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   14666篇
  免费   1116篇
  国内免费   37篇
耳鼻咽喉   162篇
儿科学   560篇
妇产科学   353篇
基础医学   1984篇
口腔科学   578篇
临床医学   2121篇
内科学   2650篇
皮肤病学   208篇
神经病学   1349篇
特种医学   248篇
外国民族医学   2篇
外科学   1119篇
综合类   154篇
一般理论   18篇
预防医学   2196篇
眼科学   311篇
药学   851篇
中国医学   44篇
肿瘤学   911篇
  2024年   28篇
  2023年   179篇
  2022年   267篇
  2021年   462篇
  2020年   348篇
  2019年   510篇
  2018年   532篇
  2017年   425篇
  2016年   399篇
  2015年   456篇
  2014年   603篇
  2013年   878篇
  2012年   1205篇
  2011年   1248篇
  2010年   647篇
  2009年   545篇
  2008年   931篇
  2007年   988篇
  2006年   862篇
  2005年   756篇
  2004年   713篇
  2003年   642篇
  2002年   599篇
  2001年   139篇
  2000年   101篇
  1999年   91篇
  1998年   115篇
  1997年   84篇
  1996年   78篇
  1995年   68篇
  1994年   70篇
  1993年   41篇
  1992年   58篇
  1991年   62篇
  1990年   33篇
  1989年   41篇
  1988年   36篇
  1987年   28篇
  1986年   28篇
  1985年   27篇
  1984年   37篇
  1983年   25篇
  1982年   27篇
  1981年   26篇
  1980年   31篇
  1979年   14篇
  1978年   15篇
  1977年   21篇
  1976年   25篇
  1968年   15篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
131.
Meal timing is suggested to influence the obesity risk in children. Our aim was to analyse the effect of energy and nutrient distributions at eating occasions (EO), including breakfast, lunch, supper, and snacks, on the BMI z-score (zBMI) during childhood in 729 healthy children. BMI and three-day dietary protocols were obtained at 3, 4, 5, 6, and 8 years of age, and dietary data were analysed as the percentage of the mean total energy intake (TEI; %E). Intakes at EOs were transformed via an isometric log–ratio transformation and added as exposure variables to linear mixed-effects models. Stratified analyses by country and recategorization of EOs by adding intake from snacks to respective meals for further analyses were performed. The exclusion of subjects with less than three observations and the exclusion of subjects who skipped one EO or consumed 5% energy or less at one EO were examined in sensitivity analyses. Around 23% of the children were overweight at a given time point. Overweight and normal-weight children showed different distributions of dietary intakes over the day; overweight children consumed higher intakes at lunch and lower intakes of snacks. However, no significant effects of timing of EOs on zBMI were found in regression analyses.  相似文献   
132.
ObjectiveThis is the second phase of a project. The aim was to explore Australian chiropractic and osteopathic new graduates'' readiness for transition to practice concerning their clinical skills, professional behaviors, and interprofessional abilities. Phase 1 explored final year students'' self-perceptions, and this part uncovered their opinions after 6 months or more in practice.MethodsInterviews were conducted with a self-selecting sample of phase 1 participant graduates from 2 Australian chiropractic and 2 osteopathic programs. Results of the thematic content analysis of responses were compared to the Australian Chiropractic Standards and Osteopathic Capabilities, the authority documents at the time of the study.ResultsInterviews from graduates of 2 chiropractic courses (n = 6) and 2 osteopathic courses (n = 8) revealed that the majority had positive comments about their readiness for practice. Most were satisfied with their level of clinical skills, verbal communication skills, and manual therapy skills. Gaps in competence were identified in written communications such as case notes and referrals to enable interprofessional practice, understanding of professional behaviors, and business skills. These identified gaps suggest that these graduates are not fully cognizant of what it means to manage their business practices in a manner expected of a health professional.ConclusionThis small study into clinical training for chiropractic and osteopathy suggests that graduates lack some necessary skills and that it is possible that the ideals and goals for clinical education, to prepare for the transition to practice, may not be fully realized or deliver all the desired prerequisites for graduate practice.  相似文献   
133.
Hepatitis B virus (HBV) infection is the first cause of liver cirrhosis and cancer in West Africa. Although the exposure to additional environmental and infectious risk factors may lead to the faster progression of liver disease, few large-scale studies have evaluated the determinants of HBV-related liver fibrosis in the region. We used transient elastography to evaluate the prevalence of liver fibrosis and assessed the association between HBV markers and significant liver fibrosis in a cohort of people living with HBV in Dakar, Senegal. The prevalence of significant liver fibrosis was 12.5% (95% confidence interval [CI] 9.6%–15.9%) among 471 people with HBV mono-infection (pwHBV) and 6.4% (95% CI 2.6%–12.7%) in 110 people with HIV/HBV co-infection (pwHIV/HBV) on tenofovir-containing antiretroviral therapy (p = 0.07). An HBV viral load > 2000 IU/mL was found in 133 (28.3%) pwHBV and 5 (4.7%) pwHIV/HBV, and was associated with significant liver fibrosis (adjusted odds ratio (aOR) 1.95, 95% CI 1.04–3.66). Male participants (aOR 4.32, 95% CI 2.01–8.96) and those with elevated ALT (aOR 4.32, 95% CI 2.01–8.96) were especially at risk of having significant liver fibrosis. Our study shows that people with an HBV viral load above 2000 IU/mL have a two-fold increase in the risk of liver fibrosis and may have to be considered for antiviral therapy, independent of other disease parameters.  相似文献   
134.
