全文获取类型
收费全文 | 8152篇 |
免费 | 854篇 |
国内免费 | 1227篇 |
专业分类
耳鼻咽喉 | 12篇 |
儿科学 | 24篇 |
妇产科学 | 13篇 |
基础医学 | 363篇 |
口腔科学 | 124篇 |
临床医学 | 336篇 |
内科学 | 555篇 |
皮肤病学 | 291篇 |
神经病学 | 125篇 |
特种医学 | 466篇 |
外科学 | 163篇 |
综合类 | 1312篇 |
现状与发展 | 2篇 |
一般理论 | 1篇 |
预防医学 | 581篇 |
眼科学 | 100篇 |
药学 | 2810篇 |
3篇 | |
中国医学 | 2798篇 |
肿瘤学 | 154篇 |
出版年
2024年 | 45篇 |
2023年 | 152篇 |
2022年 | 207篇 |
2021年 | 386篇 |
2020年 | 290篇 |
2019年 | 227篇 |
2018年 | 228篇 |
2017年 | 322篇 |
2016年 | 343篇 |
2015年 | 374篇 |
2014年 | 575篇 |
2013年 | 715篇 |
2012年 | 595篇 |
2011年 | 703篇 |
2010年 | 543篇 |
2009年 | 487篇 |
2008年 | 509篇 |
2007年 | 406篇 |
2006年 | 457篇 |
2005年 | 371篇 |
2004年 | 289篇 |
2003年 | 263篇 |
2002年 | 219篇 |
2001年 | 213篇 |
2000年 | 125篇 |
1999年 | 125篇 |
1998年 | 128篇 |
1997年 | 100篇 |
1996年 | 84篇 |
1995年 | 79篇 |
1994年 | 85篇 |
1993年 | 75篇 |
1992年 | 88篇 |
1991年 | 58篇 |
1990年 | 50篇 |
1989年 | 39篇 |
1988年 | 43篇 |
1987年 | 44篇 |
1986年 | 30篇 |
1985年 | 31篇 |
1984年 | 16篇 |
1983年 | 25篇 |
1982年 | 15篇 |
1981年 | 14篇 |
1980年 | 17篇 |
1979年 | 15篇 |
1978年 | 8篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1974年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 471 毫秒
51.
Kagayaki Kuroda Daisuke Kokuryo Etsuko Kumamoto Kyohei Suzuki Yuichiro Matsuoka Bilgin Keserci 《Magnetic resonance in medicine》2006,56(4):835-843
Referenceless, or self-reference, thermometry is a technique for mapping temperature differences in the region of interest (ROI) using the baseline phase estimated by extrapolating the field in the surrounding region for estimation (RFE) and subtracting the estimated baseline from the measured field. In the present work a self-reference technique based on complex field estimation using 2D polynomials comprising complex-valued coefficients was proposed and optimized. Numerical simulations with a Gaussian-profiled phase distribution demonstrated that the ROI radius had to be 2.3-2.5 times the standard deviation (SD) of the Gaussian function in order to keep the error below 8% of the peak phase change. The area ratio between the ROI and the RFE had to be larger than 2.0 to maintain the error level. Based on the simulations, and phantom and volunteer experiments, the complex-based method with independently optimized polynomial orders for the two spatial dimensions was compared with the phase-based method using the similar-order optimization strategy. The complex-based method appeared to be useful when phase unwrapping was not removed. Otherwise, the phase-based method yielded equivalent results with less polynomial orders. 相似文献
52.
53.
Leoncio Garrido Bettina Pfleiderer Bruce G. Jenkins Carol A. Hulka Daniel B. Kopans 《Magnetic resonance in medicine》1994,31(3):328-330
Studies using magnetic resonance spectroscopy in human volunteers to evaluate their livers in vivo and to analyze their blood in vitro suggest that there are measurable amounts of silicon compounds in the blood of some women with implants and that there is migration of silicone to other organs such as the liver. 相似文献
54.
Grant R. Caddy MD MRCP Consultant Gastroenterologist Tony C.K. Tham MD FRCP Consultant Gastroenterologist 《Best Practice & Research: Clinical Gastroenterology》2006,20(6):1085
Symptomatic BDS commonly cause significant morbidity and attempt at stone removal should be attempted if possible. Complications of CBDS include biliary colic, jaundice, cholangitis and pancreatitis. Investigations aimed to predict the presence of stones within the bile duct include serum bilirubin, AST, ALP, common bile duct diameter and age as independent predictors of choledocholithiasis. TUS is a sensitive test in detecting bile duct dilatation but the sensitivity is reduced in its ability to detect choledocholithiasis. A NIH consensus statement found that ERC, MRC and EUS were comparable in their sensitivities, specificities and accuracy rates for detection of choledocholithiasis. ERC and stone removal using a balloon or basket is often performed following EST. EBD may be performed if patients have uncorrected coagulopathies but the risk of pancreatitis is higher than for EST (although the risk of bleeding complications is lower for EBD). ML is often required in difficult to remove CBDS and using this device, CBDS can be removed in 90–95% of cases. Other forms of lithotripsy including laser lithotripsy and EHL are confined to specialised centres and the evidence for their use is based on small studies. ESWL may clear stones from the bile duct in up to 93% of patients but frequently ERC and stone fragment removal is required post ESWL. The role of medical therapy in difficult to remove CBDS (or in CBDS in patients with severe co-morbid illness preventing ERC + stone removal) is still currently uncertain due to a lack of large randomised control trials. 相似文献
55.
