全文获取类型
收费全文 | 7084篇 |
免费 | 342篇 |
国内免费 | 30篇 |
专业分类
耳鼻咽喉 | 87篇 |
儿科学 | 195篇 |
妇产科学 | 281篇 |
基础医学 | 881篇 |
口腔科学 | 323篇 |
临床医学 | 610篇 |
内科学 | 1631篇 |
皮肤病学 | 145篇 |
神经病学 | 775篇 |
特种医学 | 239篇 |
外科学 | 933篇 |
综合类 | 24篇 |
一般理论 | 1篇 |
预防医学 | 285篇 |
眼科学 | 126篇 |
药学 | 433篇 |
中国医学 | 20篇 |
肿瘤学 | 467篇 |
出版年
2023年 | 33篇 |
2022年 | 86篇 |
2021年 | 150篇 |
2020年 | 86篇 |
2019年 | 142篇 |
2018年 | 199篇 |
2017年 | 144篇 |
2016年 | 166篇 |
2015年 | 192篇 |
2014年 | 248篇 |
2013年 | 324篇 |
2012年 | 494篇 |
2011年 | 511篇 |
2010年 | 316篇 |
2009年 | 285篇 |
2008年 | 465篇 |
2007年 | 436篇 |
2006年 | 442篇 |
2005年 | 362篇 |
2004年 | 337篇 |
2003年 | 333篇 |
2002年 | 313篇 |
2001年 | 128篇 |
2000年 | 108篇 |
1999年 | 98篇 |
1998年 | 70篇 |
1997年 | 72篇 |
1996年 | 51篇 |
1995年 | 49篇 |
1994年 | 34篇 |
1993年 | 37篇 |
1992年 | 71篇 |
1991年 | 55篇 |
1990年 | 59篇 |
1989年 | 56篇 |
1988年 | 50篇 |
1987年 | 35篇 |
1986年 | 36篇 |
1985年 | 35篇 |
1984年 | 39篇 |
1983年 | 27篇 |
1982年 | 20篇 |
1981年 | 25篇 |
1980年 | 18篇 |
1979年 | 14篇 |
1978年 | 21篇 |
1976年 | 17篇 |
1974年 | 20篇 |
1972年 | 16篇 |
1971年 | 16篇 |
排序方式: 共有7456条查询结果,搜索用时 31 毫秒
1.
2.
3.
Background:
The results of a pilot colorectal cancer screening programme by biennial immunochemical faecal occult blood test (FOBT) are reported.Methods:
All residents aged between 50 and 69 years in the Italian province of Lecco were invited to have a FOBT. Those with a positive result were offered colonoscopy. FOBT uptake and compliance with colonoscopy were assessed. Detection rate and positive predictive value (PPV) for cancer and adenoma were calculated. Tumour stages were compared between screen‐detected cancers and other colorectal cancers diagnosed within the target age group.Results:
Some 38 693 (49·6 per cent) of 78 083 individuals had a FOBT and 2392 (6·2 per cent) had a positive result. Colorectal cancer was diagnosed in 4·6 per cent and advanced adenoma in 32·7 per cent. PPVs were 4·0 per cent for cancer, 28·1 per cent for advanced adenoma and 36·6 per cent for any adenoma. There was a significant difference in incidence of stage III/IV disease between screened and non‐screened cohorts. Compliance for colonoscopy was 92·0 per cent. Major determinants of compliance were age less than 59 years, female sex, high education level and non‐manual work.Conclusion:
These results justify extension of colorectal cancer screening to other regions of Italy. Copyright © 2009 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd. 相似文献4.
Erdosteine was introduced in the market as a mucolytic agent for chronic pulmonary diseases more than 10 years ago. The drug contains two blocked sulphydryl groups one of which, after hepatic metabolization and opening of the thiolactone ring, becomes available both for the mucolytic and free radical scavenging and antioxidant activity too. There are several experimental evidences which support the protective effect of erdosteine in acute injury induced by a variety of pharmacological or noxious agents, mediated by products of oxidative stress. Experimental data in animal assigned to receive the noxious agent evidence that co-treatment with erdosteine increases the tissue antioxidant enzyme activities such as superoxide dismutase, catalase and glutathione peroxidase, compared with the toxic agent alone; meanwhile erdosteine decreases the tissue level of nitric oxide, xanthine oxidase, which catalyze oxygen-free radical production. In summary, erdosteine prevents the accumulation of free oxygen radicals when their production is accelerated and increases antioxidant cellular protective mechanisms. The final result is a protective effect on tissues which reduces lipid peroxidation, neutrophil infiltration or cell apoptosis mediated by noxious agents. Recent positive clinical trials in humans seem to fulfill the impressive promises that theory and experimental research have put forward. 相似文献
5.
