全文获取类型
收费全文 | 7731篇 |
免费 | 615篇 |
国内免费 | 16篇 |
专业分类
耳鼻咽喉 | 96篇 |
儿科学 | 161篇 |
妇产科学 | 238篇 |
基础医学 | 1122篇 |
口腔科学 | 186篇 |
临床医学 | 823篇 |
内科学 | 1561篇 |
皮肤病学 | 220篇 |
神经病学 | 699篇 |
特种医学 | 320篇 |
外国民族医学 | 1篇 |
外科学 | 1063篇 |
综合类 | 96篇 |
一般理论 | 2篇 |
预防医学 | 509篇 |
眼科学 | 214篇 |
药学 | 638篇 |
中国医学 | 18篇 |
肿瘤学 | 395篇 |
出版年
2023年 | 49篇 |
2022年 | 75篇 |
2021年 | 138篇 |
2020年 | 95篇 |
2019年 | 136篇 |
2018年 | 174篇 |
2017年 | 126篇 |
2016年 | 120篇 |
2015年 | 137篇 |
2014年 | 188篇 |
2013年 | 326篇 |
2012年 | 340篇 |
2011年 | 333篇 |
2010年 | 234篇 |
2009年 | 191篇 |
2008年 | 280篇 |
2007年 | 329篇 |
2006年 | 297篇 |
2005年 | 267篇 |
2004年 | 279篇 |
2003年 | 260篇 |
2002年 | 257篇 |
2001年 | 241篇 |
2000年 | 249篇 |
1999年 | 199篇 |
1998年 | 101篇 |
1997年 | 80篇 |
1996年 | 61篇 |
1995年 | 88篇 |
1994年 | 91篇 |
1993年 | 82篇 |
1992年 | 183篇 |
1991年 | 201篇 |
1990年 | 158篇 |
1989年 | 164篇 |
1988年 | 155篇 |
1987年 | 162篇 |
1986年 | 145篇 |
1985年 | 155篇 |
1984年 | 117篇 |
1983年 | 103篇 |
1982年 | 76篇 |
1981年 | 55篇 |
1980年 | 63篇 |
1979年 | 122篇 |
1978年 | 81篇 |
1977年 | 68篇 |
1976年 | 61篇 |
1975年 | 53篇 |
1974年 | 50篇 |
排序方式: 共有8362条查询结果,搜索用时 15 毫秒
991.
992.
Larsen B Essmann MK Geletta S Duff B 《International journal of environmental health research》2012,22(4):305-316
The object of this study was to quantify vancomycin-resistant enterococci in surface water from Central Iowa obtained from April 2007 to August 2007. Water from established sampling sites in four watersheds was plated on bile-esculin agar. Presumptively identified enterococci were categorized as "above the level of concern" if the sample contained ≥ 107 CFU per 100 ml. Confirmation of isolates as enterococci was based on growth at elevated temperature in high salt and on Enterococcus agar. Isolates that grew on 6 μg/ml vancomycin agar were deemed resistant. PCR analysis of resistant strains characterized vancomycin resistance genes. 77.2% of surface water samples from Central Iowa contained enterococci. Among enterococcal isolates, 10.4% grew on media containing 6 μg/ml vancomycin. PCR analysis of resistance genes showed a preponderance of VanC2/C3 in the area studied and VanB was not detected. Vancomycin-resistant Enterococcus is present in Central Iowa surface waters but resistance rarely involved VanA genotypes. Nevertheless, the potential for community-acquired infections remains a risk. 相似文献
993.
994.
B K Yeh A J Gosselin P S Swaye P B Larsen T O Gentsch E A Traad A R Faraldo 《American heart journal》1977,93(5):610-616
The effect of the intra-arterial injection of 5 to 10 microng of sodium nitroprusside on the caliber of normal and diseased coronary arteries was evaluated in 21 patients during diagnostic cardiac catheterization. In addition, the effect of intra-graft injection of 5 microng of the same agent on the blood flow in aorta-right coronary artery saphenous vein bypass grafts was also evaluated intra-operatively in two patients. The compound induced an increase in the caliber of both normal and stenosed coronary arteries as well as an increase of flow in the grafts. Consistent with measurements of coronary flow response to sodium nitroprusside, angina pectoris which developed in four patients during cardiac catheterization was immediately relieved and the ischemic ST-segment depression significantly reversed after injection of 5 to 10 microng of the drug into the left main coronary artery. Within the dose range used, the drug caused no significant effect on systemic blood pressure or apparently deleterious electrophysiologic changes. No side effects were observed. We conclude that the primary direct action of sodium nitroprusside in the human coronary artery is vasodilatory. 相似文献
995.
Jonassen AK Aasum E Riemersma RA Mjøs OD Larsen TS 《Cardiovascular drugs and therapy / sponsored by the International Society of Cardiovascular Pharmacotherapy》2000,14(6):615-623
Coronary reperfusion improves ventricular function and survival after infarction, but the metabolic conditions at this time may not be optimal to protect the heart. The objective of this study was to evaluate if metabolic support with glucose-insulin-potassium (GIK) administered at the time of coronary reperfusion could elicit the same cardioprotection as GIK infusion during the entire ischemia/reperfusion period. Three groups of anesthetized, open-chest rats were subjected to 30 minutes of regional ischemia and 180 minutes of reperfusion. Groups 1 (controls) and 2 (GIKIR) received saline or GIK, respectively, throughout the whole experimental period, whereas a third group (GIKR) received GIK from the onset of reperfusion only. Infarct size was significantly reduced in the GIK-treated groups, compared with controls (GIKIR 44 ± 5% and GIKR 45 ± 5% vs. control 66 ± 4%; P < 0.05). Postischemic recovery of cardiac function improved when GIK was only administered during the reperfusion phase. Furthermore, infusion of GIK resulted in reduced plasma concentrations of free fatty acids and increased plasma glucose (both P < 0.05) compared with controls. This study demonstrates that glucose-insulin-potassium administration at the onset of the postischemic reperfusion period is as cardioprotective as administration of GIK during the entire ischemia/reperfusion period. 相似文献
996.
