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   1124篇
  免费   57篇
  国内免费   7篇
耳鼻咽喉   18篇
儿科学   34篇
妇产科学   21篇
基础医学   137篇
口腔科学   102篇
临床医学   71篇
内科学   235篇
皮肤病学   60篇
神经病学   53篇
特种医学   77篇
外科学   80篇
综合类   26篇
预防医学   136篇
眼科学   26篇
药学   83篇
中国医学   4篇
肿瘤学   25篇
  2023年   6篇
  2022年   22篇
  2021年   28篇
  2020年   23篇
  2019年   30篇
  2018年   36篇
  2017年   18篇
  2016年   38篇
  2015年   45篇
  2014年   48篇
  2013年   60篇
  2012年   89篇
  2011年   109篇
  2010年   59篇
  2009年   33篇
  2008年   67篇
  2007年   58篇
  2006年   50篇
  2005年   44篇
  2004年   30篇
  2003年   21篇
  2002年   19篇
  2001年   14篇
  2000年   5篇
  1999年   13篇
  1998年   22篇
  1997年   24篇
  1996年   16篇
  1995年   11篇
  1994年   7篇
  1993年   9篇
  1992年   4篇
  1991年   3篇
  1990年   9篇
  1989年   9篇
  1988年   9篇
  1987年   7篇
  1986年   7篇
  1985年   19篇
  1984年   9篇
  1983年   6篇
  1982年   7篇
  1981年   9篇
  1980年   7篇
  1978年   4篇
  1977年   3篇
  1974年   3篇
  1973年   3篇
  1970年   2篇
  1966年   2篇
排序方式: 共有1188条查询结果,搜索用时 15 毫秒
61.
62.
Emergency contraception was proven effective nearly 30 years ago yet remains greatly under-utilised. In the Latin American and Caribbean region, it would serve the goals of reducing unwanted pregnancy, unsafe abortion and related morbidity, and as a back-up to condom use and a bridge to longer-term contraceptive methods if made more widely known and available. The International Planned Parenthood Federation Western Hemisphere Region has developed a model for the integration of emergency contraception into sexual and reproductive health care services. This model is being tested in a two-year project with national affiliates in Brazil, Chile, Colombia, the Dominican Republic and Venezuela, and will contribute to the work of the Latin American Consortium for Emergency Contraception. Case studies of Brazil and Colombia describe how health sector reforms, e.g. decentralisation and managed competition among health insurers and service providers, have influenced promotion strategies. The experience of Profamilia Colombia with registration of a dedicated product and providing emergency contraception within its national network of clinics, with a focus on staff training and work with young people, is described. In Brazil, BEMFAM's study of different modalities for offering emergency contraception, e.g. through contractual agreements with municipalities and its own clinics, is highlighted.  相似文献   
63.
OBJECTIVES: Current knowledge of the cardiac manifestations of rheumatoid arthritis (RA) stems only from clinical and transthoracic echocardiography (TTE) studies. To determine the incidence and type of heart lesions in RA, we coupled TTE with transesophageal echocardiography (TEE), which is more sensitive and more accurate. METHODS: Thirty unselected RA patients (26 women and 4 men aged 27 to 84 years, with a mean age of 57.8+/-15.1 years) free of known progressive heart disease underwent a chest radiograph, an electrocardiogram, laboratory tests, and TTE coupled with TEE. Results were compared with those in age- and sex-matched patients who were free of rheumatic disease and who underwent TEE to investigate a neurologic or cardiologic disorder. RESULTS: Mitral regurgitation (MR) was evidenced in 24 cases (80%). Among the controls, only 11 (37%) had MR (P < 0.001). Aortic regurgitation was found in 10 cases (33%), versus 7 controls (not significant-NS). Seven cases (23%) versus only 2 controls (7%) had tricuspid valve abnormalities (NS). Pericarditis was found in 4 cases (13%) and in none of the controls. Eleven cases had evidence of cardiomyopathy (37%) and 12 (40%) had atheroma of the aorta, this last being missed by TTE in 10 patients. Echo-generating nodules were seen on a mitral valve in 2 cases and on an aortic valve in 1. We found no correlations linking cardiac lesions to clinical or laboratory features of RA. CONCLUSION: Our study demonstrated that cardiac involvement, particularly of the mitral valve, is extremely common in RA patients.  相似文献   
64.
BACKGROUND: Malaria represents one of the most important infectious disease threats to deployed military forces; most personnel from developed countries are nonimmune personnel and are at high risk of infection and clinical malaria. This is especially true for forces deployed to highly-endemic areas in Africa and Southeast Asia where drug-resistant malaria is common. METHODS: We conducted an outbreak investigation of malaria cases in Angola where a total of 439 nonimmune Brazilian troops were deployed for a 6-month period in 1995-1996. A post-travel medical evaluation was also performed on 338 (77%) of the 439 soldiers upon return to Brazil. Questionnaire, medical record, thick/thin smear, and serum anti-Plasmodium falciparum antibody titer (by IFA) data were obtained. Peak serum mefloquine (M) and methylmefloquine (MM) metabolite levels were measured in a subsample of 66 soldiers (42 cases, 24 nonmalaria controls) who were taking weekly mefloquine prophylaxis (250 mg). RESULTS: Seventy-eight cases of malaria occurred among the 439 personnel initially interviewed in Angola (attack rate = 18%). Four soldiers were hospitalized, and 3 subsequently died of cerebral malaria. Upon return to Brazil, 63 (19%) of 338 soldiers evaluated were documented to have had clinical symptoms and a diagnosis of malaria while in Angola. In addition, 37 (11%) asymptomatically infected individuals were detected upon return (< 1% parasitemia). Elevated, post-travel anti-P. falciparum IFA titers (> or = 1:64) were seen in 101 (35%) of 292 soldiers tested, and was associated with a prior history of malaria in-country (OR = 3.67, 95% CI 1.98-6.82, p <.001). Noncompliance with weekly mefloquine prophylaxis (250 mg) was associated with a malaria diagnosis in Angola (OR = 3.75, 95% CI 0.97-17.41, p =.03) but not with recent P. falciparum infection (by IFA titer). Mean peak levels (and ratios) of serum M and MM were also found to be lower in those who gave a history of malaria while in Angola. CONCLUSIONS: Malaria was a significant cause of morbidity among Brazilian Army military personnel deployed to Angola. Mefloquine prophylaxis appeared to protect soldiers from clinical, but not subclinical, P. falciparum infections. Mefloquine noncompliance and an erratic chemoprophylaxis prevention policy contributed to this large outbreak in nonimmune personnel. This report highlights the pressing need for development of newer, more efficacious and practical, prophylactic drug regimens that will reduce the malaria threat to military forces and travelers.  相似文献   
65.
急性淋巴细胞白血病(上)   总被引:2,自引:0,他引:2  
急性淋巴细胞白血病是淋巴前体细胞异常引起的恶性疾病,儿童与成人均可能发生。儿童发病高峰2~5岁。有效治疗的稳步进展使本病在儿童中的治愈率80%以上,同时为新的治疗方案提供了良机,新方案将保留我们在白血病无病生存病例中获得的治疗经验,同时减轻当前强化治疗方案中的毒副作用。  相似文献   
66.

