全文获取类型
收费全文 | 378949篇 |
免费 | 24160篇 |
国内免费 | 2808篇 |
专业分类
耳鼻咽喉 | 5183篇 |
儿科学 | 8198篇 |
妇产科学 | 10077篇 |
基础医学 | 53093篇 |
口腔科学 | 11773篇 |
临床医学 | 30089篇 |
内科学 | 78246篇 |
皮肤病学 | 8546篇 |
神经病学 | 27183篇 |
特种医学 | 13911篇 |
外国民族医学 | 82篇 |
外科学 | 60602篇 |
综合类 | 9953篇 |
现状与发展 | 1篇 |
一般理论 | 64篇 |
预防医学 | 17416篇 |
眼科学 | 9440篇 |
药学 | 30966篇 |
1篇 | |
中国医学 | 2193篇 |
肿瘤学 | 28900篇 |
出版年
2021年 | 2604篇 |
2019年 | 2719篇 |
2018年 | 4513篇 |
2017年 | 3429篇 |
2016年 | 3518篇 |
2015年 | 4016篇 |
2014年 | 5689篇 |
2013年 | 7372篇 |
2012年 | 10005篇 |
2011年 | 10187篇 |
2010年 | 6185篇 |
2009年 | 5839篇 |
2008年 | 9447篇 |
2007年 | 10278篇 |
2006年 | 10199篇 |
2005年 | 9259篇 |
2004年 | 8771篇 |
2003年 | 8510篇 |
2002年 | 8188篇 |
2001年 | 28243篇 |
2000年 | 28774篇 |
1999年 | 23651篇 |
1998年 | 5159篇 |
1997年 | 4251篇 |
1996年 | 3828篇 |
1995年 | 3478篇 |
1994年 | 3104篇 |
1993年 | 2842篇 |
1992年 | 16047篇 |
1991年 | 14810篇 |
1990年 | 14159篇 |
1989年 | 13958篇 |
1988年 | 12585篇 |
1987年 | 12060篇 |
1986年 | 11103篇 |
1985年 | 10322篇 |
1984年 | 6911篇 |
1983年 | 5599篇 |
1982年 | 2718篇 |
1979年 | 5477篇 |
1978年 | 3347篇 |
1977年 | 2976篇 |
1975年 | 2642篇 |
1974年 | 3065篇 |
1973年 | 2866篇 |
1972年 | 2829篇 |
1971年 | 2774篇 |
1970年 | 2510篇 |
1969年 | 2543篇 |
1968年 | 2250篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
R Maymon Y Tovbin E Dreazen Z Weinraub A Herman 《Ultrasound in obstetrics & gynecology》2004,23(6):557-560
OBJECTIVE: To compare mid-gestation sonographic measurements of all five digits of the hands of fetuses with Down syndrome with those of normal controls. METHODS: Twenty-nine fetuses between 17 and 26 weeks' gestation which had been confirmed by karyotyping to have Down syndrome were included in this prospective study. Each fetus was scanned once and the digits of only one hand were measured. Measurements were compared with those of 302 previously reported normal controls matched for gestational age. All measurements were expressed in multiples of the gestation-specific normal median (MoM) for each digit. RESULTS: Compared to 1 MoM for the length of Digits 1 to 5 from the normal population, the respective values in the Down syndrome digits were: 0.94, 0.85, 0.92, 0.88 and 0.85 MoM, representing values significantly lower than normal (P < 0.05; t-test). CONCLUSIONS: All five digits of the hands of fetuses with Down syndrome are shorter than are those of euploid fetuses. Integration of fetal digit measurement into the antenatal assessment of selected high-risk cases may be of value although confirmation of our findings should be obtained before this measurement is incorporated into Down syndrome screening in the general population. 相似文献
142.
