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   162篇
  免费   10篇
儿科学   5篇
妇产科学   1篇
基础医学   15篇
临床医学   32篇
内科学   10篇
神经病学   53篇
外科学   10篇
预防医学   20篇
眼科学   1篇
药学   11篇
肿瘤学   14篇
  2023年   1篇
  2022年   1篇
  2021年   6篇
  2020年   1篇
  2019年   6篇
  2018年   3篇
  2017年   2篇
  2016年   3篇
  2015年   4篇
  2014年   4篇
  2013年   10篇
  2012年   10篇
  2011年   15篇
  2010年   5篇
  2009年   9篇
  2008年   11篇
  2007年   20篇
  2006年   15篇
  2005年   12篇
  2004年   11篇
  2003年   7篇
  2002年   7篇
  1998年   3篇
  1997年   1篇
  1996年   2篇
  1995年   1篇
  1993年   1篇
  1988年   1篇
排序方式: 共有172条查询结果,搜索用时 15 毫秒
1.
2.
Objectives. This study examined to what extent the higher mortality in the United States compared to many European countries is explained by larger social disparities within the United States. We estimated the expected US mortality if educational disparities in the United States were similar to those in 7 European countries.Methods. Poisson models were used to quantify the association between education and mortality for men and women aged 30 to 74 years in the United States, Belgium, Denmark, Finland, France, Norway, Sweden, and Switzerland for the period 1989 to 2003. US data came from the National Health Interview Survey linked to the National Death Index and the European data came from censuses linked to national mortality registries.Results. If people in the United States had the same distribution of education as their European counterparts, the US mortality disadvantage would be larger. However, if educational disparities in mortality within the United States equaled those within Europe, mortality differences between the United States and Europe would be reduced by 20% to 100%.Conclusions. Larger educational disparities in mortality in the United States than in Europe partly explain why US adults have higher mortality than their European counterparts. Policies to reduce mortality among the lower educated will be necessary to bridge the mortality gap between the United States and European countries.The United States has lower life expectancy at birth than most Western European countries. In 2009, life expectancy in the United States was 76 years for men and 81 years for women, between 2 and 4 years less than in several European countries.1 The disadvantage is greater for women than for men and originated in the 1980s.2 The US health disadvantage is found not only for life expectancy, but also for self-reported health measures,3,4 biomarkers,3 and many specific causes of death5,6 across the entire life course.3–5,7A recent report by the National Research Council suggests that smoking and obesity explain an important part of the US mortality disadvantage.2,8,9 However, an approach that solely emphasizes behavioral differences is impoverished by ignoring the role of socioeconomic and environmental determinants.10 A substantial body of research suggests that most behavioral risk factors are socially patterned; lower education or income are associated with a higher prevalence of smoking, excessive alcohol consumption, obesity, and poor dietary patterns.11–19 In addition, European countries and the United States differ in many aspects of the physical and social environment that can affect population health and that are in turn socially patterned within each country. For example, the socioeconomic distribution of access to healthy food differs between countries.20 Social environmental factors related to safety, violence, social connections, social participation, social cohesion, social capital, and collective efficacy have also been shown to influence health and in turn differ between countries and socioeconomic groups.21 Indeed, differences in mortality between the United States and Europe are larger among those with a lower educational level,6 suggesting that larger educational disparities in mortality, which partly coincide with differences in behavior, partly explain why Americans have higher mortality than Europeans.The United States is characterized by relatively higher levels of income inequalities,22 residential and racial segregation,23–25 and financial barriers to health care access2,26 than any European country. Social protection policies and benefits are also less comprehensive in the United States than in Europe, including policies on early education and childcare programs,27 access to high-quality education,28 employment protection and support programs,29,30 and housing29,31 and income transfer programs.31,32 A plausible hypothesis is that the more unequal distribution of resources and less comprehensive policies contribute to the more unfavorable risk factor profile and poorer health of lower-educated Americans as compared with corresponding Europeans.4,33,34 A follow-up report by the National Research Council and the Institute of Medicine published in 2013 concluded that there is a lack of evidence on how these factors explain the US health disadvantage.21 The aim of this article is to assess to what extent larger educational disparities in mortality explain why Americans have higher mortality than Europeans.  相似文献   
3.
4.

Background

To investigate the association of lung cancer with occupational exposure to textile dust and specifically to cotton dust in the population‐based case‐control study ICARE.

Methods

Lifelong occupational history of 2926 cases and 3555 controls was collected using standardized questionnaires, with specific questions for textile dust exposure. Odds ratios (ORs) and 95% confidence intervals (CI) were estimated using unconditional logistic regression models controlling for confounding factors including smoking and asbestos exposure.

Results

An inverse association between textile dust exposure and lung cancer was found among workers exposed ≥5% of their work time (OR = 0.80, 95%CI = 0.58‐1.09), more pronounced for distant exposures (40+ years; up to a 56% reduced risk, statistically significant). The OR of lung cancer was significantly decreased among workers exposed to cotton fibers (OR = 0.70, 95%CI = 0.48‐0.97).

