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   115977篇
  免费   5909篇
  国内免费   138篇
耳鼻咽喉   1771篇
儿科学   5196篇
妇产科学   3928篇
基础医学   16053篇
口腔科学   2831篇
临床医学   8309篇
内科学   21965篇
皮肤病学   3355篇
神经病学   8973篇
特种医学   5043篇
外国民族医学   32篇
外科学   19013篇
综合类   1595篇
一般理论   29篇
预防医学   5805篇
眼科学   3390篇
药学   8042篇
中国医学   324篇
肿瘤学   6370篇
  2018年   888篇
  2017年   773篇
  2016年   1089篇
  2015年   1216篇
  2014年   1598篇
  2013年   2360篇
  2012年   3089篇
  2011年   3138篇
  2010年   1966篇
  2009年   1926篇
  2008年   3246篇
  2007年   3480篇
  2006年   3623篇
  2005年   3739篇
  2004年   3684篇
  2003年   3552篇
  2002年   3505篇
  2001年   7013篇
  2000年   6957篇
  1999年   5857篇
  1998年   1624篇
  1997年   1558篇
  1996年   1334篇
  1995年   1201篇
  1994年   1091篇
  1993年   1119篇
  1992年   3766篇
  1991年   3575篇
  1990年   3561篇
  1989年   3348篇
  1988年   2985篇
  1987年   2894篇
  1986年   2803篇
  1985年   2617篇
  1984年   1943篇
  1983年   1594篇
  1982年   927篇
  1981年   915篇
  1980年   765篇
  1979年   1822篇
  1978年   1346篇
  1977年   1111篇
  1976年   936篇
  1975年   1178篇
  1974年   1212篇
  1973年   1198篇
  1972年   1040篇
  1971年   975篇
  1970年   880篇
  1969年   787篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
A case-control study of squamous cell carcinoma of the upper aerodigestive tract conducted in Heidelberg and Giessen (FRG) provided information on occupational factors in 200 patients and 800 controls (adjusted to sex, age and area of living; 4:1 matched design). The number of subjects exposed to wood dusts, organic chemicals, coal products or to cement was significantly elevated in the tumour group. An increased risk for head and neck cancer was observed after exposition to wood dust (RR = 2,2), organic compounds (RR = 2,4), coal products (RR = 2,7) and especially to cement (RR = 4,4). The cancer risk due to cement exposition showed a positive correlation to the duration of exposition and remained significantly elevated after adjustment for alcohol and tobacco consumption.  相似文献   
13.
The rate of ethanol elimination and blood acetate concentrationsafter a peroral dose of alcohol were measured in eight asthmaticpatients receiving high-dose corticosteroid, sustained releasetheophylline and beta-2-sympathicomimetic treatment and in eightnonalcoholic, healthy controls. Mean ethanol elimination rate(ER) and mean blood acetate concentration (AC) were significantly(P<0.01) higher in asthmatics (ER=134.8 ± 12.9 mg/kg/hr,AC = 1.13± 0.25 mM) than in controls (ER = 100.2 ±12.3 mg/kg/hr, AC = 0.64 ± 0.10 mM). In the asthmaticsthere was a significant negative correlation between the ageand the rate of ethanol elimination (r = –0.890, P <0.01); in the control group, however, this correlation was oflower degree (r = –0.423) and did not achieve statisticalsignificance. Enhanced ethanol metabolism in asthmatics is possiblydue to the effect of drugs. Our results suggest that ethanolelimination rate is increased in asthmatics receiving medicationand that the effect is most significant in younger age groups.  相似文献   
14.
This study aimed at identifying the signal(s) that elicit myositis-induced neuroplastic changes in background activity and responsiveness of spinal neurones. It is based on previous data suggesting that in dorsal horn neurones, responsiveness to peripheral input on one hand and background activity on the other are probably controlled by different mechanisms. In anaesthetized rats, myositis was induced in the gastrocnemius-soleus muscle and the activity of single dorsal horn neurones was recorded in segment L3. Impulse traffic and axoplasmatic transport in dorsal roots L4 and L5 were selectively blocked by lignocaine or vinblastine for various time periods relative to the induction of the myositis. The results show that the main triggering signal for the myositis-induced changes in both responsiveness and background activity is the altered impulse activity in primary afferent fibres. In contrast, 'no axonally transported chemical signal controlling the discharge behaviour of dorsal horn neurones was found. However, the time course of the electrical signals that cause the myositis-induced changes in background activity and responsiveness is different. For changes in responsiveness, a rather narrow time window of 2 h directly after induction of the myositis existed, during which the impulses from the inflamed muscle must reach the spinal cord. Accordingly, to prevent the increase in responsiveness, the electrical input had to be blocked during the first 2 h; a block of the same duration at another time had no effect. The change in background activity seems to be due to a continuous input from the inflamed muscle which adds up over the hours. Therefore, with regard to background activity, blocking the electrical signals is effective at any time, but only a block of long duration has a significant effect.  相似文献   
15.
16.
17.
The aqueous, organic, and volatile oil extracts of leaves of Eugenia uniflora Linn. Family Myrtaceae were investigated for antibacterial properties using agar dilution techniques. The aqueous extract was the most active against the organisms compared to the organic and volatile oil extracts. The extracts were found to inhibit Gram positive Staphylococcus aureus and Bacillus subtilis and Gram negative Escherichia coli and Shigella dysentcriae. Pseudomonas aeruginosa, Klebsiella pneumoniac, and Salmonella typhi were not inhibited.  相似文献   
18.
19.
20.
Based on a standardized in-vitro method for quantifying the activity of prostaglandin-synthetase by means of coupling malondialdehyde with 2-thiobarbituric acid the possibility of using this method also as ex-vivo technique is described. By this, more favourable prerequisites to pharmacological valuation of the effects of potential antiinflammatory substances exists compared to the application of in-vitro results, only.  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