全文获取类型
收费全文 | 1429篇 |
免费 | 54篇 |
国内免费 | 7篇 |
专业分类
耳鼻咽喉 | 32篇 |
儿科学 | 37篇 |
妇产科学 | 38篇 |
基础医学 | 190篇 |
口腔科学 | 10篇 |
临床医学 | 72篇 |
内科学 | 313篇 |
皮肤病学 | 17篇 |
神经病学 | 82篇 |
特种医学 | 29篇 |
外科学 | 131篇 |
综合类 | 15篇 |
预防医学 | 207篇 |
眼科学 | 37篇 |
药学 | 98篇 |
中国医学 | 4篇 |
肿瘤学 | 178篇 |
出版年
2024年 | 3篇 |
2023年 | 5篇 |
2022年 | 43篇 |
2021年 | 75篇 |
2020年 | 39篇 |
2019年 | 28篇 |
2018年 | 40篇 |
2017年 | 29篇 |
2016年 | 31篇 |
2015年 | 36篇 |
2014年 | 45篇 |
2013年 | 62篇 |
2012年 | 108篇 |
2011年 | 112篇 |
2010年 | 57篇 |
2009年 | 54篇 |
2008年 | 86篇 |
2007年 | 122篇 |
2006年 | 120篇 |
2005年 | 86篇 |
2004年 | 95篇 |
2003年 | 63篇 |
2002年 | 80篇 |
2001年 | 8篇 |
2000年 | 3篇 |
1999年 | 6篇 |
1998年 | 9篇 |
1997年 | 3篇 |
1996年 | 9篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1992年 | 3篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1980年 | 4篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1960年 | 1篇 |
排序方式: 共有1490条查询结果,搜索用时 0 毫秒
141.
The coincidence of viral hepatitis and acute pancreatitis is well described. Most of the cases are related to acute hepatitis A or B. Hepatitis E virus (HEV) infections are rare in Europe, and very few reports describe HEV as a causative agent of acute pancreatitis in areas of endemic hepatitis E prevalence. We report a case of acute pancreatitis in the course of acute hepatitis E in a 28-year-old male patient. The majority of reported cases, including our case, show several common epidemiological and clinical features: young age, male predominance, onset of acute pancreatitis at the early stage of acute hepatitis, and favorable outcome. Acute pancreatitis should be considered in acute hepatitis E, especially in young, male patients presenting with severe epigastric pain early in the course of disease. The pancreatitis in these patients usually runs a benign course. The patients should be closely monitored because life-threatening complications have been reported. 相似文献
142.
Muhammad Moazam Fraz Alicja R. Rudnicka Christopher G. Owen Sarah A. Barman 《International journal of computer assisted radiology and surgery》2014,9(5):795-811
Purpose
Automatic segmentation of the retinal vasculature is a first step in computer-assisted diagnosis and treatment planning. The extraction of retinal vessels in pediatric retinal images is challenging because of comparatively wide arterioles with a light streak running longitudinally along the vessel’s center, the central vessel reflex. A new method for automatic segmentation was developed and tested.Method
A supervised method for retinal vessel segmentation in the images of multi-ethnic school children was developed based on ensemble classifier of bootstrapped decision trees. A collection of dual Gaussian, second derivative of Gaussian and Gabor filters, along with the generalized multiscale line strength measure and morphological transformation is used to generate the feature vector. The feature vector encodes information to handle the normal vessels as well as the vessels with the central reflex. The methodology is evaluated on CHASE_DB1, a relatively new public retinal image database of multi-ethnic school children, which is a subset of retinal images from the Child Heart and Health Study in England (CHASE) dataset.Results
The segmented retinal images from the CHASE_DB1 database produced best case accuracy, sensitivity and specificity of 0.96, 0.74 and 0.98, respectively, and worst case measures of 0.94, 0.67 and 0.98, respectively.Conclusion
A new retinal blood vessel segmentation algorithm was developed and tested with a shared database. The observed accuracy, speed, robustness and simplicity suggest that the algorithm may be a suitable tool for automated retinal image analysis in large population-based studies. 相似文献143.
