首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   677篇
  免费   51篇
  国内免费   6篇
耳鼻咽喉   3篇
儿科学   7篇
妇产科学   8篇
基础医学   65篇
口腔科学   4篇
临床医学   40篇
内科学   215篇
皮肤病学   15篇
神经病学   40篇
特种医学   55篇
外科学   128篇
综合类   6篇
预防医学   51篇
眼科学   3篇
药学   30篇
肿瘤学   64篇
  2023年   4篇
  2022年   8篇
  2021年   13篇
  2020年   12篇
  2019年   13篇
  2018年   24篇
  2017年   19篇
  2016年   27篇
  2015年   18篇
  2014年   23篇
  2013年   36篇
  2012年   54篇
  2011年   66篇
  2010年   23篇
  2009年   28篇
  2008年   42篇
  2007年   44篇
  2006年   51篇
  2005年   39篇
  2004年   33篇
  2003年   40篇
  2002年   19篇
  2001年   5篇
  2000年   9篇
  1999年   6篇
  1998年   2篇
  1997年   5篇
  1996年   2篇
  1993年   2篇
  1992年   7篇
  1991年   6篇
  1990年   2篇
  1989年   2篇
  1988年   6篇
  1987年   3篇
  1985年   7篇
  1982年   1篇
  1981年   3篇
  1980年   2篇
  1979年   4篇
  1978年   2篇
  1977年   2篇
  1976年   3篇
  1974年   2篇
  1973年   1篇
  1972年   3篇
  1971年   5篇
  1969年   1篇
  1968年   1篇
  1967年   2篇
排序方式: 共有734条查询结果,搜索用时 22 毫秒
61.
OBJECTIVE: Previously studies have associated visuospatial tasks, particularly 'clock-drawing', with mortality. We sought to determine whether clock-drawing also mediates the association between depressive symptoms and mortality. PARTICIPANTS: Non-institutionalized Hispanic and non-Hispanic White elderly volunteers. MEASUREMENTS: Survival curves were generated as a function of baseline depressive symptom ratings. Significant models were adjusted for CLOX performance. CLOX is divided into CLOX1, a measure of executive control, and CLOX2, a measure of visuospatial skills. DESIGN: Retrospective analysis of three longitudinal cohorts. RESULTS: CLOX2 and depressive symptoms were both associated with mortality in unadjusted models. CLOX2 predicted survival independently of CLOX1 in all three cohorts. CLOX2 also attenuated, and/or mediated the association between depressive symptoms and mortality. These results withstood adjustment for age and education in all three cohorts. CONCLUSION: Regardless of the sample examined, or the measure of depressive symptoms applied, the association between depressive symptoms and mortality appears to be at least partially mediated by visuospatial skills. This finding supports our hypothesis that right hemisphere structural brain disease, particularly that involving the insula, may mediate depression's effects on mortality.  相似文献   
62.
63.
OBJECTIVE: Mechanical signals are key determinants in tissue morphogenesis, maintenance, and restoration strategies in regenerative medicine, although molecular mechanisms of mechanotransduction remain to be elucidated. This study was undertaken to investigate the mechanotransduction process of expression of superficial zone protein (SZP), a critical joint lubricant. METHODS: Regional expression of SZP was first quantified in cartilage obtained from the femoral condyles of immature bovines, using immunoblotting, and visualized by immunohistochemistry. Contact pressure mapping in whole joints was accomplished using pressure-sensitive film and a load application system for joint testing. Friction measurements on cartilage plugs were acquired under boundary lubrication conditions using a pin-on-disk tribometer modified for reciprocating sliding. Direct mechanical stimulation by shear loading of articular cartilage explants was performed with and without inhibition of transforming growth factor beta (TGFbeta) signaling, and SZP content in media was quantified by enzyme-linked immunosorbent assay. RESULTS: An unexpected pattern of SZP localization in knee cartilage was initially identified, with anterior regions exhibiting high levels of SZP expression. Regional SZP patterns were regulated by mechanical signals and correlated with tribological behavior. Direct relationships were demonstrated between high levels of SZP expression, maximum contact pressures, and low friction coefficients. Levels of SZP expression and accumulation were increased by applying shear stress, depending on location within the knee, and were decreased to control levels with the use of a specific inhibitor of TGFbeta receptor type I kinase and subsequent phospho-Smad2/3 activity. CONCLUSION: These findings indicate a new role for TGFbeta signaling in the mechanism of cellular mechanotransduction that is especially significant for joint lubrication.  相似文献   
64.
Objective The purpose of this population-based case control study was to investigate a possible association between occupational exposure to low frequency magnetic fields and the risk of low grade glioma (LGG) and high grade glioma (HGG). Methods The study population consisted of 414 histologically confirmed cases of glioma (LGG = 110, HGG = 304), first diagnosed between July 1987 and December 1991, and 421 controls from Melbourne, Australia, matched by age, sex and postcode of residence. A detailed occupational history was obtained for each subject. Exposure to low frequency magnetic fields was estimated using three different methods: self-report, expert hygienist review and a job exposure matrix (JEM). Results Elevated but statistically non-significant risk estimates were found for all glioma and HGG when exposure was assessed by the expert hygienist. The odds ratios (OR) for the highest exposed group of workers when assessed by the expert hygienist were 1.4 (95% confidence interval, CI: 0.85–2.27) and 1.51 (95% CI: 0.90–2.53) for all glioma and HGG, respectively. There were inverse associations for the self-reported and JEM exposures for both LGG and HGG but these may reflect limitations in these exposure assessment methods. Conclusions Our results do not support a role for occupational exposure to low frequency magnetic fields in the development of either LGG or HGG. This work was performed at the Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, VIC, Australia  相似文献   
65.
