全文获取类型
收费全文 | 6121篇 |
免费 | 409篇 |
国内免费 | 24篇 |
专业分类
耳鼻咽喉 | 54篇 |
儿科学 | 109篇 |
妇产科学 | 93篇 |
基础医学 | 599篇 |
口腔科学 | 116篇 |
临床医学 | 668篇 |
内科学 | 1303篇 |
皮肤病学 | 55篇 |
神经病学 | 482篇 |
特种医学 | 512篇 |
外科学 | 954篇 |
综合类 | 97篇 |
一般理论 | 2篇 |
预防医学 | 647篇 |
眼科学 | 81篇 |
药学 | 332篇 |
1篇 | |
中国医学 | 5篇 |
肿瘤学 | 444篇 |
出版年
2021年 | 82篇 |
2020年 | 52篇 |
2019年 | 80篇 |
2018年 | 118篇 |
2017年 | 75篇 |
2016年 | 74篇 |
2015年 | 97篇 |
2014年 | 137篇 |
2013年 | 200篇 |
2012年 | 351篇 |
2011年 | 327篇 |
2010年 | 169篇 |
2009年 | 151篇 |
2008年 | 271篇 |
2007年 | 304篇 |
2006年 | 270篇 |
2005年 | 266篇 |
2004年 | 268篇 |
2003年 | 210篇 |
2002年 | 199篇 |
2001年 | 180篇 |
2000年 | 194篇 |
1999年 | 161篇 |
1998年 | 57篇 |
1997年 | 43篇 |
1996年 | 51篇 |
1995年 | 47篇 |
1994年 | 50篇 |
1993年 | 47篇 |
1992年 | 153篇 |
1991年 | 132篇 |
1990年 | 160篇 |
1989年 | 149篇 |
1988年 | 144篇 |
1987年 | 137篇 |
1986年 | 130篇 |
1985年 | 104篇 |
1984年 | 90篇 |
1983年 | 74篇 |
1982年 | 45篇 |
1980年 | 39篇 |
1979年 | 56篇 |
1978年 | 60篇 |
1977年 | 37篇 |
1976年 | 38篇 |
1974年 | 52篇 |
1973年 | 46篇 |
1972年 | 44篇 |
1970年 | 38篇 |
1969年 | 38篇 |
排序方式: 共有6554条查询结果,搜索用时 15 毫秒
21.
22.
L H Daltroy C B Phillips H M Eaton M G Larson A J Partridge M Logigian M H Liang 《American journal of public health》1995,85(4):558-560
The Physical Capacity Evaluation, a performance measure of functional capabilities comprised of 13 tasks simulating those used in activities of daily living, was tested on 289 community-dwelling elderly people and compared against a widely used self-report measure of function, the Health Assessment Questionnaire. Factor analysis identified one dominant component in each instrument. Internal consistency reliability (Cronbach's alpha) was .90 for both instruments. Global disability (Health Assessment Questionnaire) and function (Physical Capacity Evaluation) scores were correlated -.74. One-week retest reliabilities on 58 subjects were .94 for the Physical Capacity Evaluation and .95 for the Health Assessment Questionnaire. The Physical Capacity Evaluation is a valid and reliable measure of physical performance for use with elderly people. 相似文献
23.
J W Lampe M E Effertz J L Larson J L Slavin 《JPEN. Journal of parenteral and enteral nutrition》1992,16(6):538-544
Dietary fiber supplementation may improve gastrointestinal tolerance and decrease diarrhea in patients receiving enteral formula diets. To compare the effects of two dietary fibers on bowel function parameters and short-chain fatty acid excretion we fed 11 healthy men three defined enteral formula diets in random order for 18 days each. The test diets consisted of a fiber-free formula and daily intakes of maltodextrin (0 g of fiber), 15 g of total dietary fiber as an enzymatically modified guar gum, and 15 g of total dietary fiber as soy polysaccharide. Data were also collected while subjects consumed self-selected diets for 5 days. Mean transit time was longer and fecal moisture content was lower on 0 g of fiber and modified guar than on the self-selected and soy diets. Furthermore, mean transit time was slightly longer and fecal nitrogen excretion greater on modified guar compared with 0 g of fiber. Daily fecal output and frequency of defecation were greater, fecal pH was lower, and fecal butyrate concentrations were higher on the self-selected diet compared with the enteral formula diets. However, there was no difference in these parameters among the three liquid diets. Thus, despite significant differences in mean transit time, few differences in other parameters of bowel function were observed when healthy subjects consumed enteral formula diets containing 0 g of fiber and 15 g of total dietary fiber as modified guar and soy. 相似文献
24.
Scott L. Nyberg Arthur J. Matas Walter K. Kremers Jeffrey D. Thostenson Timothy S. Larson Mikel Prieto Michael B. Ishitani Sylvester Sterioff Mark D. Stegall 《American journal of transplantation》2003,3(6):715-721
We previously proposed a quantitative approach to assess donor organs for cadaver renal transplantation. To improve on our original scoring system, we studied 34 324 patients who received cadaver renal transplants from adult donors between 1994 and 1999 and were reported to the UNOS Scientific Renal Transplant Registry. A scoring system was developed from five donor variables (age, 0-25 points; history of hypertension, 0-4; creatinine clearance before procurement, 0-4; cause of death, 0-3; HLA mismatch, 0-3) that showed a significant correlation with renal function and long-term graft survival. Cadaver kidneys were stratified by cumulative donor score: grade A, 0-9 points; grade B, 10-19; grade C, 20-29; and grade D, 30-39. The influence of donor score on renal function and graft survival was most severe above 20 points, designated 'marginal' kidneys. In summary, a donor scoring system developed from a large population database was useful in predicting outcome after cadaver renal transplantation. The improved system provides a quantitative approach to evaluation of marginal kidneys and may improve allocation of these organs in cadaver renal transplantation. 相似文献
25.
26.
27.
28.
29.
Peder E Z Larson Steven M Conolly John M Pauly Dwight G Nishimura 《Magnetic resonance in medicine》2007,58(5):952-961
Ultrashort echo time (UTE) imaging is a technique that can visualize tissues with sub-millisecond T(2) values that have little or no signal in conventional MRI techniques. The short-T(2) tissues, which include tendons, menisci, calcifications, and cortical bone, are often obscured by long-T(2) tissues. This paper introduces a new method of long-T(2) component suppression based on adiabatic inversion pulses that significantly improves the contrast of short-T(2) tissues. Narrow bandwidth inversion pulses are used to selectively invert only long-T(2) components. These components are then suppressed by combining images prepared with and without inversion pulses. Fat suppression can be incorporated by combining images with the pulses applied on the fat and water resonances. Scaling factors must be used in the combination to compensate for relaxation during the preparation pulses. The suppression is insensitive to RF inhomogeneities because it uses adiabatic inversion pulses. Simulations and phantom experiments demonstrate the adiabatic pulse contrast and how the scaling factors are chosen. In vivo 2D UTE images in the ankle and lower leg show excellent, robust long-T(2) suppression for visualization of cortical bone and tendons. 相似文献
30.
James T Lane LuAnn Larson Shan Fan Julie A Stoner Eyal Margalit Carol B Toris 《BMC ophthalmology》2010,10(1):19