe mean PROPr (0.48, 0.53, 0.48; P<.01) and EQ-5D-5L scores (0.82, 0.85, 0.83; P<.01) showed significant differences of similar magnitudes (d = 0.34; d = 0.32; d = 0.35; P<.01) across all samples. The differences were invariant to sex, income, occupation, education, and most conditions but not for age. The Pearson correlation coefficients between both scores were r = 0.74, r = 0.69, and r = 0.72. PROPr’s ceiling and floor effects both were minor to moderate. The EQ-5D-5L’s ceiling (floor) effects were major (negligible).ConclusionsBoth the EQ-5D-5L and the PROPr assessed by the PROMIS-29 show high validity. The PROPr yields considerably lower HSU values than the EQ-5D-5L. Consequences for quality-adjusted life-year measurements should be investigated in future research.  相似文献   
86.
在设计随机对照试验(RCT)时,如果对照组存在患者招募和入组困难的情况,就会影响试验整体实施。近年来,真实世界数据(RWD)作为除RCT之外的数据来源,在医疗领域中发挥着越来越重要的作用。中医药RCT中可以尝试采用将RWD作为对照组的研究设计,不仅可以有效解决中医药RCT西医对照组患者入组困难的问题,同时能提供有力证据来评价中医药的疗效。倾向评分法目前已广泛应用于真实世界研究中混杂因素的处理,该文对RCT采用RWD作为对照组的这类设计中,基于倾向评分法常见的4种研究设计形式以实例分别进行了介绍,包括不对称随机分配、基于倾向评分分层法的两阶段设计、倾向评分联合复合似然法及倾向评分多种方法的联合。同时,这种设计类型也存在着方法学的挑战,包括RWD数据源必须是高质量且关键信息需要规范收集、RCT和RWD患者基线特征应该具有可比性、协变量选择时需要把所有已知与干预措施和结局相关的协变量都纳入进行分析等。在中医药领域采用这种设计时,还存在着有些RWD中医证型信息缺失、中医结局指标缺失等问题,在使用RWD时,需要根据数据实际情况决定如何分析。该文对以RWD作为RCT对照组的设计类型及面临的方法学挑战进行了介绍,期望能为研究者今后使用这类设计提供方法学借鉴。  相似文献   
87.
Our aim was to assess the association between a priori defined dietary patterns and incident depressive symptoms. We used data from The Maastricht Study, a population-based cohort study (n = 2646, mean (SD) age 59.9 (8.0) years, 49.5% women; 15,188 person-years of follow-up). Level of adherence to the Dutch Healthy Diet (DHD), Mediterranean Diet, and Dietary Approaches To Stop Hypertension (DASH) were derived from a validated Food Frequency Questionnaire. Depressive symptoms were assessed at baseline and annually over seven-year-follow-up (using the 9-item Patient Health Questionnaire). We used Cox proportional hazards regression analyses to assess the association between dietary patterns and depressive symptoms. One standard deviation (SD) higher adherence in the DHD and DASH was associated with a lower hazard ratio (HR) of depressive symptoms with HRs (95%CI) of 0.78 (0.69–0.89) and 0.87 (0.77–0.98), respectively, after adjustment for sociodemographic and cardiovascular risk factors. After further adjustment for lifestyle factors, the HR per one SD higher DHD was 0.83 (0.73–0.96), whereas adherence to Mediterranean and DASH diets was not associated with incident depressive symptoms. Higher adherence to the DHD lowered risk of incident depressive symptoms. Adherence to healthy diet could be an effective non-pharmacological preventive measure to reduce the incidence of depression.  相似文献   
88.
Dietary habits have considerable impact on brain development and mental health. Despite long-standing interest in the association of dietary habits with mental health, few population-based studies of dietary habits have assessed depression and fluid intelligence. Our aim is to investigate the association of dietary habits with depression and fluid intelligence. In total, 814 independent loci were utilized to calculate the individual polygenic risk score (PRS) for 143 dietary habit-related traits. The individual genotype data were obtained from the UK Biobank cohort. Regression analyses were then conducted to evaluate the association of dietary habits with depression and fluid intelligence, respectively. PLINK 2.0 was utilized to detect the single nucleotide polymorphism (SNP) × dietary habit interaction effect on the risks of depression and fluid intelligence. We detected 22 common dietary habit-related traits shared by depression and fluid intelligence, such as red wine glasses per month, and overall alcohol intake. For interaction analysis, we detected that OLFM1 interacted with champagne/white wine in depression, while SYNPO2 interacted with coffee type in fluid intelligence. Our study results provide novel useful information for understanding how eating habits affect the fluid intelligence and depression.  相似文献   
89.
Over the past 4 decades, China has experienced a nutritional transition and has developed the largest population of internet users. In this study, we evaluated the impacts of internet access on the nutritional intake in Chinese rural residents. An IV-Probit-based propensity score matching method was used to determine the impact of internet access on nutritional intake. The data were collected from 10,042 rural households in six Chinese provinces. The results reveal that rural residents with internet access have significantly higher energy, protein, and fat intake than those without. Chinese rural residents with internet access consumed 1.35% (28.62 kcal), 5.02% (2.61 g), and 4.33% (3.30 g) more energy, protein, and fat, respectively. There was heterogeneity in regard to the intake of energy, protein, and fat among those in different income groups. Moreover, non-staple food consumption is the main channel through which internet access affects nutritional intake. The results demonstrate that the local population uses the internet to improve their nutritional status. Further studies are required to investigate the impact of internet use on food consumed away from home and micronutrient intake.  相似文献   
90.
目的:运用层次分析法(AHP)确定医疗设备维护中的优先级,增加医疗设备的可用性并降低维护成本。方法:采用AHP对医疗设备标准、子标准和等级进行评定获取其关键评分,基于多标准决策方法确定医疗设备维护的优先级,对选定设备进行评估,以准分子激光器和视力计为例,根据其标准权重、子标准权重和强度计算其总评分,确定维护优先级。结果:医疗设备维护的优先顺序由医疗设备评分的评估结果决定,医疗设备风险是医学技术人员在确定医疗设备维护优先级时的最重要标准。准分子激光器和视力计的关键评分权重分别为0.877和0.373,准分子激光器相比视力计在设备维护方面具有更高的优先级。结论:医疗设备维护优先级评估模型能确定医疗设备维护优先级,根据优先级规模规划医疗设备维护方案,以使资源更多地集中于具有高和中关键度的医疗设备。  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