全文获取类型
收费全文 | 7026篇 |
免费 | 263篇 |
国内免费 | 49篇 |
专业分类
耳鼻咽喉 | 80篇 |
儿科学 | 389篇 |
妇产科学 | 90篇 |
基础医学 | 1352篇 |
口腔科学 | 133篇 |
临床医学 | 389篇 |
内科学 | 635篇 |
皮肤病学 | 29篇 |
神经病学 | 1380篇 |
特种医学 | 67篇 |
外科学 | 253篇 |
综合类 | 648篇 |
预防医学 | 857篇 |
眼科学 | 84篇 |
药学 | 692篇 |
4篇 | |
中国医学 | 210篇 |
肿瘤学 | 46篇 |
出版年
2023年 | 121篇 |
2022年 | 170篇 |
2021年 | 243篇 |
2020年 | 178篇 |
2019年 | 235篇 |
2018年 | 158篇 |
2017年 | 194篇 |
2016年 | 177篇 |
2015年 | 159篇 |
2014年 | 373篇 |
2013年 | 430篇 |
2012年 | 333篇 |
2011年 | 409篇 |
2010年 | 334篇 |
2009年 | 345篇 |
2008年 | 312篇 |
2007年 | 296篇 |
2006年 | 311篇 |
2005年 | 229篇 |
2004年 | 206篇 |
2003年 | 172篇 |
2002年 | 144篇 |
2001年 | 125篇 |
2000年 | 137篇 |
1999年 | 114篇 |
1998年 | 94篇 |
1997年 | 72篇 |
1996年 | 81篇 |
1995年 | 102篇 |
1994年 | 80篇 |
1993年 | 80篇 |
1992年 | 65篇 |
1991年 | 68篇 |
1990年 | 49篇 |
1989年 | 52篇 |
1988年 | 62篇 |
1987年 | 41篇 |
1986年 | 40篇 |
1985年 | 80篇 |
1984年 | 62篇 |
1983年 | 44篇 |
1982年 | 53篇 |
1981年 | 48篇 |
1980年 | 49篇 |
1979年 | 34篇 |
1978年 | 31篇 |
1977年 | 28篇 |
1975年 | 22篇 |
1973年 | 17篇 |
1972年 | 20篇 |
排序方式: 共有7338条查询结果,搜索用时 46 毫秒
1.
《Seminars in perinatology》2022,46(7):151635
The Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network (NRN) maintains a database of extremely preterm infants known as the Generic Database (GDB). Begun in 1987, this database now includes more than 91,000 infants, most of whom are extremely preterm (<29 weeks gestation). The GDB has been the backbone of the NRN, providing high quality, prospectively collected data to study the changing epidemiology of extreme prematurity and its outcomes over time. In addition, GDB data have been used to generate hypotheses for prospective studies and to develop new clinical trials by providing information about the numbers and characteristics of available subjects and the expected event rates for conditions and complications to be studied. Since its inception, the GDB has been the basis of more than 200 publications in peer-reviewed journals, many of which have had a significant impact on the field of neonatology. 相似文献
2.
《Vaccine》2022,40(24):3380-3388
BackgroundWe evaluated the safety and immunogenicity of NVX-CoV2373, a recombinant SARS-CoV-2 nanoparticle vaccine, in healthy Japanese participants.MethodsThis phase 1/2, randomized, observer-blind, placebo-controlled trial conducted in Japan (two sites), enrolled healthy Japanese adults aged ≥ 20 years with no history/risk of SARS-CoV-2 infection and no prior exposure to other approved/investigational SARS-CoV-2 vaccines or treatments. Participants were stratified by age (< 65 or ≥ 65 years) and randomized to receive two doses of either NVX-CoV2373 (5 μg SARS-CoV-2 rS; 50 μg Matrix-M1) or placebo, 21 days apart. Primary outcomes were safety and immunogenicity assessed by serum IgG antibody levels against SARS-CoV-2 rS protein on day 36. Herein, we report the primary data analysis at 4 weeks after the second dose, ahead of 12-month follow-up completion (data cut-off: 8 May 2021).ResultsBetween 12 February 2021 and 17 March 2021, 326 subjects were screened, and 200 participants enrolled and randomized: NVX-CoV2373, n = 150; placebo, n = 50. Solicited adverse events (AEs) through 7 days after each injection occurred in 121/150 (80.7%) and 11/50 (22.0%) participants in the NVX-CoV2373 and placebo arms, respectively. In the NVX-CoV2373 arm, tenderness and injection site pain were the most frequently reported solicited AEs after each vaccination, irrespective of age. Robust immune responses occurred with NVX-CoV2373 (n = 150) by day 36: IgG geometric mean fold rise (95% confidence interval) 259 (219, 306); seroconversion rate 100% (97.6, 100). No such response occurred with placebo (n = 49).ConclusionTwo doses of NVX-CoV2373 given with a 21-day interval demonstrated acceptable safety and induced robust anti-SARS-CoV-2 immune responses in healthy Japanese adults. Funding: Takeda Pharmaceutical Company Limited and Japan Agency for Medical Research and Development (AMED). ClinicalTrials.gov identifier: NCT04712110. 相似文献
3.