Objective

this study aimed to determine the incidence of nosocomial infections, the risk factors and the impact of these infections on mortality among patients undergoing to cardiac surgery.

Methods

Retrospective cohort study of 2060 consecutive patients from 2006 to 2012 at the Santa Casa de Misericórdia de Marília.

Results

351 nosocomial infections were diagnosed (17%), 227 non-surgical infections and 124 surgical wound infections. Major infections were mediastinitis (2.0%), urinary tract infection (2.8%), pneumonia (2.3%), and bloodstream infection (1.7%). The in-hospital mortality was 6.4%. Independent variables associated with non-surgical infections were age > 60 years (OR 1.59, 95% CI 1.09 to 2.31), ICU stay > 2 days (OR 5, 49, 95% CI 2.98 to 10, 09), mechanical ventilation > 2 days (OR11, 93, 95% CI 6.1 to 23.08), use of urinary catheter > 3 days (OR 4.85 95% CI 2.95 -7.99). Non-surgical nosocomial infections were more frequent in patients with surgical wound infection (32.3% versus 7.2%, OR 6.1, 95% CI 4.03 to 9.24). Independent variables associated with mortality were age greater than 60 years (OR 2.0; 95% CI 1.4 to3.0), use of vasoactive drugs (OR 3.4, 95% CI 1.9 to 6, 0), insulin use (OR 1.8; 95% CI 1.2 to 2.8), surgical reintervention (OR 4.4; 95% CI 2.1 to 9.0) pneumonia (OR 4.3; 95% CI 2.1 to 8.9) and bloodstream infection (OR = 4.7, 95% CI 2.0 to 11.2).