香茶菜属植物的化学成分与药理作用研究进展 总被引:2,自引:0,他引:2
我们主要综述了国内近年来有关香茶菜属植物在化学成分、药理作用、临床应用方面的研究进 展,并且讨论了这一领域的研究方向。 相似文献
56.
利用热解-色质联用分析系统,对文题进行了研究,发现其热解过程是一个复杂的多元反应过程。在500~800℃,钛酸丁酯(Ⅰ)热解尾气产物主要是烯烃、醇、醚和醛类化合物。经热解机理分析,发现Ⅰ的重排断裂反应是整个热解过程的主反应,其反应动力学常数为3.87×10~5,活化能为69.3 kJ/ 相似文献
57.
自拟人参二苓解毒汤联合盐酸恩丹西酮注射液治疗顺铂引起恶心呕吐临床观察 总被引:1,自引:0,他引:1
傅大治 《浙江中医药大学学报》2006,30(6):653-654
[目的]探讨顺铂引起恶心呕吐的有效治疗途径。[方法]对肺癌患者64例,随机分2组。自拟人参二苓解毒汤联合盐酸恩丹西酮注射液(以下简称商品名欧贝)(B组)和单独使用欧贝(A组)对顺铂为主的静脉化疗后镇吐疗效。[结果]B组(78·13%,93·75%)较A组(59·38%,75·00%)在近期镇吐治疗(指化疗后24-48h出现恶心呕吐)有明显差异(P<0·05),并在副作用方面,如便秘,乏力症状和血三系下降有明显差异(P<0·05)。[结论]辅以自拟人参二苓解毒汤确有增效解毒功能。 相似文献
58.
云南傣族药物灯台叶中黄酮类成分 总被引:1,自引:0,他引:1
目的:研究云南傣族传统药物灯台叶Alstonia scholaris中黄酮类化学成分.方法:用色谱分离,用理化性质和波谱鉴定化学结构.结果:分离鉴定了山柰酚(1),槲皮素(2),异鼠李素(3),山柰酚-3-O-β-D-半乳糖苷(4),槲皮素_3-O-β-D-半乳糖苷(5),异鼠李素-3-O-β-D-半乳糖苷(6),山柰酚-3-O-β-D-半乳糖-(2→1)-O-β-D-木糖苷(7),槲皮素-3-O-β-D-半乳糖-(2→1)-O-β-D-木糖苷(8)共8个黄酮类成分.结论:化合物1-7为首次从傣药灯台叶分离得到. 相似文献
59.
目的 研究鬼箭羽( Euonymus alatus )的化学成分。 方法 采用硅胶, Sephadex LH - 20 ,大孔树脂, 制备高效液相色谱仪 等柱色谱及重结晶等方法分离纯化,通过理化常数测定和光谱分析鉴定化合物的结构。 结果 从中分离得到 8 个已知化合物分别为:雷公藤内酯甲 (1) ,槲皮素 (2) ,苯甲酸 (3) ,何帕 -22(29)- 烯 -3 β- 醇 (4) , 5- 羟甲基糠醛 (5) ,咖啡因 (6) ,角鲨烯 (7) ,正二十五烷 (8) 。 结论 化合物 4 ~ 8 为首次从该植物中得到。 相似文献
60.
Zhiqiang Li Arthur F Gmitro Ali Bilgin Maria I Altbach 《Magnetic resonance in medicine》2007,57(6):1047-1057
Three-point Dixon techniques achieve good lipid-water separation by estimating the phase due to field inhomogeneities. Recently it was demonstrated that the combination of an iterative algorithm (iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL)) with a fast spin-echo (FSE) three-point Dixon method yielded robust lipid-water decomposition. As an alternative to FSE, the gradient- and spin-echo (GRASE) technique has been developed for efficient data collection. In this work we present a method for lipid-water separation by combining IDEAL with the GRASE technique. An approach to correct for errors in the lipid-water decomposition caused by phase distortions due to the switching of the readout gradient polarities inherent to GRASE is presented. The IDEAL-GRASE technique is demonstrated in phantoms and in vivo for various applications, including pelvic, musculoskeletal, and (breath-hold) cardiac imaging. 相似文献