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   8608篇
  免费   530篇
  国内免费   13篇
耳鼻咽喉   98篇
儿科学   226篇
妇产科学   249篇
基础医学   1555篇
口腔科学   146篇
临床医学   683篇
内科学   1667篇
皮肤病学   208篇
神经病学   832篇
特种医学   400篇
外科学   1177篇
综合类   45篇
一般理论   1篇
预防医学   442篇
眼科学   203篇
药学   701篇
中国医学   4篇
肿瘤学   514篇
  2022年   50篇
  2021年   111篇
  2020年   69篇
  2019年   101篇
  2018年   124篇
  2017年   111篇
  2016年   131篇
  2015年   154篇
  2014年   197篇
  2013年   233篇
  2012年   395篇
  2011年   415篇
  2010年   265篇
  2009年   254篇
  2008年   381篇
  2007年   438篇
  2006年   422篇
  2005年   415篇
  2004年   431篇
  2003年   405篇
  2002年   397篇
  2001年   240篇
  2000年   255篇
  1999年   201篇
  1998年   125篇
  1997年   115篇
  1996年   96篇
  1995年   92篇
  1994年   66篇
  1993年   83篇
  1992年   165篇
  1991年   140篇
  1990年   142篇
  1989年   134篇
  1988年   102篇
  1987年   83篇
  1986年   107篇
  1985年   107篇
  1984年   82篇
  1983年   84篇
  1982年   59篇
  1981年   61篇
  1980年   64篇
  1979年   87篇
  1978年   50篇
  1977年   58篇
  1976年   56篇
  1975年   47篇
  1973年   62篇
  1972年   45篇
排序方式: 共有9151条查询结果,搜索用时 15 毫秒
51.
52.
Fatigue is a frequent and disabling phenomenon among patients with multiple sclerosis (MS). Daytime sleepiness is a typical symptom of the sleep apnoea/hypopnoea syndrome due to nocturnal hypoxia and recurrent arousals causing sleep fragmentation. Since MS plaques are often found in the midbrain, brain stem and upper cervical cord on magnetic resonance imaging (MRI) we hypothesized that fatigue in MS patients might be caused by a central respiratory dysfunction. We investigated 10 patients with definite MS by oligography, two questionnaires assessing fatigue (Fatigue Severity Scale, FSS) and daytime sleepiness (Epworth Sleepiness Scale, ESS), MRI and pulmonary function tests. A total of six patients had either an elevated FSS and/or an elevated ESS. None of the six patients with an elevated FSS and/or ESS has an apnoea index > 5/hour. CT90 was normal in nine patients. We conclude that fatigue and daytime sleepiness in MS cannot be explained by nocturnal apnoeas or oxygen desaturations. The Fatigue Severity Scale should be integrated to the extended Barthel index, which is a new instrument for disability assessment in MS patients.  相似文献   
53.
The circulating concentration of 1,25-dihydroxycholecalciferol [1,25-(OH)2D3] is a physiologic index of enzymatic activity of the renal 1-hydroxylase of 25-hydroxychole-calciferol (25-OH-D3). Hydroxylation of 25-OH-D3 and circulating 1,25-(OH)2D3 are decreased in the streptozotocin diabetic rat. We previously found that activity of another redox enzyme system, cytosolic superoxide dismutase, also decreased in streptozotocin diabetes, can be restored by treatment with glutathione. In the present experiment we tested the effect of glutathione treatment on vitamin D metabolism in control and diabetic rats. Enteral glutathione increased circulating 1,25-(OH)2D3 and decreased 25-OH-D3 in both control and diabetic animals. These results suggest that exogenous glutathione increases 25-OH-D3 1-hydroxylation both under basal conditions in the normal animal and in diabetes-induced depression.  相似文献   
54.
To study efficacy of a purified and biologically standardized house dust mite extract 66 allergic children were investigated. 26 patients on immunotherapy and 21 controls with symptomatic treatment only finished the study. A significant reduction of the skin reactivity associated with an increase of allergen specific IgG-antibodies was observed. However, no significant differences were found correlating the results of inhalative provocation tests, specific IgE antibodies and symptom scores. The immunotherapy with house dust mite extracts needs further evaluation.  相似文献   
55.
