全文获取类型
收费全文 | 10903篇 |
免费 | 686篇 |
国内免费 | 59篇 |
专业分类
耳鼻咽喉 | 90篇 |
儿科学 | 280篇 |
妇产科学 | 167篇 |
基础医学 | 1495篇 |
口腔科学 | 204篇 |
临床医学 | 1101篇 |
内科学 | 2614篇 |
皮肤病学 | 227篇 |
神经病学 | 1085篇 |
特种医学 | 412篇 |
外科学 | 1522篇 |
综合类 | 57篇 |
一般理论 | 5篇 |
预防医学 | 957篇 |
眼科学 | 97篇 |
药学 | 686篇 |
中国医学 | 43篇 |
肿瘤学 | 606篇 |
出版年
2023年 | 43篇 |
2022年 | 100篇 |
2021年 | 229篇 |
2020年 | 171篇 |
2019年 | 268篇 |
2018年 | 314篇 |
2017年 | 201篇 |
2016年 | 239篇 |
2015年 | 272篇 |
2014年 | 396篇 |
2013年 | 563篇 |
2012年 | 789篇 |
2011年 | 867篇 |
2010年 | 480篇 |
2009年 | 431篇 |
2008年 | 696篇 |
2007年 | 798篇 |
2006年 | 713篇 |
2005年 | 686篇 |
2004年 | 666篇 |
2003年 | 587篇 |
2002年 | 558篇 |
2001年 | 157篇 |
2000年 | 138篇 |
1999年 | 131篇 |
1998年 | 112篇 |
1997年 | 89篇 |
1996年 | 76篇 |
1995年 | 64篇 |
1994年 | 55篇 |
1993年 | 58篇 |
1992年 | 61篇 |
1991年 | 81篇 |
1990年 | 44篇 |
1989年 | 64篇 |
1988年 | 46篇 |
1987年 | 40篇 |
1986年 | 44篇 |
1985年 | 45篇 |
1984年 | 39篇 |
1983年 | 29篇 |
1982年 | 21篇 |
1981年 | 20篇 |
1980年 | 11篇 |
1979年 | 27篇 |
1976年 | 15篇 |
1975年 | 10篇 |
1974年 | 10篇 |
1973年 | 12篇 |
1972年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Conall T. Morgan Brigitte Mueller Varsha Thakur Vitor Guerra Callaghan Jull Luc Mertens Mark Friedberg Fraser Golding Mike Seed Steven E.S. Miner Edgar T. Jaeggi Cedric Manlhiot Lynne E. Nield 《The Canadian journal of cardiology》2019,35(4):453-461
Background
The purpose of the study was to evaluate the association between fetal echocardiographic measurements and the need for intervention (primary coarctation repair, staged coarctation repair, or catheter intervention) in prenatally diagnosed coarctation of the aorta.Methods
A single-centre retrospective cohort study (2005-2015) of 107 fetuses diagnosed with suspected coarctation of the aorta in the setting of an apex-forming left ventricle and antegrade flow across the mitral and aortic valves.Results
Median gestational age at diagnosis was 32 weeks (interquartile range, 23-35 weeks). Fifty-six (52%) did not require any neonatal intervention, 51 patients (48%) underwent a biventricular repair. In univariable analysis, an increase in ascending aorta (AAo) peak Doppler flow velocity (odds ratio [OR], 1.40 [95% confidence interval [CI], 1.05-1.91] per 20 cm/s; P = 0.03) was associated with intervention. No intervention was associated with larger isthmus size (OR, 0.23; P < 0.001), transverse arch diameter (OR, 0.23; P < 0.001), and aortic (OR, 0.72; P = 0.02), mitral (OR, 0.58; P = 0.001), and AAo (OR, 0.53; P < 0.001) z-scores. In multivariable analysis, higher peak AAo Doppler (OR, 2.51 [95% CI, 1.54-4.58] per 20 cm/s; P = 0.001) and younger gestational age at diagnosis (OR, 0.81 [95% CI, 0.70-0.93] per week; P = 0.005) were associated with intervention, whereas a higher AAo z-score (OR, 0.65 [95% CI, 0.43-0.94] per z; P = 0.029) and transverse arch dimension (OR, 0.44 [95% CI, 0.18-0.97]; P = 0.05) decreased the risk of intervention.Conclusions
In prenatally suspected coarctation, the variables associated with intervention comprised smaller AAo and transverse arch size, earlier gestational age at diagnosis, and the additional finding of a higher peak AAo Doppler. 相似文献2.
