收费全文 | 4119篇 |
免费 | 408篇 |
国内免费 | 39篇 |
耳鼻咽喉 | 3篇 |
儿科学 | 542篇 |
妇产科学 | 1116篇 |
基础医学 | 222篇 |
口腔科学 | 29篇 |
临床医学 | 444篇 |
内科学 | 436篇 |
皮肤病学 | 10篇 |
神经病学 | 62篇 |
特种医学 | 41篇 |
外科学 | 68篇 |
综合类 | 487篇 |
现状与发展 | 1篇 |
一般理论 | 1篇 |
预防医学 | 738篇 |
眼科学 | 28篇 |
药学 | 247篇 |
3篇 | |
中国医学 | 38篇 |
肿瘤学 | 50篇 |
2023年 | 93篇 |
2022年 | 126篇 |
2021年 | 273篇 |
2020年 | 230篇 |
2019年 | 238篇 |
2018年 | 217篇 |
2017年 | 220篇 |
2016年 | 302篇 |
2015年 | 193篇 |
2014年 | 323篇 |
2013年 | 398篇 |
2012年 | 219篇 |
2011年 | 270篇 |
2010年 | 188篇 |
2009年 | 187篇 |
2008年 | 169篇 |
2007年 | 150篇 |
2006年 | 143篇 |
2005年 | 119篇 |
2004年 | 73篇 |
2003年 | 77篇 |
2002年 | 44篇 |
2001年 | 33篇 |
2000年 | 44篇 |
1999年 | 24篇 |
1998年 | 12篇 |
1997年 | 23篇 |
1996年 | 19篇 |
1995年 | 12篇 |
1994年 | 15篇 |
1993年 | 9篇 |
1992年 | 14篇 |
1991年 | 9篇 |
1990年 | 7篇 |
1989年 | 6篇 |
1988年 | 6篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 16篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 10篇 |
1980年 | 5篇 |
1979年 | 5篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1975年 | 5篇 |
1972年 | 3篇 |
1971年 | 2篇 |
1968年 | 3篇 |
Method: This study included 225 singleton pregnancies attending Canakkale Onsekiz Mart University Obstetrics and Gynecology clinic for all monitoring and examinations, and gave birth at our clinic between January 2011 and December 2012. Data sources were clinical records and the hospital's automation system, and the study was planned as retrospective cohort. NT measurement was made between 10 weeks 3 days and 13 weeks 6 days gestation. For data analysis, the chi-square, Mann–Whitney U test and Spearman correlation were used.
Results: Of pregnancies, in the study, 5 (2.2%) developed GDM, 6 (2.6%) developed GHT, 2 (0.89%) developed IUGR and 10 (4.4%) developed oligohydramnios. There was no correlation identified between NT measurements and development of GDM, GHT, IUGR and oligohydramnios.
Conclusion: There was no relationship found between first trimester NT measurements and complications that could develop in pregnancy. For the first time in the literature, NT and oligohydramnios were studied and no relationship was observed. 相似文献
Methods: A prospective, non-interventional study was conducted, in 55 singleton fetuses, between 18 and 24 weeks’ gestation. Fetal nasal bone length was measured in the midsagittal plane by two-dimensional imaging and in the midsagittal and coronal plane with three-dimensional ultrasound. All three measurements were compared with one another using one-way repeated samples-measures ANOVA and paired samples t-test.
Results: The average fetal nasal bone length (mean?±?SD) as determined by the three methods was 7.01?±?0.94?mm for the two-dimensional midsagittal, 6.96?±?1.34?mm for the three-dimensional midsagittal, and 6.98?±?1.32?mm for the three-dimensional coronal plane; comparisons between one another were not statistically significant. Unilateral hypoplasia and bifid shape of the fetal nasal bone were detected in 8.2% and 20.4% of cases, respectively, by three-dimensional ultrasound, whereas all cases evaded detection with two-dimensional ultrasound (p?<?0.001 and p?=?0.001, respectively).
Conclusions: Fetal nasal bone length measured with two-dimensional ultrasound does not differ significantly from three-dimensional measurements. However, three-dimensional ultrasound is superior in detecting unilateral nasal bone hypoplasia or absence and in assessing fetal nasal bone shape. Hence, fetal nasal bone examination in the second trimester should include three-dimensional ultrasound evaluation. 相似文献
Methods: This study was designed as a retrospective study of birth weights over a 12-month period at the Royal Hobart Hospital (RHH) and Barwon Health (BH). Data were collected from the discharge summaries and medical records at both hospitals targeting abnormal fetal weight below 10th percentile (small for gestational age – SGA) and above 90th percentile (large for gestational age – LGA).
Results: There were 4079 study patients from both hospitals. After weight adjustment by gender and gestational age, an abnormal fetal weight was detected in 741 cases (babies over the 90th percentile or below 10th percentile). One hundred and twenty-eight patients with high-risk pregnancies were excluded. Therefore, a total of 613 patients remained that were considered to be low-risk pregnancies with abnormal foetal growth; 305 patients from RHH and 308 from BH. The antenatal detection rate for LGA was 35.9%, at RHH by combination of US and clinical evaluation, while for BH it was 34.8% by clinical evaluation alone (p?=?0.910). The antenatal detection rate for SGA was 36.8% via US and clinical evaluation at RHH and 54.5% by clinical evaluation alone at BH (p?=?0.006).
Conclusion: This study shows no benefit in the use of routine US for the antenatal diagnosis of LGA compared with clinical evaluation in low-risk pregnancies. US evaluation was inferior to clinical evaluation in the antenatal diagnosis of SGA in low-risk pregnancies. 相似文献