Growth monitoring, oral rehydration, breast-feeding and immunisation--female education, family spacing and food supplementation (GOBI-FFF) are a selective package of World Health Organisation primary health care strategies recommended by UNICEF. Changes over a 1-year period in the implementation of the components of GOBI-FFF were investigated in a rural village in Ciskei to detect any changes associated with a newly modified village health-worker (VHW) programme. A baseline survey was conducted before the introduction of a modified VHW programme and a second survey took place a year later. The principles of GOBI-FFF were already familiar to and have since been increasingly practised by the community and health personnel. Breast-feeding is widespread, most carers know how to make oral rehydration solution and most children have a 'Road to Health' card and are being weighed regularly. However, malnutrition remains a major problem and the food supplementation programme is operating poorly. The high coverage of the community by the village health-workers and the clinic suggest that these two channels should be used more intensively to strengthen the GOBI-FFF programme in the area.  相似文献   
56.
Despite the existence of a well-defined abstinence syndrome in offspring of opiate-dependent mothers, the mechanisms involved in neonatal abstinence remain unclear. The goal of the present study was to determine the contribution of noradrenergic neurons in the opiate abstinence syndrome in neonatal rats (10 days old). First, the ability of the α2-adrenergic agonist, clonidine to attenuate the symptoms of neonatal opiate abstinence precipitated by naloxone was determined. Secondly, the activity of noradrenergic neurons was determined by measuring postmortem levels of 3-methoxy-4-hydroxyphenylglycol (MHPG) in the hypothalamus, hippocampus and cortex in opiate-abstinent pups. Neonatal opiate abstinence was characterized by an increased incidence of wall climbing, tremors and mouthing. Acute treatment with morphine and naloxone in chronic saline-treated pups also produced the tremor, albeit less severe than in pups treated chronically with morphine. Clonidine (0.2 mg/kg) attenuated the expression of tremor and mouthing in neonates, but increased wall climbing. Clonidine elicited wall climbing in opiate-naive neonates. Treatment with morphine followed by naltrexone increased MHPG levels in all of the brain areas examined, irrespective of the chronic treatment, but naltrexone treatment elicited a larger increase in MHPG levels in pups treated chronically with morphine. Acute morphine treatment increased MHPG levels only in the hypothalamus. The results of the present study provide behavioral and neurochemical data supporting the hypothesis that noradrenergic hyperactivity plays a role in neonatal opiate abstinence.  相似文献   
57.

Background  

It is often stated that external validity is not sufficiently considered in the assessment of clinical studies. Although tools for its evaluation have been established, there is a lack of awareness of their significance and application. In this article, a comprehensive checklist is presented addressing these relevant criteria.  相似文献   
58.
59.
Studied children with mild to moderate juvenile rheumatoid arthritiswho were massaged by their parents 15 minutes a day for 30 days(and a control group engaged in relaxation therapy). The children'sanxiety and stress hormone (cortisol) levels were immediatelydecreased by the massage, and over the 30-day period their paindecreased on self-reports, parent reports, and their physician'sassessment of pain (both the incidence and severity) and pain-limitingactivities  相似文献   
60.
Students (N = 377) from four Cape Town township high schools were surveyed to obtain information on their knowledge of and attitudes towards the acquired immunodeficiency syndrome (AIDS), and on their sexual behaviour. The study was undertaken to provide information for planning an AIDS education intervention. Three-quarters of students reported that they had had sexual intercourse. Most students had heard of AIDS, and the majority of these knew that it was infectious. More than half of the students were confused or lacked knowledge about the modes of transmission. Two-thirds of the students believed AIDS could be prevented, but knowledge of prevention strategies was superficial. Of the sexually active students only 11.4% had ever used a condom, and of all students 39.6% stated that they would use a condom in the future. Two-thirds of the students were not aware that there is no cure for AIDS. Students did not acknowledge that AIDS could affect them directly, and attributed the problem to prostitutes and 'promiscuous' people in 36.4% of responses, and to 'white' people in 23.8% of responses. Students expressed intolerance, fear and rejection of people with AIDS, and only 6.4% would accept an affected person into their class. Almost all the students wanted AIDS education at school, and most of these requested that the school nurse facilitate this education. It is concluded that appropriate AIDS prevention education is urgently required for both high school and junior school students.  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