Brazil is blessed with a great biodiversity, which constitutes one of the most important sources of biologically active compounds, even if it has been largely underexplored. As is the case of the Amazon and Atlantic rainforests, the Brazilian marine fauna remains practically unexplored in the search for new biologically active natural products. Considering that marine organisms have been shown to be one of the most promising sources of new bioactive compounds for the treatment of different human diseases, the 8000 km of the Brazilian coastline represents a great potential for finding new pharmacologically active secondary metabolites. This review presents the status of marine natural products chemistry in Brazil, including results reported by different research groups with emphasis on the isolation, structure elucidation, and evaluation of biological activities of natural products isolated from sponges, ascidians, octocorals, and Opistobranch mollusks. A brief overview of the first Brazilian program on the isolation of marine bacteria and fungi, directed toward the production of biologically active compounds, is also discussed. The current multidisciplinary collaborative program under development at the Universidade de S?o Paulo proposes to establish a new paradigm toward the management of the Brazilian marine biodiversity, integrating research on the species diversity, ecology, taxonomy, and biogeography of marine invertebrates and microorganisms. This program also includes a broad screening program of Brazilian marine bioresources, to search for active compounds that may be of interest for the development of new drug leads.  相似文献   
135.
Introduction: Increasing numbers of pre-lingually profoundly deaf adults are seeking a cochlear implant (CI). Pre- and post-operative outcomes are presented on 20 of these patients.

Results: An Adult Pre-Lingually Profoundly Deaf Implant Profile (APDIP) weighted the pre-operative level of concern about potential CI benefit. Results indicated no group mean post-operative open-set improvement. However CUNY sentence testing (auditory plus lip-reading cues) revealed improved performance with a CI. Twelve out of 20 patients used their CIs for more than 10 hours per day, suggesting good usage. Moreover, hours of usage were positively associated with measured benefit on CUNY sentences in the lip-reading plus sound via CI condition. There was no apparent relationship between pre-operative level of concern and post-operative CI performance or hours of processor use.

Conclusion: Results suggest implantation is beneficial and effective in this group.  相似文献   
136.
IntroductionOxidative stress (OS) occurs in cystic fibrosis (CF).ObjectiveThe objective of this work is to evaluate the influence of bacterial infection on biomarkers of OS (catalase [CAT], glutathione peroxidade [GPx], reduced glutathione [GSH]), markers of oxidative damage (protein carbonyls [PC], thiobarbituric acid reactive substances [TBARS]), together with the nutritional status and lung function in children with CF.MethodsCross‐sectional study including CF group (CFG, n = 55) and control group (CG, n = 31), median age: 3.89 and 4.62 years, respectively. CFG was distributed into CFG negative bacteriology (CFGB−, n = 27) or CFG positive bacteriology (CFGB+, n = 28), and CFG negative Pseudomonas aeruginosa (CFGPa−, n = 36) or CFG positive Pseudomonas aeruginosa (CFGPa+, n = 19).ResultsCompared with CG, CFG (P = .034) and CFGB+ (P = .042) had lower body mass index‐for‐age z‐score; forced expiratory volume in the first second was lower in CFGB+ and CFGPa+ (both P < .001). After adjusting for confounders and compared with CG: CFG showed higher TBARS (P ≤ .001) and PC (P = .048), and lower CAT (P = .004) and GPx (P = .003); the increase in PC levels was observed in CFGB+ (P = .011) and CFGPa+ (P = .001) but not in CFGB− (P = .510) and CFGPa− (P = .460).ConclusionsThese results indicate a systemic OS in children with CF. The presence of bacterial infection particularly Pseudomonas aeruginosa seems to be determinant to exacerbate the oxidative damage to proteins, in which PC may be a useful biomarker of OS in CF.  相似文献   
137.