Y Imamura K Yanagihara Y Fukuda Y Kaneko M Seki K Izumikawa Y Miyazaki Y Hirakata T Sawa J P Wiener-Kronish S Kohno 《The European respiratory journal》2007,29(5):965-968
Pseudomonas aeruginosa is one of the most important pathogens in patients with chronic airway conditions, such as cystic fibrosis and diffuse panbronchiolitis. Type III secretion system-mediated virulence factors contribute to the lung damage in chronic P. aeruginosa infection. The effects of the anti-PcrV immunoglobulin (Ig)G, which blocks the type III secretion system, were evaluated in a mouse model of chronic P. aeruginosa infection. On bacteriological examination, anti-PcrV IgG showed no bactericidal effects. On bronchoalveolar lavage fluid (BALF) analysis, total cell number and neutrophil ratios in the anti-PcrV IgG-treated groups were lower than those in the control group. In addition, macrophage inflammatory protein-2, tumour necrosis factor-alpha, and interleukin-beta concentrations in BALF were lower in the anti-PcrV IgG-treated groups when compared with controls. Plasma anti-PcrV IgG titre was elevated after administration of anti-PcrV IgG. Although plasma titre decreased gradually, a significant concentration was maintained during the experimental period. These data suggest that anti-PcrV immunoglobulin G reduces the inflammatory reaction caused by chronic Pseudomonas aeruginosa respiratory infection and may be useful in treating respiratory diseases. 相似文献
143.
W De Wever Y Vankan S Stroobants J Verschakelen 《The European respiratory journal》2007,29(5):995-1002
The aim of the present study was to assess retrospectively the additional value of positron emission tomography (PET)/computed tomography (CT) in the detection of unexpected extrapulmonary lesions in the staging of patients with a malignant pulmonary lesion in comparison with CT and PET used alone. A total of 217 patients with a pathologically proven lung tumour underwent PET/CT. CT, PET and PET/CT were evaluated in the detection of extrapulmonary lesions. These abnormalities were compared with the final diagnosis obtained from the medical records and statistical analysis was carried out. In total, 108 lesions were clinically detected. PET/CT showed a sensitivity, specificity, positive and negative predictive values and accuracy of 100, 81, 71, 100 and 87%, respectively, for the detection of extrapulmonary lesions and 92, 98, 89, 98 and 97%, respectively, for the detection of malignant extrapulmonary lesions. PET/CT was significantly better than CT and PET used alone. Conventional staging work-up has a poor sensitivity in detecting second primary cancers or unexpected metastases. The detection of malignant extrapulmonary lesions is necessary for correct tumour staging. By combining both metabolic and anatomical information, positron emission tomography/computed tomography is able to depict more unexpected extrapulmonary lesions than computed tomography and positron emission tomography used alone, and positron emission tomography/computed tomography provides more additional information of malignancy or benignancy of lesions detected with one of the two imaging modalities alone. 相似文献
144.
Benign strictures of the biliary ducts are treated surgically in 90% of cases. Usually they are caused by trauma to the choledochous duct during gallbladder operations. Younger patients are frequently affected and, particularly if the strictures go untreated, can suffer from secondary complications such as cholangitis or secondary biliary cirrhosis with the serious dangers of portal hypertension and even hepatic failure and death. Although immediate treatment by end-to-end anastomosis has sometimes been described, this method is reasonable only for smooth cuts to the choledochous duct. Good long-term results have been achieved in 86% of cases with Roux-en-Y hepaticojejunostomy. In general, the best way to avoid complications is the all-important surgical maxim of correct indication for the primary operation. The best course is to limit the decision for surgery to symptomatic gallstones. 相似文献
145.
