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   614篇
  免费   9篇
  国内免费   34篇
儿科学   16篇
妇产科学   1篇
基础医学   51篇
口腔科学   8篇
临床医学   43篇
内科学   73篇
皮肤病学   7篇
神经病学   105篇
特种医学   170篇
外科学   40篇
综合类   19篇
预防医学   79篇
眼科学   11篇
药学   15篇
中国医学   1篇
肿瘤学   18篇
  2023年   4篇
  2022年   5篇
  2021年   8篇
  2020年   5篇
  2019年   1篇
  2018年   12篇
  2017年   9篇
  2016年   11篇
  2015年   17篇
  2014年   15篇
  2013年   14篇
  2012年   31篇
  2011年   29篇
  2010年   25篇
  2009年   41篇
  2008年   34篇
  2007年   41篇
  2006年   34篇
  2005年   31篇
  2004年   16篇
  2003年   9篇
  2002年   17篇
  2001年   24篇
  2000年   11篇
  1999年   21篇
  1998年   26篇
  1997年   33篇
  1996年   20篇
  1995年   11篇
  1994年   8篇
  1993年   12篇
  1992年   5篇
  1991年   1篇
  1990年   6篇
  1989年   13篇
  1988年   18篇
  1987年   7篇
  1986年   8篇
  1985年   4篇
  1984年   1篇
  1983年   2篇
  1982年   2篇
  1981年   5篇
  1979年   2篇
  1978年   1篇
  1977年   3篇
  1976年   1篇
  1975年   3篇
排序方式: 共有657条查询结果,搜索用时 31 毫秒
71.
Cognitive functions show large variation in elderly people and are substantially heritable. Animal studies revealed that dynorphins influence cognition and memory, especially in aged animals. Thus, we tested the effect of four SNPs (rs7272891, rs1997794, rs2235751 and rs910080) and the VNTR promoter polymorphism in the prodynorphin gene (PDYN) on episodic memory and verbal fluency in a large (n = 1619) sample of elderly people (mean age: 80 ± 3.39 years; range 75–90 years) recruited through the German study on ageing, cognition and dementia in primary care patients (AgeCoDe). We found that carriers of the minor alleles of rs1997794 (P < 0.002) and rs910080 (P < 0.005) presented with higher episodic memory scores than homozygote carriers of the major allele. Also, a three marker haplotype including these two SNPs and rs2235751 was associated with better episodic memory scores. Verbal fluency scores were non-significantly better in carriers of these respective alleles. Thus, our results suggest a role of PDYN gene variations in determining memory function also in elderly humans.  相似文献   
72.
Background and purpose Periprosthetic bone loss after uncemented femoral hip revision is a matter of concern. We have used a proximally porous- and hydroxyapatite-coated prosthesis (Bi-Metric) in revision since 1989 and now we report the bone changes. This prosthesis is intended to distribute the forces more evenly and to avoid proximal femoral unloading.Methods 22 patients were unilaterally reoperated because of aseptic loosening. Only patients with a healthy contralateral hip were included. Mean age at revision was 69 (55–80) years. Bone defects were graded by Gustilo-Pasternak and Endo-Klinik classifications. Clinical assessment was performed with Harris hip score. We used radiographs and dual-energy X-ray absorptiometry to evaluate migration, femoral remodeling, and bone mineral density after 72 (30–158) months.Results The mean Harris hip score was 74 (30–100) points at follow-up. Mild thigh discomfort was present in 1 patient and moderate thigh pain in 3 patients. There was no loosening or subsidence. Osteolysis seen at revision had diminished in 19 of the 22 hips at follow-up. We noted a large reduction in bone mineral density. It was most pronounced in Gruen regions 1, 2, 6, and 7.Interpretation Revision with this stem is a reliable procedure; however, we noted a large degree of proximal bone loss that could lead to later mechanical complications or fractures.  相似文献   
73.
Background In persons free of dementia, accelerated cognitive decline might be an indicator of pathological impairment and a potential predictor of future dementia. However, the reliable detection of cognitive decline is a challenging task in some cases. Changes in psychometric test scores do not necessarily result from ‘true’ clinical change and may result from factors like measurement error and regression to the mean. Reliable Change Indices (RCI) facilitate the interpretation of changes in psychometric test scores. However, it is unknown whether RCI predict future dementia in persons who are presently free of dementia. Aim To examine for a widely used screening instrument for cognitive impairment and dementia (SIDAM) whether RCI methods contribute to the prediction of dementia diagnosis in older adults who are presently free of dementia. Methods A sample of 554 elderly individuals aged 75 and over who participated in the Leipzig Longitudinal Study of the Aged (LEILA 75+) and had no diagnosis of dementia at the first two visits. Participants have been tested with the test part of the SIDAM at maximal six visits with 1.5 year intervals. In all participants, RCI for change in SIDAM score (Time 1 to Time 2) have been computed. The main outcome measure was the diagnosis of dementia. Results ROC analyses showed that RCI were significant predictors of future dementia. Participants who deteriorated in SIDAM score –4 points or more had a three-fold increased risk of developing dementia (odds ratio 2.71, CI 1.6 to 4.6). However, RCI were not independent predictors of dementia in multivariate analysis. Conclusion RCI may support the early diagnosis of dementia.  相似文献   
74.
Background The aim of the study was to analyze the physical activity, dietary, drinking, and smoking habits of schizophrenia patients (SP). Methods Data from 194 schizophrenia outpatients collected using sections of the German National Health Interview and Examination Survey were compared with data from the German general population (GP). In addition to univariate data analyses, a multivariate regression analysis was performed. Results Schizophrenia patients have a supper snack more frequently, consume instant meals and calorie-reduced food more frequently, and eat healthy groceries more rarely. Though they drink less alcohol, a greater proportion currently smokes, smoking on average 4 cigarettes more per day. On workdays they spend less time with strenuous activities, and in leisure time a greater proportion is involved in no sports. Regression analysis revealed that schizophrenia by itself or in interaction with demographic variables influences physical activity as well as alcohol, nicotine, and healthy grocery consumption. Health habits were particularly disadvantageously affected by schizophrenia in connection with unemployment. Conclusions Schizophrenia patients are an appropriate target group for public health interventions. They need information about a healthy diet and motivation to prepare their own meals, to quit smoking, and to exercise.  相似文献   
75.
BACKGROUND: We reviewed studies of in-service interventions for caregivers of persons with dementia in nursing homes published between 1990 and 2004. The aim was to obtain an overview of the evaluated interventions and to characterize their methodological quality. METHODS: A thorough literature search was conducted, including searching electronic databases for selected intervention studies and previous reviews. Selected studies were summarized and compared along certain categories, and methodological quality was assessed. RESULTS: A total of 21 studies were identified, mostly published in the United States. Most were of poor methodological quality. Although nearly all reported positive effects, their results must be interpreted cautiously due to methodological weaknesses. Extensive interventions with ongoing support successfully demonstrated sustained implementation of new knowledge. Owing to methodological weaknesses and a lack of follow-up evaluations, little or no evidence existed for the efficacy or, particularly, the transfer of knowledge in simpler interventions when reinforcing and enabling factors were not present. CONCLUSION: On an international and, particularly, on a national level a lack of evaluated in-service training programs for caregivers in homes for people with dementia is apparent. Methodological weakness is common. This study highlights the need for well-defined methodologically improved studies, providing conclusive evidence of the effects of intervention types to help improve the quality of dementia care.  相似文献   
76.