3.
Philippe Nickers Luc Coppens Jean de Leval Nicolas Jansen Jean-Marie Deneufbourg 《Radiotherapy and oncology》2006,79(3):329-334
BACKGROUND AND PURPOSE: To evaluate on 201 locally advanced prostatic cancers prospectively treated in a phase II trial, the efficacy of a combination of external beam radiotherapy (39.6 Gy) and (192)Ir low dose rate brachytherapy (Bt) (40-45 Gy). PATIENTS AND METHODS: Sixty-four patients were included in the intermediate prognosis group with only one of the following adverse factors (PSA > 10 ng/ml, Gleason score > or = 7 or clinical stage > or =T2b) and 137 in the unfavourable group when at least two of these factors were present. RESULTS: The actuarial 4 years biochemical no evidence of disease is 82.8% for the entire population. It is, respectively, 97 and 76% in the intermediate and unfavourable prognosis groups (P < 0.0001). Grade > or =3 late urinary complications occurred in 13 patients (6.5%). Eight patients (4%) presented late grade 2 rectal complications but no grades 3-5 was observed. CONCLUSIONS: Even if an alpha/beta of 1.5-3 Gy theoretically favours the use of a high dose rate mode of irradiation, the early results presented here are as good as those reported for similar groups of patients with high dose rate treatments. Late toxicity is identical but our urinary toxicity is within the less favourable and rectal toxicity within the most favourable results. We can postulate that while inducing very high hyperdosage regions (V150) mainly focused on the peripheral zone, most of the Bt techniques consist of a more ablative treatment. Many of the radiobiological studies on Bt did not in fact take into account the heterogeneity of irradiation inside the CTV. This study highlights the need to explore pulsed dose rate therapies, permanent implant and new available radioisotopes such as (169)Ytterbium that will offer the safety of low and lower dose rates. The actual late toxicity of the different Bt techniques is not yet inexistent indeed. 相似文献
4.
5.
Although extracellular matrix (ECM) glycoproteins play important roles in neural development, their levels are generally believed to decrease in the adult brain. Immunohistochemical analysis indicates that the anti-adhesive ECM glycoprotein SPARC/osteonectin, which contains a follistatin ‘module’, is expressed in the adult rabbit nervous system. In the cerebellum, SPARC is present in Bergmann glia, with a strong signal along their radial fibres. SPARC, while enriched in membrane fractions, is not a transmembrane protein. In the hippocampus, colocalization of SPARC is observed in cells which express the astrocytic marker GFAP. The expression of SPARC by a subset of astrocytes, particularly in synaptic enriched areas, suggests a continuing role for the ECM in the adult brain. 相似文献
6.
This study investigates the contribution of body fat stores on the age-associated increase in serum cholesterol and triglyceride levels. Percentage of body fat was measured by hydrostatic weighing, and serum cholesterol, triglyceride, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol levels were determined in a sample of 472 healthy men and women ages 18-50 years. In both sexes, body fat mass was significantly correlated with serum cholesterol (r = 0.21 in men and r = 0.24 in women, P less than 0.01) and triglyceride (r = 0.33 in men and r = 0.24 in women, P less than 0.01) levels. After adjustment for the association between age and serum cholesterol, no correlation was observed between body fat mass and serum cholesterol (r = 0.01 in men and r = 0.09 in women). After correction for age, serum triglyceride levels remained significantly correlated with body fat mass (r = 0.26 and r = 0.17 in men and women, respectively, P less than 0.05). As body fat also increases with age, the possibility that a partial correlation coefficient procedure eliminated a portion of the age effect mediated by an age-related increase in fat, was addressed by performing further analyses. Within each sex subsample two sets of analyses were performed on (a) three groups of subjects individually paired for age but with different levels of body fat stores, and (b) three groups of subjects paired for the amount of body fat but differing in age.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
7.
