收费全文 | 2051181篇 |
免费 | 145149篇 |
国内免费 | 3129篇 |
耳鼻咽喉 | 29356篇 |
儿科学 | 62233篇 |
妇产科学 | 57279篇 |
基础医学 | 295133篇 |
口腔科学 | 59660篇 |
临床医学 | 175799篇 |
内科学 | 400858篇 |
皮肤病学 | 42734篇 |
神经病学 | 159404篇 |
特种医学 | 80394篇 |
外国民族医学 | 438篇 |
外科学 | 324311篇 |
综合类 | 41588篇 |
现状与发展 | 2篇 |
一般理论 | 510篇 |
预防医学 | 144557篇 |
眼科学 | 47335篇 |
药学 | 158243篇 |
3篇 | |
中国医学 | 4301篇 |
肿瘤学 | 115321篇 |
2018年 | 19094篇 |
2016年 | 16331篇 |
2015年 | 18838篇 |
2014年 | 25812篇 |
2013年 | 38814篇 |
2012年 | 53221篇 |
2011年 | 56549篇 |
2010年 | 33525篇 |
2009年 | 31772篇 |
2008年 | 55083篇 |
2007年 | 59052篇 |
2006年 | 60116篇 |
2005年 | 58576篇 |
2004年 | 56573篇 |
2003年 | 54686篇 |
2002年 | 53845篇 |
2001年 | 102497篇 |
2000年 | 105733篇 |
1999年 | 89199篇 |
1998年 | 23159篇 |
1997年 | 20592篇 |
1996年 | 20811篇 |
1995年 | 19525篇 |
1994年 | 18398篇 |
1993年 | 17008篇 |
1992年 | 70297篇 |
1991年 | 68327篇 |
1990年 | 66890篇 |
1989年 | 65136篇 |
1988年 | 60297篇 |
1987年 | 58829篇 |
1986年 | 55688篇 |
1985年 | 53199篇 |
1984年 | 38895篇 |
1983年 | 33472篇 |
1982年 | 18836篇 |
1981年 | 16566篇 |
1979年 | 35896篇 |
1978年 | 24812篇 |
1977年 | 21422篇 |
1976年 | 19567篇 |
1975年 | 21509篇 |
1974年 | 25669篇 |
1973年 | 24449篇 |
1972年 | 23354篇 |
1971年 | 21860篇 |
1970年 | 20531篇 |
1969年 | 19672篇 |
1968年 | 18243篇 |
1967年 | 16131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Aims
To examine the influence of pre-existing psychiatric disorder on the choice of treatment in patients with gynaecological cancer.Materials and methods
The analyses were based on all patients who underwent surgical treatment for endometrial, ovarian or cervical cancer who were registered in the Danish Gynecological Cancer Database in the years 2007–2014 (3059 patients with ovarian cancer, 5100 patients with endometrial cancer and 1150 with cervical cancer). Logistic regression model and Cox regression model, adjusted for relevant confounders, were used to estimate the effect of pre-existing psychiatric disorder on the course of cancer treatment. Our outcomes were (i) presurgical oncological treatment, (ii) macroradical surgery for patients with ovarian cancer, (iii) radiation/chemotherapy within 30 days and 100 days after surgery and (iv) time from surgery to first oncological treatment.Results
In the group of patients with ovarian cancer, more patients with a psychiatric disorder received macroradical surgery versus patients without a psychiatric disorder, corresponding to an adjusted odds ratio of 1.24 (95% confidence interval 0.62–2.41) and the chance for having oncological treatment within 100 days was odds ratio = 1.26 (95% confidence interval 0.77–2.10). As for patients with endometrial cancer, all outcome estimates were close to unity. The adjusted odds ratio for oncological treatment within 30 days after surgery in patients with cervical cancer with a history of psychiatric disorder was 0.20 (95% confidence interval 0.03–1.54).Conclusions
We did not find any significant differences in the treatment of ovarian and endometrial cancer in patients with pre-existing psychiatric diagnoses. When it comes to oncological treatment, we suggest that increased attention should be paid to patients with cervical cancer having a pre-existing psychiatric diagnosis. 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