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   1335篇
  免费   81篇
  国内免费   22篇
耳鼻咽喉   3篇
儿科学   56篇
妇产科学   35篇
基础医学   170篇
口腔科学   36篇
临床医学   113篇
内科学   326篇
皮肤病学   7篇
神经病学   71篇
特种医学   128篇
外科学   251篇
综合类   11篇
预防医学   79篇
眼科学   5篇
药学   62篇
中国医学   3篇
肿瘤学   82篇
  2022年   6篇
  2021年   10篇
  2020年   6篇
  2019年   20篇
  2018年   22篇
  2017年   14篇
  2016年   20篇
  2015年   27篇
  2014年   30篇
  2013年   46篇
  2012年   49篇
  2011年   45篇
  2010年   41篇
  2009年   48篇
  2008年   37篇
  2007年   62篇
  2006年   50篇
  2005年   58篇
  2004年   92篇
  2003年   50篇
  2002年   65篇
  2001年   30篇
  2000年   38篇
  1999年   41篇
  1998年   39篇
  1997年   41篇
  1996年   35篇
  1995年   30篇
  1994年   30篇
  1993年   20篇
  1992年   30篇
  1991年   24篇
  1990年   29篇
  1989年   34篇
  1988年   28篇
  1987年   24篇
  1986年   25篇
  1985年   37篇
  1984年   19篇
  1983年   13篇
  1982年   17篇
  1981年   11篇
  1980年   6篇
  1979年   7篇
  1978年   3篇
  1977年   4篇
  1976年   3篇
  1975年   9篇
  1972年   2篇
  1971年   4篇
排序方式: 共有1438条查询结果,搜索用时 46 毫秒
1.
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   
2.
We investigated the antitumoral effect of bovine seminal RNase (BS-RNase) in vivo and in vitro on a model system of epithelial tumor- and metastasis-derived cells as well as on epithelial tumors derived from the same system. We found that while BS-RNase significantly inhibited the growth in vitro of the epithelial tumor-derived cells, its inhibitory effect was even more dramatic on the growth of metastasis-derived cells. BS-RNase exerted no appreciable growth inhibition on normal thyroid epithelial cells. When administered in vivo to rats bearing solid carcinomas, having the same thyroid origin, BS-RNase induced a drastic reduction in the tumor weight, with no detectable toxic effects on the treated animals. These data show, for the first time on a system of neoplastically transformed epithelial cells, that BS-RNase has a potent specific antitumoral activity.  相似文献   
3.
4.
5.
Physical inactivity is associated with alteration of normal physiologic processes leading to muscle atrophy, reduced exercise capacity, insulin resistance, and altered energy balance. Bed rest studies in human beings using stable isotopes of amino acids indicate that muscle unloading decreases the turnover rates of muscle and whole-body proteins, with a prevailing inhibition of protein synthesis. In the fasting state, muscle and whole-body nitrogen loss was not accelerated during bed rest. In experimental postprandial states, the amino acid-mediated stimulation of protein synthesis was impaired, whereas the ability of combined insulin and glucose infusion to decrease whole-body proteolysis was not affected by muscle inactivity. Thus, an impaired ability of protein/amino acid feeding to stimulate body protein synthesis is the major catabolic mechanism for the effect of bed rest on protein metabolism. This suggests that a protein intake level greater than normal could be required to achieve the same postprandial anabolic effect during muscle inactivity. Metabolic adaptation to muscle inactivity also involves development of resistance to the glucoregulatory action of insulin, decreased energy requirements, and increased insulin and leptin secretion. These alterations may lead to the development of the metabolic syndrome that is defined as the association of hyperinsulinemia, dyslipidemia, hypertension, hyperglycemia, and abdominal obesity. This cluster of metabolic abnormalities is a risk factor for coronary artery disease and stroke. Evidence indicates that exercise training programs may counteract all of these abnormalities both in healthy sedentary subjects and in patients affected by a variety of chronic disease states.  相似文献   
6.
7.
8.
9.
10.
Predominance of null mutations in ataxia-telangiectasia   总被引:15,自引:4,他引:15  
Ataxia-telangiectasia (A-T) is an autosomal recessive disorder involving cerebellar degeneration, immunodeficiency, chromosomal instability, radiosensitivity and cancer predisposition. The responsible gene, ATM, was recently identified by positional cloning and found to encode a putative 350 kDa protein with a Pl 3-kinase-like domain, presumably involved in mediating cell cycle arrest in response to radiation-induced DNA damage. The nature and location of A-T mutations should provide insight into the function of the ATM protein and the molecular basis of this pleiotropic disease. Of 44 A-T mutations identified by us to date, 39 (89%) are expected to inactivate the ATM protein by truncating it, by abolishing correct initiation or termination of translation, or by deleting large segments. Additional mutations are four smaller in-frame deletions and insertions, and one substitution of a highly conserved amino acid at the Pl 3-kinase domain. The emerging profile of mutations causing A-T is thus dominated by those expected to completely inactivate the ATM protein. ATM mutations with milder effects may result in phenotypes related, but not identical, to A-T.   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