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   1020篇
  免费   77篇
  国内免费   1篇
耳鼻咽喉   7篇
儿科学   31篇
妇产科学   40篇
基础医学   144篇
口腔科学   6篇
临床医学   151篇
内科学   157篇
皮肤病学   6篇
神经病学   120篇
特种医学   12篇
外科学   104篇
综合类   6篇
一般理论   2篇
预防医学   140篇
眼科学   9篇
药学   95篇
中国医学   3篇
肿瘤学   65篇
  2024年   3篇
  2023年   11篇
  2022年   28篇
  2021年   50篇
  2020年   19篇
  2019年   43篇
  2018年   58篇
  2017年   35篇
  2016年   34篇
  2015年   49篇
  2014年   65篇
  2013年   70篇
  2012年   104篇
  2011年   79篇
  2010年   48篇
  2009年   38篇
  2008年   64篇
  2007年   59篇
  2006年   55篇
  2005年   39篇
  2004年   33篇
  2003年   27篇
  2002年   29篇
  2001年   6篇
  2000年   7篇
  1999年   7篇
  1998年   6篇
  1997年   2篇
  1996年   4篇
  1995年   4篇
  1994年   2篇
  1993年   1篇
  1990年   1篇
  1989年   1篇
  1988年   2篇
  1987年   2篇
  1985年   2篇
  1984年   2篇
  1983年   1篇
  1982年   2篇
  1980年   4篇
  1979年   1篇
  1973年   1篇
排序方式: 共有1098条查询结果,搜索用时 15 毫秒
1.
As countries implement Article 11 of the World Health Organization (WHO) Framework Convention on Tobacco Control, graphic warning labels that use images of people and their body parts to illustrate the consequences of smoking are being added to cigarette packs. According to exemplification theory, these case examples—exemplars—can shape perceptions about risk and may resonate differently among demographic subpopulations. Drawing on data from eight focus groups (N = 63) with smokers and nonsmokers from vulnerable populations, this qualitative study explores whether people considered exemplars in their reactions to and evaluations of U.S. graphic health warning labels initially proposed by the Food and Drug Administration. Participants made reference to prior and concurrent mass media messages and exemplars during the focus groups and used demographic cues in making sense of the images on the warning labels. Participants were particularly sensitive to age of the exemplars and how it might affect label effectiveness and beliefs about smoking. Race and socioeconomic status also were salient for some participants. We recommend that exemplars and exemplification be considered when selecting and evaluating graphic health warnings for tobacco labels and associated media campaigns.  相似文献   
2.
Neuropsychiatric disturbances are extremely common in Alzheimer’s disease (AD), and represent integral features of the illness, as well as appropriate targets for therapy. We are interested in designing trials aimed at preventing or delaying the emergence of psychopathology in AD. For symptomatic treatment of agitation, mood stabilizers, particularly sodium valproate, have proved to be beneficial in some patients. Since these effects take several weeks to emerge, we considered that they might be dependent on potentially neuroprotective actions of valproate, such as inhibition of apoptosis and slowing of neurofibrillary tangle formation. In this article we present the rationale for testing the neuroprotective potential of valproate experimentally in mouse models of tauopathy and in a clinical trial of patients with AD who lack psychopathology at baseline. Together, these studies will provide important tests of the hypothesis that valproate, either through inhibition of tau phosphorylation or some other mechanism, is a useful therapeutic agent to modify disease progression in AD.  相似文献   
3.
OBJECTIVES: To determine if experienced clinical educators (CEs) can improve their teaching by incorporating 4 literature-based teaching methods into their instruction. METHODS: We trained 7 experienced CEs on the teaching methods during a monthly faculty development program. Each CE recorded use of these methods during 10 months on a personal digital assistant. We compared the CEs' teaching evaluations with those of nonparticipating faculty by analysis of variance at baseline, during the study period, and for 1 year after the study. RESULTS: Reported use of 2 teaching methods (priming and feedback) increased significantly over use at baseline; use of 2 other methods (teaching in the patient's presence and 1-2 focal teaching points) remained constant. Scores on the CEs' teaching evaluations were significantly higher during the study period on 1 item, whereas the comparison group showed no changes. The changes persisted during the follow-up period. CEs reported that the teaching methods focused the learner and teacher, making subsequent encounters more productive. They also found that the act of entering data daily prompted them to reflect on their teaching. CONCLUSIONS: Experienced teachers can be persuaded to incorporate new methods into their daily teaching. Reflection on teaching is enhanced with group support and daily reminders. With these interventions, teaching effectiveness of these experienced educators improved.  相似文献   
4.
5.
6.
