全文获取类型
收费全文 | 34549篇 |
免费 | 7270篇 |
国内免费 | 147篇 |
专业分类
耳鼻咽喉 | 815篇 |
儿科学 | 1033篇 |
妇产科学 | 965篇 |
基础医学 | 2149篇 |
口腔科学 | 2898篇 |
临床医学 | 5781篇 |
内科学 | 7725篇 |
皮肤病学 | 673篇 |
神经病学 | 3132篇 |
特种医学 | 1379篇 |
外国民族医学 | 1篇 |
外科学 | 5560篇 |
综合类 | 363篇 |
现状与发展 | 12篇 |
一般理论 | 9篇 |
预防医学 | 4162篇 |
眼科学 | 540篇 |
药学 | 1469篇 |
中国医学 | 27篇 |
肿瘤学 | 3273篇 |
出版年
2024年 | 173篇 |
2023年 | 1149篇 |
2022年 | 448篇 |
2021年 | 851篇 |
2020年 | 1347篇 |
2019年 | 697篇 |
2018年 | 1598篇 |
2017年 | 1451篇 |
2016年 | 1699篇 |
2015年 | 1758篇 |
2014年 | 2245篇 |
2013年 | 2728篇 |
2012年 | 1356篇 |
2011年 | 1339篇 |
2010年 | 1677篇 |
2009年 | 2270篇 |
2008年 | 1321篇 |
2007年 | 1081篇 |
2006年 | 1201篇 |
2005年 | 999篇 |
2004年 | 840篇 |
2003年 | 777篇 |
2002年 | 746篇 |
2001年 | 866篇 |
2000年 | 704篇 |
1999年 | 768篇 |
1998年 | 660篇 |
1997年 | 646篇 |
1996年 | 685篇 |
1995年 | 543篇 |
1994年 | 438篇 |
1993年 | 392篇 |
1992年 | 565篇 |
1991年 | 483篇 |
1990年 | 431篇 |
1989年 | 426篇 |
1988年 | 445篇 |
1987年 | 403篇 |
1986年 | 352篇 |
1985年 | 301篇 |
1984年 | 316篇 |
1983年 | 274篇 |
1982年 | 216篇 |
1981年 | 173篇 |
1980年 | 151篇 |
1979年 | 220篇 |
1978年 | 151篇 |
1977年 | 145篇 |
1976年 | 156篇 |
1975年 | 149篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
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
32.
33.
S W Rogers T E Hughes M Hollmann G P Gasic E S Deneris S Heinemann 《The Journal of neuroscience》1991,11(9):2713-2724
The cloning of cDNAs that encode functional glutamate receptors makes it possible to produce antibodies that can be used as high-affinity probes for the localization and characterization of these receptors in the mammalian brain. We have made antibodies to different regions of the first cloned member of this family, GluR1, using bacterially overproduced antigen. On Western blots, these antisera detect glycoprotein(s) of 105 kDa present in crude membranes of the hippocampus and cerebellum. The 105-kDa band is associated with postsynaptic densities, and it is observed in cultured cells upon transfection with the GluR1 cDNA. Although glutamate receptors are thought to be the most prevalent excitatory ligand-gated ion channel in the mammalian brain, immunohistochemistry reveals that the receptors recognized by these antisera are localized predominantly in neurons of the cerebellum and some structures of the limbic system, including the hippocampus, the central nucleus of the amygdala, and portions of the septum. This pattern of expression is, in general, consistent with the distribution of GluR1 mRNA as determined by in situ hybridization histochemistry. Our results suggest that glutamate excitatory circuits recognized by these antisera are predominantly found in regions of the limbic system that are reciprocally interconnected. 相似文献
34.
35.
Symptoms of tobacco withdrawal. A replication and extension 总被引:19,自引:0,他引:19
Smokers (n = 315) who wished to quit were randomly assigned in a double-blind manner to groups using either nicotine or placebo gum. Self-reported and observed symptoms of tobacco withdrawal were collected before cessation and at follow-ups of 1 to 2 weeks, 1 month, and 6 months. Self-reported and/or observed anger, anxiety, craving, difficulty concentrating, hunger, impatience, and restlessness were the most prominent symptoms of tobacco withdrawal. These symptoms had returned to precessation levels by 1 month except increased weight, hunger, and craving continued for 6 months in many smokers. Nicotine gum decreased most symptoms, including craving and hunger but not weight. Abstinent smokers with more intense withdrawal were not more likely to relapse. Abstinent smokers who gained more weight were less likely to relapse. 相似文献
36.
1. The action of (1-28) alpha-human atrial natriuretic peptide (ANP) was studied on human isolated resistance arteries. 2. Renal, skeletal muscle, omental and subcutaneous resistance arteries were taken from tissue removed at surgery and isometric tension responses were measured with a myograph. 3. ANP (10(-9)-10(-6) M) relaxed precontracted segments of renal and skeletal muscle arteries in a concentration-dependent manner. ANP failed to relax isolated omental or subcutaneous arteries. 4. The effect of ANP on human isolated resistance arteries varies depending on the site of origin of the artery. 相似文献
37.
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
38.
39.
40.