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   19217篇
  免费   1286篇
  国内免费   74篇
耳鼻咽喉   220篇
儿科学   427篇
妇产科学   389篇
基础医学   2667篇
口腔科学   331篇
临床医学   1733篇
内科学   4829篇
皮肤病学   410篇
神经病学   1646篇
特种医学   690篇
外科学   2743篇
综合类   234篇
一般理论   8篇
预防医学   1441篇
眼科学   413篇
药学   1134篇
中国医学   81篇
肿瘤学   1181篇
  2023年   121篇
  2022年   200篇
  2021年   549篇
  2020年   311篇
  2019年   455篇
  2018年   526篇
  2017年   349篇
  2016年   371篇
  2015年   457篇
  2014年   637篇
  2013年   858篇
  2012年   1373篇
  2011年   1383篇
  2010年   795篇
  2009年   680篇
  2008年   1159篇
  2007年   1219篇
  2006年   1206篇
  2005年   1138篇
  2004年   1033篇
  2003年   990篇
  2002年   975篇
  2001年   156篇
  2000年   136篇
  1999年   175篇
  1998年   208篇
  1997年   168篇
  1996年   173篇
  1995年   128篇
  1994年   120篇
  1993年   104篇
  1992年   119篇
  1991年   115篇
  1990年   98篇
  1989年   85篇
  1988年   95篇
  1987年   96篇
  1986年   87篇
  1985年   108篇
  1984年   107篇
  1983年   101篇
  1982年   114篇
  1981年   123篇
  1980年   107篇
  1979年   67篇
  1978年   76篇
  1977年   88篇
  1976年   63篇
  1975年   51篇
  1974年   55篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
951.
BACKGROUND: Trafermin (basic fibroblast growth factor) has been shown to reduce infarct volume in acute ischemic stroke models, and to promote functional recovery and new synapse formation when given to animals with completed cerebral infarction. A previous study in acute stroke patients suggested that trafermin was safe and well tolerated when given over a 3-hour period over a wide dose range. METHODS AND RESULTS: Double-blind, parallel group, placebo-controlled trial of a single 24-hour intravenous infusion of trafermin. Patients having onset of stroke symptoms within 6 h and a baseline score of >/=7 on the NIH Stroke Scale (>/=2 motor) were randomized to receive 5 or 10 mg of trafermin or placebo intravenously infused over 24 h. The primary efficacy outcome was a categorized combination of the Barthel and Rankin scales assessed at 90 days. A total of 286 patients had been enrolled at 55 sites in 11 countries when the sponsor directed that enrollment be stopped because an interim analysis of efficacy data predicted too small a chance of demonstrating a statistically significant benefit after recruitment of the planned 900 patients. The 5-mg group showed a slight but nonsignificant advantage over placebo (OR 1.2, 95% CI 0.72-2.00, p = 0.48); the 10-mg group showed a nonsignificant disadvantage (OR 0.74, 95% CI 0.44-1.22, p = 0.24). Mortality rates at 90 days were 17% in the 5-mg group, 24% in the 10-mg group and 18% in the placebo group. Treatment with trafermin was associated with an increased leukocytosis and a decrease in blood pressure: mean decrease in systolic blood pressure from baseline was 19 mm Hg in the 5-mg group, 22 mm Hg in the 10-mg group and 8 mm Hg in the placebo group. In a post hoc subgroup analysis, patients in the 5-mg group treated more than 5 h after the onset of symptoms showed an apparent advantage over placebo (OR 2.1, 95% CI 1.00-4.41, p = 0.044; after age adjustment: OR 1.9, 95% CI 0.91-4.13, p = 0.08). CONCLUSIONS: With the proper treatment regimen, trafermin can likely be given safely to stroke patients. The 5-mg dose showed a trend toward a treatment advantage. The ideal time window for this agent may exceed 5 h. This may open new avenues for acute stroke therapy, aiming at enhancing recovery mechanisms rather than immediate neuroprotection.  相似文献   
952.
