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   70743篇
  免费   4494篇
  国内免费   266篇
耳鼻咽喉   1110篇
儿科学   2026篇
妇产科学   1326篇
基础医学   7827篇
口腔科学   1451篇
临床医学   6964篇
内科学   14609篇
皮肤病学   1113篇
神经病学   6889篇
特种医学   2485篇
外国民族医学   5篇
外科学   12344篇
综合类   845篇
一般理论   94篇
预防医学   5873篇
眼科学   1371篇
药学   4537篇
中国医学   111篇
肿瘤学   4523篇
  2023年   352篇
  2022年   324篇
  2021年   1763篇
  2020年   928篇
  2019年   1550篇
  2018年   1811篇
  2017年   1306篇
  2016年   1338篇
  2015年   1474篇
  2014年   2274篇
  2013年   3204篇
  2012年   4852篇
  2011年   5033篇
  2010年   2760篇
  2009年   2450篇
  2008年   4451篇
  2007年   4712篇
  2006年   4569篇
  2005年   4546篇
  2004年   4288篇
  2003年   3950篇
  2002年   3667篇
  2001年   558篇
  2000年   486篇
  1999年   634篇
  1998年   743篇
  1997年   668篇
  1996年   592篇
  1995年   522篇
  1994年   511篇
  1993年   430篇
  1992年   380篇
  1991年   378篇
  1990年   306篇
  1989年   289篇
  1988年   280篇
  1987年   261篇
  1986年   272篇
  1985年   365篇
  1984年   430篇
  1983年   360篇
  1982年   513篇
  1981年   483篇
  1980年   449篇
  1979年   205篇
  1978年   272篇
  1977年   255篇
  1976年   200篇
  1975年   219篇
  1973年   183篇
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
31.
HIV risk in vulnerable groups such as itinerant male street labourers is often examined via a focus on individual determinants. This study provides a test of a modified Information-Motivation-Behavioral Skills (IMB) model to predict condom use behaviour among male street workers in urban Vietnam. In a cross-sectional survey using a social mapping technique, 450 male street labourers from 13 districts of Hanoi, Vietnam were recruited and interviewed. Collected data were first examined for completeness; structural equation modelling was then employed to test the model fit. Condoms were used inconsistently by many of these men, and usage varied in relation to a number of factors. A modified IMB model had a better fit than the original IMB model in predicting condom use behaviour. This modified model accounted for 49% of the variance, versus 10% by the original version. In the modified model, the influence of psychosocial factors was moderately high, whilst the influence of HIV prevention information, motivation and perceived behavioural skills was moderately low, explaining in part the limited level of condom use behaviour. This study provides insights into social factors that should be taken into account in public health planning to promote safer sexual behaviour among Asian male street labourers.  相似文献   
32.
33.
34.

Objectives

The current study investigated the effects of two exercise interventions on cognitive function amongst breast cancer survivors.

Design

Pilot randomised-controlled trial.

Methods

Seventeen female cancer survivors (mean: 62.9 ± 7.8 years) were randomised into three groups: high-intensity interval training (HIIT, n = 6); moderate-intensity continuous training (MOD, n = 5); or wait-list control (CON, n = 6). The HIIT and MOD groups exercised on a cycle ergometer 3 days/week for 12-weeks. Primary outcomes were cognitive function assessments utilising CogState. Secondary outcomes were resting middle cerebral artery blood flow velocity, cerebrovascular reactivity and aerobic fitness (VO2peak). Data were analysed with General Linear Mixed Models and Cohen’s d effect sizes were calculated.

Results

All 17 participants who were randomised were available for follow-up analysis and adherence was similar for HIIT and MOD (78.7 ± 13.2% vs 79.4 ± 12.0%; p = 0.93). Although there were no significant differences in the cognitive and cerebrovascular outcomes, HIIT produced moderate to large positive effects in comparison to MOD and CON for outcomes including episodic memory, working memory, executive function, cerebral blood flow and cerebrovascular reactivity. HIIT significantly increased VO2peak by 19.3% (d = 1.28) and MOD had a non-significant 5.6% (d = 0.72) increase, compared to CON which had a 2.6% decrease.

