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   7193篇
  免费   511篇
  国内免费   43篇
耳鼻咽喉   49篇
儿科学   383篇
妇产科学   199篇
基础医学   914篇
口腔科学   151篇
临床医学   1180篇
内科学   1108篇
皮肤病学   112篇
神经病学   550篇
特种医学   105篇
外科学   756篇
综合类   99篇
一般理论   6篇
预防医学   878篇
眼科学   235篇
药学   597篇
中国医学   13篇
肿瘤学   412篇
  2023年   42篇
  2022年   22篇
  2021年   158篇
  2020年   105篇
  2019年   146篇
  2018年   140篇
  2017年   126篇
  2016年   124篇
  2015年   172篇
  2014年   220篇
  2013年   368篇
  2012年   457篇
  2011年   545篇
  2010年   288篇
  2009年   274篇
  2008年   463篇
  2007年   513篇
  2006年   509篇
  2005年   516篇
  2004年   461篇
  2003年   378篇
  2002年   432篇
  2001年   85篇
  2000年   49篇
  1999年   72篇
  1998年   97篇
  1997年   70篇
  1996年   56篇
  1995年   43篇
  1994年   56篇
  1993年   41篇
  1992年   36篇
  1991年   39篇
  1990年   30篇
  1989年   24篇
  1988年   24篇
  1987年   28篇
  1986年   28篇
  1985年   31篇
  1984年   36篇
  1983年   32篇
  1982年   39篇
  1981年   43篇
  1980年   43篇
  1979年   29篇
  1978年   28篇
  1977年   17篇
  1975年   20篇
  1974年   25篇
  1972年   18篇
排序方式: 共有7747条查询结果,搜索用时 31 毫秒
81.
Spinal instrumentation for primary pyogenic infection report of 31 patients   总被引:3,自引:0,他引:3  
The role of spinal instrumentation in the presence of infection is still controversial. Radical debridements of infected vertebrae and disc material and bone grafting usually leaves the spine unstable without some surgical stabilisation. We reviewed 31 cases of primary pyogenic spinal infection treated by radical debridement, bone grafting and posterior (30) or anterior (1) spinal instrumentation. The indication for surgery was the failure of conservative treatment (8), progressive neurological deficit (19) or the lack of diagnosis (3). The clinical, laboratory and radiological parameters were assessed pre and postoperatively. The mean period of follow-up was 3.8 years (1-12 years). The neurological deficit was progressive in 19 patients, following surgery all these patients were improved. The neurological deficit was established in one patient; following surgery, his neurological deficit did not improve. The infection was eradicated in all our patients. The following complications were encountered: (1) three patients developed deep wound infection, which responded to repeated debridement; (2) one death resulted from nosocomial septicaemia, (3) reoperation was carried out on one patient for implant failure and on another for a dislodged anterior bone graft. We conclude that spinal instrumentation may be indicated when after radical debridement of infected vertebrae and disc material and bone grafting the stability of the spine is still compromised. According to the location of the infection and the availability of suitable implants, anterior or posterior instrumentation may be necessary. With appropriate antimicrobial agents, the outcome has been satisfactory in our patients.  相似文献   
82.
Faraj AA  Kumar MS  Ketzer B  Rawes M 《Injury》2000,31(9):746-748
Epiphyseal fractures of the distal radius are common in children but those involving the distal ulna are rare. Distal ulna epiphyseal injuries are usually Salter-Harris type II and are usually reduced closed and held in plaster to produce good results. In this paper we describe a Salter-Harris type IV injury of the distal ulna epiphysis which required open reduction and internal fixation due to soft tissue interposition.  相似文献   
83.
OBJECTIVE: Community-based lifestyle intervention may offer the best means of reducing the global epidemic of childhood obesity and its consequences, yet few successful interventions have been reported. The objective was to determine whether increasing extra-curricular levels of activity could reduce weight gain in children. METHODS: A controlled intervention study was conducted using standardised methods to assess outcomes. Two comparable relatively rural communities in Otago, New Zealand formed intervention and control settings. Height, weight, waist circumference and participation in physical activity (by accelerometry) were measured at baseline and at 1 year in 384 children aged 5 to 12 years representing the majority of children in this age group in intervention and control communities. Community Activity Co-ordinators were employed at each school in the intervention area. Their brief was to widen exposure to activity and engage children not interested in traditional sporting activities by encouraging lifestyle-based activities (e.g. walking) and non-traditional sports (e.g. golf and taekwondo) during extra-curricular time at school, after school and during vacations. Simple dietary advice was offered and the wider community was encouraged to participate. RESULTS: Average accelerometry counts at 1 year were 28% (95% CI: 11 to 47%) higher in intervention compared with control children after adjusting for age, sex, baseline values and school. Intervention children spent less time in sedentary activity (ratio 0.91, p = 0.007) and more time in moderate (1.07, p = 0.001) and moderate/vigorous (1.10, p = 0.01) activity. Adjusted mean BMI Z-score was lower in intervention relative to control children by -0.12 units (95% CI: -0.22 to -0.02). CONCLUSION:. An intervention designed to maximise opportunities for physical activity during extra-curricular time at school and during leisure time through the provision of community-based Activity Co-ordinators significantly increased participation in physical activity and slowed unhealthy weight gain in primary school-aged children.  相似文献   
84.