T cell vaccination in multiple sclerosis: results of a preliminary study   总被引:2,自引:0,他引:2  
Myelin basic protein (MBP)-reactive T cells are potentially involved in the pathogenesis of multiple sclerosis (MS), and can be depleted by subcutaneous inoculations with irradiated autologous MBP-reactive T cells (T cell vaccination). This preliminary open label study was undertaken to evaluate whether depletion of MBP-reactive T cells would be clinically beneficial to patients with MS. Fifty-four patients with relapsing-remitting (RR) MS (n=28) or secondary progressive (SP) MS (n=26) were immunized with irradiated autologous MBP-reactive T cells and monitored for changes in rate of relapse, expanded disability scale score (EDSS) and MRI lesion activity over a period of 24 months. Depletion of MBP-reactive T cells correlated with a reduction (40 %) in rate of relapse in RR-MS patients as compared with the pre-treatment rate in the same cohort. However, the reduction in EDSS was minimal in RR-MS patients while the EDSS was slightly increased in SP-MS patients over a period of 24 months. Serial semi-quantitative MRI examinations suggest stabilization in lesion activity as compared with baseline MRI. The findings suggest some potential clinical benefit of T cell vaccination in MS and encourage further investigations to evaluate the treatment efficacy of T cell vaccination in controlled trials. Received: 27 November 2000, Received in revised form: 10 May 2001, Accepted: 11 June 2001  相似文献   
953.
954.
The association of epilepsy, occipital calcifications, and celiac disease has been recognized as a distinct syndrome. The objective of this study was to present the clinical, electrophysiologic, and neuroradiologic features in a series of patients with this syndrome. Thirty-two patients with the constellation of epilepsy, occipital calcifications, and celiac disease were identified in our epilepsy clinic. The mean age was 11 years and the mean length of follow-up was 7.4 years. The 1990 criteria of the European Society of Pediatric Gastroenterology and Nutrition were used to diagnose celiac disease. The Kruskal-Wallis statistics test was employed with a signficance of P < .05. Thirty-one patients had partial seizures, 21 of them with symptoms related to the occipital lobe. In most patients, the epilepsy was controlled or the seizures were sporadic. Three developed severe epilepsy. Occipital calcifications were present in all cases. Computed tomography in 7 patients showed hypodense areas in the white matter around calcifications, which decreased or disappeared after a period of gluten-free diet in 3 patients. A favorable outcome of epilepsy was detected in patients with the earliest dietary therapy. This study presents the largest series of children with this syndrome outside Italy. White-matter hypodensities surrounding calcifications are rarely reported. A prompt diagnosis of celiac disease might improve the evolution of the epilepsy and may improve cognitive status.  相似文献   
955.
The aim of this study was to determine if testosterone and estrogen levels correlate with aggression in older men with dementia. Plasma total and free testosterone and estrogen levels and scores for behavioral disturbances, in particular aggression, were measured in 50 elderly males who had a diagnosis of dementia. Aggression was analyzed separately from agitation. Pearson correlations were calculated to determine the association between testosterone and estrogen and aggression. Linear regression analyses determined the influence of hormone levels on aggression, controlling for age, medical burden, and dementia severity. Free testosterone levels showed significant positive correlations with measures of aggression. Estrogen levels showed significant negative correlations with measures of aggression.  相似文献   
956.
957.
Mammography uptake predictors in older women   总被引:1,自引:0,他引:1  
BACKGROUND: In women aged under 65 years, socio-economic factors and general health behaviours are important predictors of mammography uptake. Little is known about whether these factors are important in older women. OBJECTIVE: To examine a broad range of mammography uptake predictors in women aged 65 and older registered with a London (UK) practice. METHODS: A survey of all female patients aged 65 and over (n = 613) in a south London practice included questions on mammography and cervical screening, general health and functional ability, socio-economic factors, mental health, health behaviours, and attitudes to health. Associations between mammography uptake and other factors were examined using logistic regression. RESULTS: The response rate was 70% (432/613). Increased age was strongly associated with decreased mammography uptake. Additionally, socio-economic factors and general health behaviours (previous cervical smear, drinking alcohol and being a non-smoker) were independently predictive of mammography uptake. Measures of physical and mental health and health attitudes were not independent predictors. Restricting analyses to the oldest women, outside the national screening programme, gave very similar results. CONCLUSIONS: In this sample of older women, socio-economic factors and general health behaviours were more predictive of mammography uptake than measures of physical and mental health or attitudes to health. Knowledge of these predictors is of increasing importance as the screening programme in the UK is extended up to age 70.  相似文献   
958.