Conclusions

This study provides preliminary evidence that HIIT may be an effective exercise intervention to improve cognitive performance, cerebrovascular function and aerobic fitness in breast cancer survivors. Considering the sample size is small, these results should be confirmed through larger clinical trials.  相似文献   
35.
Trabecular bone score (TBS) is used for fracture prediction in adults, but its utility in children is limited by absence of appropriate reference values. We aimed to develop reference ranges for TBS by age, sex, and population ancestry for youth ages 5 to 20 years. We also investigated the association between height, body mass index (BMI), and TBS, agreement between TBS and lumbar spine areal bone mineral density (aBMD) and bone mineral apparent density (BMAD) Z-scores, tracking of TBS Z-scores over time, and precision of TBS measurements. We performed secondary analysis of spine dual-energy X-ray absorptiometry (DXA) scans from the Bone Mineral Density in Childhood Study (BMDCS), a mixed longitudinal cohort of healthy children (n = 2014) evaluated at five US centers. TBS was derived using a dedicated TBS algorithm accounting for tissue thickness rather than BMI. TBS increased only during ages corresponding to pubertal development with an earlier increase in females than males. There were no differences in TBS between African Americans and non-African Americans. We provide sex-specific TBS reference ranges and LMS values for calculation of TBS Z-scores by age and means and SD for calculation of Z-scores by pubertal stage. TBS Z-scores were positively associated with height Z-scores at some ages. TBS Z-scores explained only 27% and 17% of the variance of spine aBMD and BMAD Z-scores. Tracking of TBS Z-scores over 6 years was lower (r = 0.47) than for aBMD or BMAD Z-scores (r = 0.74 to 0.79), and precision error of TBS (2.87%) was greater than for aBMD (0.85%) and BMAD (1.22%). In sum, TBS Z-scores provide information distinct from spine aBMD and BMAD Z-scores. Our robust reference ranges for TBS in a well-characterized pediatric cohort and precision error estimates provide essential tools for clinical assessment using TBS and determination of its value in predicting bone fragility in childhood and adolescence. © 2022 American Society for Bone and Mineral Research (ASBMR).  相似文献   
36.
Annals of Hematology - This study assessed treatment patterns and healthcare resource utilization (HRU) of patients with severe aplastic anemia (SAA) with insufficient response to immunosuppressive...  相似文献   
37.
38.

Objectives

This document offers guidance to clinicians and facilities on the use of telemedicine to deliver medically necessary evaluation and management of change of condition for nursing home residents.

Settings and participants

Members of the telemedicine workgroup of AMDA—The Society for Post-Acute Long-Term Medicine-developed this guideline through both telephonic and face-to-face meetings between April 2017 and September 2018. The guideline is based on the currently available research, experience, and expertise of the workgroup's members, including a summary of a recently completed systematic mixed studies literature review to determine evidence for telemedicine to reduce emergency department visits or hospitalizations of nursing home residents.

Results

Research and experience to date support the use of telemedicine as a tool in change of condition assessment and management as a means of reducing unnecessary emergency department visits and hospitalization. Telemedicine-delivered care should be integrated into the primary care of the resident and delivered by providers with competency in post-acute long-term care. The development and sustainability of telemedicine programs is heavily dependent on financial implications. Quality measures should be defined for telemedicine programs in nursing homes.

Conclusions/Implications

Telemedicine programs in nursing homes can contribute to the delivery of timely, high quality medical care, which reduces unnecessary hospitalization. Reimbursement for telemedicine-driven care should be based upon medical necessity of visits to care and the maintenance of quality standards. More studies are needed to understand which telemedicine tools and processes are most effective in improving outcomes for nursing home residents.  相似文献   
39.
Schizophrenia is a chronic and severe psychiatric disorder that has profound impact on an individual’s life and on society. Thus, developing more effective therapeutic interventions is essential. Over the past quarter‐century, an abundance of evidence from pharmacologic challenges, post‐mortem studies, brain imaging, and genetic studies supports the role of glutamatergic dysregulation in the pathophysiology of schizophrenia, and the results of recent randomized clinical trials based on this evidence have yielded promising results. In this article, we review the evidence that alterations in glutamatergic neurotransmission, especially focusing on the N‐methyl‐d ‐aspartate receptor (NMDAR) function, may be a critical causative feature of schizophrenia, how this contributes to pathologic circuit function in the brain, and how these insights are revealing whole new avenues for treatment development that could reduce treatment‐resistant symptoms, which account for persistent disability.  相似文献   
40.
Congenital heart disease is a rare but important finding in adults who experience sudden death. Examination of the congenitally malformed heart has historically been considered esoteric and best left to those with expertise. The Cardiac Risk in the Young cardiovascular pathology laboratory based at St George's University of London has now received over 6,000 cases. Of these, 21 congenitally malformed hearts were retained for research and educational purposes. Hearts were assessed using sequential segmental analysis, and causes of death were adjudicated based on thorough macroscopic examination and histology. Congenital malformations that were encountered included atrial septal defects, ventricular septal defects, tetralogy of Fallot, and transposition of the great arteries in both its regular and congenitally corrected variants. Findings also included hearts with mirror-imaged and isomeric atrial appendages. Direct causes of death included myocardial fibrosis, pulmonary hypertension, and hemorrhage. A small but notable proportion did not reveal a substrate for arrhythmia, raising the question of whether the terminal event was due to the congenital heart disease itself, or an underlying channelopathy. Here, we demonstrate the value of simple sequential segmental analysis in describing and categorizing the cases, with the concept of the “morphological method” serving to identify the distinguishing features of the cardiac components. Clin. Anat. 33:394–404, 2020. © 2019 Wiley Periodicals, Inc.  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