This paper reviews the literature on the association between exercise and sleep. The epidemiological and experimental evidence for whether or not acute and chronic exercise promote sleep is discussed, as well as moderating factors and agendas for future directions of study. The expectation that exercise will benefit sleep can partly be attributed to traditional hypotheses that sleep serves energy conservation, body restoration or thermoregulatory functions, all of which have guided much of the research in this field. Exercise is a complex activity that can be beneficial to general well-being but may also stress the body. Differences in the exercise protocols studied (e.g. aerobic or anaerobic, intensity, duration) and interactions between individual characteristics (e.g. fitness, age and gender) cloud the current experimental evidence supporting a sleep-enhancing effect of exercise. In addition, the tendency to study changes in small groups of good sleepers may also underestimate the efficacy of exercise for promoting sleep. Athough only moderate effect sizes have been noted, meta-analytical techniques have shown that exercise increased total sleep time and delayed REM sleep onset (10 min), increased slow-wave sleep (SWS) and reduced REM sleep (2-5 min). The sleep-promoting efficacy of exercise in normal and clinical populations has yet to be established empirically.  相似文献   
85.
The use of 24-hour urinary sucrose and fructose as potential biomarkers for sugars consumption was investigated in two studies of 21 healthy participants living in a volunteer suite where dietary intake was known and all specimens collected. The dose-response was assessed in 12 males using a randomized crossover design of three diets containing constant levels of 63, 143, and 264 g of sugars for 10 days each. Both sugars and sucrose intake were significantly correlated with the sum of sucrose and fructose concentration in urine (0.888; P < 0.001). To assess effects with volunteers consuming their habitual varying diets, seven males and six females were fed their usual diet (assessed beforehand from four consecutive self-completed 7-day food diaries) for 30 days under controlled conditions in the volunteer suite. The mean (+/-SD) calculated total sugars intake was 202 +/- 69 g/d, 41% from sucrose. Mean (+/-SD) urinary sucrose and fructose were 36.6 +/- 16.6 and 61.8 +/- 61.3 mg/d, respectively. The sum of sucrose and fructose in urine was significantly correlated with sugars (0.841; P < 0.001) and sucrose intake (0.773; P = 0.002). In the regression, 200 g of sugars intake predicted approximately 100 mg of sucrose and fructose in urine. The correlation between individual means of randomized 16 days of sugars intake and 8 days of sugars excretion data (as used in validation studies) remained as high as that obtained with the means of 30-day measurements and the regression estimates were very similar. Twenty-four-hour urinary sucrose and fructose could be grouped into a new category of biomarkers, predictive biomarkers, that can be used in studies determining the structure of dietary measurement error in free living individuals and to relate sugars intake to disease risk.  相似文献   
86.
Dextroamphetamine administration in healthy controls produces a range of subjective and physiological effects, which have been likened to those occurring during mania. However, it is uncertain if these can be attenuated by lithium since conflicting results have been reported. To date there have been no previous studies examining the effects of valproate on dextroamphetamine-induced mood and physiological changes. The current study was a double-blind, placebo-controlled, study in which volunteers received either 1000 mg sodium valproate (n = 12), 900 mg lithium (n = 9), or placebo (n = 12) pre-treatment for 14 days. Subjective and physiological measures were then obtained prior to administration of a 25 mg dose of dextroamphetamine, and at two time points after administration. Differences in the response to dextroamphetamine were assessed between the three treatment groups. The results of this study show that pre-treatment with lithium only significantly attenuated dextroamphetamine-induced change in happiness, while valproate pre-treatment significantly attenuated the effects of dextroamphetamine on happiness, energy, alertness and on the diastolic blood pressure. These results suggest that lithium and valproate do not have the same mechanism of action on dextroamphetamine-induced changes, and this finding may relate to differences in their mechanism of action in mood disorders.  相似文献   
87.
88.

The effect of periodontal treatment on clinical, microbiological and serological parameters of patients with rheumatoid arthritis (RA) are scarce and controversial. The aim of this study was to investigate the influence of non-surgical periodontal treatment on clinical periodontal status, subgingival bacterial levels of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola and RA activity through a controlled clinical trial on individuals with RA and periodontitis (PE). From a convenience sample, 107 individuals were considered eligible and consecutively allocated in four groups: (1) individuals without PE and RA (− PE-RA, n = 30); (2) individuals without PE and with RA (− PE + RA, n = 23); (3) individuals with PE and RA (+ PE + RA, n = 24); and (4) individuals with PE and without RA (+ PE-RA, n = 30). Full-mouth periodontal clinical examinations, microbiological analysis and Disease Activity Score (DAS-28) evaluations were performed at baseline (T1) and 45 days after non-surgical periodontal treatment (T2). At T1, individuals + PE + RA showed greater severity of PE than + PE-RA individuals. At T2, significant reductions were observed in all periodontal clinical parameters in both groups (p < 0.001) with a significant reduction in DAS-28 in + PE + RA (p = 0.011). Individuals + PE-RA and + PE-RA showed significant reductions for all bacteria (p < 0.001). Additionally, P. gingivalis demonstrated an expressively significant reduction in + PE + RA (p < 0.001). Non-surgical periodontal treatment was effective on improving the clinical periodontal condition, improving the RA clinical status and reducing the presence of periodontal pathogens. Brazilian Registry of Clinical Trials (ReBEC) protocol #RBR-8g2bc8 (https://www.ensaiosclinicos.gov.br/rg/RBR-8g2bc8/).

  相似文献   
89.
90.
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