全文获取类型
收费全文 | 4367篇 |
免费 | 259篇 |
国内免费 | 12篇 |
专业分类
耳鼻咽喉 | 68篇 |
儿科学 | 201篇 |
妇产科学 | 122篇 |
基础医学 | 503篇 |
口腔科学 | 67篇 |
临床医学 | 389篇 |
内科学 | 956篇 |
皮肤病学 | 52篇 |
神经病学 | 215篇 |
特种医学 | 117篇 |
外科学 | 603篇 |
综合类 | 64篇 |
预防医学 | 338篇 |
眼科学 | 249篇 |
药学 | 332篇 |
中国医学 | 22篇 |
肿瘤学 | 340篇 |
出版年
2023年 | 26篇 |
2022年 | 114篇 |
2021年 | 179篇 |
2020年 | 97篇 |
2019年 | 132篇 |
2018年 | 162篇 |
2017年 | 116篇 |
2016年 | 143篇 |
2015年 | 148篇 |
2014年 | 198篇 |
2013年 | 194篇 |
2012年 | 372篇 |
2011年 | 389篇 |
2010年 | 208篇 |
2009年 | 182篇 |
2008年 | 265篇 |
2007年 | 263篇 |
2006年 | 236篇 |
2005年 | 229篇 |
2004年 | 224篇 |
2003年 | 186篇 |
2002年 | 175篇 |
2001年 | 27篇 |
2000年 | 24篇 |
1999年 | 27篇 |
1998年 | 34篇 |
1997年 | 23篇 |
1996年 | 19篇 |
1995年 | 11篇 |
1994年 | 11篇 |
1993年 | 15篇 |
1992年 | 22篇 |
1991年 | 22篇 |
1990年 | 14篇 |
1989年 | 12篇 |
1988年 | 11篇 |
1987年 | 8篇 |
1986年 | 6篇 |
1985年 | 11篇 |
1984年 | 11篇 |
1983年 | 6篇 |
1982年 | 9篇 |
1981年 | 10篇 |
1980年 | 15篇 |
1979年 | 11篇 |
1978年 | 8篇 |
1976年 | 6篇 |
1974年 | 7篇 |
1973年 | 4篇 |
1971年 | 4篇 |
排序方式: 共有4638条查询结果,搜索用时 15 毫秒
1.
Usha Patel Manish Pandey Sadhana Kannan Tanuja A. Samant Poonam Gera Neha Mittal Swapnil Rane Asawari Patil Vanita Noronha Amit Joshi Vijay M. Patil Kumar Prabhash Manoj B. Mahimkar 《British journal of cancer》2020,123(12):1757
Background Anti-EGFR-based therapies have limited success in HNSCC patients. Predictive biomarkers are greatly needed to identify the patients likely to be benefited from these targeted therapies. Here, we present the prognostic and predictive association of biomarkers in HPV-negative locally advanced (LA) HNSCC patients.Methods Treatment-naive tumour tissue samples of 404 patients, a subset of randomised Phase 3 trial comparing cisplatin radiation (CRT) versus nimotuzumab plus cisplatin radiation (NCRT) were analysed to evaluate the expression of HIF1α, EGFR and pEGFR by immunohistochemistry and EGFR gene copy change by FISH. Progression-free survival (PFS), locoregional control (LRC) and overall survival (OS) were estimated by Kaplan–Meier method. Hazard ratios were estimated by Cox proportional hazard models.Results Baseline characteristics of the patients were balanced between two treatment groups (CRT vs NCRT) and were representative of the trial cohort. The median follow-up was of 39.13 months. Low HIF1α was associated with better PFS [HR (95% CI) = 0.62 (0.42–0.93)], LRC [HR (95% CI) = 0.56 (0.37–0.86)] and OS [HR (95% CI) = 0.63 (0.43–0.93)] in the CRT group. Multivariable analysis revealed HIF1α as an independent negative prognostic biomarker. For patients with high HIF1α, NCRT significantly improved the outcomes [PFS:HR (95% CI) = 0.55 (0.37–0.82), LRC:HR (95% CI) = 0.55 (0.36–0.85) and OS:HR (95% CI) = 0.54 (0.36–0.81)] compared to CRT. While in patients with low HIF1α, no difference in the clinical outcomes was observed between treatments. Interaction test suggested a predictive value of HIF1α for OS (P = 0.008).Conclusions High HIF1α expression is a predictor of poor clinical response to CRT in HPV-negative LA-HNSCC patients. These patients with high HIF1α significantly benefited with the addition of nimotuzumab to CRT.Clinical trial registration Registered with the Clinical Trial Registry of India (Trial registration identifier—CTRI/2014/09/004980).Subject terms: Tumour biomarkers, Head and neck cancer, Tumour biomarkers, Head and neck cancer, Predictive markers 相似文献
2.