Effects of androgen treatment in impotent men with normal and low levels of free testosterone 总被引:1,自引:0,他引:1
Cesare Carani M.D. Dante Zini M.D. Augusto Baldini M.D. Luciano Della Casa M.D. Anna Ghizzani M.D. Paolo Marrama M.D. 《Archives of sexual behavior》1990,19(3):223-234
The relation between sexual function and serum free testosterone (fT) levels, which represent the active fraction of circulating testosterone, was evaluated. Two groups of impotent male subjects with mild hypogonadism were treated with oral testosterone undecanoate (TU); these men presented with tT/luteinizing hormone (LH) ratio and tT levels at the lower limits of normal. The first group had serum fT below 6.6 ng/ml, considered the lower normal value, according to our laboratory method, whereas the second group had normal fT limits. Administration of TU improved sexual function only in impotent men with low fT levels, but not in subjects with normal fT levels, even though the tT levels and the tT/LH ratio of the two groups were not significantly different. The results of our study suggest the presence of a minimun serum fT threshold, lying near the lower normal range, which determines the male sexual function. Moreover, serum fT levels were a more sensitive index than tT for identifying impotent men who can be successfully treated with androgens. 相似文献
6.
Luciano Potena Francesco Grigioni Gaia Magnani Paolo Ortolani Fabio Coccolo Simonetta Sassi Koen Koessels Cinzia Marrozzini Antonio Marzocchi Samuela Carigi Anna C. Musuraca Antonio Russo Carlo Magelli Angelo Branzi 《American journal of transplantation》2005,5(9):2258-2264
Although observational studies suggest that hyperhomocysteinemia may be a risk factor for coronary allograft vasculopathy (CAV), prospective data on homocysteine-lowering interventions and CAV development are lacking. We, therefore, randomized 44 de novo heart transplant (HT) recipients to 15 mg/day of 5-methyl-tetrahydrofolate (n=22), or standard therapy (control group, n=22) to investigate the effect of homocysteine lowering on the change in coronary intimal hyperplasia during the first 12 months after transplant, as detected by intra-vascular ultrasound (IVUS). Although 12 months after HT, homocysteinemia was lower in folate-treated patients (p<0.001), coronary intimal area increased similarly in the two groups (p>0.4). Conversely, hypercholesterolemia and cytomegalovirus infection were both associated with increased intimal hyperplasia (p<0.04), independently from folate intake. Sub-group analysis revealed that folate therapy reduced intimal hyperplasia in patients with hyperhomocysteinemia before randomization (n=19; p=0.02), but increased intimal hyperplasia in patients with normal homocysteine plasma concentrations (p=0.02). This bimodal effect of folate therapy persisted significantly after adjusting for cytomegalovirus infection and hypercholesterolemia. Despite effective in prevent hyperhomocysteinemia after heart transplantation, folate therapy does not seem to affect early CAV onset. However, sub-group analysis suggests that folate therapy may delay CAV development only in patients with baseline hyperhomocysteinemia, while may favor CAV progression in recipients with normal baseline homocysteinemia. 相似文献
7.
Claudio Babiloni Giuliano Binetti Emanuele Cassetta Gloria Dal Forno Claudio Del Percio Florinda Ferreri Raffaele Ferri Giovanni Frisoni Koichi Hirata Bartolo Lanuzza Carlo Miniussi Davide V Moretti Flavio Nobili Guido Rodriguez Gian Luca Romani Serenella Salinari Paolo M Rossini 《Clinical neurophysiology》2006,117(2):252-268
OBJECTIVE: The present study tested the hypothesis that cortical electroencephalographic (EEG) rhythms. change across normal elderly (Nold), mild cognitive impairment (MCI), and Alzheimer's disease (AD) subjects as a function of the global cognitive level. METHODS: Resting eyes-closed EEG data were recorded in 155 MCI, 193 mild AD, and 126 age-matched Nold subjects. EEG rhythms of interest were delta (2-4 Hz), theta (4-8 Hz), alpha 1 (8-10.5 Hz), alpha 2 (10.5-13 Hz), beta 1 (13-20 Hz), and beta 2 (20-30 Hz). EEG cortical sources were estimated by LORETA. RESULTS: Occipital delta and alpha 1 sources in parietal, occipital, temporal, and 'limbic' areas had an intermediate magnitude in MCI subjects compared to mild AD and Nold subjects. These five EEG sources presented both linear and nonlinear (linear, exponential, logarithmic, and power) correlations with the global cognitive level (as revealed by mini mental state examination score) across all subjects. CONCLUSIONS: Cortical EEG rhythms change in pathological aging as a function of the global cognitive level. SIGNIFICANCE: The present functional data on large populations support the 'transitional hypothesis' of a shadow zone across normality, pre-clinical stage of dementia (MCI), and AD. 相似文献
8.
