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   19780篇
  免费   1794篇
  国内免费   22篇
耳鼻咽喉   105篇
儿科学   606篇
妇产科学   541篇
基础医学   2878篇
口腔科学   286篇
临床医学   2574篇
内科学   3823篇
皮肤病学   440篇
神经病学   1921篇
特种医学   755篇
外科学   2515篇
综合类   610篇
一般理论   15篇
预防医学   1660篇
眼科学   264篇
药学   1287篇
中国医学   15篇
肿瘤学   1301篇
  2021年   306篇
  2020年   215篇
  2019年   320篇
  2018年   370篇
  2017年   299篇
  2016年   282篇
  2015年   307篇
  2014年   446篇
  2013年   666篇
  2012年   935篇
  2011年   903篇
  2010年   514篇
  2009年   497篇
  2008年   868篇
  2007年   892篇
  2006年   902篇
  2005年   816篇
  2004年   834篇
  2003年   791篇
  2002年   680篇
  2001年   681篇
  2000年   718篇
  1999年   624篇
  1998年   227篇
  1997年   195篇
  1996年   201篇
  1995年   187篇
  1994年   177篇
  1993年   169篇
  1992年   467篇
  1991年   449篇
  1990年   415篇
  1989年   369篇
  1988年   355篇
  1987年   395篇
  1986年   363篇
  1985年   367篇
  1984年   291篇
  1983年   251篇
  1982年   160篇
  1981年   161篇
  1980年   132篇
  1979年   241篇
  1978年   199篇
  1977年   139篇
  1975年   116篇
  1974年   166篇
  1973年   162篇
  1972年   152篇
  1971年   133篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
152.
We report a case of the heparin-induced thrombocy-topenia and thrombosis syndrome presenting with acute ischemia of a lower limb. The patient was successfully treated by withdrawal of heparin products, intraarterial urokinase, and platelet anti-aggregation therapy consisting of Dextran and aspirin.  相似文献   
153.
154.
The purpose of this study was to determine the magnitude and clinical significance of surface measurement error in the determination of lumbar spinal flexion. Intrarater, inter-rater and intermethod reliability estimates were obtained using single inclinometry, double inclinometry and back range-of-motion inclinometry methods. Eight healthy subjects were examined independently by two experienced observers and three replicates of each measurement were obtained by each observer in a random sequence. In addition, three replicates of lumbar flexion angles were obtained for each subject by a single observer using the B-200. Reliability estimates were determined by intraclass correlation coefficients and were further compared by paired t tests between observation series. The median range of error was 8.5 degrees using the single inclinometer, 10.5 degrees using the double inclinometer and 16 degrees using the back range-of-motion. The intrarater reliability was generally higher than inter-rater reliability and intermethod reliability was low in most cases reflecting the poor cross-validity across inclinometry methods and between each inclinometry method and the B-200. In conclusion, significant measurement error in estimating lumbar flexion by inclinometry may be expected to occur even in a "controlled" setting using experienced observers, standard examination techniques and asymptomatic healthy subjects. These findings appear to undermine the expectation that the clinician can reliably apply surface inclinometry to estimate loss of spinal mobility for purposes of impairment determination.  相似文献   
155.
156.
Rotational ablation of balloon angioplasty failures   总被引:1,自引:0,他引:1  
In this series, we evaluated the use of rotational ablation in stenoses that were previously refractory to balloon angioplasty. Forty-one stenoses were treated; in 26, the balloon did not adequately expand within the lesion and in 15 the balloon could not be delivered to the stenosis. Rotational ablation was technically successful in 40 of 41 (97.6%) of the lesions attempted. Twenty-four patients have been followed (mean time = 9 +/- 5 months) and the restenosis rate was similar to that of balloon angioplasty. Rotational ablation appears well suited and may be the treatment of choice for heavily calcified, severely angulated, and diffusely diseased vessels.  相似文献   
157.
Achalasia of the Cardia Associated with Hereditary Cerebellar Ataxia   总被引:1,自引:0,他引:1  
Achalasia of the cardia, a disorder associated with degenerative loss of esophageal myenteric ganglion cells, is reported in association with a recently described progressive neurological disorder, "early onset cerebellar ataxia with retained reflexes." This form of cerebellar ataxia is thought to be inherited as an autosomal recessive disorder. The occurrence of these two very rare neurodegenerative disorders in a single individual is of interest because of the potential genetic and pathogenetic implications of the association.  相似文献   
158.
A 40 year old man with a history of myocardial infarction and hypertension presented with transient cerebral ischaemic attacks, aortic regurgitation, a raised erythrocyte sedimentation rate, and thrombocytopenia. The anticardiolipin syndrome was diagnosed and he was treated with prednisolone and warfarin. He died two years later after the development of acute heart failure. At necropsy his heart showed widespread arteriolar thrombosis without vasculitis, recanalised large vessel occlusion, and a "post-inflammatory" valvulitis of the aortic valve.  相似文献   
159.
Addition of quisqualate to mouse hippocampal neurons in vitro elicited two types of changes in [Ca2+]i as assessed by fura-2-based microfluorimetry. The first was a transient spike or group of oscillations and the second was a long lasting "plateau" response. The long-lasting response was abolished on removal of either Ca2+ or Na+ from the external medium or by blocking voltage-sensitive Ca2+ channels. Furthermore, the novel glutamate antagonist 6-nitro-7-cyano-quinoxaline-2,3-dione was a competitive inhibitor of this response. In contrast, none of these manipulations abolished the transient [Ca2+]i spike. Transient [Ca2+]i spikes or oscillations could also be produced by the alpha 1-adrenergic agonist phenylephrine. Production of such an alpha 1-response reduced the size of a subsequently elicited quisqualate response. However production of transient [Ca2+]i spikes with caffeine did not alter the size of the quisqualate-induced spike. We conclude that hippocampal neurons possess two different types of quisqualate receptors. The first mediates quisqualate-induced depolarization and the second mediates Ca2+ mobilization from intracellular stores.  相似文献   
160.
Rabbits fed a lipid-rich, cholesterol-poor diet and given concomitant injections of foreign protein, over a period as long as 17 months, developed in their coronary arteries both a) proliferative fibromuscular intimal thickening closely resembling the diffuse intimal thickening that commonly occurs in coronary arteries of man, and b) fatty-proliferative fibromuscular intimal thickening that closely resembles coronary atherosclerosis in man. In contrast, rabbits of another group that were concurrently fed the same diet for as long as 22 months without injections of foreign protein developed changes in arteries of their hearts that resemble neither coronary atherosclerosis nor diffuse intimal thickening in man. Fatty-proliferative changes in aortas of the first group of rabbits are strikingly greater and more closely resemble human aortic atherosclerosis than those in the latter group. In the course of the experiments, the average serum cholesterol was not significantly different in the two groups of rabbits. It was approximately 200 to 250 mg%, which is the average serum cholesterol in adult humans in the United States. These experiments support the hypothesis that the synergy of arterial injury, in particular immunologic injury, and a diet rich in lipid can lead to atherosclerosis in man.  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