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   33624篇
  免费   2748篇
  国内免费   76篇
耳鼻咽喉   586篇
儿科学   1363篇
妇产科学   1093篇
基础医学   4614篇
口腔科学   873篇
临床医学   2939篇
内科学   7674篇
皮肤病学   793篇
神经病学   3561篇
特种医学   1052篇
外国民族医学   4篇
外科学   4242篇
综合类   548篇
一般理论   43篇
预防医学   2431篇
眼科学   681篇
药学   1917篇
中国医学   11篇
肿瘤学   2023篇
  2021年   420篇
  2020年   298篇
  2019年   513篇
  2018年   574篇
  2017年   399篇
  2016年   439篇
  2015年   513篇
  2014年   724篇
  2013年   1095篇
  2012年   1420篇
  2011年   1479篇
  2010年   859篇
  2009年   753篇
  2008年   1358篇
  2007年   1441篇
  2006年   1461篇
  2005年   1403篇
  2004年   1369篇
  2003年   1249篇
  2002年   1286篇
  2001年   1177篇
  2000年   1257篇
  1999年   1026篇
  1998年   344篇
  1997年   284篇
  1996年   303篇
  1995年   312篇
  1994年   294篇
  1993年   314篇
  1992年   902篇
  1991年   838篇
  1990年   714篇
  1989年   755篇
  1988年   711篇
  1987年   733篇
  1986年   681篇
  1985年   695篇
  1984年   556篇
  1983年   469篇
  1982年   301篇
  1980年   263篇
  1979年   466篇
  1978年   311篇
  1977年   262篇
  1976年   278篇
  1975年   271篇
  1974年   305篇
  1973年   299篇
  1972年   271篇
  1971年   267篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
2.

Introduction

The Advisory Committee on Immunization Practices (ACIP) has focused on maternal Tdap immunization as an important means to protect neonates from pertussis infections. There is little published data on provider and/or clinic characteristics as predictors of maternal Tdap uptake. This study examined differences in maternal Tdap coverage in women delivering at a single academic institution, but cared for prenatally in different clinical settings, in 2013, 2014, and 2015. Additionally, the accuracy and utilization of Vermont's immunization information system (IIS) was assessed.

Methods

This was a retrospective, multiple time-point cross-sectional analysis of annual maternal Tdap coverage in women delivering at a single academic institution in the 3?years following a fundamental change in national maternal Tdap vaccination guidelines. Tdap administration was examined across different obstetric groups using chart review and data from the state's IIS.

Results

All obstetric care groups except the resident-staffed clinic significantly increased maternal Tdap coverage in 2014, compared to 2013 coverage, with no further increase in 2015. In contrast, there was no increase in maternal Tdap coverage in 2014 in the resident-staffed clinics, but then a statistically significant increase in 2015. Overall Tdap coverage in 2014 was 80.4%, with variation in Tdap coverage between clinics types. In the subset of women who were cared for by the University-based groups, there was significant variation in Tdap coverage between clinics, despite racial homogeneity, which persisted after adjustment for maternal age and insurance type. The state's IIS was found to be highly accurate, using individual chart review as the “gold standard.”

Discussion

While we demonstrated high maternal Tdap coverage in women delivering at our institution, differences in clinic type and provider training appeared to impact immunization rates, as well as how quickly evolving national recommendations were adopted. Additionally, the fidelity of the state's IIS data was verified.  相似文献   
3.
4.
Our knowledge of the radiological spectrum of myelin oligodendrocyte glycoprotein antibody associated disease (MOGAD) is growing rapidly. An update on the radiological features of the disease, and its evolution is thus necessary. Magnetic resonance imaging (MRI) has an increasingly important role in the differential diagnosis of MOGAD particularly from aquaporin-4 antibody-positive neuromyelitis optica spectrum disorder (AQP4-NMOSD), and multiple sclerosis (MS). Differentiating these conditions is of prime importance because the management is different between the three inflammatory diseases, and thus could prevent further attack-related disability. Therefore, identifying the MRI features suggestive of MOGAD has diagnostic and prognostic implications. We herein review optic nerve, spinal cord and the brain MRI findings from MOGAD adult patients, and compare them to AQP4-NMOSD and MS.  相似文献   
5.

Objectives

To identify temporal trends in muscular fitness of English children using allometric scaling for height and weight to adjust for the influence of body size.

Design

Repeated cross-sectional study.

Methods

We measured; height, weight, standing broad-jump, handgrip, sit-ups and bent-arm hang in 10-year-old boys and girls from Chelmsford, England in: 2014 (n = 306), 2008 (n = 304) and 1998 (n = 310). Physical activity was (PAQ-C) was assessed in 2008 and 2014. Muscular fitness was allometrically scaled for height and weight. We assessed temporal trends using General Linear Models (fixed factors: wave and sex) and reported effect sizes using partial eta squared (ηP2). We compared percentage change per year 1998–2008 with 2008–2014.

Results

Ten-year-olds in 2014 were taller and heavier than in 2008 and 1998 but there were no differences in BMI. Compared with 2008, physical activity was lower in boys (ηP2 = 0.012) and girls (ηP2 = 0.27) assessed in 2014. There were significant main effects of wave for handgrip (ηP2 = 0.060), sit-ups (ηP2 = 0.120) and bent-arm hang (ηP2 = 0.204). Pairwise comparisons showed muscular fitness of both sexes was significantly lower in 2014 than in 1998. From 2008 to 2014 percent change per year in handgrip (1.6%) and sit-ups (3.9%) were greater than for the preceding decade (handgrip 0.6%, sit-ups 2.6%).

