全文获取类型
收费全文 | 3059086篇 |
免费 | 221927篇 |
国内免费 | 5251篇 |
专业分类
耳鼻咽喉 | 41768篇 |
儿科学 | 100693篇 |
妇产科学 | 82911篇 |
基础医学 | 448528篇 |
口腔科学 | 85358篇 |
临床医学 | 277546篇 |
内科学 | 588381篇 |
皮肤病学 | 67641篇 |
神经病学 | 243684篇 |
特种医学 | 115430篇 |
外国民族医学 | 775篇 |
外科学 | 456797篇 |
综合类 | 65191篇 |
现状与发展 | 12篇 |
一般理论 | 1227篇 |
预防医学 | 243827篇 |
眼科学 | 71121篇 |
药学 | 225317篇 |
13篇 | |
中国医学 | 6018篇 |
肿瘤学 | 164026篇 |
出版年
2021年 | 24308篇 |
2019年 | 25091篇 |
2018年 | 34636篇 |
2017年 | 26378篇 |
2016年 | 29648篇 |
2015年 | 33392篇 |
2014年 | 47009篇 |
2013年 | 70609篇 |
2012年 | 96738篇 |
2011年 | 102751篇 |
2010年 | 61087篇 |
2009年 | 57791篇 |
2008年 | 96173篇 |
2007年 | 102283篇 |
2006年 | 103095篇 |
2005年 | 99840篇 |
2004年 | 95563篇 |
2003年 | 91851篇 |
2002年 | 88890篇 |
2001年 | 137258篇 |
2000年 | 140862篇 |
1999年 | 118656篇 |
1998年 | 34881篇 |
1997年 | 30750篇 |
1996年 | 30908篇 |
1995年 | 29357篇 |
1994年 | 27134篇 |
1993年 | 25502篇 |
1992年 | 92657篇 |
1991年 | 90597篇 |
1990年 | 88501篇 |
1989年 | 85273篇 |
1988年 | 78296篇 |
1987年 | 77201篇 |
1986年 | 72331篇 |
1985年 | 69553篇 |
1984年 | 51962篇 |
1983年 | 44146篇 |
1982年 | 26392篇 |
1979年 | 47889篇 |
1978年 | 34309篇 |
1977年 | 28670篇 |
1976年 | 27423篇 |
1975年 | 29228篇 |
1974年 | 35259篇 |
1973年 | 33619篇 |
1972年 | 31410篇 |
1971年 | 29714篇 |
1970年 | 27376篇 |
1969年 | 25987篇 |
排序方式: 共有10000条查询结果,搜索用时 17 毫秒
61.
62.
63.
64.
Christine E. East Fung Yee Chan Shaun P. Brennecke James F. King Paul B. Colditz 《分娩》2006,33(2):101-109
Abstract: Background: Fetal pulse oximetry improves the assessment of fetal well‐being during labor. The objective of this study was to evaluate women's satisfaction with their experience with this additional technology. Methods: We surveyed women participating in the FOREMOST trial, a randomized controlled trial comparing the addition of fetal pulse oximetry (FPO) to conventional cardiotocograph (CTG) monitoring (intervention group), versus CTG‐only (control group), in the presence of nonreassuring fetal status during labor. Our survey evaluated 3 aspects of women's experience: labor, fetal monitoring, and participation in the research. The survey was administered within a few days of giving birth and repeated 3 months later. Results: No differences were found between the intervention and control groups for women's evaluations of their labor, fetal monitoring, research, or overall experiences when surveyed on both occasions. Within each study group, a small but statistically significant decline occurred in women's scores for their experience of labor and overall experience from the initial survey close to the time of giving birth, to 3 months later. The magnitude of differences in responses over time was similar for the both groups. Women were more satisfied after a spontaneous or assisted vaginal birth than after cesarean section. Length of time the research midwife was present had a significant positive effect on women's ratings of their experience several days after giving birth (p = 0.006), but no effect at 3 months. Conclusions: The addition of fetal pulse oximetry for the assessment of fetal well‐being during labor did not affect childbearing women's perceptions of fetal monitoring or their labor. Women evaluated their experience in the research process positively overall. Small changes occurred in women's perception of their satisfaction over time. (BIRTH 33:2 June 2006) 相似文献
65.
