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   2029418篇
  免费   155313篇
  国内免费   5651篇
耳鼻咽喉   27916篇
儿科学   63512篇
妇产科学   56739篇
基础医学   297286篇
口腔科学   57248篇
临床医学   190153篇
内科学   386982篇
皮肤病学   40652篇
神经病学   168128篇
特种医学   76810篇
外国民族医学   531篇
外科学   294354篇
综合类   49391篇
现状与发展   3篇
一般理论   694篇
预防医学   169107篇
眼科学   46337篇
药学   150764篇
  7篇
中国医学   4429篇
肿瘤学   109339篇
  2018年   21926篇
  2017年   16687篇
  2016年   18288篇
  2015年   21144篇
  2014年   29564篇
  2013年   45482篇
  2012年   62094篇
  2011年   65671篇
  2010年   38298篇
  2009年   35467篇
  2008年   60717篇
  2007年   64745篇
  2006年   64718篇
  2005年   63124篇
  2004年   60797篇
  2003年   58088篇
  2002年   56244篇
  2001年   87483篇
  2000年   89650篇
  1999年   75625篇
  1998年   22151篇
  1997年   20205篇
  1996年   19852篇
  1995年   18834篇
  1994年   17841篇
  1993年   16683篇
  1992年   61815篇
  1991年   60532篇
  1990年   59069篇
  1989年   56321篇
  1988年   52585篇
  1987年   51538篇
  1986年   49079篇
  1985年   47155篇
  1984年   35993篇
  1983年   30771篇
  1982年   18934篇
  1981年   17058篇
  1979年   34449篇
  1978年   24697篇
  1977年   20516篇
  1976年   19630篇
  1975年   20577篇
  1974年   25399篇
  1973年   24625篇
  1972年   23122篇
  1971年   21517篇
  1970年   20138篇
  1969年   19015篇
  1968年   17562篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
ABSTRACT

Purpose

New instrument-based techniques for anterior chamber (AC) cell counting can offer automation and objectivity above clinician assessment. This review aims to identify such instruments and its correlation with clinician estimates.  相似文献   
52.
53.
ABSTRACT

Background

Post-stroke dysphagia is characterized by reduced corticolingual excitability and lingual pressure; however, it remains unknown if transcranial magnetic stimulation (TMS) directly facilitates lingual pressure generation.  相似文献   
54.
ABSTRACT

Background

Reactive balance training (RBT) has been previously found to reduce fall risk in individuals with sub-acute stroke; however, our understanding of the effects of RBT on specific balance impairments is lacking.  相似文献   
55.
Abstract

Background: Wheelchair users (WCUs) often rely on ramps for access to transit buses. Previous studies indicate WCUs have difficulty using ramps for bus ingress/egress and many transportation-related incidents occur on ramps. However, experiences of WCU ramp usage during ingress/egress have not been fully described.

Methods: Cross-sectional, internet-based survey of WCUs who ride transit buses was conducted. The participants were queried on frequency of bus usage, difficulty and incidents involving ramps, and factors contributing to difficulty and incidents. Wheelchair characteristics, primary condition, and whether participants received travel training were also captured. Chi-square was used to describe relationships between wheelchair type and frequency of difficulties and incidents, and odd ratios were used to determine likelihood of the incidents.

Results: The majority (55.7%) of 384 participants reported using public transportation ≥ 1 per week. Seventy-eight percent of WCUs had ≥ 1 ramp incident over the past 3?years, with an increased likelihood of incidents occurring during ingress (OR = 1.53; CI 1.21–1.86). Of those who had an incident, 22% were injured or had damage to their wheelchair. Over 60% of those who had an incident identified steep ramp slope as being the contributing factor. Steep ramp slope, exterior ramp thresholds and wet surfaces were the most common contributing factors to difficulty using ramps.

Conclusion: This is the first large-scale US study enabling WCUs to describe their experiences using transit bus ramps. Despite ADA guidelines, steep ramps remain the primary factor contributing to incidents and difficulty when using ramps to access transit buses.
  • Implications for rehabilitation
  • The discrepancy between ADA maximum allowable ramp slopes for the built environment and transit buses may require an increased level of effort that is a barrier to transportation accessibility for some wheelchair users.