Alicja Chrzanowska Wojciech GrabońMagdalena Mielczarek-Puta Anna Barańczyk-Kuźma 《Clinical biochemistry》2014
Objective
To assess the utility of arginase activity and expression in diagnosis of liver diseases.Design and methods
Arginase activity, sensitivity and specificity were determined in serum of 140 patients including 50 with HCC, 60 with LC, 30 with choledocholithiasis (CDL) and 90 healthy controls. In HCC and LC arginase activity in serum was studied before and after tumor resection or liver transplantation. Arginase sensitivity in HCC was compared to that of alpha-fetoprotein (AFP) and aminotransferases (AST, ALT). In LC the activity was determined also in bile before and after transplantation. The expression of arginase isoenzymes in serum was studied by Western blotting.Results
In HCC and LC the preoperative arginase activity was significantly higher compared to controls, and it decreased after surgery. The sensitivity of arginase in HCC was much higher than that of AFP, AST and ALT (96, 40, 20 and 18%, respectively). In HCC it was higher than in LC (93%) and CDL (33%). The specificity of arginase was above 80%. In bile of cirrhotic patients the highest activity was immediately after liver transplantation. It decreased with time but increased dramatically at the time of the graft rejection. Arginase AII was present in serum of HCC and LC but not the control cases.Conclusions
The increase of arginase activity in serum accompanied by the presence of isoenzyme AII can be useful in HCC and LC diagnosis. The determination of arginase activity in bile may be helpful in monitoring liver graft recipients. 相似文献144.
Epidemiological characteristics of inflammatory bowel disease in North-Eastern Poland 总被引:4,自引:0,他引:4
Wiercinska-Drapalo A Jaroszewicz J Flisiak R Prokopowicz D 《World journal of gastroenterology : WJG》2005,11(17):2630-2633
AIM: To provide the clinical and epidemiological data of inflammatory bowel disease (IBD) patients of North-Eastern Poland. METHODS: A total of 248 IBD patients diagnosed and hospitalized in the Department of Infectious Diseases in Bialystok between 1990 and 2003 were included in the study. We analyzed age, sex, education, characteristics of job, type of the environment, discontinuation of employment due to IBD, colitis extent, need of surgical treatment, and coexistence of other diseases. RESULTS: Two hundred and thirty-three IBD patients (94%) were diagnosed as ulcerative colitis (DC), and only 15 (6%) were diagnosed as Crohn's disease (CD). Patients with CD were significantly younger at the time of diagnosis and male predominance was observed. The mean age of the patients at the time UC diagnosis was 44.9±1.1 years. Histogram of the age of patients showed the characteristic biphasic distribution with two peaks between 20 and 40 years and between 60 and 70 years. The predominant form of UC was left sided colitis, which affected almost 80% of the studied population. The most extensive form - pancolitis was present in 34 patients (15%). Only 6% of UC patients required surgery, whereas 36% of CD patients underwent surgery (P<0.005). Among coexisting disorders, cholelithiasis was the most prevalent and demonstrated in 35 patients (14%), pulmonary disorders were diagnosed in 2%, and psoriasis in 1.4%. Since 1998, the number of admitted IBD patients has slightly increased. CONCLUSION: Occurrence of UC in Poland is much higher than that of CD. The majority of UC cases are diagnosed in young people (20-40 years) with the predominance of male patients. The most common clinical form of UC is left sided colitis. 相似文献
145.
Streeck H Kwon DS Pyo A Flanders M Chevalier MF Law K Jülg B Trocha K Jolin JS Anahtar MN Lian J Toth I Brumme Z Chang JJ Caron T Rodig SJ Milner DA Piechoka-Trocha A Kaufmann DE Walker BD Altfeld M 《Blood》2011,117(19):5112-5122
Under persistent antigenic stimulation, virus-specific CD8? T cells become increasingly dysfunctional and up-regulate several inhibitory molecules such as killer lectin-like receptor G1 (KLRG1). Here, we demonstrate that HIV-1 antigen-specific T cells from subjects with chronic-progressive HIV-1 infection have significantly elevated KLRG1 expression (P < .001); show abnormal distribution of E-cadherin, the natural ligand of KLRG1, in the intestinal mucosa; and have elevated levels of systemic soluble E-cadherin (sE-cadherin) that significantly correlate with HIV-1 viral load (R = 0.7, P = .004). We furthermore demonstrate that in the presence of sE-cadherin, KLRG1(hi) HIV-1-specific CD8? T cells are impaired in their ability to respond by cytokine secretion on antigenic stimulation (P = .002) and to inhibit viral replication (P = .03) in vitro. Thus, these data suggest a critical mechanism by which the disruption of the intestinal epithelium associated with HIV-1 leads to increased systemic levels of sE-cadherin, which inhibits the effector functions of KLRG1(hi)-expressing HIV-1-specific CD8? T cells systemically. 相似文献
146.
