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   13238篇
  免费   1236篇
  国内免费   25篇
耳鼻咽喉   178篇
儿科学   400篇
妇产科学   297篇
基础医学   1661篇
口腔科学   178篇
临床医学   1734篇
内科学   2351篇
皮肤病学   265篇
神经病学   1552篇
特种医学   346篇
外科学   1749篇
综合类   123篇
一般理论   19篇
预防医学   1812篇
眼科学   140篇
药学   729篇
  1篇
中国医学   6篇
肿瘤学   958篇
  2024年   30篇
  2023年   220篇
  2022年   289篇
  2021年   674篇
  2020年   441篇
  2019年   655篇
  2018年   698篇
  2017年   440篇
  2016年   480篇
  2015年   479篇
  2014年   593篇
  2013年   823篇
  2012年   1055篇
  2011年   1000篇
  2010年   528篇
  2009年   429篇
  2008年   657篇
  2007年   611篇
  2006年   558篇
  2005年   506篇
  2004年   417篇
  2003年   367篇
  2002年   352篇
  2001年   119篇
  2000年   115篇
  1999年   122篇
  1998年   77篇
  1997年   57篇
  1996年   75篇
  1995年   52篇
  1994年   51篇
  1993年   42篇
  1992年   95篇
  1991年   105篇
  1990年   107篇
  1989年   124篇
  1988年   81篇
  1987年   67篇
  1986年   65篇
  1985年   96篇
  1984年   68篇
  1983年   47篇
  1982年   30篇
  1980年   34篇
  1979年   48篇
  1978年   35篇
  1977年   34篇
  1974年   39篇
  1971年   30篇
  1970年   32篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
2.
Potential for widespread transmission of HIV/AIDS among American Indian (AI) adolescents exists, yet no evidence-based interventions (EBIs) have been adapted and evaluated with this population. Intensive psychoeducation may improve knowledge and decision-making which could potentially translate to reductions in HIV risk behaviors. A peer group randomized controlled comparison of an adapted EBI vs. control was delivered over an eight-day summer basketball camp in one reservation-based tribal community to adolescents ages 13–19. Outcome data were gathered immediately post-camp and at 6 and 12 months follow-up. Self-selected peer groups were randomized to intervention (n = 138) or control (n = 129) conditions for a total sample of 267 participants (56.2% female), mean age 15.1 years (SD = 1.7). Intervention participants had better condom use self-efficacy post-camp (Adjusted Mean Difference [AMD] = ?0.75, p < 0.005) and at 6 (AMD = ?0.44, p < 0.005) and 12 months (AMD = ?0.23, p < 0.05) follow-up. Intervention participants also had higher HIV prevention and transmission knowledge (post-camp: AMD = 0.07, p < 0.01; 6 months: AMD = 0.06, p < 0.01) were more likely to believe condoms prevent sexually transmitted infections (post-camp: RR = 1.41, p < 0.005; 6 months: RR = 1.34, p < 0.05), to talk with an adult about HIV/AIDS (post-camp: RR=1.78, p < 0.005; 6 months: RR = 1.14, p < 0.005), had higher partner negotiation efficacy related to substance use during sex (post-camp: AMD = 0.37, p < 0.01), and were more likely to intend to use a condom (post-camp: RR = 1.39, p < 0.01). The adapted intervention had short- and medium-term impacts on AI adolescent risk for HIV/AIDS, but attenuated at 12 months. Intervention delivery through a community-based camp is feasible and acceptable with strong retention. Additional study is needed to evaluate the adapted intervention's impact on sexual risk behaviors and if booster sessions and parent involvement translate to long-term impacts.  相似文献   
3.