Understanding why persons with human immunodeficiency virus (HIV) have accelerated atherosclerosis and its sequelae, including coronary artery disease (CAD) and myocardial infarction, is necessary to provide appropriate care to a large and aging population with HIV. In this review, we delineate the diverse pathophysiologies underlying HIV-associated CAD and discuss how these are implicated in the clinical manifestations of CAD among persons with HIV. Several factors contribute to HIV-associated CAD, with chronic inflammation and immune activation likely representing the primary drivers. Increased monocyte activation, inflammation, and hyperlipidemia present in chronic HIV infection also mirror the pathophysiology of plaque rupture. Furthermore, mechanisms central to plaque erosion, such as activation of toll-like receptor 2 and formation of neutrophil extracellular traps, are also abundant in HIV. In addition to inflammation and immune activation in general, persons with HIV have a higher prevalence than uninfected persons of traditional cardiovascular risk factors, including dyslipidemia, hypertension, insulin resistance, and tobacco use. Antiretroviral therapies, although clearly necessary for HIV treatment and survival, have had varied effects on CAD, but newer generation regimens have reduced cardiovascular toxicities. From a clinical standpoint, this mix of risk factors is implicated in earlier CAD among persons with HIV than uninfected persons; whether the distribution and underlying plaque content of CAD for persons with HIV differs considerably from uninfected persons has not been definitively studied. Furthermore, the role of cardiovascular risk estimators in HIV remains unclear, as does the role of traditional and emerging therapies; no trials of CAD therapies powered to detect clinical events have been completed among persons with HIV. 相似文献
3.
4.
5.
Postoperative nomogram for disease-specific survival after an R0 resection for gastric carcinoma. 总被引:8,自引:0,他引:8
Michael W Kattan Martin S Karpeh Madhu Mazumdar Murray F Brennan 《Journal of clinical oncology》2003,21(19):3647-3650
PURPOSE: Few published studies have addressed individual patient risk after R0 resection for gastric cancer. We developed and internally validated a nomogram that combines these factors to predict the probability of 5-year gastric cancer-specific survival on the basis of 1,039 patients treated at a single institution. METHODS: Nomogram predictor variables included age, sex, primary site (distal one-third, middle one-third, gastroesophageal junction, and proximal one-third), Lauren histotype (diffuse, intestinal, mixed), number of positive lymph nodes resected, number of negative lymph nodes resected, and depth of invasion. Death as a result of gastric cancer was the predicted end point. The concordance index was used as an accuracy measure, with bootstrapping to correct for optimistic bias. Calibration plots were constructed. RESULTS: Gastric cancer-specific survival at 5 years was 50%. A nomogram was constructed on the basis of a Cox regression model. The bootstrap-corrected concordance index was 0.80. When compared with the predictive ability of American Joint Committee on Cancer stage, the nomogram discrimination was superior (P <.001). Nomogram calibration appeared to be excellent. CONCLUSION: A nomogram was developed to predict 5-year disease-specific survival after R0 resection for gastric cancer. This tool should be useful for patient counseling, follow-up scheduling, and clinical trial eligibility determination. 相似文献
6.
Rajesh Venkataraman Karthik R. Vaidyanathan Madhu N. Sankar Kotturathu M. Cherian 《Journal of cardiac surgery》2009,24(4):443-445
Abstract Dissection of the pulmonary autograft is an extremely rare complication requiring emergent treatment as there is a chance of rupture and proximal aortic involvement. The autograft dissection can involve the aortic annulus, causing separation of leaflets from the annulus in addition to causing annular dilatation, thereby precluding resuspension of leaflets. The usual treatment in such cases is to perform the Bentall procedure, which involves placing a valved conduit (usually mechanical valve) and thereby necessitating anticoagulation. This report describes a case of successful valve-sparing aortic root replacement following the Ross procedure with dissection of autograft. 相似文献
7.
Usha Chinappen-Horsley Glen M Blake Ignac Fogelman Tim D Spector 《BMC musculoskeletal disorders》2007,8(1):113
Background
Skeletal ratios and bone lengths are widely used in anthropology and forensic pathology and hip axis length is a useful predictor of fracture. The aim of this study was to show that skeletal ratios, such as length of femur to height, could be accurately measured from a DXA (dual energy X-ray absorptiometry) image. 相似文献8.