Conclusions

Our results provide some evidence of a decreased risk of lung cancer associated with exposure to textile dust, particularly cotton.
  相似文献   
5.
Changes in gastric myoelectric activity during space flight   总被引:1,自引:0,他引:1  
The purpose of the present study was to examine postprandial myoelectric activity of the stomach and gastric activity associated with space motion sickness using electrogastrography. Three crewmembers participated in this investigation. Preflight, subjects exhibited normal postprandial responses to the ingestion of a meal. Inflight, crewmembers exhibited an abnormal decrease in the power of the normal gastric slow wave after eating on flight day 1, but had a normal postprandial response by flight day 3. Prior to and during episodes of nausea and vomiting, the electrical activity of the stomach became dysrhythmic with 60–80% of the spectral power in the bradygastric and tachygastric frequency ranges. These findings indicate that gastric motility may be decreased during the first few days of space flight. In addition, changes in the frequency of the gastric slow wave associated with space motion sickness symptoms are consistent with those reported for laboratory-induced motion sickness.  相似文献   
6.
The serotonin (5-HT) neurotransmitter system, which has a widespread distribution in the central nervous system, has been implicated in regulating mood and many human behaviors. There is evidence from postmortem human studies and limited information from prior in vivo studies to support a decline in 5-HT2A receptor density with aging. We examined nine elderly (ages 61–76) and nine young (ages 18–29) healthy individuals with positron emission tomography (PET) and [ ]altanserin, a ligand with high affinity for the 5-HT2A binding site. The PET data were corrected for differences in brain tissue volume between the young and elderly subjects using a magnetic resonance (MR) imaging-based partial volume correction method. Highly significant and widespread cortical reductions in 5-HT2A specific binding were demonstrated in the elderly group relative to young controls. Regional losses averaged 61% before and 57% following correction for effects of cerebral atrophy. This finding, which is consistent with prior postmortem and in vivo studies, has both etiological and potential therapeutic implications for behavioral changes commonly observed in the elderly, including geriatric depression.  相似文献   
7.
We tested the hypothesis that the DYT1 genotype is associated with a disorder of anatomical connectivity involving primarily the sensorimotor cortex. We used diffusion tensor magnetic resonance imaging (DTI) to assess the microstructure of white matter pathways in mutation carriers and control subjects. Fractional anisotropy (FA), a measure of axonal integrity and coherence, was reduced (p < 0.005) in the subgyral white matter of the sensorimotor cortex of DYT1 carriers. Abnormal anatomical connectivity of the supplementary motor area may contribute to the susceptibility of DYT1 carriers to develop clinical manifestations of dystonia.  相似文献   
8.
Applications of neuroreceptor imaging to psychiatry research   总被引:4,自引:0,他引:4  
Over the past two decades, there have been significant advances in the ability to study the neurochemistry of the living brain using neuroreceptor radiotracers with Positron Emission Tomography (PET) and Single Photon Emission Computed Tomography (SPECT) imaging modalities. The greater availability of radiotracers for neurotransmitter synthesis/metabolism, enzymes, transporters and receptors, as well as neuromodulators and second messengers has enabled the evaluation of hypotheses regarding neurotransmitter function and regulation that are generated from basic neuroscience studies in animals, and the investigation of the neurochemical substrates of psychiatric disorders and the mechanism of action of psychotropic medications. This review will focus on the status of radiotracer development, on the clinical and methodological considerations regarding neurochemical brain imaging study design and data interpretation. The applications of neurochemical brain imaging methods to the study of specific psychiatric disorders, including schizophrenia, anxiety disorders, depression and Alzheimer's Disease, will be reviewed and potential future directions of research in these areas identified. Finally, the studies of the neurochemical substrates of personality traits will be reviewed. Thus far, fundamental observations have been made with respect to 1). detecting abnormalities in the availability of neurotransmitter transporter and receptor sites in psychiatric patients; 2). evaluating the relationship of these neurochemical measures to symptomatology; and 3). assessing the magnitude of occupancy of the initial target sites of action of psychotropic medication relative to treatment response and drug concentrations. Further advances in instrumentation and radiotracer chemistry will enable investigators to conduct pre-clinical and clinical mechanistic studies focused on other neurotransmitters and neuromodulators. These data will provide important insights into the neurochemical substrates of treatment response variability in psychiatric disorders that will have important implications for the refinement of pharmacotherapy.  相似文献   
9.