Clinical trial endpoints are fundamental for evaluating the safety and efficacy of cancer therapies, yet it is not well understood how they are selected or the role of stakeholder groups in deciding endpoints. This study aimed to explore how clinical trial endpoints are selected in breast cancer trials of anti-cancer drugs through semi structured interviews with purposively selected stakeholders involved in breast cancer clinical trials (clinicians, consumers, pharmaceutical company representatives, and members of drug regulatory agencies). Participants were asked to describe the process of selecting trial endpoints. Interviews were transcribed verbatim and analysed using inductive thematic analysis supported by NVivo software. Saturation of the main themes was reached and the final sample included 25 participants from 14 countries (9 clinicians, 7 consumers, 5 members of regulatory agencies, 4 pharmaceutical company representatives). Pharmaceutical companies were almost always identified as the main decision maker. While most consumers and pharmaceutical company representatives felt clinicians and consumers influenced trial design, some clinicians and regulators reported consumers and clinicians had little influence. Factors identified as important considerations in determining trial endpoints included the main goal of the trial, established standardised endpoints, resources, and the investigational agent studied. All pharmaceutical advisors reported that meeting the requirements for regulatory approval was the major factor considered. Clinical trial endpoint selection is largely decided by the pharmaceutical industry, driven by requirements for regulatory approval. Given the limited influence from clinicians and consumers, guidance by regulatory agencies will be important for future inclusion of novel endpoints in clinical trials.  相似文献   
138.
The retina and the optic nerve are considered extensions of the central nervous system (CNS) and thus can serve as the window for evaluation of CNS disorders. Spectral domain optical coherence tomography (OCT) allows for detailed evaluation of the retina and the optic nerve. OCT can non-invasively document changes in single retina layer thickness and structure due to neuronal and retinal glial cells (RGC) modifications in systemic and local inflammatory and neurodegenerative diseases. These can include evaluation of retinal nerve fibre layer and ganglion cell complex, hyper-reflective retinal spots (HRS, sign of activated microglial cells in the retina), subfoveal neuroretinal detachment, disorganization of the inner retinal layers (DRIL), thickness and integrity of the outer retinal layers and choroidal thickness. This review paper will report the most recent data on the use of OCT as a non invasive imaging biomarker for evaluation of the most common systemic neuroinflammatory and neurodegenerative/neurocognitive disorders in the adults and in paediatric population. In the adult population the main focus will be on diabetes mellitus, multiple sclerosis, optic neuromyelitis, neuromyelitis optica spectrum disorders, longitudinal extensive transverse myelitis, Alzheimer and Parkinson diseases, Amyotrophic lateral sclerosis, Huntington’s disease and schizophrenia. In the paediatric population, demyelinating diseases, lysosomal storage diseases, Nieman Pick type C disease, hypoxic ischaemic encephalopathy, human immunodeficiency virus, leukodystrophies spinocerebellar ataxia will be addressed.Subject terms: Retina, Prognostic markers, Retinal diseases, Predictive markers  相似文献   
139.
Gingival inflammation is clinically characterized by gingival redness, swelling and increased tendency of bleeding of the soft tissue. Bacterial biofilm is the etiological agent. If, at this stage, the bacterial biofilm is removed and appropriate control methods are applied, remission of gingival inflammation occurs. This study evaluated the effectiveness of a single session of ultrasonic prophylaxis for the reduction of gingivitis in an adolescent population using the Plaque Index (PI) and Gingival Index (GI). The study sample consisted of 15 male adolescent students selected at a dentist's office of a public high school. Prior to treatment (baseline), plaque index (PI) and bleeding on probing (BOP) were recorded. The patients then received oral hygiene instructions and ultrasonic prophylaxis. Follow-up exams were made 15 and 30 days after the ultrasonic prophylaxis, again recording PI and BOP. The data were analyzed by the Student's t-test for dependent samples. Correlation analysis between presence of biofilm and bleeding on probing was also made using the Pearson correlation test. There was a statistically significant decrease in the plaque index and bleeding on probing between baseline and examinations at both 15 days and 30 days (p<0.05). However, the difference between the means at 15 and 30 days was statistically similar. The correlation analysis showed correlation between both parameters (p<0.05). The results indicate that a single session of ultrasonic prophylaxis associated to oral hygiene instructions is efficient to reverse gingivitis in adolescents.  相似文献   
140.
IntroductionChildren and adolescents with autism spectrum disorder (ASD) appear to be at greater risk of excess weight gain. The aim of this systematic review and meta-analysis was to examine whether children with ASD have a greater prevalence of obesity and whether the prevalence of ASD is higher in children with obesity.MethodsWe conducted a systematic search on PubMed, Scopus, and PsychINFO until May 21, 2021. We used the meta package in the R in order to calculate the pooled prevalence and relative risk of obesity in children with ASD.ResultsWe found 20 eligible studies investigating the prevalence of obesity in children with ASD, with the prevalence ranging from 7.9 to 31.8% and from 1.4 to 23.6% among controls. All but three studies originated from the USA. The proportion of children with obesity in ASD populations was 17% (95% confidence interval [CI]: 13–22). The relative risk of obesity in children with ASD compared with control children was 1.58 (95% CI: 1.34–1.86). There were no controlled studies reporting on the prevalence of ASD in children with obesity.ConclusionChildren and adolescents with ASD have a higher prevalence of obesity than healthy controls. There is a need for further prevalence studies of obesity in children with ASD, especially outside the USA, since the few European studies carried out have failed to show a significant difference between obesity prevalence in children with and without ASD. There is no knowledge at all regarding the prevalence of ASD among children with obesity.  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