  • Wheelchair users who access transit buses should be made aware of, and trained, to navigate ramp configurations found in the environment.

  • We suggest rehabilitation therapists provide skills training specific to navigating transit bus ramp slopes that may be steeper and narrower than building ramps.

  相似文献   
56.

Objectives

Triazole resistance in Aspergillus spp. is emerging and complicates prophylaxis and treatment of invasive aspergillosis (IA) worldwide. New polymerase chain reaction (PCR) tests on broncho-alveolar lavage (BAL) fluid allow for detection of triazole resistance at a genetic level, which has opened up new possibilities for targeted therapy. In the absence of clinical trials, a modelling study delivers estimates of the added value of resistance detection with PCR, and which empiric therapy would be optimal when local resistance rates are known.

Design

A decision-analytic modelling study was performed based on epidemiological data of IA, extended with estimated dynamics of resistance rates and treatment effectiveness. Six clinical strategies were compared that differ in use of PCR diagnostics (used vs not used) and in empiric therapeutic choice in case of unknown triazole susceptibility: voriconazole, liposomal amphotericin B (LAmB) or both. Outcome measures were proportion of correct treatment, survival and serious adverse events.

Results

Implementing aspergillus PCR tests was projected to result in residual treatment-susceptibility mismatches of <5% for a triazole resistance rate up to 20% (using voriconazole). Empiric LAmB outperformed voriconazole at resistance rates >5–20%, depending on PCR use and estimated survival benefits of voriconazole over LAmB. Combination therapy of voriconazole and LAmB performed best at all resistance rates, but the advantage over the other strategies should be weighed against the expected increased number of drug-related serious adverse events. The advantage of combination therapy over LAmB monotherapy became smaller at higher triazole resistance rates.

Conclusions

Introduction of current aspergillus PCR tests on BAL fluid is an effective way to increase the proportion of patients that receive targeted therapy for IA. The results indicate that close monitoring of background resistance rates and adverse drug events are important to attain the potential benefits of LAmB. The choice of strategy ultimately depends on the probability of triazole resistance, the availability of PCR and individual patient characteristics.  相似文献   
57.
ABSTRACT

Food-handler hand-hygiene can be a contributory factor for food-borne illness. Cognitive data (knowledge/attitudes/self-reported practices), while informative, are not indicative of behaviour, and are subject to biases. Consequently, observation of behaviour is superior to survey data. However, researcher presence in direct observation increases reactivity, whereas video observation gives comprehensive analysis over a longer period, furthermore, familiarity reduces reactivity. Although video observation has been used to assess food safety at retail/foodservice, this valuable method is under-utilized in food-manufacturing environments. For the study, footage (24 h) was reviewed to assess compliance in a food-manufacturing site with company protocol. Video observation of food-handlers entering production (n = 674) was assessed; upon 70 occasions no attempt to implement hand-hygiene was observed. Of attempted hand-hygiene practices (n = 604), only 2% implemented compliant practices. Although 78% of attempts utilized soap, only 42% included sanitizer. Duration ranged from 1 to 69 s (Median 17 s). The study provides hand-hygiene data in an area that observational data is seldom captured.  相似文献   
58.
Objective: Shoulder pain after spinal cord injury (SCI) is attributed to increased mobility demands on the arms and negatively impacts independence and quality of life. Repetitive superior and posterior shoulder joint forces produced during traditional wheelchair (WC) locomotion can result in subacromial impingement if unopposed, as with muscular fatigue or weakness. ROWHEELS® (RW), geared rear wheels that produce forward WC movement with backward rim pulling, could alter these forces.

Design: Cross sectional.

Setting: Research laboratory at a rehabilitation hospital.

Participants: Ten manual WC users with paraplegia.