A review of US poison center data for 2004 showed over 8,000 ingestions of methylphenidate. A guideline that determines the conditions for emergency department referral and prehospital care could potentially optimize patient outcome, avoid unnecessary emergency department visits, reduce health care costs, and reduce life disruption for patients and caregivers. An evidence-based expert consensus process was used to create the guideline. Relevant articles were abstracted by a trained physician researcher. The first draft of the guideline was created by the lead author. The entire panel discussed and refined the guideline before distribution to secondary reviewers for comment. The panel then made changes based on the secondary review comments. The objective of this guideline is to assist poison center personnel in the appropriate out-of-hospital triage and initial out-of-hospital management of patients with suspected ingestions of methylphenidate by 1) describing the process by which a specialist in poison information should evaluate an exposure to methylphenidate, 2) identifying the key decision elements in managing cases of methylphenidate ingestion, 3) providing clear and practical recommendations that reflect the current state of knowledge, and 4) identifying needs for research. This review focuses on the ingestion of more than a single therapeutic dose of methylphenidate and the effects of an overdose and is based on an assessment of current scientific and clinical information. The expert consensus panel recognizes that specific patient care decisions may be at variance with this guideline and are the prerogative of the patient and the health professionals providing care, considering all of the circumstances involved. This guideline does not substitute for clinical judgment. Recommendations are in chronological order of likely clinical use. The grade of recommendation is in parentheses. 1) All patients with suicidal intent, intentional abuse, or in cases in which a malicious intent is suspected (e.g., child abuse or neglect) should be referred to an emergency department (Grade D). 2) In patients without evidence of self-harm, abuse, or malicious intent, poison center personnel should elicit additional information including the time of the ingestion, the precise dose ingested, and the presence of coingestants (Grade D). 3) Patients who are chronically taking a monoamine oxidase inhibitor and who have ingested any amount of methylphenidate require referral to an emergency department (Grade D). 4) Patients experiencing any changes in behavior other than mild stimulation or agitation should be referred to an emergency department. Examples of moderate to severe symptoms that warrant referral include moderate-to-severe agitation, hallucinations, abnormal muscle movements, headache, chest pain, loss of consciousness, or convulsions (Grade D). 5) For patients referred to an emergency department, transportation via ambulance should be considered based on several factors including the condition of the patient and the length of time it will take for the patient to arrive at the emergency department (Grade D). 6) If the patient has no symptoms, and more than 3 hours have elapsed between the time of ingestion and the call to the poison center, referral to an emergency department is not recommended (Grade D). 7) Patients with acute or acute-on-chronic ingestions of less than a toxic dose (see recommendations 8, 9, and 10) or chronic exposures to methylphenidate with no or mild symptoms can be observed at home with instructions to call the poison center back if symptoms develop or worsen. For acute-on-chronic ingestions, the caller should be instructed not to administer methylphenidate to the patient for the next 24 hours. The poison center should consider making a follow-up call at approximately 3 hours after ingestion (Grade D). 8) Patients who ingest more than 2 mg/kg or 60 mg, whichever is less, of an immediate-release formulation (or the equivalent amount of a modified-release formulation that has been chewed) should be referred to an emergency department (Grade C). 9) If a patch has been swallowed, consider the entire contents of the patch (not just the labeled dose of the patch) to have been ingested. Patients who ingest more than 2 mg/kg or 60 mg, whichever is less should be referred to an emergency department. If it is known that the patch has been chewed only briefly, and the patch remains intact, significant toxicity is unlikely and emergency department referral is not necessary (Grade D). 10) Patients who ingest more than 4 mg/kg or 120 mg, whichever is less, of an intact modified-release formulation should be referred to an emergency department (Grade D). 11) For oral exposures, do not induce emesis (Grade D). 12) Pre-hospital activated charcoal administration, if available, should only be carried out by health professionals and only if no contraindications are present. Do not delay transportation in order to administer activate charcoal (Grade D). 13) Benzodiazepines can be administered by EMS personnel if agitation, dystonia, or convulsions are present and if authorized by EMS medical direction expressed by written treatment protocol or policy or direct medical oversight (Grade C). 14) Standard advanced cardiac life support (ACLS) measures should be administered by EMS personnel if respiratory arrest, cardiac dysrhythmias, or cardiac arrest are present and if authorized by EMS medical direction expressed by written treatment protocol or policy or direct medical oversight (Grade C).  相似文献   
10.
Unique physiological, developmental, and psychological attributes of children make them one of the more vulnerable populations during mass-casualty incidents. Because of their distinctive vulnerabilities, it is crucial that pediatric needs are incorporated into every stage of disaster planning. Individuals, families, and communities can help mitigate the effects of disasters on pediatric populations through ongoing awareness and preventive practices. Mitigation efforts also can be achieved through education and training of the healthcare workforce. Preparedness activities include gaining Emergency Medical Services for Children Pediatric Facility Recognition, conducting pediatric disaster drills, improving pediatric surge capacity, and ensuring that the needs of children are incorporated into all levels of disaster plans. Pediatric response can be improved in a number of ways, including: (1) enhanced pediatric disaster expertise; (2) altered decontamination protocols that reflect pediatric needs; and (3) minimized parent-child separation. Recovery efforts at the pediatric level include promoting specific mental health therapies for children and incorporating children into disaster relief and recovery efforts. Improving pediatric emergency care needs should be at the forefront of every disaster planner's agenda.  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