收费全文 | 2033289篇 |
免费 | 143401篇 |
国内免费 | 3935篇 |
耳鼻咽喉 | 30083篇 |
儿科学 | 59529篇 |
妇产科学 | 56325篇 |
基础医学 | 287942篇 |
口腔科学 | 61980篇 |
临床医学 | 176086篇 |
内科学 | 393490篇 |
皮肤病学 | 44890篇 |
神经病学 | 160682篇 |
特种医学 | 80353篇 |
外国民族医学 | 501篇 |
外科学 | 318519篇 |
综合类 | 45161篇 |
现状与发展 | 7篇 |
一般理论 | 641篇 |
预防医学 | 142079篇 |
眼科学 | 48592篇 |
药学 | 154876篇 |
7篇 | |
中国医学 | 4517篇 |
肿瘤学 | 114365篇 |
2018年 | 18726篇 |
2016年 | 16621篇 |
2015年 | 18713篇 |
2014年 | 25891篇 |
2013年 | 39019篇 |
2012年 | 51946篇 |
2011年 | 54808篇 |
2010年 | 32512篇 |
2009年 | 31403篇 |
2008年 | 52891篇 |
2007年 | 56676篇 |
2006年 | 57641篇 |
2005年 | 55743篇 |
2004年 | 54185篇 |
2003年 | 52221篇 |
2002年 | 51425篇 |
2001年 | 100650篇 |
2000年 | 103627篇 |
1999年 | 87415篇 |
1998年 | 22647篇 |
1997年 | 20456篇 |
1996年 | 19993篇 |
1995年 | 18873篇 |
1994年 | 17559篇 |
1993年 | 16297篇 |
1992年 | 67627篇 |
1991年 | 65409篇 |
1990年 | 64051篇 |
1989年 | 62323篇 |
1988年 | 57748篇 |
1987年 | 56642篇 |
1986年 | 53721篇 |
1985年 | 51397篇 |
1984年 | 37903篇 |
1983年 | 32385篇 |
1982年 | 18579篇 |
1981年 | 16809篇 |
1979年 | 35941篇 |
1978年 | 25295篇 |
1977年 | 21995篇 |
1976年 | 19674篇 |
1975年 | 22163篇 |
1974年 | 26440篇 |
1973年 | 25542篇 |
1972年 | 24295篇 |
1971年 | 22775篇 |
1970年 | 21681篇 |
1969年 | 20631篇 |
1968年 | 19226篇 |
1967年 | 17279篇 |
Background
The purpose of the study was to evaluate the association between fetal echocardiographic measurements and the need for intervention (primary coarctation repair, staged coarctation repair, or catheter intervention) in prenatally diagnosed coarctation of the aorta.Methods
A single-centre retrospective cohort study (2005-2015) of 107 fetuses diagnosed with suspected coarctation of the aorta in the setting of an apex-forming left ventricle and antegrade flow across the mitral and aortic valves.Results
Median gestational age at diagnosis was 32 weeks (interquartile range, 23-35 weeks). Fifty-six (52%) did not require any neonatal intervention, 51 patients (48%) underwent a biventricular repair. In univariable analysis, an increase in ascending aorta (AAo) peak Doppler flow velocity (odds ratio [OR], 1.40 [95% confidence interval [CI], 1.05-1.91] per 20 cm/s; P = 0.03) was associated with intervention. No intervention was associated with larger isthmus size (OR, 0.23; P < 0.001), transverse arch diameter (OR, 0.23; P < 0.001), and aortic (OR, 0.72; P = 0.02), mitral (OR, 0.58; P = 0.001), and AAo (OR, 0.53; P < 0.001) z-scores. In multivariable analysis, higher peak AAo Doppler (OR, 2.51 [95% CI, 1.54-4.58] per 20 cm/s; P = 0.001) and younger gestational age at diagnosis (OR, 0.81 [95% CI, 0.70-0.93] per week; P = 0.005) were associated with intervention, whereas a higher AAo z-score (OR, 0.65 [95% CI, 0.43-0.94] per z; P = 0.029) and transverse arch dimension (OR, 0.44 [95% CI, 0.18-0.97]; P = 0.05) decreased the risk of intervention.Conclusions
In prenatally suspected coarctation, the variables associated with intervention comprised smaller AAo and transverse arch size, earlier gestational age at diagnosis, and the additional finding of a higher peak AAo Doppler. 相似文献Objectives
To investigate whether functional overreaching affects locomotor system behaviour when running at fixed relative intensities and if any effects were associated with changes in running performance.Design
Prospective intervention study.Methods
Ten trained male runners completed three training blocks in a fixed order. Training consisted of one week of light training (baseline), two weeks of heavy training designed to induce functional overreaching, and ten days of light taper training designed to allow athletes to recover from, and adapt to, the heavy training. Locomotor behaviour, 5-km time trial performance, and subjective reports of training status (Daily Analysis of Life Demands for Athletes (DALDA) questionnaire) were assessed at the completion of each training block. Locomotor behaviour was assessed using detrended fluctuation analysis of stride intervals during running at speeds corresponding to 65% and 85% of maximum heart rate (HRmax) at baseline.Results
Time trial performance (effect size ±95% confidence interval (ES): 0.16 ± 0.06; p < 0.001), locomotor behaviour at 65% HRmax (ES: ?1.12 ± 0.95; p = 0.026), and DALDA (ES: 2.55 ± 0.80; p < 0.001) were all detrimentally affected by the heavy training. Time trial performance improved relative to baseline after the taper (ES: ?0.16 ± 0.10; p = 0.003) but locomotor behaviour at 65% HRmax (ES: ?1.18 ± 1.17; p = 0.048) and DALDA (ES: 0.92 ± 0.90; p = 0.045) remained impaired.Conclusions
Locomotor behaviour during running at 65% HRmax was impaired by functional overreaching and remained impaired after a 10-day taper, despite improved running performance. Locomotor changes may increase injury risk and should be considered within athlete monitoring programs independently of performance changes. 相似文献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Material and methods: original research studies were searched from seven databases (MEDLINE, EMBASE, CENTRAL, CINAHL, SCOPUS, PEDro and PubMed). Subsequently, two independent reviewers screened the titles and abstracts followed by full-text reviews to assess the studies' eligibility.
Results: eleven studies met the inclusion criteria and had data abstracted and quality assessed. Methodology varied considerably and yet cognitive tasks resulted in the ΔO2Hb increasing in 8 of the 11 and ΔHHb decreasing in 8 of 8 studies that reported this outcome. The cognitive tasks from 10 of the 11 studies were classified as “Working Memory” and “Verbal Fluency Tasks”.
Conclusions: although, the data comparison was challenging provided the heterogeneity in methodology, the results across studies were similar. 相似文献