Antonczak AK Simova Z Yonemoto IT Bochtler M Piasecka A Czapinska H Brancale A Tippmann EM 《Proceedings of the National Academy of Sciences of the United States of America》2011,108(4):1320-1325
The site-selective encoding of noncanonical amino acids (NAAs) is a powerful technique for the installation of novel chemical functional groups in proteins. This is often achieved by recoding a stop codon and requires two additional components: an evolved aminoacyl tRNA synthetase (AARS) and a cognate tRNA. Analysis of the most successful AARSs reveals common characteristics. The highest fidelity NAA systems derived from the Methanocaldococcus jannaschii tyrosyl AARS feature specific mutations to two residues reported to interact with the hydroxyl group of the substrate tyrosine. We demonstrate that the restoration of just one of these determinants for amino acid specificity results in the loss of fidelity as the evolved AARSs become noticeably promiscuous. These results offer a partial explanation of a recently retracted strategy for the synthesis of glycoproteins. Similarly, we reinvestigated a tryptophanyl AARS reported to allow the site-selective incorporation of 5-hydroxy tryptophan within mammalian cells. In multiple experiments, the enzyme displayed elements of promiscuity despite its previous characterization as a high fidelity enzyme. Given the many similarities of the TyrRSs and TrpRSs reevaluated here, our findings can be largely combined, and in doing so they reinforce the long-established central dogma regarding the molecular basis by which these enzymes contribute to the fidelity of translation. Thus, our view is that the central claims of fidelity reported in several NAA systems remain unproven and unprecedented. 相似文献
147.
Pace D Williams TN Grochowska A Betts A Attard-Montalto S Boffa MJ Vella C 《Travel medicine and infectious disease》2011,9(1):37-46
Leishmania infantum is endemic in the Maltese archipelago, a group of islands in the Mediterranean which are visited frequently by tourists from Northern European countries. The burden of leishmaniasis is highest in children who may present with cutaneous or visceral manifestations. We describe systematically the manifestations, diagnosis and management of leishmaniasis in children <14 years of age, who had a histopathological diagnosis of leishmaniasis in Malta, from 2004 to 2008. Eleven children were diagnosed with leishmaniasis; 8 children (15-44 months of age) had visceral disease and three (aged 9-13 years) suffered cutaneous infections. Prolonged high grade fever, pallor, hepatosplenomegaly, and pancytopenia were common presenting features of visceralisation. Diagnosis was based on the visualisation of amastigotes from bone marrow aspirates. Pentavalent antimonials were associated with treatment failure in two children, whilst liposomal amphotericin B was curative in all. Children with cutaneous leishmaniasis had dry crusted ulcero-nodular lesions on exposed areas which responded to intra-lesional instillation of sodium stibogluconate or to cryotherapy. Leishmaniasis should be included in the differential diagnosis of fever and hepatosplenomegaly or chronic cutaneous lesions in children who travel to Malta. 相似文献
148.
