全文获取类型
收费全文 | 1087篇 |
免费 | 55篇 |
国内免费 | 59篇 |
专业分类
耳鼻咽喉 | 4篇 |
儿科学 | 49篇 |
妇产科学 | 9篇 |
基础医学 | 115篇 |
口腔科学 | 13篇 |
临床医学 | 160篇 |
内科学 | 291篇 |
皮肤病学 | 20篇 |
神经病学 | 34篇 |
特种医学 | 235篇 |
外科学 | 71篇 |
综合类 | 31篇 |
预防医学 | 55篇 |
眼科学 | 20篇 |
药学 | 47篇 |
中国医学 | 2篇 |
肿瘤学 | 45篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 15篇 |
2020年 | 4篇 |
2019年 | 6篇 |
2018年 | 16篇 |
2017年 | 7篇 |
2016年 | 7篇 |
2015年 | 20篇 |
2014年 | 28篇 |
2013年 | 37篇 |
2012年 | 32篇 |
2011年 | 25篇 |
2010年 | 31篇 |
2009年 | 30篇 |
2008年 | 24篇 |
2007年 | 59篇 |
2006年 | 24篇 |
2005年 | 30篇 |
2004年 | 25篇 |
2003年 | 23篇 |
2002年 | 17篇 |
2001年 | 15篇 |
2000年 | 14篇 |
1999年 | 16篇 |
1998年 | 59篇 |
1997年 | 38篇 |
1996年 | 61篇 |
1995年 | 51篇 |
1994年 | 41篇 |
1993年 | 51篇 |
1992年 | 10篇 |
1991年 | 17篇 |
1990年 | 22篇 |
1989年 | 30篇 |
1988年 | 36篇 |
1987年 | 42篇 |
1986年 | 30篇 |
1985年 | 33篇 |
1984年 | 17篇 |
1983年 | 15篇 |
1982年 | 14篇 |
1981年 | 25篇 |
1980年 | 20篇 |
1979年 | 11篇 |
1978年 | 14篇 |
1977年 | 22篇 |
1976年 | 9篇 |
1975年 | 12篇 |
1970年 | 2篇 |
排序方式: 共有1201条查询结果,搜索用时 328 毫秒
1.
Jan Willem R. Pott Kwok H. Wong 《Albrecht von Graefes Archiv fur klinische und experimentelle Ophthalmologie》2006,244(10):1357-1359
Background Leber’s hereditary optic neuropathy (LHON) is a maternally inherited optic neuropathy caused by mutations in mitochondrial DNA (mtDNA). It is also believed that several epigenetic factors have an influence on the development of LHON.Methods A case series was observed.Results Three patients who developed bilateral optic neuropathy are presented. All patients had a primary LHON mutation in their mtDNA, but also a subnormal vitamin B12 serum level at the time of presentation.Conclusions The clinical picture of optic neuropathy associated with vitamin B12 deficiency shows similarity to that of LHON. Both involve the nerve fibres of the papillomacular bundle. The present case reports suggest that optic neuropathy in patients carrying a primary LHON mtDNA mutation may be precipitated by vitamin B12 deficiency. Therefore, known carriers should take care to have an adequate dietary intake of vitamin B12 and malabsorption syndromes like those occurring in familial pernicious anaemia or after gastric surgery should be excluded. 相似文献
2.
3.
4.
5.
6.
Short-Ti inversion-recovery pulse sequence: analysis and initial experience in cancer imaging 总被引:2,自引:0,他引:2
Inversion recovery (IR), commonly considered a pulse sequence capable of producing T1-weighted images with excellent display of normal anatomy, is versatile: The null point and peak time provide a useful, succinct summary of the properties of IR and its capacity for producing both T1- and T2-weighted images. Shortening of the inversion time (TI) and creation of a short-TI inversion-recovery (STIR) pulse sequence increases sensitivity to malignancy and other abnormalities by making the effects of prolonged T1 and T2 on signal intensity additive and by nulling the signal from fat. The authors examined over 300 patients with various malignancies and compared STIR images with T1- and T2-weighted images obtained at 0.5 T. In 43 cases, signal-difference-to-noise ratios (SD/Ns) were calculated between tumor, fat, and muscle. In general, STIR images demonstrated tumor as a conspicuously high-intensity area in a background of muted, discernible anatomic detail. The good contrast achieved with STIR sequences between tumor and fat (SD/N = 18.1) and tumor and muscle (SD/N = 12.9) consolidated into a single image the information contained separately on T1- and T2-weighted images, which facilitates efficient detection and localization of malignancy. 相似文献
7.
Sixteen cases of histopathologically proved solitary rectal ulcer syndrome were encountered. Fifteen patients underwent barium enema study; in nine cases the findings--including rectal stricture, granularity of the mucosa, and thickened rectal folds-were nonspecific. In six cases the study was normal. All patients had a long history of defecation disorders, and defecography was performed in all. In seven cases, intussusception of the rectal wall was seen; in another case the intussusception was accompanied by a rectocele. One case showed rectal prolapse. In four cases, failed relaxation of the puborectalis occurred and prevented the passage of the bolus; in another case there was abnormal perineal descent. In two patients studies were normal. In patients with defecation disorders, the possibility of this syndrome should be considered. Defecography is the method of choice for establishing the diagnosis. 相似文献
8.
9.
F. Pott F. S. Larsen E. Ejlersen P. Linkis L. G. Jrgensen N. H. Secher 《Clinical physiology and functional imaging》1995,15(2):119-130
Summary. During transplantation of the liver cerebral perfusion was monitored by transcranial Doppler determined middle cerebral artery mean flow velocity (Vmean) and pulsatility index (PI) in six fulminant hepatic failure patients and 11 patients with chronic liver disease. In both groups of patients Vmean, PI and central haemodynamic variables were recorded during (1) the last preanhepatic hour; (2) the anhepatic phase; (3) the first 15 min of reperfusion; and (4) for the following 45 min of reperfusion. No significant differences were detected between the two groups of patients with respect to changes of variables with time. The Vmean (40±13 cm s-1 [mean±SD]), thoracic electrical impedance (TI) (30±7 Ohm), heart rate (97±19 beats min-1), mean arterial pressure (84±9 mmHg) and arterial carbon dioxide tension (PaCO2, 4.5±0.4 kPa) remained stable in the anhepatic phase, while cardiac output (CO, 7.6±2.7 to 5.4±1.41 min-1), stroke volume (SV, 79±26 to 56±15 ml) and PI (1.2±0.3 to 0.9±0.2) decreased (P<0.05). During reperfusion, CO (9.9±4.01 min-1), SV (105±40 ml), PaCO2 (5.5±0.6 kPa), Vmean (57±17 cm s-1) and PI (1.2±0.2) became elevated. Taken together, during the anhepatic phase of the liver transplantation a maintained central blood volume as indicated by the constant TI served for a stable blood pressure and in turn cerebral perfusion, whereas revascularization of the graft increased cerebral perfusion concomitant with an elevated carbon dioxide tension. 相似文献
10.