Prevalence of silent myocardial ischemia in asymptomatic individuals with subclinical atherosclerosis detected by electron beam tomography 总被引:3,自引:0,他引:3
Anand D. Vijay Lim Eric Raval Usha Lipkin David Lahiri Avijit 《Journal of nuclear cardiology》2004,11(4):450-457
BACKGROUND: Electron beam tomography coronary calcium imaging is an evolving technique for the early detection of coronary atherosclerosis, and recent studies have established its prognostic value in asymptomatic individuals. The relationship of coronary artery calcium scores (CAC) to obstructive coronary artery disease (CAD) has been poorly studied but is clinically relevant because it determines which individuals are likely to benefit from revascularization procedures. Hence, we prospectively evaluated the prevalence of myocardial ischemia in asymptomatic patients with cardiovascular risk factors and subclinical atherosclerosis. METHODS AND RESULTS: We studied 864 asymptomatic patients with no previous CAD but with cardiovascular risk factors, referred for electron beam tomography coronary calcium imaging to our institution over an 18-month period. From this group, 220 consecutive patients (85% men; mean age, 61 +/- 9 years; age range, 31-84 years) with moderate to severe atherosclerotic disease (coronary calcium score > or =100 Agatston units) were prospectively evaluated by technetium 99m sestamibi single photon emission computed tomography (SPECT). Patients were followed up (mean follow-up, 14 months) and data regarding their subsequent clinical management recorded. Of the 220 patients, 119 had moderate atherosclerosis (CAC score of 100-400 Agatston units) and 101 had severe atherosclerosis (CAC score > or =400 Agatston units). Abnormal SPECT findings were seen in 18% of patients with moderate atherosclerosis (n = 21) and 45% of patients with severe atherosclerosis (n = 45). Increasing severity of atherosclerosis was related to increasing ischemic burden (summed difference score = 1 +/- 0.2 for CAC score of 100-400 Agatston units and 3.2 +/- 0.5 for CAC score > or =400 Agatston units). In a multivariate linear regression model incorporating risk factors, CAC was the only predictor of silent ischemia. CONCLUSION: In comparison to previously published data, we detected a higher prevalence of silent ischemia even in patients with moderate coronary atherosclerosis (18%). This may reflect the differing risk factor profile of our patient population. When coronary calcium screening is used to preselect asymptomatic patients with cardiovascular risk factors for myocardial perfusion imaging, the optimum coronary calcium score threshold will depend on the population prevalence of risk factors and asymptomatic obstructive CAD. 相似文献
9.
Dorit Naot Usha Bava Brya Matthews Karen E Callon Gregory D Gamble Michael Black Sarah Song Rocco P Pitto Tim Cundy Jill Cornish Ian R Reid 《Journal of bone and mineral research》2007,22(2):298-309
Paget's disease is a focal condition of bone. To study changes in cells within pagetic lesions, we cultured osteoblasts and stromal cells from 22 patients and compared gene expression in these cells to cells from healthy bone. We identified several differentially regulated genes, and we suggest that these changes could lead to the formation of the lesions. INTRODUCTION: Paget's disease is a focal condition of bone of unknown cause. Although it is regarded as primarily an osteoclast disorder, the tight coupling of the activity of osteoclasts and osteoblasts suggests that the osteoblast could play a key role in its pathogenesis. The aim of the study was to identify possible changes in pagetic osteoblasts and stromal cells that might contribute to the development of pagetic lesions. MATERIALS AND METHODS: Candidate genes were identified based on known bone cell regulators, supplemented with microarray analysis. Gene expression was determined by real-time PCR in primary cultures of osteoblasts and bone marrow stromal cells from pagetic patients and control subjects. Concentrations of secreted proteins were determined by ELISA. RESULTS: Dickkopf1 mRNA and protein levels were increased in both pagetic osteoblast and stromal cell cultures, and interleukin (IL)-1 and IL-6 were overexpressed in pagetic osteoblasts. These changes parallel recent findings in myeloma bone disease, which shares some clinical similarities with Paget's disease. Alkaline phosphatase was overexpressed, and bone sialoprotein and osteocalcin were underexpressed in pagetic osteoblasts, consistent with their circulating levels in pagetic patients. It is hypothesized that overexpression of Dickkopf1, IL-1, and IL-6 would result in stimulation of osteoclast proliferation and inhibition of osteoblast growth, leading to the development of the characteristic lytic bone lesions. By stimulating osteoblast differentiation, Dickkopf1 and IL-6 may also promote mineralization, leading to the conversion of lytic lesions to sclerotic. CONCLUSIONS: These findings suggest that dysregulated gene expression in pagetic osteoblasts could cause the changes in bone cell number and function characteristic of Paget's disease. 相似文献
10.