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   1279篇
  免费   61篇
  国内免费   56篇
耳鼻咽喉   3篇
儿科学   69篇
妇产科学   15篇
基础医学   131篇
口腔科学   21篇
临床医学   154篇
内科学   315篇
皮肤病学   52篇
神经病学   33篇
特种医学   321篇
外科学   76篇
综合类   23篇
预防医学   50篇
眼科学   5篇
药学   69篇
中国医学   2篇
肿瘤学   57篇
  2023年   4篇
  2022年   4篇
  2021年   10篇
  2020年   10篇
  2019年   12篇
  2018年   19篇
  2017年   4篇
  2016年   8篇
  2015年   18篇
  2014年   20篇
  2013年   42篇
  2012年   31篇
  2011年   34篇
  2010年   40篇
  2009年   65篇
  2008年   23篇
  2007年   67篇
  2006年   33篇
  2005年   32篇
  2004年   20篇
  2003年   14篇
  2002年   17篇
  2001年   13篇
  2000年   16篇
  1999年   21篇
  1998年   73篇
  1997年   80篇
  1996年   101篇
  1995年   61篇
  1994年   59篇
  1993年   53篇
  1992年   19篇
  1991年   18篇
  1990年   27篇
  1989年   43篇
  1988年   41篇
  1987年   37篇
  1986年   46篇
  1985年   40篇
  1984年   9篇
  1983年   14篇
  1982年   14篇
  1981年   9篇
  1980年   12篇
  1979年   8篇
  1978年   12篇
  1977年   9篇
  1976年   13篇
  1975年   13篇
  1973年   3篇
排序方式: 共有1396条查询结果,搜索用时 15 毫秒
101.
Venous clots: evaluation with MR imaging   总被引:2,自引:0,他引:2  
In vitro and in vivo studies were performed to determine the proton relaxation and imaging characteristics of static blood and acute and organized clot in canine jugular veins. In vivo, it was found that two inversion recovery sequences using a short inversion time (100 msec) demonstrated better differentiation of signal intensity of intravascular clot from surrounding soft tissues than did standard T1- and T2-weighted sequences. In vitro, quantitative measurements showed marked reduction of both T1 and T2 relaxation time of acute clot compared with stagnant blood. In addition, the T1 relaxation time, and to a lesser extent the T2 relaxation time, shortened as the clot aged, indicating a potential role for magnetic resonance imaging in determining the age of venous thrombi.  相似文献   
102.
It has been shown that acquisition rates in the water maze vary across strains of mice, although the differential effects of previous experience in this spatial task have been scarcely evaluated. The aim of the present study was to evaluate the effects of training in the water maze at an early age (2 months) in two strains of mice (NMRI and C57BL) using a longitudinal study. Mice with or without previous training were tested when they were 6 months, and retested when 10 months old. The results showed that trained NMRI mice performed better than all the other groups, both at test and retest, indicating that previous training had more beneficial effects in NMRI than in C57BL mice. These results demonstrate that the effects of an early training in the water maze may be influenced by the characteristics of the strain of mice. It could have implications in longitudinal studies evaluating effects of pharmacological or behavioral manipulations.  相似文献   
103.
104.
High-field surface coil magnetic resonance (MR) images were obtained of 12 ankles: two from healthy volunteers, seven from patients, and three from fresh cadavers. The cadaver ankles were sectioned in the coronal, sagittal, and axial planes for direct comparison with the MR images. Plain film confirmation of pathologic conditions was obtained in all patients, and five underwent arthroscopy or surgery, or both. MR imaging provided excellent delineation of ligaments and cartilaginous structures in all cases.  相似文献   
105.
106.
本文报道了以1,7-双取代-1,4-二氢-4-酮-1,8-萘啶-3-羧酸,用混合酸酐法与7-ACA,7-ADCA,7-ACT和7-ACD缩合,合成了24个1,7-双取代-1,4-二氢-4-酮-1,8-萘啶-3-甲酰胺头孢菌素衍生物,通过葡聚糖凝胶(Sephadex LH-20)及离心薄层层析纯化精制,得到纯品。体外抑菌试验结果表明:大多数新头孢菌素衍生物对革兰氏阳性菌具有较好的抗菌作用。尚有一些新头孢菌素衍生物对某些革兰氏阴性菌具有中等敏感程度。  相似文献   
107.
108.
DiSantis  DJ; Cramer  MS; Scatarige  JC 《Radiology》1987,164(2):363-364
To test the feasibility of teleradiology for use with excretory urograms obtained in the emergency department in cases for suspected renal colic, radiographs from 43 patients were digitized, transmitted via standard phone lines, and viewed on a video monitor 2 miles distant. Diagnostic interpretations of the video image and the original radiograph were reviewed for degree of concordance. The video and film images of the 27 examinations showing obstruction were interpreted with 100% correlation. Agreement as to the site of obstruction was present in 93% of cases. Only two-thirds of renal and ureteral calculi seen on the radiographs were discerned on the video images, however. Teleradiology proved as useful for ongoing monitoring and modification of these examinations as for initial interpretation.  相似文献   
109.
110.
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