Krzentowska-Korek A Gołkowski F Bałdys-Waligórska A Hubalewska-Dydejczyk A 《Pituitary》2011,14(2):157-162
The aim of the study was to evaluate the frequency of occurrence of pituitary failure following neurosurgery and the efficacy
of transsphenoidal tumour resection in acromegalic patients. We retrospectively evaluated 85 patients (60 female and 25 male),
of mean age 43.9 ± 13.2 years, treated by transsphenoidal neurosurgery. Macroadenoma and microadenoma of pituitary were found
in 66 (77.6%) and 19 (22.4%) of these patients, respectively. Criteria of cure following neurosurgery were: basal GH < 2.5 μg/l,
GH at 120 min in OGTT < 1.0 μg/l and serum concentration of IGF-1 within normal ranges for age and sex. After surgery 32 patients
(37.6%) were cured and 53 patients (62.4%) required somatostatin analogue treatment. In patients cured by surgery, lower levels
of basal GH (P < 0.05), IGF-1 (P < 0.001), GH at 120 min in OGTT and smaller size of pituitary tumour (P < 0.05) were found at diagnosis, as compared to patients in whom surgery was unsuccessful. Significant correlation between
basal serum level of GH at diagnosis and size of pituitary tumour was found (P < 0.001). Invasive tumours were found in 45 of 53 (84.9%) patients not cured and in only 8 of 32 (25.0%) patients cured (P < 0.001). Impaired function of pituitary anterior lobe after surgery was observed in 30% and 4% of patients with macro- and
microadenoma, respectively (P < 0.05). The efficacy of neurosurgery is affected by concentration of basal serum GH and IGF-1, GH at 120 min in OGTT, tumour
size and invasiveness. Hypopituitarism after surgery is more frequent in patients with macroadenoma. Pituitary insufficiency,
as a consequence of surgery, was found in 21% of patients with normal pituitary function prior to operation. 相似文献
149.
Objective
The aim of this study was to investigate the possible urinary markers of hormonal activity in patients with non-functioning adrenal incidentalomas. In order to evaluate the endocrine activity of forementioned tumours, urinary steroid metabolite levels were analyzed in samples from patients and controls. Possible blocks in metabolic pathways of the examined hormones were determined by comparing selected urinary steroid metabolite sums and ratios in both groups of interest.Design
Urine samples were collected from 20 patients with non-functioning adrenal incidentalomas and from 25 controls matched in terms of age, sex and BMI. Excretion of 19 major urinary steroid metabolites was analyzed by gas chromatography. The results were subjected to statistical analysis.Results
In patients with adrenal incidentalomas sum of total urinary cortisol metabolites was significantly increased in respect to the control group. We also observed a shift towards tetrahydrocorticosterone, cortisol and etiocholanolone production in patients. No significant differences in production of other urinary steroid metabolites were noted in patients with adrenal incidentalomas in respect to control group.Conclusions
Our data suggests that not only urinary free cortisol but also its metabolite such as tetrahydrocortisol and other steroids including etiocholanolone and corticosterone tetrahydrometabolite might be urinary markers for the endocrine activity of adrenal incidentalomas. Enhanced levels of these urinary steroid metabolites indicate an impairment of 11β-hydroxysteroid dehydrogenase activity and slightly increased activity of 5β-reductase in patients with adrenal incidentalomas. 相似文献150.
Adnan S Balamurugan A Trocha A Bennett MS Ng HL Ali A Brander C Yang OO 《Blood》2006,108(10):3414-3419
HIV-1 Nef and HIV-1-specific cytotoxic T lymphocytes (CTLs) have important and opposing roles in the immunopathogenesis of HIV-1 infection. Nef-mediated down-modulation of HLA class I on infected cells can confer resistance to CTL clearance, but the factors determining the efficiency of this process are unknown. This study examines the impact of Nef on the antiviral activity of several CTL clones recognizing epitopes from early and late HIV-1 proteins, restricted by HLA-A, -B, and -C molecules. CTL-targeting epitopes in early proteins remained susceptible to the effects of Nef, although possibly to a lesser degree than CTL-targeting late protein epitopes, indicating that significant Nef-mediated HLA down-regulation can precede even the presentation of early protein-derived epitopes. However, HLA-C-restricted CTLs were unaffected by Nef, consistent with down-regulation of cell-surface HLA-A and -B but not HLA-C molecules. Thus, CTLs vary dramatically in their susceptibility to Nef interference, suggesting differences in the relative importance of HLA-A- and HLA-B- versus HLA-C-restricted CTLs in vivo. The data thus indicate that HLA-C-restricted CTLs may have an under-appreciated antiviral role in the setting of Nef in vivo and suggest a benefit of promoting HLA-C-restricted CTLs for immunotherapy or vaccine development. 相似文献