4.
《Pediatric Dental Journal》2019,29(3):116-122
ObjectiveInvestigation of dynamic occlusal contacts when food particles are being pulverized during chewing is of interest for many researchers and clinicians. However, measurement of dynamic occlusal contacts during chewing is difficult, and differences between children and adults have not been established. The purpose of this study is to test the hypothesis that dynamic occlusal contacts of children differ from those of adult females.Subjectsand methods: Thirteen healthy children (4–6 years of age; mean age 5 years, 7 months) and thirteen adult females (18–26 years of age; mean age 20 years, 7 months) with normal occlusion participated in this study. Occlusal contact area (OCA) was estimated with a developed measurement system combining 3-D digitization of tooth shape with 3-D tracking of mandibular movements (1) during the closing stroke, (2) at the maximum closing position (MCP), and (3) during the opening stroke. OCA at static maximum intercuspation (ICP) was also estimated.ResultsAt the MCP, the children's OCA was less than 76.4% of the contact area seen at the ICP. The timing of maximum OCA in children was shifted more towards the opening stroke compared with adults, and the OCA remained greater during opening in children than adults. The occurrence of the MCP was less stable in children than in adults, both between subjects and within subjects.ConclusionsWe conclude that both the amount of OCA and the pattern of occlusal contacts during the occlusal phase of chewing completely differ between children and adult females. 相似文献
5.
6.
7.
《Clinical neurophysiology》2019,130(10):1859-1868
ObjectivePreterm infants are at risk for altered brain maturation resulting in neurodevelopmental impairments. Topographical analysis of high-density electroencephalogram during sleep matches underlying brain maturation. Using such an EEG mapping approach could identify preterm infants at risk early in life.Methods20 preterm (gestational age < 32 weeks) and 20 term-born infants (gestational age > 37 weeks) were recorded by 18-channel daytime sleep-EEG at term age (GA 40 weeks for preterm and 2–3 days after birth for term infants) and 3 months (corrected age for preterm infants).ResultsPreterm infant’s power spectrum at term age is immature, leveling off with term infants at 3 months of age. Topographical distribution of maximal power density however, reveals qualitative differences between the groups until 3 months of age. Preterm infants exhibit more temporal than central activation at term age and more occipital than central activation at 3 months of age. Moreover, being less mature at term age predicts being less mature at 3 months of age.ConclusionTopographical analysis of sleep EEG reveals changes in brain maturation between term and preterm infants early in life.SignificanceIn future, automated analysis tools using topographical power distribution could help identify preterm infants at risk early in life. 相似文献
8.
9.
《The British journal of oral & maxillofacial surgery》2022,60(4):499-506
The aim of this study was to carry out a retrospective multicentre study comparing the morphological outcome of 8 techniques used for the management of sagittal synostosis versus a large cohort of control patients. Computed tomographic (CT) images were obtained from children CT-scanned for non-craniosynostosis related events (n = 241) and SS patients at preoperative and postoperative follow-up stages (n = 101). No significant difference in morphological outcomes was observed between the techniques considered in this study. However, the majority of techniques showed a tendency for relapse. Further, the more invasive procedures at older ages seem to lead to larger intracranial volume compared to less invasive techniques at younger ages. This study can be a first step towards future multicentre studies, comparing surgical results and offering a possibility for objective benchmarking of outcomes between methods and centres. 相似文献
10.
We investigated behavioral and neural mechanisms in the relation between social media use (SMU) and self-concept, as well as longitudinal developmental outcomes. Adolescents and young adults (N = 150, 11–21 years old at T1) rated themselves on 60 traits in the academic, physical and prosocial domain, and also indicated how they thought peers would judge them (reflected-peer-judgements). Longitudinal questionnaires (1- and 2-year follow-up) were collected to assess positive (prosocial behavior, self-concept clarity) and negative (clinical symptoms) long-term outcomes.Results indicated that heavier self-reported SMU was linked with lower difference scores between self-judgements and reflected-peer-judgements. Lower SMU was related to more positive ratings from self-judgements vs. reflected-peer-judgements. SMU was also associated with less positive self-concept, particularly in the academic domain (boys and girls) and physical domain (girls). Neurally, increased SMU was linked to heightened mPFC-activity during self-judgements compared to reflected-peer-judgements, and increased activity during physical compared to academic and prosocial self-judgements. Longitudinal analyses indicated no evidence for long-term effects of social media use, self/reflected-peer-difference scores and mPFC-activity on clinical symptoms, prosocial behavior or self-concept clarity. This study highlights the complex relationship between social media use and wellbeing and future research is needed to confirm the lack of long-term effects. 相似文献