Luca Belli M.D. Alberto Reggiori M.D. Eugenio Cocozza M.D. Luciano Riboldi M.D. 《Skeletal radiology》1992,21(2):107-109
Tropical pyomyositis is an infection of muscles mainly presenting in black people, occurring in the trunk and limbs. At Hoima Hospital, Uganda, 58 patients (30 men and 28 women) with a mean age of 21 years have been investigated by ultrasound; a total of 81 lesions were present. Two different characteristic images were found; abscess was present in 65 cases while 16 patients showed a diffuse infiltration among the muscular fibers. These two different images correspond to the two stages of histologic and clinical progression described by other authors. Ultrasound is useful to demonstrate the progression of pyomyositis and to determine when and where to drain any abscess. 相似文献
9.
Antinori Andrea Cingolani Antonella Lorenzini Patrizia Giancola Maria Letizia Uccella Ilaria Bossolasco Simona Grisetti Susanna Moretti Francesca Vigo Beniamino Bongiovanni Marco Del Grosso Bruno Arcidiacono Maria Irene Fibbia Giovanni Carlo Mena Maurizio Finazzi Maria Grazia Guaraldi Giovanni Ammassari Adriana Monforte Antonella dArminio Cinque Paola De Luca Andrea 《Journal of neurovirology》2003,9(1):47-53
Human immunodeficiency virus (HIV)-associated progressive multifocal leukoencephalopathy (PML) remains a relevant clinical problem even in the era of highly active antiretroviral therapy (HAART). Aims of the study were to analyze clinical and treatment-related features and the survival probability of PML patients observed within the Italian Registry Investigative Neuro AIDS (IRINA) during a 29-month period of HAART. Intravenous drug use, the presence of focal signs, and the involvement of white matter at neuroradiology increased the risk of having PML. A reduced probability of PML was observed when meningeal signs were reported. Patients starting HAART at PML diagnosis and previously naïve for antiretrovirals showed significantly higher 1-year probability of survival (.58), compared to those continuing HAART (.24), or never receiving HAART (.00). Higher CD4 cell count were associated with a higher survival probability (.45). At multivariate analysis, a younger age, higher CD4, starting HAART at PML diagnosis, the absence of previous acquired immunodeficiency syndrome (AIDS)-defining events, and the absence of a severe neurologic impairment were all associated with a reduced hazard of death. The use of cidofovir showed a trend towards a reduced risk of death. 相似文献
10.
Interactions of phenylalkylamines with human lung membrane and microsome preparation 总被引:1,自引:0,他引:1
J L Moretti R Zini D Morin Y Joulin G Desplanches N Caillat-Vigneron J P Tillement 《Nuclear medicine communications》1987,8(2):115-120
Lipophilic amines are recognized as important tracers for brain imaging. Their pulmonary accumulation was a drawback for optimal concentration in the brain. We used IMP, HIPDM, IP, amphetamine derivatives to determine the relation between structure and accumulation in the lung. The incubation of phenylalkylamines in competition with 3H-Imipramine, for human lung membrane and microsomes was performed and led to the extraction of a competitive constant (KI). The results showed that the compounds can be classified in order of their decreasing affinity: Iodoamphetamine, iodoisopropylamphetamine, dimethyliodophentermine, hydroxyiodobenzyl propane diamine (HIPDM), isopropylamphetamine and amphetamine. Iodine set in the para position of the ring seemed to increase the affinity of phenylalkylamines for the lung. Adjunction of isopropyl or methyl groups to the lateral chain decreased this affinity. 相似文献