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   13869篇
  免费   754篇
  国内免费   95篇
耳鼻咽喉   118篇
儿科学   331篇
妇产科学   257篇
基础医学   1933篇
口腔科学   356篇
临床医学   1229篇
内科学   3742篇
皮肤病学   227篇
神经病学   1418篇
特种医学   432篇
外科学   1968篇
综合类   42篇
一般理论   4篇
预防医学   641篇
眼科学   191篇
药学   767篇
中国医学   29篇
肿瘤学   1033篇
  2023年   91篇
  2022年   179篇
  2021年   371篇
  2020年   265篇
  2019年   315篇
  2018年   405篇
  2017年   304篇
  2016年   350篇
  2015年   420篇
  2014年   560篇
  2013年   721篇
  2012年   1136篇
  2011年   1123篇
  2010年   654篇
  2009年   570篇
  2008年   944篇
  2007年   948篇
  2006年   909篇
  2005年   866篇
  2004年   805篇
  2003年   674篇
  2002年   639篇
  2001年   117篇
  2000年   95篇
  1999年   118篇
  1998年   122篇
  1997年   106篇
  1996年   104篇
  1995年   73篇
  1994年   71篇
  1993年   55篇
  1992年   58篇
  1991年   57篇
  1990年   45篇
  1989年   45篇
  1988年   36篇
  1987年   34篇
  1986年   34篇
  1985年   26篇
  1984年   43篇
  1983年   37篇
  1982年   29篇
  1981年   26篇
  1980年   14篇
  1979年   15篇
  1978年   13篇
  1977年   11篇
  1976年   14篇
  1975年   10篇
  1974年   14篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
3.
4.
Background:Workplace hazards are a significant source of health impairment for workers and of financial losses for firms. EU directives on workers’ health and safety standards significantly contributed to reduce reported occupational injuries, yet the incidence and prevalence of work-related mental illness is still very high.Objectives:We investigated the association between work-related hazards and individuals’ perceived mental health. We reviewed the existing evidence on the channels through which task-related factors, adverse agents and psychosocial factors are expected to affect workers’ health, with specific regard to mental health.Methods:We used data from the fifth wave of the European Working Conditions Survey, covering over 40,000 face-to-face interviews with workers in 34 countries, which includes information on socio-demographic characteristics, firms and jobs attributes, employment status, as well as working conditions and health status. We carried out an empirical analysis with multivariate regression models in order to estimate the relationship between workers’ mental health problems and workplace risk factors.Results:21,020 interviews were used in the multivariate analysis. We found strong correlations between hazards and various indicators of mental health. Among hazardous agents, low temperatures (β=0.0287) and contact with infectious materials (β=0.0394) were positively associated with mental health outcomes. Among task/sequence-related factors, tiring or painful positions (β=0.0713), repetitive hand/arm movements (β=0.0255), working with VDUs (β=0.0301), repetitive tasks <10 min (β=0.0859) and working in evenings (β=0.00754) were positively associated with mental health. Various psychosocial risk factors related to both the content of the job (for example, frequent disruptive interruptions: β=0.219, working in free time: β=0.0759, poor work-life balance: β=0.228) as well as the job context (for example, bad employment prospects: β=0.177, low decisional autonomy: β=0.245, bad social relations: β=0.186, workplace violence: β=0.411) were positively associated with mental health. The main results of the decomposition show that an important contribution to workers’ overall mental distress at work is associated with psychosocial risk factors (up to 60% for depression/anxiety symptoms and sleep disorders), while the contribution of somatic factors is on average lower (up to 20% for overall fatigue).Conclusions:We argue that action is needed to improve workers’ mental well-being, and reduce the economic costs for both the national health system and employers. Regulations and traditional economic measures are unlikely to prove successful in providing adequate standards of primary and secondary preventive measures in the work place without an appropriate and reliable Risk Assessment Procedure.Key words: Work hazards, risk assessment, job content, mental health  相似文献   
5.
6.
7.
8.
OBJECTIVE: Respiratory muscle endurance of able-bodied persons, assessed by normocapnic hyperpnoea at 70% of their maximal voluntary ventilation, usually ranges from 10 to 20 minutes. The aim of this study was to determine the level of ventilation that patients with paraplegia and tetraplegia can sustain for 10-20 minutes to later be used as the guideline for respiratory muscle endurance training. DESIGN: Pilot study; cross-over setting. SUBJECTS: Two groups, 8 patients with paraplegia and 6 with tetraplegia. METHODS: Respiratory muscle endurance tests were performed at 3 different intensities of normocapnic hyperpnoea, i.e. 20%, 40% and 60% maximal voluntary ventilation. Subjects performed partial re-breathing from a bag to assure normocapnia. Respiratory endurance was separately analysed for patients with paraplegia and tetraplegia. RESULTS: Mean respiratory endurance times were 46.0, 18.9 and 4.2 minutes at 20%, 40% and 60% maximal voluntary ventilation in patients with tetraplegia and 51.8, 38.8 and 12.2 minutes in patients with paraplegia. The duration differed significantly at 60% maximal voluntary ventilation between the groups. CONCLUSION: Minute ventilation to perform respiratory muscle endurance training can be set at around 40% of maximal voluntary ventilation for patients with tetraplegia and around 60% of maximal voluntary ventilation for patients with paraplegia, as these levels can be sustained for 10-20 minutes.  相似文献   
9.
10.
OBJECTIVE: The effects of major lung resections on cardiac function in the medium and long term have not been thoroughly evaluated. We have studied right heart function with serial Doppler echocardiography in patients undergoing lobectomy and pneumonectomy during 4 years of follow-up after surgery. METHODS: Thirty-six patients undergoing lobectomy and 15 receiving pneumonectomy were evaluated with one- and two-dimensional Doppler standard transthoracic echocardiography before surgery and 1 week, 3 months, 6 months, 1 year, and 4 years postoperatively. We have studied the right midventricular diastolic diameter (RVDD), the right ventricle free wall thickness, the tricuspid valve insufficiency (TVI) and regurgitation jet (TRJ), and the pulmonary artery systolic pressure (PASP). RESULTS: None of the patients died within the first postoperative year. After lobectomy there were no significant modifications of any variable at any time. RVDD progressively increased after pneumonectomy (26.5+/-2.2mm preoperatively vs 34.3+/-7.6 at 4 years; p<0.001). Four years after surgery all patients undergoing pneumonectomy had moderate TVI while only 55% of patients receiving lobectomy showed it (low grade in 50% and moderate in 5%). In this group of patients PASP increased from 26.1+/-2.6 mmHg preoperatively to 34.3+/-7.6 mmHg at 4 years (p<0.00001). CONCLUSIONS: Right ventricle modifications are clearly evident after pneumonectomy and even if they do not show a clear clinical impact they should not be neglected.  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