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   3243007篇
  免费   253724篇
  国内免费   6273篇
耳鼻咽喉   48110篇
儿科学   99944篇
妇产科学   89036篇
基础医学   454155篇
口腔科学   96093篇
临床医学   290862篇
内科学   631050篇
皮肤病学   68738篇
神经病学   268903篇
特种医学   129130篇
外国民族医学   1251篇
外科学   494395篇
综合类   78205篇
现状与发展   7篇
一般理论   1308篇
预防医学   252654篇
眼科学   78145篇
药学   243982篇
  8篇
中国医学   6365篇
肿瘤学   170663篇
  2018年   31636篇
  2016年   27217篇
  2015年   30712篇
  2014年   44115篇
  2013年   67414篇
  2012年   89978篇
  2011年   95085篇
  2010年   56113篇
  2009年   54179篇
  2008年   90751篇
  2007年   97276篇
  2006年   98230篇
  2005年   95851篇
  2004年   92397篇
  2003年   89541篇
  2002年   88445篇
  2001年   149456篇
  2000年   154542篇
  1999年   131052篇
  1998年   37289篇
  1997年   33993篇
  1996年   33160篇
  1995年   32042篇
  1994年   30025篇
  1993年   27938篇
  1992年   104859篇
  1991年   101216篇
  1990年   98240篇
  1989年   95099篇
  1988年   88344篇
  1987年   87071篇
  1986年   82944篇
  1985年   79234篇
  1984年   59896篇
  1983年   51037篇
  1982年   31010篇
  1981年   27779篇
  1980年   26029篇
  1979年   56767篇
  1978年   40161篇
  1977年   34347篇
  1976年   31748篇
  1975年   34472篇
  1974年   41891篇
  1973年   40144篇
  1972年   37986篇
  1971年   35388篇
  1970年   33428篇
  1969年   31360篇
  1968年   28856篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
In an attempt to identify a cause for the alteration in breathing pattern seen when conventional respiratory apparatus is applied to the face, we have studied the effects of causing the subject to focus attention on breathing by counting breaths in threes for 5 min. We used the respiratory inductance plethysmograph in 18 naive subjects who were unaware that their breathing was being measured. In the control periods, distraction was provided by a recorded story played through head-phones. The experiment was repeated with the rim of a facemask applied to the face. Focusing attention on breathing caused a prolongation of inspiration at a constant mean inspiratory flow, and lengthening of expiration. Tidal volume but not ventilation was increased. The facemask rim caused no significant change. It is concluded that conscious awareness of breathing could account for a major part of the effect of conventional respiratory apparatus.  相似文献   
992.
An epidemiologic study of coeliac disease in a geographically defined area of Sweden showed that the prevalence was 95.5/10(5) inhabitants aged 15 years or more. The highest prevalence, 178/10(5) inhabitants, was found in the age group 65-74 years. The lowest prevalence, 39/10(5) inhabitants, was found in patients aged 15-24 years. Among the associated diseases an especially high incidence of associated thyroid disease was observed: thyrotoxicosis occurred in 5.0% and hypothyroidism in 5.8% of the patients.  相似文献   
993.
In any case of acute bronchoconstriction the possibility of an adverse reaction to a drug should be considered. In many of such side reactions no allergic mechanism can be detected. Therefore, they are included into the category of pseudoallergic reactions (PAR). The clinically most important form of drug-induced bronchial asthma, analgesics asthma, belongs to this PAR group. A further risk for asthmatics are intravenous applications of contrast-media for roentgenography which in about 15% induce a severe, sometimes life-threatening pseudo-allergic adverse reaction. In asthmatics, the application of any beta-receptor blocking agents and also the use of parasympathicotonic eye drops for treatment of glaucoma are contraindicated. Paradoxical bronchial constriction following application of antiasthmatics are preponderantly caused by locally irritative actions, less frequently by genuine allergic phenomena or additive intolerance. The most reliable prophylaxis against drug-induced bronchial asthma consists in strong avoidance of all derivatives possibly capable to trigger any intolerance. A respective warning should entered into the emergency passport.  相似文献   
994.
Today old age represents no contraindication to operative treatment. The age dependence of normal coagulation, immunological system and connective tissue components is described with respect to the course of wound healing. Possible misinterpretations that may occur, if preoperative values do not exist and the subsequent course is not observed, are pointed out.  相似文献   
995.
The role of hypertension and antihypertensive drugs in cardiovascular complications was evaluated in 380 elderly people living in the Tokyo Metropolitan Gerontology Center. The subjects were classified into four groups according to the presence or absence of hypertension and their antihypertensive treatment, and followed up prospectively for 5 years from 1979 to 1984. The average age of each group was 74 to 76 years. Cerebrovascular disease was observed in 19.3% of male hypertensives and 10.1% of male normotensives (p = 0.078). The drug treated group revealed no cerebral hemorrhage and less cerebral infarction. This tendency was not observed in females. Ischemic heart disease was prevalent in the drug treated group (10.9% vs 4.5%, p = 0.023) irrespective of blood pressure level. Risk factors such as body mass index, skinfold thickness, serum cholesterol, albumin, creatinine, blood urea nitrogen and uric acid at entry were elevated in the drug treated group. Diuretics were used in 92% of the drug treated group; in 53% as monotherapy and in 39% as combination therapy with other antihypertensive agents. The metabolic effect of diuretics may increase the incidence of ischemic heart disease in the elderly. We might conclude that hypertension in the aged accelerates cerebrovascular complications, and that antihypertensive treatment is effective even in this group. However, the wide use of diuretics could increase the incidence of ischemic heart disease. Careful selection of antihypertensive drugs as well as dose adjustment are needed in the treatment of elderly hypertensives.  相似文献   
996.
Despite growing concern with rural elderly populations, little attention has focused on their mental health, ways it may correlate with physical health, or how rural mental health patterns compare to urban. Popular wisdom contends that elderly people in general, and rural elderly persons in particular, are at increased risk for mental illness. This article examines these questions. A review of available literature suggests that elderly people may be at only slightly greater risk of mental illness than the population at large, though there are some indications that rates of depression may be somewhat higher among the elderly population. Much of this same literature implies that objective environmental conditions play a significant role in the incidence of depression. Analysis of data gathered in a statewide random poll (N = 743) indicates that while physical health tends to be poorer among rural populations, when health is held constant there is actually an inverse relationship between age and depression. Therefore, rural elderly persons are no more likely to be depressed than their urban counterparts despite harsher living conditions. Both conceptual and policy implications are discussed.  相似文献   
997.
Brain tissues from 38 patients with a clinical suspicion of encephalitis or encephalopathy were examined by two immunoenzymatic techniques for the detection of arboviral antigen. Group B arboviral antigen was identified in 23 of these tissues. This simple method could be used for the diagnosis of the causal agent of encephalitis.  相似文献   
998.
The intimate and complex relationship that exists between man and mollusc makes the group an ideal target for the application of biotechnology. The paper discusses and reviews the application of both the conventional and new molecular techniques to the study of the molluscan hosts of animal parasites. The remarkable advances in molluscan biology which have occurred during the past two decades as a consequence of conventional technological methods are noted and applications pertinent to problems in Southeast Asia are cited. Applications of new biotechniques, including those of molecular biology, to problems of the host-parasite interaction are discussed. Examples of how the new biotechnology may resolve present and future problems in applied malacology are presented.  相似文献   
999.
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