Outcome measures: Propulsion characteristics and right upper extremity/trunk kinematics and shoulder muscle activity were collected during ergometer propulsion: (1) self-selected free speed reverse propulsion with RW, (2) matched-speed reverse (rSW), and (3) forward propulsion (fSW) with instrumented Smartwheels (SW). Inverse dynamics using right-side SW rim kinetics and kinematics compared shoulder kinetics during rSW and fSW.

Results: Free propulsion velocity, cycle distance and cadence were similar during RW, rSW and fSW. Overall shoulder motion was similar except that peak shoulder extension was significantly reduced in both RW and rSW versus fSW. Anteriorly and inferiorly directed SW rim forces were decreased during rSW versus fSW propulsion, but posteriorly and superiorly directed rim forces were significantly greater. Superior and posterior shoulder joint forces and flexor, adductor, and external rotation moments were significantly less during rSW, without a significant difference in net shoulder forces and moments. Traditional propulsive-phase muscle activity was significantly reduced and recovery-phase muscle activity was increased during reverse propulsion.

Conclusion: These results suggest that reverse propulsion may redirect shoulder demands and prevent subacromial impingement, thereby preventing injury and preserving independent mobility for individuals with paraplegia.  相似文献   
59.
During the ongoing public health crisis, many agencies are reporting COVID-19 health outcome information based on the overall population. This practice can lead to misleading results and underestimation of high risk areas. To gain a better understanding of spatial and temporal distribution of COVID-19 deaths; the long term care facility (LTCF) and household population (HP) deaths must be used. This approach allows us to better discern high risk areas and provides policy makers with reliable information for community engagement and mitigation strategies. By focusing on high-risk LTCFs and residential areas, protective measures can be implemented to minimize COVID-19 spread and subsequent mortality.  These areas should be a high priority target when COVID-19 vaccines become available

During the current public health crisis, many agencies and media outlets are reporting COVID-19 health outcome information based on the overall population of Cook County. As we have demonstrated, overall COVID-19 case counts and mortality can be misleading (details in >Story Map 1). Moreover, they offer little guidance for delivering public health interventions to high risk populations, a critical need during this second and potentially more devastating wave of the pandemic. The University of Illinois Chicago School of Public Health’s Public Health Geographic Information System Program (UIC-SPH-PHGIS) and Purdue research team has been examining spatial and temporal patterns of COVID-19 mortality with a focus on the significant loss of life from COVID-19 among Long-Term Care Facility (LTCF) residents in contrast to mortality in the community among residents of private households (non-LTCF; referred to as household population, HP). The goals of the study are:
  • Improve the accuracy of commonly quoted COVID-19 mortality indicators;
  • Gain a better understanding of spatial and temporal distribution of COVID-19 deaths;
  • Examine the role of race, ethnicity, and socioeconomic status in COVID-19 mortality;
  • Identify population and organizational parameters that can inform strategies for public health interventions.
Prioritizing the allocation of resources based on reliable information is a prerequisite of a successful mitigation strategy and immunization plan. Findings from our research have significant practical implications. The state and federal government face a series of policy decisions both due to the recent surge in positive cases and, when the time comes, the need to rationalize distribution of vaccines to high priority groups beyond healthcare workers and nursing home residents in critical areas. The research team seeks to modify prevailing practices in order to derive reliable information that guides policy decisions. At this stage of the study, we identified high-risk LTCFs and residential areas (HP) of Cook County from readily available, real-time mortality data.  相似文献   
60.
Abstract

In light of a growing body of evidence demonstrating pervasive health disparities, medical schools are increasingly incorporating educational programs on social medicine in undergraduate and graduate medical curricula. In 2015, we significantly restructured the cultural competency instruction for medical students at our institution, focusing on achieving greater health equity through caring for vulnerable populations and acknowledging and addressing bias and stereotyping. In order to facilitate educational sustainability while students were immersed in clinical care, a key element of our approach included extending teaching into the clerkship year. The resulting longitudinal thread, Health Equity and Social Justice, empowers future physicians with the knowledge and skills to work towards greater health equity. This article discusses the lessons learned in the implementation of this novel educational program. Our approach can serve as a model for other institutions considering similar instructional reform.  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