OBJECTIVE: Depression after hip fracture surgery is prevalent and associated with increased mortality rates and impaired functional recovery. The incidence of new-onset depressive symptoms in patients initially not depressed after hip fracture surgery and their relationship with functional recovery is unknown. METHODS: A cohort of 139 nondepressed elderly patients (>60 years) hospitalized for hip fracture surgery were followed up for six months. Clinically significant depressive symptoms were defined as a score of 7 or more on the 15-item Geriatric Depression Scale. RESULTS: The authors found a cumulative incidence rate of 20.5% adjusted for dropouts. Multiple Cox-regression analyses yielded the presence of subthreshold symptoms of depression, anxiety, pain, and cognitive impairment at baseline, the premorbid level of mobility, and a history of (treated) depression as risk factors for incident depression (p <0.05). A forward, conditional procedure identified postoperative pain (hazard ratio [HR] = 1.32, 95% confidence interval [CI]: 1.14-1.53, Wald chi(2) = 13.57, df = 1, p <0.001) and baseline anxiety (HR = 1.25, 95% CI: 1.08-1.44, Wald chi(2) = 8.86, df = 1, p = 0.003) as the strongest independent risk factors. Incident depression was associated with a less favorable outcome at 3 months follow-up. CONCLUSION: This exploratory study identified two treatable baseline characteristics that predicted incident depression in nondepressed patients after hip-fracture surgery.  相似文献   
7.
Alveolar capillary dysplasia with misalignment of the pulmonary veins (ACDMPV) is a rare, autosomal dominant disorder of interstitial lung development, leading to pulmonary hypertension, and death in infancy. Associated features include malformations of the heart, gastrointestinal tract, and genitourinary system. ACDMPV is caused by heterozygous variants in the FOXF1 gene or microdeletions involving FOXF1. We present a male infant with ACDMPV, hypoplastic left heart sequence (HLHS), duodenal atresia, and imperforate anus due to a de novo, in frame deletion in FOXF1: c.209_214del (p.Thr70_Leu71del). Previous reports have suggested that microdeletions involving FOXF1 are associated with ACDMPV with congenital heart defects, including HLHS, gastrointestinal atresias, and other anomalies; whereas likely pathogenic variants within FOXF1 have not been reported with ACDMPV and HLHS. This is the first patient reported with ACDMPV, HLHS, imperforate anus, and duodenal atresia associated with a likely pathogenic variant in the FOXF1 gene.  相似文献   
8.
Fluorescence spectroscopy has shown promise for the detection of precancerous changes in vivo. The epithelial and stromal layers of tissue have very different optical properties; the albedo is relatively low in the epithelium and approaches one in the stroma. As precancer develops, the optical properties of the epithelium and stroma are altered in markedly different ways: epithelial scattering and fluorescence increase, and stromal scattering and fluorescence decrease. We present an analytical model of the fluorescence spectrum of a two-layer medium such as epithelial tissue. Our hypothesis is that accounting for the two different tissue layers will provide increased diagnostic information when used to analyze tissue fluorescence spectra measured in vivo. The Beer-Lambert law is used to describe light propagation in the epithelial layer, while light propagation in the highly scattering stromal layer is described with diffusion theory. Predictions of the analytical model are compared to results from Monte Carlo simulations of light propagation under a range of optical properties reported for normal and precancerous epithelial tissue. In all cases, the mean square error between the Monte Carlo simulations and the analytical model are within 15%. Finally, model predictions are compared to fluorescence spectra of normal and precancerous cervical tissue measured in vivo; the lineshape of fluorescence agrees well in both cases, and the decrease in fluorescence intensity from normal to precancerous tissue is correctly predicted to within 5%. Future work will explore the use of this model to extract information about changes in epithelial and stromal optical properties from clinical measurements and the diagnostic value of these parameters.  相似文献   
9.
Migratory birds could introduce West Nile (WN) virus to Arkansas. The purpose of this study was to establish a cooperative arbovirus surveillance program to monitor mosquitoes and birds in Arkansas for arboviruses. Our objectives were to: 1) perform routine, multicounty collections of mosquitoes and test them for eastern equine encephalitis, St. Louis encephalitis, and WN viruses; and 2) conduct passive surveillance by testing dead wild birds for WN virus. Arbovirus surveillance was organized by the Arkansas Department of Health, University of Arkansas, and Vector Disease Control Incorporated. None of the 14,560 mosquitoes (425 pools) tested were virus positive. Two hundred forty-two dead birds from 62 counties were tested for WN virus. Four blue jays in three counties were positive. These infections are the first reported incidences of WN virus in Arkansas. Sera from five horses with suspected encephalitis all tested negative for WN, eastern equine encephalitis, and western equine encephalitis viruses.  相似文献   
10.
Lymphoid organogenesis is dependent upon a series of intricate cellular interactions involving adhesion molecules, chemokines, and cytokines that generate fully compartmentalized lymphoid structures. Development of organized lymphoid structures in the intestine begins prenatally and continues through adulthood, with constant adaptations to changes in the luminal flora. While much is known about the mechanisms that govern the development of macroscopic intestinal lymphoid structures (mesenteric lymph node and Peyer's patches), the organogenesis of the microscopic lymphoid tissues (including cryptopatches and isolated lymphoid follicles) is an emerging field. This review examines the current state of knowledge about organogenesis of the known types of organized lymphoid tissue in the intestine and identifies unique and common features in the development of each of the structures discussed.  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