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   2638755篇
  免费   199319篇
  国内免费   4993篇
耳鼻咽喉   37802篇
儿科学   83986篇
妇产科学   76103篇
基础医学   371208篇
口腔科学   79576篇
临床医学   229307篇
内科学   512298篇
皮肤病学   58384篇
神经病学   212786篇
特种医学   105338篇
外国民族医学   879篇
外科学   403916篇
综合类   64362篇
现状与发展   9篇
一般理论   919篇
预防医学   196000篇
眼科学   62122篇
药学   199493篇
  7篇
中国医学   5391篇
肿瘤学   143181篇
  2018年   24086篇
  2015年   24276篇
  2014年   33713篇
  2013年   51691篇
  2012年   68731篇
  2011年   72632篇
  2010年   43150篇
  2009年   41288篇
  2008年   69737篇
  2007年   74623篇
  2006年   75578篇
  2005年   73518篇
  2004年   71972篇
  2003年   69411篇
  2002年   68199篇
  2001年   122326篇
  2000年   126085篇
  1999年   107395篇
  1998年   29280篇
  1997年   26626篇
  1996年   26122篇
  1995年   25101篇
  1994年   23598篇
  1993年   22143篇
  1992年   86580篇
  1991年   83949篇
  1990年   82200篇
  1989年   80102篇
  1988年   74575篇
  1987年   73417篇
  1986年   70091篇
  1985年   67236篇
  1984年   50365篇
  1983年   43245篇
  1982年   25669篇
  1981年   23218篇
  1980年   21753篇
  1979年   48285篇
  1978年   34037篇
  1977年   29072篇
  1976年   26827篇
  1975年   29315篇
  1974年   35472篇
  1973年   34221篇
  1972年   32035篇
  1971年   30121篇
  1970年   28139篇
  1969年   26731篇
  1968年   24858篇
  1967年   22383篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Caffeine is the most widely consumed drug in Western society. The intake of caffeine-containing beverages in many adults and children often reaches levels that can induce pharmacological effects. Ninety-nine percent of ingested caffeine is absorbed and distributed to all tissues and organs. The effects of caffeine intake differ greatly according to acute or chronic intake, level of intake, and the development of tolerance. Caffeine administered acutely to non-users or recent abstainers can induce hypertension, arrhythmias, altered myocardial function, increased plasma catecholamine levels, plasma renin activity, serum cholesterol levels, increased production of urine, gastric acid secretion, and alterations in mood and sleep patterns. Tolerance to chronic caffeine intake develops in most individuals, with the cessation of its effects on the renal system, the cardiovascular system, the gastrointestinal system and, to some extent, the central nervous system. Moderate caffeine consumers probably need to have little concern for the effect of caffeine intake on their health if their other life-style habits are also moderate.  相似文献   
992.
Relatives of 22 schizotypal probands were evaluated for lifetime psychiatric diagnoses. Forty-four (N = 44) of the 97 available relatives were interviewed directly using the Diagnostic Interview Schedule. The rates of psychiatric diagnoses were compared with those of sixty-six (N = 66) of 140 relatives of 30 depressed patients. Family history of mental illness was ascertained by the informant method on the remainder of relatives of both proband groups. The rate of depression found in the relatives of schizotypal patients was 52% in those directly interviewed and 25.7% when informants' reports on unavailable relatives are pooled with direct interview data. These rates were not significantly higher than those found for the relatives of depressed probands (34.8% by direct interview and 21% including reports from informants). The high rates of depression in the relatives of schizotypal probands may indicate that schizotypal personality is associated with affective disorder and not only with schizophrenia. However, the high rates may be due to the presence of depressive character traits in relatives, which inflate the rates of dysthymic disorder and other chronic depressive disorders in the relatives of borderline patients.  相似文献   
993.
A 68 year-old woman presented with a two-week history of amaurosis fugax, ipsilateral fronto-temporal headache and jaw claudication suggesting carotid giant cell arteritis. However, this syndrome proved to be due to atherosclerosis causing complete occlusion of the external carotid artery at its origin and narrowing of the internal carotid artery. Combined external and internal carotid endarterectomy relieved the symptoms. The symptom complex of temporal arteritis may be rarely mimicked by carotid atherosclerotic occlusive disease.  相似文献   
994.
L H Phillips 《Neurology》1986,36(9):1251-1253
Long thoracic nerve palsy causes weakness of the serratus anterior muscle and winging of the scapula. It is usually traumatic in origin. Isolated long thoracic nerve palsy has not been recognized as the major manifestation of familial brachial plexus neuropathy, but I have studied the syndrome in four members of three generations of one family. One individual suffered an episode of facial paresis. The inheritance pattern was autosomal dominant.  相似文献   
995.
996.
Numerous surveys at the national and regional level have demonstrated that large inequalities in infant health status exist in Southern Africa. Few studies have assessed infant mortality at the intra-urban scale of geographic analysis. Comparisons between infant mortality rates from different areas are made even more meaningful if the data are divided into two primary categories based on period-of-death; these being the neonatal and post-neonatal components. This study presents the results of a survey undertaken in Metropolitan Cape Town (population 1.6 million) during 1982. The aim was to determine the spatial variation of neonatal and post-neonatal mortality at the suburb (or community) level within the city. Overall, a total of 36,789 live births and 928 infant deaths were recorded; 53.4% in the neonatal period and 46.6% in the post-neonatal period. The mean infant mortality rate was 25.2 per 1000 live births; the neonatal mortality rate and post-neonatal mortality rate being 13.5/1000 and 11.7/1000, respectively. A marked range in death rates was evident for both components. For the neonatal category it was 0.0-49.9/1000 and 0.0-40.0/1000 for the post-neonatal period. The generally low post-neonatal mortality rate among the 69 suburbs studied has made the neonatal component the dominant contributor to the infant mortality rate. However, in the lowest socio-economic areas the post-neonatal mortality rate was responsible for over 60% of infant deaths.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
997.
998.
Health risks among submarine personnel in the U.S. Navy, 1974-1979   总被引:1,自引:0,他引:1  
This study evaluated health risks associated with U.S. Navy submarine duty by comparing hospitalization rates of submariners with surface ship personnel. The groups were compared using age-adjusted hospitalization rates for 16 major diagnostic categories and several specific diagnoses postulated to be submarine associated. Submarine personnel did not have significantly higher hospitalization rates for any diagnostic categories nor for any of the submarine-associated illnesses. Submariner relative risk of hospital admissions was greater for a few selected diagnoses but statistical significance was not attained. Submarine personnel had lower hospitalization rates for nearly all of the diagnostic categories examined. Reasons for these lower rates may be stringent screening of submariners, higher levels of education among submariners, difficulty of evacuation from a submarine, and the healthy-worker effect. The health status of U.S. Navy personnel does not seem to be adversely affected by submarine duty.  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