Background  

Street-involved youth contend with an array of health and social challenges, including elevated rates of blood-borne infections and mortality. In addition, there has been growing concern regarding high-risk drug use among street-involved youth, in particular injection drug use. We undertook this study to examine the prevalence of injection drug use and associated risks among street-involved youth in Vancouver, Canada.  相似文献   
77.

Background  

There has emerged growing recognition of the link between housing and health. Since Vancouver, Canada has had increasing concerns with homelessness brought about by urban renewal in the lead-up to the 2010 Winter Olympic Games, we evaluated hepatitis C virus (HCV) incidence among injection drug users (IDU) with and without stable housing.  相似文献   
78.
In 2006, Germany’s sixth national health target entitled “Depressive illnesses – prevention, early diagnosis, sustainable treatment” was developed by an interdisciplinary group of experts. A total of six areas of activity and proposals for action with potential for improvement were defined. Subsequently, a group of experts was entrusted with designing evaluation strategies, defining indicators of progress, and examining the accessibility of data sources for evaluation. For the primary start-up activities set out in the health targets, specific progress indicators were deduced, and routine data available for evaluation were identified. As a next step, the limitations of these data sources were analyzed and necessary improvements described. Relevant indicators of progress for specific areas of activity have been described, the availability and usability of different existing data sources examined, and further supplements or additional specifications with respect to the indicators described. Due to inadequate data sources, additional systematic surveys are required to evaluate the health target and its implementation. Existing German surveys should be extended by questions concerning relevant measures and progress indicators; various progress indicators should be analyzed on a general basis.  相似文献   
79.
80.
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