OBJECTIVES: To define ultrasonographic patterns reflecting different states of Peyronie's disease (PD) and to use them to evaluate the natural history of the disease. MATERIAL AND METHODS: Diagnosis of PD was based on medical and sexual history, physical examination, intracavernosal injection test, and penile ultrasonography. Patients with penile fracture history were excluded from the study. Three groups were formed according to ultrasonographic patterns: solitary hyperechoic lesion without acoustic shadow (group A), moderately hyperechoic multiple scattered calcified lesions with acoustic shadows (group B), dense calcified hyperechoic plaque with acoustic shadow (group C). All patients entered a watchful waiting protocol for 1 yr followed by a new penile ultrasonography. RESULTS: Ninety-five 95 patients with PD were included in the study (mean age, 57.2+/-9.1 yr; mean duration of disease, 12.9+/-8.9 mo). Risk factors associated with cardiovascular disease were present in 79 of 95 patients (83.16%). Eleven (11.6%), 35 (36.8%), and 49 (51.6%) patients were classified into groups A, B and C, respectively. At the end of the study, in group A, reduction of fibrotic lesions and curvature angle was noticed in 9 of 11 (81.8%) patients, whereas plaque formation was noticed in 2 of 11 (18.2%) patients. In group B, plaque and curvature reduction was noticed in 15 of 35 (42.9%) and 12 of 35 (34.3%) respectively, whereas in the rest a dense calcified plaque was noticed. In group C, no ultrasonographic evidence of improvement was noticed; curvature angle was reduced in 4 of 49 (8.2%), owing to the extension of the plaque circumferentially. Significant hemodynamic changes were noticed at the two time points tested (30.53% diagnosed with vascular disease at baseline vs. 46.32% at the end of the study, p=0.03). CONCLUSIONS: Corporal ultrasonography in patients with PD allows objective evaluation and classification of disease. The density of echogenic areas and presence of acoustic shadows are predictors of disease stability.  相似文献   
66.
67.
The effects of disability on an aging population's health and welfare are an important issue in gerontological research. The rapid growth of the elderly population and increases in longevity have led to an ongoing debate about whether longer lives can be matched by longer active lives that are free from disability. After a detailed review of current disability literature, the authors discuss the impact of disability in the elderly, defining disability and reviewing three classes of disability—physical, mental, and social. Both subjective and objective disability measures are described, and disability trends and prevalence rates are reviewed and compared cross culturally, by gender, by age, and over time. The path from chronic disease to disability is described and the consequences of living with disability are discussed in terms of family burdens and the increased need for medical care.  相似文献   
68.
69.
Medical doctors, who practice interventional cardiology, receive a noticeable radiation dose. In this study, we measured the radiation dose to 9 cardiologists during 144 procedures (72 coronary angiographies and 70 percutaneus translumined coronary angioplasties) in two Greek hospitals. Absorbed doses were measured with TLD placed underneath and over the lead apron at the thyroid protective collar. Based on these measurements, the effective dose was calculated using the Niklason method. In addition, dose area product (DAP) was registered. The effective doses, E, were normalised to the total DAP measured in each procedure, producing the E/DAP index. The mean effective dose values were found to be in the range of 1.2-2.7 microSv while the mean E/DAP values are in the range of 0.010-0.035 microSv/Gycm2. The dependence of dose to the X-ray equipment, the exposure parameters and the technique of the cardiologist were examined. Taking under consideration the laboratories' annual workload, the maximum annual dose was estimated to be 1.9 and 2.8 mSv in the two hospitals.  相似文献   
70.
AIMS: In this study, we investigated the combined effect of increased high-sensitivity C-reactive protein (hs-C-reactive protein) and hypoadiponectinaemia on aortic stiffness in essential hypertensive subjects. METHODS AND RESULTS: A total of 267 untreated patients with stage I-II essential hypertension underwent ambulatory BP and carotid-femoral pulse wave velocity (c-f PWV) evaluation. The distributions of hs-C-reactive protein and adiponectin were split by the median (1.3 mg/L and 7.8 microg/mL, respectively) and accordingly subjects were stratified into those with high and low values. Patients with high (n = 134) compared with those with low hs-C-reactive protein (n = 133) values exhibited greater c-f PWV levels (by 0.8 m/s, P < 0.0001), whereas patients with low (n = 133) compared with those with high (n = 134) adiponectin levels had higher c-f PWV (by 0.9 m/s, P < 0.0001). Stepwise regression analysis revealed that age, 24 h systolic BP, hs-C-reactive protein and adiponectin were independent predictors of arterial stiffness. In patients with low hs-C-reactive protein, hypoadiponectinaemia (n = 46) compared with high adiponectin (n = 87) was accompanied by increased c-f PWV (by 0.8 m/s, P < 0.0001). Similarly in patients with high hs-C-reactive protein, hypoadiponectinaemia (n = 84) compared with high adiponectin (n = 50) was related to heightened c-f PWV (by 0.7 m/s, P = 0.008). CONCLUSION: In essential hypertension, pronounced low-grade inflammation in conjunction with hypoadiponectinaemia exerts an additive detrimental effect on aortic stiffness, accelerating the vascular ageing process.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号