In a double-blind, 12-week study of corticosteroid-dependent reversible bronchial asthma, 20 of 31 (64.5%) patients receiving triamcinolone acetonide aerosol, 800 microgram daily, were able to discontinue oral steroid therapy. This compares with three of 29 (10.3%) treated with aerosol placebo. At the end of the 12-week period, the mean 8 AM plasma cortisol level had increased from 5.3 +/- 4.1 to 8.6 +/- 5.2 microgram/dl in those receiving triamcinolone acetonide. The mean percent predicted values in the triamcinolone group for forced expiratory volume in the first second rose from 44.8 to 62.4 at two weeks (P less than .005), for forced vital capacity from 64.1 to 79.9 (P less than .005), and for maximum midexpiratory flow rate from 26.7 to 46.7 (P less than .005). The improved pulmonary function values persisted while the oral prednisone equivalent daily dose decreased from a mean of 13.3 to 2.9 mg at 12 weeks. Significant oral candidiasis was detected in two patients. Aerosol triamcinolone acetonide appears to be an effective alternative to beclomethasone dipropionate for use in patients with bronchial asthma. 相似文献
997.
J Myren R Stave J Mosvold L E Hanssen P Linnestad M Osnes S Larsen S Berstad K Valnes S Lorentzen-Lund 《Scandinavian journal of gastroenterology》1985,20(8):1025-1034
Thirteen male patients with a history of duodenal ulcer were given 150 mg RP 40 749 or placebo tablets at bedtime in a double-blind crossover study. The medication was given for two periods of 10 days with an 11-day wash-out period between. pH and pepsin concentrations were determined each hour in aspirates of gastric juice for 24 h on day 1, 10, 22, 31, and a 2-h collection of gastric juice was examined in the middle of the treatment and wash-out periods. At defined hours blood samples were examined for gastrin, somatostatin, and pancreatic polypeptide (PP) by radioimmunological methods, and concentrations of RP 40 749 were determined in blood and gastric juice. Meals were served at fixed hours on days 1, 10, 22, and 31. After treatment with RP 40 749 a highly significant elevation of pH was found after the 1st day compared with placebo, most pronounced during night hours. The pepsin activity was slightly elevated. The serum concentrations of gastrin were increased and those of somatostatin and PP decreased during the first 3-4 h after medication, with a subsequent normalization. No side effects were observed. 相似文献
998.
The 1-g 14C-D-xylose breath test in gallstone patients with and without duodenal diverticula 总被引:1,自引:0,他引:1
To assess whether gallstone patients with duodenal diverticula have bacterial overgrowth in the proximal small bowel, the results of the 1-g 14C-D-xylose breath test were compared in 24 patients with duodenal diverticula and in 24 without diverticula. All patients had been treated with endoscopic papillotomy (EPT) for stones in the common bile duct before the study, and cholecystectomy had previously been performed in 20 patients. No significant differences between the groups were found concerning age, sex, and body weight. Cumulative 14CO2 expired in 3 h in percentage of administered dose of 14C-D-xylose was 8.55% (7.58-9.57%) and 7.38% (6.32-8.96%) in patients with and without diverticula, respectively (p = 0.06), indicating a higher bacterial activity in the small bowel in patients with duodenal diverticula than in those without diverticula. The results appeared to be influenced by cholecystectomy. 相似文献
999.
Jan Carstens Henning Gr?nb?k Helle K Larsen Erling B Pedersen Hendrik Vilstrup 《BMC gastroenterology》2007,7(1):1
Background
Sodium retention and ascites are serious clinical problems in cirrhosis. Urodilatin (URO) is a peptide with paracrine effects in decreasing sodium reabsorption in the distal nephron. Our aim was to investigate the renal potency of synthetic URO on urine sodium excretion in cirrhosis patients with sodium retention and ascites. 相似文献1000.
Relationship of overweight to hiatus hernia and reflux oesophagitis 总被引:14,自引:0,他引:14
G Stene-Larsen R Weberg I Fr?yshov Larsen O Bj?rtuft B Hoel A Berstad 《Scandinavian journal of gastroenterology》1988,23(4):427-432
In a prospective study in 1224 patients referred for upper alimentary endoscopy, reflux oesophagitis was found in 195 (16%) of the patients and hiatus hernia in 249 (20%). In patients with reflux oesophagitis a coexisting hiatus hernia was found in 68%. The weight-for-height index (W/H1.8), which expresses the degree of overweight, was significantly higher both in patients with hiatus hernia and in the patients with reflux oesophagitis, indicating an overweight of approximately 5% in both groups. The overweight was most pronounced in oesophagitis grades 1 and 2, whereas in patients with severe oesophagitis (grade 3) body weight was normal, possibly owing to weight loss caused by dysphagia and excessive regurgitation. The results support the view that adiposity is associated with both sliding hiatus hernia and reflux oesophagitis and that hiatus hernia plays a role in the development of reflux oesophagitis. 相似文献