全文获取类型
收费全文 | 3726篇 |
免费 | 247篇 |
国内免费 | 85篇 |
专业分类
耳鼻咽喉 | 28篇 |
儿科学 | 286篇 |
妇产科学 | 55篇 |
基础医学 | 485篇 |
口腔科学 | 73篇 |
临床医学 | 429篇 |
内科学 | 745篇 |
皮肤病学 | 97篇 |
神经病学 | 169篇 |
特种医学 | 460篇 |
外科学 | 380篇 |
综合类 | 107篇 |
一般理论 | 11篇 |
预防医学 | 355篇 |
眼科学 | 45篇 |
药学 | 145篇 |
2篇 | |
中国医学 | 5篇 |
肿瘤学 | 181篇 |
出版年
2022年 | 23篇 |
2021年 | 34篇 |
2020年 | 32篇 |
2019年 | 36篇 |
2018年 | 59篇 |
2017年 | 42篇 |
2016年 | 44篇 |
2015年 | 64篇 |
2014年 | 74篇 |
2013年 | 106篇 |
2012年 | 119篇 |
2011年 | 108篇 |
2010年 | 127篇 |
2009年 | 120篇 |
2008年 | 123篇 |
2007年 | 168篇 |
2006年 | 142篇 |
2005年 | 156篇 |
2004年 | 100篇 |
2003年 | 88篇 |
2002年 | 119篇 |
2001年 | 92篇 |
2000年 | 92篇 |
1999年 | 75篇 |
1998年 | 144篇 |
1997年 | 170篇 |
1996年 | 143篇 |
1995年 | 116篇 |
1994年 | 124篇 |
1993年 | 106篇 |
1992年 | 58篇 |
1991年 | 65篇 |
1990年 | 65篇 |
1989年 | 89篇 |
1988年 | 82篇 |
1987年 | 67篇 |
1986年 | 71篇 |
1985年 | 62篇 |
1984年 | 52篇 |
1983年 | 32篇 |
1982年 | 34篇 |
1981年 | 40篇 |
1980年 | 40篇 |
1979年 | 28篇 |
1978年 | 28篇 |
1977年 | 31篇 |
1976年 | 31篇 |
1971年 | 22篇 |
1969年 | 23篇 |
1967年 | 20篇 |
排序方式: 共有4058条查询结果,搜索用时 31 毫秒
11.
12.
13.
14.
15.
16.
Ralls PW; Johnson MB; Kanel G; Dobalian DM; Colletti PM; Boswell WD Jr; Radin DR; Halls JM 《Radiology》1986,161(2):451-454
FM sonography - a signal-processing technique that uses frequency and phase information as well as amplitude data - shows promise in evaluation of patients with diffuse liver disease. In a prospective blinded review of 37 patients with biopsy-proved liver disease and 42 healthy volunteers, FM sonography was clearly superior to traditional amplitude-based (AM) sonography in distinguishing healthy from diseased subjects. Statistically significant differences were seen in accuracy (FM, 98.7%; AM, 84.8%), sensitivity (FM, 97.3%; AM, 70.3%), and negative predictive value (FM, 97.7%; AM, 78.8%). Our data also suggest that current FM sonographic techniques cannot differentiate among histologic findings associated with different hepatic parenchymal abnormalities. It is unclear, therefore, whether FM imaging can reduce the numbers of patients who require biopsy for diagnosis or the frequency of biopsy procedures in patients with known disease. 相似文献
17.
3D PET using a conventional multislice tomograph without septa 总被引:3,自引:0,他引:3
A conventional multislice positron emission tomography scanner was modified to operate without interplane septa to evaluate its performance in collecting and reconstructing data in a three-dimensional (3D) format, thereby significantly increasing system sensitivity. A 3D filtered backprojection algorithm was implemented and tested, using both computer simulations and phantom measurements. No artifacts were apparent in the test images, although the algorithm was shown to lead to a 11% degradation in transaxial resolution in the outer planes. Following septa removal, sensitivity was found to increase by a factor of 7 with an increase in scatter fraction from 16 to 41%. Axial resolution degraded from 6.9 to 7.7 mm full width at half maximum at the center of the field of view. The maximum count rate without septa was 2.4 x 10(5) cps, at a concentration of 0.4 microCi/ml, compared with 1.3 x 10(5) cps at 1.5 microCi/ml with septa. Brain studies were performed with volunteers using 18F-fluorodeoxyglucose, 18F-fluorodopa, and H2 15O to compare noise-equivalent count rates and qualitatively assess image quality over a wide range of imaging conditions. 相似文献
18.
19.
20.