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   133485篇
  免费   7942篇
  国内免费   1829篇
耳鼻咽喉   1748篇
儿科学   3255篇
妇产科学   4601篇
基础医学   20026篇
口腔科学   4347篇
临床医学   10669篇
内科学   24446篇
皮肤病学   2592篇
神经病学   9489篇
特种医学   4524篇
外国民族医学   3篇
外科学   18671篇
综合类   6103篇
一般理论   35篇
预防医学   9647篇
眼科学   3233篇
药学   11184篇
  4篇
中国医学   996篇
肿瘤学   7683篇
  2021年   1303篇
  2019年   1296篇
  2018年   1904篇
  2017年   1459篇
  2016年   1481篇
  2015年   1843篇
  2014年   2291篇
  2013年   3008篇
  2012年   4227篇
  2011年   4630篇
  2010年   2897篇
  2009年   2595篇
  2008年   4082篇
  2007年   4376篇
  2006年   4298篇
  2005年   3794篇
  2004年   3579篇
  2003年   3363篇
  2002年   3196篇
  2001年   7194篇
  2000年   7361篇
  1999年   6083篇
  1998年   2020篇
  1997年   1543篇
  1996年   1070篇
  1995年   979篇
  1992年   3960篇
  1991年   4025篇
  1990年   3748篇
  1989年   3744篇
  1988年   3614篇
  1987年   3433篇
  1986年   3248篇
  1985年   3119篇
  1984年   2155篇
  1983年   1902篇
  1982年   1056篇
  1979年   1994篇
  1978年   1260篇
  1977年   1054篇
  1976年   966篇
  1975年   1286篇
  1974年   1428篇
  1973年   1477篇
  1972年   1425篇
  1971年   1303篇
  1970年   1191篇
  1969年   1177篇
  1968年   1065篇
  1967年   950篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
The clinical, radiologic, and histopathologic findings of a case of bilateral dacryops is reported in a 49-year-old man. The patient presented with cystic masses located in superior lateral orbits and underwent bilateral excisions of these without any postoperative complications.  相似文献   
32.
A patient with Graves' disease had a symptomatic thrombocytopathy during periods of remission. When euthyroid, she noticed bruising, petechiae, and epistaxis. Hemostatic abnormalities included prolongation of the bleeding time by aspirin, reduced platelet retention (a second-phase defect), and abnormal thrombin-induced aggregation and serotonin release. When hyperthyroid, bleeding symptoms resolved, and platelet function returned to normal. These observations suggest that mild bleeding disorders may be influenced either directly or indirectly by thyroid hormone levels.  相似文献   
33.
Measurements of the fetal eyeball and its pattern of growth   总被引:1,自引:0,他引:1  
  相似文献   
34.
35.
The possible reversal by calcium of the inhibitory action of verapamil on the atrioventricular (AV) node was investigated in anesthetized, atropinized dogs, with cardiac pacing. The His bundle potentials were recorded by endocavitory electrode and the AV node effective refractory period measured by the extrastimulus method. Calcium infusion was effective against the impairment of AV nodal conduction induced by verapamil, provided it remained moderate: the gradual rise in the plasma calcium concentration counteracted the effects of an infusion of verapamil on conduction time and effective refractory period in the AV node, as long as it did not exceed 5 mmol/L. However, beyond this level, calcium appeared less and less capable of reversing the effects of verapamil. Thus, the protective action of calcium had a bell-shaped dose-response curve, with the optimum at 5 mmol/L. This biphasic influence is consistent with the opposite opinions previously given concerning the antagonism between calcium and calcium blockers, depending on whether hypercalcemia brought into play was mild or major. In any case, the prominent role played by calcium in the slow inward current in the AV node accounts for the antagonism, observed in vivo, between calcium and verapamil. The pacemaker activity of the sinoatrial (SA) node was less influenced by both calcium blocker and calcium.  相似文献   
36.
37.
Computed tomography of the brain in the Smith-Lemli-Opitz syndrome   总被引:1,自引:0,他引:1  
Computed tomographic (CT) scans of the brain in a child with Smith-Lemli-Opitz syndrome revealed enlargement of the ventricular system, hypoplasia of the cerebellum, and abnormal thickening of the gray matter, consistent with pachygyria. These findings have been previously noted in autopsies performed on patients with this disorder. We conclude that CT scanning is a valuable tool in the evaluation of children suspected of having the Smith-Lemli-Opitz syndrome.  相似文献   
38.
Normal seminal vesicles were studied histologically in 80, and by Feulgen’s cytophotometric method in 10 autopsied cases (males, 44–82 years of age). In every case large, hyperchromatic nuclei were found. By cytophotometry euploid polyploid atypia was also shown in every case, which is characteristic of benign hormonal dysplasia.  相似文献   
39.
The authors present an improvement to a sigma-filter extrapolation method for the reconstruction of magnetic resonance (MR) images from symmetric discrete Fourier data. By making use of the phase information in the image data, the proposed method can overcome the data inconsistency problem of the original method for handling MR image data with large phase variations, such as those obtained in gradient-echo pulse sequences. Reconstruction results show that its performance is comparable with that of the modified complex sigma-filter method proposed previously to handle the inconsistency problem. However, the new approach has the advantage of reducing computation time by a factor of two with use of a sigma filter applied to real instead of complex images. It is expected that this method will be more practical for use in clinical MR imaging systems.  相似文献   
40.
Seventy seven antral biopsies were collected from patients attending endoscopy clinic at King Khalid University Hospital, Riyadh, Saudi Arabia during a period of six months between December 1988 to May 1989. Of these 69 (89.6%) showed chronic gastritis as well as Helicobacter-like organisms (HLOs) in the biopsy specimens while 63 (81.8%) of biopsies grew Helicobacter pylori on culture. These findings indicate a good correlation between the histological diagnosis of chronic gastritis and isolation of H. pylori on culture.  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