全文获取类型
收费全文 | 22952篇 |
免费 | 6136篇 |
国内免费 | 128篇 |
专业分类
耳鼻咽喉 | 649篇 |
儿科学 | 709篇 |
妇产科学 | 757篇 |
基础医学 | 577篇 |
口腔科学 | 2684篇 |
临床医学 | 4359篇 |
内科学 | 5488篇 |
皮肤病学 | 470篇 |
神经病学 | 2042篇 |
特种医学 | 1093篇 |
外科学 | 4019篇 |
综合类 | 131篇 |
现状与发展 | 12篇 |
一般理论 | 3篇 |
预防医学 | 2892篇 |
眼科学 | 358篇 |
药学 | 302篇 |
中国医学 | 10篇 |
肿瘤学 | 2661篇 |
出版年
2024年 | 135篇 |
2023年 | 1092篇 |
2022年 | 370篇 |
2021年 | 676篇 |
2020年 | 1238篇 |
2019年 | 513篇 |
2018年 | 1365篇 |
2017年 | 1314篇 |
2016年 | 1546篇 |
2015年 | 1601篇 |
2014年 | 2007篇 |
2013年 | 2432篇 |
2012年 | 859篇 |
2011年 | 826篇 |
2010年 | 1407篇 |
2009年 | 1982篇 |
2008年 | 843篇 |
2007年 | 567篇 |
2006年 | 726篇 |
2005年 | 540篇 |
2004年 | 391篇 |
2003年 | 332篇 |
2002年 | 343篇 |
2001年 | 457篇 |
2000年 | 331篇 |
1999年 | 439篇 |
1998年 | 519篇 |
1997年 | 495篇 |
1996年 | 551篇 |
1995年 | 405篇 |
1994年 | 321篇 |
1993年 | 271篇 |
1992年 | 221篇 |
1991年 | 195篇 |
1990年 | 165篇 |
1989年 | 178篇 |
1988年 | 159篇 |
1987年 | 151篇 |
1986年 | 127篇 |
1985年 | 121篇 |
1984年 | 102篇 |
1983年 | 125篇 |
1982年 | 96篇 |
1981年 | 89篇 |
1980年 | 62篇 |
1979年 | 53篇 |
1978年 | 52篇 |
1977年 | 66篇 |
1976年 | 55篇 |
1974年 | 44篇 |
排序方式: 共有10000条查询结果,搜索用时 952 毫秒
31.
32.
Transcutaneous oxygen (TcPO(2)) measurements provide a noninvasive, objective determination of the oxygen level at the skin surface. This offers a means of estimating the underlying circulation and tissue oxygenation. The purpose of the pilot study was to measure the TcPO(2) value of the lower extremity of healthy men and women and of patients with peripheral arterial disease (PAD) in 4 different body and leg positions 24 hours after peripheral vascular surgery reconstruction. The specific aim was to determine if lower-extremity TcPO(2) measurements were affected by changes in extremity position in these subject populations. A convenience sample of 4 healthy health care professionals and 4 patients who had peripheral vascular reconstruction surgery 24 hours before the measurements were studied. Subjects were studied in 4 different leg and body positions: supine with legs extended, sitting with legs dependent, a 5 degrees head-up reverse Trendelenburg, and supine with legs elevated 10 in. The Radiometer TCM30 TcPO(2) monitor was used to carry out these measures. Findings revealed a statistically significant difference in TcPO(2) measurements between the 2 groups, with the healthy subjects having a significantly higher TcPO(2) measurement in all extremity positions compared with the revascularized subjects with PAD (P =.02-.05). Significant changes were noted in both the foot temperature (P =.03) and TcPO(2) measurements with extremity positions within the healthy subject group (P =.001). The foot and leg TcPO(2) measurements affect from leg and body position did not reach significance (P =.09) in the subjects with PAD. No change in foot temperature with extremity positioning (P =.42) was noted in the subjects with PAD. This pilot study provides a base in which additional research will be performed with TcPO(2) measurements in both the healthy and revascularized person. 相似文献
33.