Conclusion

Non-surgical hospital infections are common in patients undergoing cardiac surgery; they increase the chance of surgical wound infection and mortality.  相似文献   
67.
68.

Purpose

It has been suggested that subjective measures of oral health are influenced by both individual and contextual characteristics. This study assessed the relationship between neighborhood and individual social networks and child oral health-related quality of life (COHRQoL).

Methods

This study followed a cross-sectional design using a multistage sample of 478 children aged 1–5 years old. Caregivers completed the Brazilian version of the Early Childhood Oral Health Impact Scale (ECOHIS) and answered questions related to socioeconomic status and social network. The dental examination provided information on the prevalence of dental caries, dental trauma, and occlusion. Contextual social determinants included the presence of cultural community centers and of workers’ association in the neighborhood. Data analysis considered the total ECOHIS scores as the outcome and neighborhood/individual social networks as the independent variables. A multilevel Poisson regression model was used to investigate the association among individual and contextual characteristics and COHRQoL.

Results

Total ECOHIS scores ranged from 0 to 41 (possible range 0–52). The mean ECOHIS score was low (mean = 1.8, SD = 3.9), and the functional domain presented the highest mean impact on COHRQoL (mean = 0.5, SD = 1.4). Following adjusted analysis, low household income, visiting a neighbor less than once a month, the presence of anterior open bite, dental trauma, and dental caries were identified as individual determinants of negative impact on a child’s quality of life. These variables remained associated with the outcome even after adding the contextual-level variables in the model. At the contextual level, the presence of community cultural centers was associated with overall mean ECOHIS score; higher impacts on COHRQoL were observed in those living in neighborhoods without cultural community centers.

Conclusion

There is a significant association between individual and contextual social determinants and COHRQoL; unfavorable social conditions and poor socioeconomic status have a negative impact on caregiver reports of children’s oral health-related quality of life.  相似文献   
69.
In this 2 × 2 factorial, outcome-assessor blinded, feasibility randomised trial we explored the effect of a non-pharmaceutical multi-component intervention on periodontal health and metabolic and inflammatory profiles among pregnant women with periodontitis receiving prenatal care in a Brazilian public health centre. 69 pregnant women (gestational age ≤20 weeks, T0) were randomly allocated into four groups: (1) fortified sachet (vitamin D and calcium) and powdered milk plus periodontal therapy during pregnancy (early PT) (n = 17); (2) placebo sachet and powdered milk plus early PT (n = 15); (3) fortified sachet and powdered milk plus late PT (after delivery) (n = 19); (4) placebo sachet and powdered milk plus late PT (n = 18). Third trimester (T1) and 6–8 weeks postpartum (T2) exploratory outcomes included periodontal health (% sites with bleeding on probing (BOP)), glucose, insulin, C-Reactive Protein, serum calcium and vitamin D. The mean BOP was significantly reduced in the early PT groups, while BOP worsened in the late PT groups. No significant effect of fortification on BOP was observed. Changes in glucose levels and variation on birthweight did not differ among groups This feasibility trial provides preliminary evidence for estimating the minimum clinically important differences for selected maternal outcomes. A large-scale trial to evaluate the interventions’ clinical benefits and cost-effectiveness is warranted.  相似文献   
70.
The effects of prenatal exposure to dichlorvos (DDVP), an organophosphate (OP) pesticide, on pups' physical and neurobehavioral developments were investigated. Forty pregnant rats were treated by gavage with 8.0 mg/kg DDVP or its vehicle (1 ml/kg) from the 6th to the 15th day of pregnancy. At birth, pups were weighed, the litters culled to eight animals (four male and four female), and then observed for physical (pinna detachment, incisor eruption, eye opening, testes descent, and vaginal opening) and neurobehavioral developments (palmar grasp, surface righting, negative geotaxis, and open-field behaviors). As adults, open-field, apomorphine-induced stereotypy, and passive avoidance behaviors were also assessed. Results showed no differences between the body weight of DDVP and control-treated groups. No differences were observed on the measures of physical and neurobehavioral development. Locomotor activity of male pups at 21 days of age was decreased by DDVP exposure. Adult experimental offspring showed a decreased locomotor frequency and an increased immobility duration on open-field behavior in relation to control animals; the apomorphine-induced stereotyped behavior was decreased by the pesticide exposure as well as performance on the passive avoidance task. These data suggest that prenatal DDVP exposure was able to decrease offspring motor function (adolescence and adults) and conditioned response learning, probably by interference with the cholinergic-dopaminergic balance of activity involved with the control of motor function as well as the cholinergic system that modulates learning 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