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   34521篇
  免费   3000篇
  国内免费   124篇
耳鼻咽喉   320篇
儿科学   814篇
妇产科学   650篇
基础医学   4843篇
口腔科学   487篇
临床医学   3741篇
内科学   7476篇
皮肤病学   417篇
神经病学   3068篇
特种医学   1234篇
外国民族医学   10篇
外科学   5507篇
综合类   533篇
现状与发展   1篇
一般理论   30篇
预防医学   2699篇
眼科学   609篇
药学   2402篇
中国医学   53篇
肿瘤学   2751篇
  2023年   305篇
  2022年   528篇
  2021年   1150篇
  2020年   602篇
  2019年   971篇
  2018年   1114篇
  2017年   793篇
  2016年   795篇
  2015年   928篇
  2014年   1244篇
  2013年   1585篇
  2012年   2445篇
  2011年   2530篇
  2010年   1334篇
  2009年   1177篇
  2008年   1989篇
  2007年   1973篇
  2006年   1830篇
  2005年   1760篇
  2004年   1662篇
  2003年   1561篇
  2002年   1543篇
  2001年   472篇
  2000年   430篇
  1999年   461篇
  1998年   366篇
  1997年   289篇
  1996年   257篇
  1995年   245篇
  1994年   237篇
  1993年   191篇
  1992年   330篇
  1991年   259篇
  1990年   258篇
  1989年   229篇
  1988年   232篇
  1987年   252篇
  1986年   250篇
  1985年   238篇
  1984年   197篇
  1983年   191篇
  1982年   164篇
  1981年   142篇
  1980年   151篇
  1979年   171篇
  1978年   156篇
  1977年   117篇
  1976年   128篇
  1974年   133篇
  1973年   151篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
In the past 5 years, the use of nicotine delivered through electronic cigarettes (“e-cigarettes”) has sky-rocketed among adolescents and young adults. E-cigarettes, with their high nicotine content, appealing flavors, low costs, wide availability, and discreet designs threaten 5 decades of progress in the fight against tobacco use. Aside from the increased risk of subsequent use of traditional cigarettes, marijuana, opioids, and other illicit drugs, building evidence indicates that e-cigarette use also exposes youth to several acute and long-term health risks that greatly outweigh the as-yet unfounded potential benefits from the use of e-cigarettes as a smoking reduction or cessation tool in this age group. We discuss some of the latest research on e-cigarettes, highlighting risks and harms associated with their use in adolescents and young adults, and suggest opportunities for action, including the enforcement of age, sales and marketing limitations, and concerted research and public health efforts to help curb what has become a new nicotine epidemic among youth.  相似文献   
992.
993.
Next-generation sequencing identified about 60 genes recurrently mutated in chronic lymphocytic leukemia (CLL). We examined the additive prognostic value of the total number of recurrently mutated CLL genes (i.e., tumor mutational load [TML]) or the individually mutated genes beyond the CLL international prognostic index (CLL-IPI) in newly diagnosed CLL and high-count monoclonal B-cell lymphocytosis (HC MBL). We sequenced 59 genes among 557 individuals (112 HC MBL/445 CLL) in a multi-stage design, to estimate hazard ratios (HR) and 95% confidence intervals (CI) for time-to-first treatment (TTT), adjusted for CLL-IPI and sex. TML was associated with shorter TTT in the discovery and validation cohorts, with a combined estimate of continuous HR = 1.27 (CI:1.17-1.39, P = 2.6 × 10−8; c-statistic = 0.76). When stratified by CLL-IPI, the association of TML with TTT was stronger and validated within low/intermediate risk (combined HR = 1.54, CI:1.37-1.72, P = 7.0 × 10−14). Overall, 80% of low/intermediate CLL-IPI cases with two or more mutated genes progressed to require therapy within 5 years, compared to 24% among those without mutations. TML was also associated with shorter TTT in the HC MBL cohort (HR = 1.53, CI:1.12-2.07, P = .007; c-statistic = 0.71). TML is a strong prognostic factor for TTT independent of CLL-IPI, especially among low/intermediate CLL-IPI risk, and a better predictor than any single gene. Mutational screening at early stages may improve risk stratification and better predict TTT.  相似文献   
994.
Clinical Rheumatology - In this systematic review and meta-analysis of psoriatic arthritis (PsA) studies, we pooled data from existing literature to (1) estimate the prevalence of mental...  相似文献   
995.