Michael C. Dalsing MD Melissa Kevorkian BS Beth Raper BA Craig Nixon MS Stephen G. Lalka MD Dolores F. Cikrit MD Joseph L. Unthank PhD Malcolm B. Herring MD 《Annals of vascular surgery》1989,3(2):127-133
This study evaluates the potential for endothelial seeding of a collagen-impregnated Dacron graft with or without surface modifiers (fibronectin, heparin) to attach and retain these cells during flow. Human umbilical endothelial cells were harvested, cultured, labeled with Indium111-oxine and seeded onto 30 mm X 4 mm diameter grafts. Six graft surfaces were studied: 1) a collagen-impregnated Dacron graft, HemashieldR (C); 2) C + fibronectin (C + F); 3) C + heparin (C + H); 4) C + F + H; 5) HytrelR + F (Hyt + F); and 6) Hyt + F + H. Radioactive loss determined the percentage attachment and then percentage retention of labeled inoculum after a one-hour in vitro perfusion. Scanning electron and light microscopy demonstrated the endothelium on the graft surface following perfusion. Fibronectin-coated grafts had a significantly higher percentage attachment than those without fibronectin (ANOVA, P less than 0.05). However, the percentage retention following perfusion was similar for all Dacron grafts and statistically inferior to the HytrelR grafts studied (ANOVA, P less than 0.05). SEM evaluation of the C + F + H graft surface was qualitatively the most impressive Dacron surface for seeding, yet was inferior to the HytrelR graft. We conclude that fibronectin benefits the initial attachment of endothelium to collagen-coated Dacron rivaling the HytrelR surface. Fibronectin does not improve percentage retention of the HemashieldR surface during perfusion, therefore, some of its initial benefit is lost. 相似文献
34.
35.
36.
37.
38.
Quantitative diagnostic performance of myocardial perfusion SPECT with attenuation correction in women. 总被引:1,自引:0,他引:1
Arik Wolak Piotr J Slomka Mathews B Fish Santiago Lorenzo Daniel S Berman Guido Germano 《Journal of nuclear medicine》2008,49(6):915-922
Attenuation correction (AC) for myocardial perfusion SPECT (MPS) had not been evaluated separately in women despite specific considerations in this group because of breast photon attenuation. We aimed to evaluate the performance of AC in women by using automated quantitative analysis of MPS to avoid any bias. METHODS: Consecutive female patients--134 with a low likelihood (LLk) of coronary artery disease (CAD) and 114 with coronary angiography performed within less than 3 mo of MPS--who were referred for rest-stress electrocardiography-gated 99mTc-sestamibi MPS with AC were considered. Imaging data were evaluated for contour quality control. An additional 50 LLk studies in women were used to create equivalent normal limits for studies with AC and with no correction (NC). An experienced technologist unaware of the angiography and other results performed the contour quality control. All other processing was performed in a fully automated manner. Quantitative analysis was performed with the Cedars-Sinai myocardial perfusion analysis package. All automated segmental analyses were performed with the 17-segment, 5-point American Heart Association model. Summed stress scores (SSS) of > or =3 were considered abnormal. RESULTS: CAD (> or =70% stenosis) was present in 69 of 114 patients (60%). The normalcy rates were 93% for both NC and AC studies. The SSS for patients with CAD and without CAD for NC versus AC were 10.0 +/- 9.0 (mean +/- SD) versus 10.2 +/- 8.5 and 1.6 +/- 2.3 versus 1.8 +/- 2.5, respectively; P was not significant (NS) for all comparisons of NC versus AC. The SSS for LLk patients for NC versus AC were 0.51 +/- 1.0 versus 0.6 +/- 1.1, respectively; P was NS. The specificity for both NC and AC was 73%. The sensitivities for NC and AC were 80% and 81%, respectively, and the accuracies for NC and AC were 77% and 78%, respectively; P was NS for both comparisons. CONCLUSION: There are no significant diagnostic differences between automated quantitative MPS analyses performed in studies processed with and without AC in women. 相似文献
39.
40.