The Promoting Healthy Lifestyles: Alternative Models' Effects (PHLAME) study evaluates the efficacy of two intervention strategies for improving nutrition and physical activity practices in fire fighters: a team-centered program and a one-on-one format targeting the individual. PHLAME compares these two behavior change models (the team-based versus the one-on-one approaches) against a usual-care control group. As a group, fire fighters have a concentration of the same harmful behaviors and health risks commonly afflicting the US population. Fire fighters have a unique work structure which is ideal for a team-centered model of behavior change. This strategy, based on Social Learning Theory, focuses on a team of fire fighters who work together on the same shift. If this team-centered model proves successful, it could provide a cost-effective method to impact behavior, and be disseminated among fire bureaus and in other team settings. The one-on-one intervention incorporates the Transtheoretical Model of behavior change, uses Motivational Interviewing for its counseling strategy and could be used in the more typical provider-client clinic setting. Findings from PHLAME will provide information about the process and outcomes of these models' ability to achieve health behavior change.  相似文献   
959.
The purpose of our study was to examine the incidence patterns of 2 major histologic types of esophageal cancer, in selected countries world-wide and to identify components of birth cohort, period and age as determinants of observed time trends using regression modeling. The roles of temporal changes in specification of histology of tumors and of classification of cancers at the gastroesophageal junction as esophageal or gastric in origin were taken into consideration. In all, 56,426 esophageal cancer cases were included. The results indicate that the incidence rate of squamous cell carcinoma of the esophagus has been relatively stable in most of the countries analyzed, although increasing trends were observed in Denmark and the Netherlands (Eindhoven) among men and in Canada, Scotland and Switzerland among women. There was a significant increase in the incidence of esophageal adenocarcinomas in both sexes in the United States (among whites and blacks), Canada and South Australia and in 6 European countries (Scotland, Denmark, Iceland, Finland, Sweden and Norway). In France the increase was limited to men and in Switzerland the increase was observed only in women. Modeling was unable to distinguish which trends were the results of changes in risk between generations (as cohort effects), or changes in all age groups simultaneously (as a period effect).  相似文献   
960.
Adenocarcinoma (AC), squamous cell carcinoma (SCC) and adenosquamous carcinoma (ASC) of the lung are morphologically distinguished in part by cyto-architectural features. However, little is known about the relative expression and distribution of cyto-architectural proteins among AC, SCC and ASC. Initial microarray analysis revealed significant differences in expression of two cyto-architectural genes in AC, SCC and ASC. Desmoplakin (DP) 1 and 2, which link desmosomes to intermediate filaments, was strongly expressed in SCC relative to AC and ASC. Cytokeratin 18 (CK18), an intermediate filament that is commonly linked to desmoplakin, was strongly expressed in AC and ASC relative to SCC. Western blot analysis demonstrated that AC and ASC had abundant CK18 protein, whereas CK18 was weakly detected in SCC. DP 1 and 2 are strongly expressed in SCC and minimally expressed in AC and ASC. However, the ratio of one to the other is the same in SCC and AC, but DP2 is lost in ASC. Microscopic analysis with fluorescence-labeled antibodies for CK18 and DP 1 and 2 revealed abundant membrane localization of DP and minimal perinuclear localization of CK18 in SCC. In contrast, in both AC and ASC, the CK18 protein was diffusely distributed within the cytoplasm, and DP showed both membranous and cytoplasmic localization. In conclusion, the data here shows that AC, SCC and ASC each have specific patterns of DP 1 and 2 and CK18 gene expression, protein content and biodistribution.  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