Structure-activity relationship (SAR) between some natural flavonoids and ocular blood flow in the rabbit. 总被引:1,自引:0,他引:1
PURPOSE: Flavonoids with two to five hydroxy groups, with or without sugar, and/or methoxy groups were studied on their effects to affect ocular blood flow. METHODS: Colored microsphere technique was used to determine the ocular blood flow in rabbit eyes. RESULTS: Flavonoids with three free hydroxy (OH) groups seemed to produce the optimal effects in increasing ocular blood flow (naringenin and hesperitin, Pfalts and Bauer, Waterbury, CT). Whether the OH groups are below three (naringenin, hesperitin, Pfalts and Bauer, Waterbury, CT) or above four (Quercetin, Pfalts and Bauer, Waterbury, CT), they produced no effects on the ocular blood flow. When OH groups are four (rutin, Aldrich, Milwaukee, WI), it produced mixed effects on ocular blood flow. The attachment of rutinose and/or methoxy group in the structure did not affect the ocular blood flow one way or the other. CONCLUSION: The ocular blood flow is increased significantly by the number of OH group in the molecule, with three the best to increase the ocular blood flow. 相似文献
146.
147.
148.
T Y Tang S R Walsh J H Gillard K Varty J R Boyle M E Gaunt 《European journal of vascular and endovascular surgery》2007,34(3):304-311
OBJECTIVES: Local anaesthetic infiltration into the carotid sinus during carotid endarterectomy (CEA) has been recommended to minimise blood pressure fluctuations but its use remains controversial. The aim of this meta-analysis was to determine whether intra-operative administration of local anaesthetic reduces the incidence of haemodynamic instability following CEA. MATERIALS AND METHODS: A search of the Medline, Pubmed and Embase databases and the Current Controlled Trials register identified four trials, which met the pre-defined inclusion criteria for data extraction. Pooled odds ratios with 95 per cent confidence intervals (c.i.) for the development of post-operative hypotension and hypertension were calculated using a random-effects model. RESULTS: Outcomes of 432 patients were studied. Local anaesthetic blockade of the carotid sinus was associated with a pooled odds ratio of 1.25 (95 per cent c.i. 0.496 to 3.15); p=0.216) and 1.28 (95 per cent c.i. 0.699 to 2.33; p=0.428) for the development of post-operative hypotension and hypertension respectively. Although none reach significance there was a trend towards increased risk of developing a complication in those patients who received local anaesthetic. CONCLUSIONS: There are insufficient data to determine the role of intra-operative local anaesthetic administration in reducing post-operative blood pressure lability following CEA. Conversely, the possibility of harm cannot be excluded on the basis of the currently available data. 相似文献
149.
150.
Y K Murali P Anand V Tandon R Singh R Chandra P S Murthy 《Experimental and clinical endocrinology & diabetes》2007,115(10):641-646
The aqueous extract of the fruits of Terminalia chebula Retz. has been evaluated for its antidiabetic activity in streptozotocin (STZ) induced mild diabetic rats and compared with a known drug, tolbutamide. The oral effective dose (ED) of the extract was observed to be 200 mg/kg body weight, which produced a fall of 55.6% (p<0.01) in the oral glucose tolerance test. Oral administration of ED of aqueous extract of T.chebula (AETC) daily once for two months reduced the elevated blood glucose by 43.2% (p<0.01) and significantly reduced the increase in glycosylated hemoglobin (HbA1c) (p<0.01). The same dose also showed a marked improvement in controlling the elevated blood lipids as well as decreased serum insulin levels in contrast to the untreated diabetic animals. Hepatic and skeletal muscle glycogen content decreased by 75% and 62.9% respectively in diabetic controls, these alterations were partly prevented (34.9% and 21.17%) in AETC treated group when compared to the healthy controls. The in vitro studies with pancreatic islets showed that the insulin release was nearly two times more than that in untreated diabetic animals. The treatment did not have any unfavorable effect on other blood parameters of liver and kidney function tests. LD 50 was found to be above 3 g/kg bw i.e. 15 times of ED, because there were no deaths of animals even at this dose indicating high margin of safety. These findings suggest further investigations for the possible use of the aqueous extract of fruits of T.chebula for the treatment of diabetes. 相似文献