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   1862篇
  免费   165篇
  国内免费   59篇
耳鼻咽喉   5篇
儿科学   64篇
妇产科学   28篇
基础医学   276篇
口腔科学   61篇
临床医学   252篇
内科学   499篇
皮肤病学   43篇
神经病学   87篇
特种医学   248篇
外科学   148篇
综合类   56篇
一般理论   1篇
预防医学   98篇
眼科学   15篇
药学   112篇
中国医学   2篇
肿瘤学   91篇
  2022年   8篇
  2021年   21篇
  2020年   14篇
  2019年   15篇
  2018年   33篇
  2017年   7篇
  2016年   18篇
  2015年   26篇
  2014年   27篇
  2013年   52篇
  2012年   38篇
  2011年   53篇
  2010年   38篇
  2009年   48篇
  2008年   55篇
  2007年   103篇
  2006年   49篇
  2005年   56篇
  2004年   65篇
  2003年   72篇
  2002年   52篇
  2001年   64篇
  2000年   58篇
  1999年   49篇
  1998年   64篇
  1997年   45篇
  1996年   72篇
  1995年   54篇
  1994年   55篇
  1993年   53篇
  1992年   35篇
  1991年   41篇
  1990年   50篇
  1989年   54篇
  1988年   57篇
  1987年   64篇
  1986年   58篇
  1985年   49篇
  1984年   32篇
  1983年   25篇
  1982年   24篇
  1981年   37篇
  1980年   31篇
  1979年   19篇
  1978年   16篇
  1977年   26篇
  1976年   18篇
  1975年   16篇
  1974年   7篇
  1971年   11篇
排序方式: 共有2086条查询结果,搜索用时 0 毫秒
51.
Existing models of muscle deconditioning such as bed rest are expensive and time-consuming. We propose a new model utilizing a weighted suit to manipulate muscle strength, power, or endurance relative to body weight. The aims of the study were to determine as to which muscle measures best predict functional task performance and to determine muscle performance thresholds below which task performance is impaired. Twenty subjects performed seven occupational astronaut tasks (supine and upright seat egress and walk, rise from fall, hatch opening, ladder climb, object carry, and construction board activity), while wearing a suit weighted with 0–120 % of body weight. Models of the relationship between muscle function/body weight and task completion time were developed using fractional polynomial regression and verified with pre- and post-flight astronaut performance data. Spline regression was used to identify muscle function thresholds for each task. Upright seat egress and walk was the most difficult task according to the spline regression analysis thresholds. Thresholds normalized to body weight were 17.8 N/kg for leg press isometric force, 17.6 W/kg for leg press power, 78.8 J/kg for leg press work, 5.9 N/kg isometric knee extension and 1.9 Nm/kg isokinetic knee extension torque. Leg press maximal isometric force/body weight was the most reliable measure for modeling performance of ambulatory tasks. Laboratory-based manipulation of relative strength has promise as an analog for spaceflight-induced loss of muscle function. Muscle performance values normalized to body weight can be used to predict occupational task performance and to establish relevant strength thresholds.  相似文献   
52.
53.
Modern population based oral health management requires a complete understanding of the impact of disease in order to provide efficient and effective oral health care and guidance. Periodontitis is an important cause of tooth loss and has been shown to be associated with a number of systemic conditions. The impact of oral conditions and disorders on quality of life has been extensively studied. However, the impact of periodontitis on quality of life has received less attention. This review summarizes the literature on the impact of periodontitis on oral health‐related quality of life (OHRQoL). Relevant publications were identified after searching the MEDLINE and EMBASE electronic databases. Screening of titles and abstracts and data extraction was conducted. Only observational studies were included in this review. Most of the reviewed studies reported a negative impact of periodontitis on OHRQoL. However, the reporting standards varied across studies. Moreover, most of the studies were conducted in developed countries.  相似文献   
54.
55.
56.
BRIDGE 2 (Building the Relationship Between Body Image and Disordered Eating Graph and Explanation): Interventions and Transitions, builds upon the framework presented in the first publication of BRIDGE. BRIDGE 2 moves beyond increasing the understanding of the relationship between body image and eating disorders and encourages a movement into action. First, it suggests the appropriate point of intervention for both parents and teachers. Second, the continuum of health care from promotion to prevention, to early intervention, and to basic and specialized treatment services is positioned on the BRIDGE framework. This added dimension offers a new level of understanding specific to eating disorders by utilizing concepts from mental health promotion and mental illness prevention literature.  相似文献   
57.
58.
Type 2 diabetes, the most common form of diabetes, is characterized by abnormalities in hepatic glucose production, insulin resistance, and a progressive decline in beta-cell function over time. To treat effectively the individual with type 2 diabetes, the provider must have a thorough understanding of the underlying pathophysiology to provide treatment that precisely addresses the metabolic abnormalities. Currently, the provider who cares for subjects with type 2 diabetes can choose an antidiabetic agent from no less than eight pharmacologic classes. These classes include agents that increase insulin secretion, improve insulin action, and delay absorption of carbohydrates. The newer treatments available, specifically incretin therapy, address a previously unmet need in diabetes by modulating glucose supply. The currently available agents can be combined and combination therapy markedly improves glycemic control. This allows the provider to design regimens to specifically address underlying abnormalities. A review of all currently available agents is provided.  相似文献   
59.

INTRODUCTION

No national recording systems for knife injuries exist in the UK. Understanding the true size and nature of the problem of knife injuries is the first stage in reducing the burden of this injury. The aim of this study was to survey every knife injury seen in a single inner city emergency department (ED) over a one-year period.

METHODS

A cross-sectional observational study was performed of all patients attending with a knife injury to the ED of a London major trauma centre in 2011. Demographic characteristics, patterns of injury, morbidity and mortality data were collected.

RESULTS

A total of 938 knife injuries were identified from 127,191 attendances (0.77% of all visits) with a case fatality rate of 0.53%. A quarter (24%) of the major trauma team’s caseload was for knife injuries. Overall, 44% of injuries were selfreported as assaults, 49% as accidents and 8% as deliberate self-harm. The highest age specific incident rate occurred in the 16–24 year age category (263/100,000). Multiple injuries were seen in 19% of cases, of which only 81% were recorded as assaults. The mean length of stay for those admitted to hospital was 3.04 days. Intrathoracic injury was seen in 26% of cases of chest trauma and 24% of abdominal injuries had a second additional chest injury.

CONCLUSIONS

Violent intentional injuries are a significant contributory factor to the workload of the major trauma team at this centre. This paper contributes to a more comprehensive understanding of the nature of these injuries seen in the ED.  相似文献   
60.
Charache  S; Dover  GJ; Moyer  MA; Moore  JW 《Blood》1987,69(1):109-116
Five patients with sickle cell anemia were treated with hydroxyurea (HU), in hopes of augmenting their production of fetal hemoglobin. Laboratory responses in two patients treated for more than 2 years were encouraging and there were suggestions of clinical improvement. Long- term HU therapy should be considered for severely affected adults with sickle cell anemia who are willing to accept what is probably a small risk of carcinogenesis. Preliminary chromosomal analysis and knowledge of the clastogenic properties of HU suggest that conception and pregnancy should be avoided. Pharmacokinetic studies will probably be necessary to adjust individual dosage schedules so that cytotoxicity is avoided. F cell responses can be seen in 2 to 3 weeks if the HU dose is optimal, but establishment of a large number of F cells in the circulation may take a month or longer.  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