8.
Nicolas Borenstein Valérie Chetboul Patrick Bruneval Mehrak Hekmati Renaud Tissier Luc Behr Geneviève Derumeaux Didier Montarras 《European journal of cardio-thoracic surgery》2007,31(3):444-451
OBJECTIVE: Cell therapy may be a promising alternative or adjunct to current treatment modalities for ischemic heart failure. But little is known on the impact of myogenic cell transplantation in large animal models of non-ischemic cardiomyopathy. The aim of the present study was to explore whether an ovine model of toxin-induced heart disease could benefit from non-cultured skeletal muscle cell transplantation. METHODS: Sequential intracoronary injections of doxorubicin (0.75 mg/kg) were carried out every 2 weeks until echocardiographic detection of myocardial dysfunction. Sheep were then randomly assigned to either non-cultured cell transplantation (n=8) or placebo injection (n=5). For the cell therapy group, a skeletal muscle biopsy (about 10 g) was explanted from each animal approximately 3h before grafting. After thoracotomy, 20 epicardial injections were carried out. The animals were assessed one last time before sacrifice, 2 months after the thoracotomy. Cells were tracked with cmDiI (red fluorescence) and characterized with immunohistochemistry with monoclonal antibodies to a fast skeletal isoform of myosin heavy chain. RESULTS: Two months after intramyocardial grafting, tissue Doppler imaging and conventional echocardiographic assessment of the groups showed a marked improvement in the non-cultured cell therapy group. Ejection fraction (EF) (p<0.05) as well as systolic endocardial velocities (p<0.01) improved versus the placebo group. CmDiI and skeletal myosin heavy chain expression was detected in all animals at 2 months after implantation confirming engraftment of skeletal muscle cells. CONCLUSIONS: In conclusion, our data indicate that non-cultured muscle cell transplantation is feasible and may translate into a functional benefit in an ovine model of dilated heart failure. 相似文献
9.
Anita Rachlis Jonathan Angel Marianne Harris Richard Lalonde Fiona Smaill Cecile Tremblay Chris Tsoukas Sharon Walmsley 《The Canadian Journal of Infectious Diseases & Medical Microbiology》2006,17(3):155-163
BACKGROUND AND OBJECTIVES: An eight-member group consisting of Canadian infectious disease and immunology specialists and a family physician with significant experience in HIV management was convened to update existing recommendations, specifically intended for use by Canadian HIV-treating physicians, on the appropriate use of enfuvirtide in HIV/AIDS patients with resistance to other antiretroviral drugs. METHODS: Evidence from the literature and expert opinions of the group members formed the basis of the guidelines. Comments on the draft guidelines were obtained from other physicians across Canada with HIV expertise. The final guidelines represent the group's consensus agreement. RESULTS AND CONCLUSIONS: The recommendations were developed to guide physicians in optimal practices in patient selection for enfuvirtide treatment and subsequent patient management. The issues considered include positive predictors of response to enfuvirtide, stage of disease, optimization of the background regimen, early indicators of enfuvirtide response, and patient education and support. 相似文献
10.
It has been proposed that administration of non-nitrogenous precursors to glycine is necessary to realize the full potential of benzoate metabolism as a pathway for disposal of waste nitrogen during ammonia intoxication (Coude et al., Clin Chim Acta 136: 211-217, 1984). However, when glyoxylate, a keto acid precursor to glycine, was administered with benzoate 1 hr prior to a challenge of ammonia, protection against ammonia toxicity was less successful than with benzoate alone. At the cellular and subcellular levels, glyoxylate and benzoate each inhibited the urea cycle in isolated hepatocytes and pyruvate carboxylase in isolated mitochondria. The action of each drug was associated with depletion of aspartate content in isolated hepatocytes and reduction of pyruvate-dependent incorporation of CO2 into aspartate in assays with isolated mitochondria. Depression of aspartate regeneration by inhibition of pyruvate carboxylase is a likely mechanism for impairment of urea cycle activity by both drugs. In whole animals, inhibition of pyruvate carboxylase may contribute to benzoate toxicity and the adverse influence of glyoxylate on benzoate therapy. 相似文献