66.
67.
68.
69.
C F A Peralta P Cavoretto B Csapo O Falcon K H Nicolaides 《Ultrasound in obstetrics & gynecology》2006,27(2):128-133
OBJECTIVE: To establish reference intervals for the fetal right, left and total lung volumes and heart volume between 12 and 32 weeks of gestation. METHODS: Fetal lung and heart volumes were measured using three-dimensional (3D) ultrasound in 650 normal singleton pregnancies at 12-32 weeks. The VOCAL (Virtual Organ Computer-aided AnaLysis) technique was used to obtain a sequence of six sections of each lung and the heart around a fixed axis, each after a 30 degrees rotation from the previous one. The rotation axis for the lungs extended from the apex to the upper limit of the diaphragm dome, and the rotation axis for the heart extended from its apex to its connection to the great vessels. The contour of each of these organs was drawn manually in the six different rotation planes to obtain the 3D volume measurement. In 60 cases the fetal lungs and heart volumes were measured by the same sonographer twice and also by a second sonographer once in order to compare the measurements and calculate intra- and interobserver agreement. RESULTS: The total lung volume and heart volume increased with gestation, from respective mean values of 1.6 and 0.6 mL at 12 weeks to 10.9 and 4.3 mL at 20 weeks and 49.3 and 26.6 mL at 32 weeks. The right to left lung volume ratio did not change significantly with gestation (median, 0.7), whereas the heart to total lung volume ratio increased with gestation from about 0.3 at 12 weeks to 0.5 at 32 weeks. In the Bland-Altman plot, the difference between paired measurements by two sonographers was, in 95% of the cases, less than 0.05, 0.5 and 1.9 mL for each lung at 12-13, 19-22 and 29-32 weeks, respectively, and the corresponding values for the heart volumes were 0.04, 0.4 and 2.3 mL. CONCLUSIONS: In normal fetuses the lung and heart volumes increase between 12 and 32 weeks of gestation. The extent to which in pathological pregnancies possible deviations in these measurements from normal prove to be useful in the prediction of outcome remains to be determined. 相似文献
70.
B Sedgmen C McMahon D Cairns R J Benzie R L Woodfield 《Ultrasound in obstetrics & gynecology》2006,27(3):245-251
OBJECTIVE: To explore the impact of timing and type of ultrasound, particularly three-dimensional (3D), exposure on maternal-fetal attachment and maternal health behavior during pregnancy. METHODS: Subjects were 68 women aged 18 years or older expecting their first child who presented for a routine ultrasound scan at around either 12 or 18 weeks' gestation in Nepean Hospital, Western Sydney. Women completed questionnaires assessing maternal-fetal attachment and health behavior, and were then allocated arbitrarily to either two-dimensional (2D) or 3D ultrasound examination. Repeat questionnaires were completed 1 week later. RESULTS: Maternal-fetal attachment increased after both 2D and 3D ultrasound exposure, and the effect was moderated by the timing of exposure, with women receiving their first ultrasound examination at around 12 weeks showing the greatest change. Alcohol consumption was the only behavior to show significant change following ultrasound exposure, with a reduction in the reported average number of drinks per week. There was no significant difference in the pattern of change for 2D compared with 3D ultrasound exposure, and no effect of ultrasound exposure on maternal perception of the fetus. CONCLUSIONS: Ultrasound has a positive impact on maternal-fetal attachment, particularly in the first trimester. 3D ultrasound did not offer enhanced benefits. Associations between ultrasound exposure and alcohol consumption warrant further investigation. Larger samples are needed to clarify the moderating effects of gestational age and type of ultrasound exposure. 相似文献