Conclusions

Downward temporal trends in muscular fitness appear independent of secular changes in body size. We found a decrease in self-reported physical activity concurrent with the accelerated declines in fitness from 2008 to 2014. These findings suggest the declines in children are not engaging in physical activities which support development of muscular fitness.  相似文献   
6.

Introduction

Physician communication impacts patient outcomes. However, communication skills, especially around difficult conversations, remain suboptimal, and there is no clear way to determine the validity of entrustment decisions. The aims of this study were to 1) describe the development of a simulation-based mastery learning (SBML) curriculum for breaking bad news (BBN) conversation skills and 2) set a defensible minimum passing standard (MPS) to ensure uniform skill acquisition among learners.

Innovation

An SBML BBN curriculum was developed for fourth-year medical students. An assessment tool was created to evaluate the acquisition of skills involved in a BBN conversation. Pilot testing was completed to confirm improvement in skill acquisition and set the MPS.

Outcomes

A BBN assessment tool containing a 15-item checklist and six scaled items was developed. Students' checklist performance improved significantly at post-test compared to baseline (mean 65.33%, SD = 12.09% vs mean 88.67%, SD = 9.45%, P < 0.001). Students were also significantly more likely to have at least a score of 4 (on a five-point scale) for the six scaled questions at post-test. The MPS was set at 80%, requiring a score of 12 items on the checklist and at least 4 of 5 for each scaled item. Using the MPS, 30% of students would require additional training after post-testing.

Comments

We developed a SBML curriculum with a comprehensive assessment of BBN skills and a defensible competency standard. Future efforts will expand the mastery model to larger cohorts and assess the impact of rigorous education on patient care outcomes.  相似文献   
7.
BackgroundSexual dysfunction is common among adults and takes a toll on quality of life for both men and women.AimTo determine whether higher levels of weekly cardiovascular exercise are protective against self-reported sexual dysfunction among men and women.MethodsWe conducted an international online, cross-sectional survey of physically active men and women between April and December 2016, assessing exercise activity categorized into sextiles of weekly metabolic equivalent-hours. Odds ratios (ORs) of sexual dysfunction for each activity sextile compared with the lowest sextile were calculated using multivariable logistic regression, controlling for age, body mass index, diabetes mellitus, tobacco/alcohol use, sport, and marital status.Main Outcome MeasuresFemale sexual dysfunction was defined as a score ≤26.55 on the Female Sexual Function Inventory and erectile dysfunction (ED) was defined as a score ≤21 on the Sexual Health Inventory for Men.Results3,906 men and 2,264 women (median age 41–45 and 31–35 years, respectively) met the inclusion criteria for the study. Men in sextiles 2–6 had reduced odds of ED compared with the reference sextile in adjusted analysis (Ptrend = .03), with an OR of 0.77 (95% CI = 0.61–0.97) for sextile 4 and 0.78 (95% CI = 0.62–0.99) for sextile 6, both statistically significant. Women in higher sextiles had a reduced adjusted OR of female sexual dysfunction (Ptrend = .02), which was significant in sextile 4 (OR = 0.70; 95% CI = 0.51–0.96). A similar pattern held true for orgasm dissatisfaction (Ptrend < .01) and arousal difficulty (Ptrend < .01) among women, with sextiles 4–6 reaching statistical significance in both.Clinical ImplicationsMen and women at risk for sexual dysfunction regardless of physical activity level may benefit by exercising more rigorously.Strengths & LimitationsStrengths include using a large international sample of participants with a wide range of physical activity levels. Limitations include the cross-sectional design, and results should be interpreted in context of the study population of physically active adults.ConclusionHigher cardiovascular exercise levels in physically active adults are inversely associated with ED by self-report in men and protective against female sexual dysfunction in women.Fergus KB, Gaither TW, Baradaran N, et al. Exercise Improves Self-Reported Sexual Function Among Physically Active Adults. J Sex Med 2019;16:1236–1245.  相似文献   
8.
Background and objectivesThe role of schools in the spread of SARS-CoV-2 infections in the community is still controversial. The objective of our study was to describe the epidemiology of SARS-CoV-2 infections in different pediatric age groups during the first 2 months of the fall back-to-school period, in the context of increasing viral transmission in France.MethodsWeekly epidemiological data provided by Santé Publique France and the Ministry of National Education were analyzed according to the age groups defined by the different school levels. Weeks (W) 34–42 were considered for analysis.ResultsThe PCR positivity rate and incidence rate increased in all age groups during the study period, in an age-dependent manner. At W42, with adults being considered as reference, the risk ratio for a positive PCR test was 0.46 [95% CI: 0.44–0.49] and 0.69 [0.68–0.70] for children aged 0–5 years and 6–17 years, respectively. Similarly, the incidence rate ratio was 0.09 [0.08–0.09], 0.31 [0.30–0.32], 0.64 [0.63–0.66], and 1.07 [1.05–1.10] for children aged 0–5 years, 6–10 years, 11–14 years, and 15–17 years, respectively. Children and adolescents accounted for 1.9% of the newly hospitalized patients between W34 and W42, and for 1.3% of new intensive care admissions. No death was observed. Among infected children and adolescents, the percentage of asymptomatic individuals was 57% at W34 and 48% at W42. The number of schools closed remained low, less than 1% throughout the study period. The number of confirmed cases among school staff was consistent with the data measured in the general population.ConclusionIn the context of increasing viral transmission in the population, the spread among children and adolescents remained lower than that observed among adults, despite keeping schools open. However, the impact was age-dependent, with data in high schools close to those observed in adults.  相似文献   
9.
10.
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