There is increasing evidence for the role of exercise-based cardiac rehabilitation in the management of patients with atrial fibrillation (AF). However, this intervention has not yet been widely adopted within the National Health Service (NHS).We performed a feasibility study on the utilisation of an established NHS cardiac rehabilitation programme in the management of AF, and examined the effects of this intervention on exercise capacity, weight, and psychological health. We then identified factors that might prevent patients from enrolling on our programme.Patients with symptomatic AF were invited to participate in an established six-week exercise-based cardiac rehabilitation programme, composed of physical activity and education sessions. At the start of the programme, patients were weighed and measured, performed the six-minute walk test (6MWT), completed the Generalised Anxiety Disorder Questionnaire (GAD-7), and the Patient Health Questionnaire (PHQ-9). Measurements were repeated on completion of the programme.Over two years, 77 patients were invited to join the programme. Twenty-two patients (28.5%) declined participation prior to initial assessment and 22 (28.5%) accepted and attended the initial assessment, but subsequently withdrew from the programme. In total, 33 patients completed the entire programme (63.9 ± 1.7 years, 58% female). On completion, patients covered longer distances during the 6MWT, had lower GAD-7 scores, and lower PHQ-9 scores, compared with their baseline results. Compared with patients that completed the entire programme, those who withdrew from the study had, at baseline, a significantly higher body mass index (BMI), covered a shorter distance during the 6MWT, and had higher PHQ-9 and GAD-7 scores.In conclusion, enrolling patients with AF into an NHS cardiac rehabilitation programme is feasible, with nearly half of those invited completing the programme. In this feasibility study, cardiac rehabilitation resulted in an improved 6MWT, and reduced anxiety and depression levels, in the short term. Severe obesity, higher anxiety and depression levels, and lower initial exercise capacity appear to be barriers to completing exercise-based cardiac rehabilitation. These results warrant further investigation in larger cohorts.Key words: atrial fibrillation, cardiac rehabilitation, National Health Service  相似文献   
996.
997.
Background: Epidemiological studies have reported associations between air pollution exposure and increases in cardiovascular morbidity and mortality. Exposure to air pollutants can influence cardiac autonomic tone and reduce heart rate variability, and may increase the risk of cardiac arrhythmias, particularly in susceptible patient groups.Objectives: We investigated the incidence of cardiac arrhythmias during and after controlled exposure to air pollutants in healthy volunteers and patients with coronary heart disease.Methods: We analyzed data from 13 double-blind randomized crossover studies including 282 participants (140 healthy volunteers and 142 patients with stable coronary heart disease) from whom continuous electrocardiograms were available. The incidence of cardiac arrhythmias was recorded for each exposure and study population.Results: There were no increases in any cardiac arrhythmia during or after exposure to dilute diesel exhaust, wood smoke, ozone, concentrated ambient particles, engineered carbon nanoparticles, or high ambient levels of air pollution in either healthy volunteers or patients with coronary heart disease.Conclusions: Acute controlled exposure to air pollutants did not increase the short-term risk of arrhythmia in participants. Research employing these techniques remains crucial in identifying the important pathophysiological pathways involved in the adverse effects of air pollution, and is vital to inform environmental and public health policy decisions.Citation: Langrish JP, Watts SJ, Hunter AJ, Shah AS, Bosson JA, Unosson J, Barath S, Lundbäck M, Cassee FR, Donaldson K, Sandström T, Blomberg A, Newby DE, Mills NL. 2014. Controlled exposures to air pollutants and risk of cardiac arrhythmia. Environ Health Perspect 122:747–753; http://dx.doi.org/10.1289/ehp.1307337  相似文献   
998.
999.
Free clinics provide free or reduced fee healthcare to individuals who lack access to primary care and are socio-economically disadvantaged. The purpose of this study is to examine health-related quality of life (HRQoL) among free clinic patients and its association with somatic symptoms, depression, and perceived neighborhood environment. Free clinic patients (n = 186) aged 18 years or older completed a self-administered survey. HRQoL, depression, somatic symptoms, and perceived neighborhood environment were measured using standardized instruments. Overall, the participants reported low level of HRQoL compared to the general healthy population. US born participants (n = 97) reported poorer psychological QoL and social relations, more somatic symptoms, and were more likely to be depressed than non-US born participants (n = 89). Higher numbers of somatic symptoms were associated with poorer environmental QoL. Depression was associated with all aspects of QoL; a higher level of depression was related to poorer QoL in all aspects. Our findings show that free clinic patients, especially US born patients, have poor HRQoL. Depression and perceived neighborhood satisfaction are key factors to determine HRQoL among free clinic patients. Mental health services and collaboration with other community organizations may help in improving HRQoL among free clinic patients. Finally, health promotion programs at the community level, not just at the clinic level, would be valuable to improve health of free clinic patients as perceived neighborhood environment is associated with their HRQoL.  相似文献   
1000.
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