Prevalence of osteoporosis is more than 50% in older adults, yet current clinical methods for diagnosis that rely on areal bone mineral density (aBMD) fail to detect most individuals who have a fragility fracture. Bone fragility can manifest in different forms, and a “one-size-fits-all” approach to diagnosis and management of osteoporosis may not be suitable. High-resolution peripheral quantitative computed tomography (HR-pQCT) provides additive information by capturing information about volumetric density and microarchitecture, but interpretation is challenging because of the complex interactions between the numerous properties measured. In this study, we propose that there are common combinations of bone properties, referred to as phenotypes, that are predisposed to different levels of fracture risk. Using HR-pQCT data from a multinational cohort (n = 5873, 71% female) between 40 and 96 years of age, we employed fuzzy c-means clustering, an unsupervised machine-learning method, to identify phenotypes of bone microarchitecture. Three clusters were identified, and using partial correlation analysis of HR-pQCT parameters, we characterized the clusters as low density, low volume, and healthy bone phenotypes. Most males were associated with the healthy bone phenotype, whereas females were more often associated with the low volume or low density bone phenotypes. Each phenotype had a significantly different cumulative hazard of major osteoporotic fracture (MOF) and of any incident osteoporotic fracture (p < 0.05). After adjustment for covariates (cohort, sex, and age), the low density followed by the low volume phenotype had the highest association with MOF (hazard ratio = 2.96 and 2.35, respectively), and significant associations were maintained when additionally adjusted for femoral neck aBMD (hazard ratio = 1.69 and 1.90, respectively). Further, within each phenotype, different imaging biomarkers of fracture were identified. These findings suggest that osteoporotic fracture risk is associated with bone phenotypes that capture key features of bone deterioration that are not distinguishable by aBMD. © 2021 American Society for Bone and Mineral Research (ASBMR).  相似文献   
4.
DNA methylation at CpG dinucleotides is an important epigenetic regulator common to virtually all mammalian cell types, but recent evidence indicates that during early postnatal development neuronal genomes also accumulate uniquely high levels of two alternative forms of methylation, non-CpG methylation and hydroxymethylation. Here we discuss the distinct landscape of DNA methylation in neurons, how it is established, and how it might affect the binding and function of protein readers of DNA methylation. We review studies of one critical reader of DNA methylation in the brain, the Rett syndrome protein methyl CpG-binding protein 2 (MeCP2), and discuss how differential binding affinity of MeCP2 for non-CpG and hydroxymethylation may affect the function of this methyl-binding protein in the nervous system.  相似文献   
5.
Effective communication between clinicians, patients, and families at end of life is associated with better clinical outcomes. A large body of literature describes the key skills needed for effective communication. We believe that clinicians could also benefit from communication skills more commonly associated with business or law negotiations. We will demonstrate via analogy (i.e. buying a house) how four key business/law negotiation techniques – 1. Determine your Reservation and Aspiration Value; 2. Separate People from their Positions; 3. Separate Positions from Interests; and 4. Logrolling of Interests – can be applied to a difficult family meeting in a home hospice patient.  相似文献   
6.
7.
We report a case of disseminated Trichosporon asahii in a patient on systemic antifungal therapy who presented with multiple cutaneous nodules suggestive of fungal infection. Histologic features resembled neutrophilic eccrine hidradenitis but staining with periodic acid‐Schiff and Gomori methenamine silver confirmed the clinical diagnosis. This case highlights the importance of maintaining suspicion for trichosporonosis and contextualizing histologic findings within the underlying clinical picture.  相似文献   
8.
Shaving and other modes of epilation can cause undue anxiety, pain, or skin irritation in children. Here, we present hair trimming as a safe, painless, and cost‐effective alternative for patients with unwanted hair which may be performed indefinitely or until the child is old enough to direct management. In select cases, removing unwanted hair using this technique may facilitate dermatologic surveillance.  相似文献   
9.
10.
Capillary malformation–arteriovenous malformation syndrome (CM‐AVM) is an autosomal dominant disorder caused by RASA1 mutations. The prevalence and phenotypic spectrum are unknown. Evaluation of patients with multiple CMs is challenging because associated AVMs can be life threatening. The objective of this study was to describe the clinical characteristics of children presenting with features of CM‐AVM to an academic pediatric dermatology practice. After institutional review board approval was received, a retrospective chart review was performed of patients presenting between 2009 and 2012 with features of CM‐AVM. We report nine cases. Presenting symptoms ranged from extensive vascular stains and cardiac failure to CMs noted incidentally during routine skin examination. All demonstrated multiple CMs, two had Parkes Weber syndrome, and two had multiple infantile hemangiomas. Seven patients had family histories of multiple CMs; three had family histories of large, atypical CMs. Six had personal or family histories of AVMs. Genetic evaluation was recommended for all and was pursued by six families; four RASA1 mutations were identified, including one de novo. Consultations with neurology, cardiology, and orthopedics were recommended. Most patients (89%) have not required treatment to date. CM‐AVM is an underrecognized condition with a wide clinical spectrum that often presents in childhood. Further evaluation may be indicated in patients with multiple CMs. This study is limited by its small and retrospective nature.  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