全文获取类型
收费全文 | 44906篇 |
免费 | 7489篇 |
国内免费 | 295篇 |
专业分类
耳鼻咽喉 | 537篇 |
儿科学 | 1388篇 |
妇产科学 | 1692篇 |
基础医学 | 2958篇 |
口腔科学 | 2275篇 |
临床医学 | 8780篇 |
内科学 | 10042篇 |
皮肤病学 | 1068篇 |
神经病学 | 3854篇 |
特种医学 | 1137篇 |
外国民族医学 | 5篇 |
外科学 | 5715篇 |
综合类 | 1222篇 |
现状与发展 | 2篇 |
一般理论 | 19篇 |
预防医学 | 5246篇 |
眼科学 | 1181篇 |
药学 | 2315篇 |
1篇 | |
中国医学 | 379篇 |
肿瘤学 | 2874篇 |
出版年
2024年 | 255篇 |
2023年 | 1587篇 |
2022年 | 1049篇 |
2021年 | 1818篇 |
2020年 | 1887篇 |
2019年 | 1377篇 |
2018年 | 2610篇 |
2017年 | 2445篇 |
2016年 | 2565篇 |
2015年 | 2562篇 |
2014年 | 3121篇 |
2013年 | 3277篇 |
2012年 | 2789篇 |
2011年 | 3052篇 |
2010年 | 2417篇 |
2009年 | 2440篇 |
2008年 | 2144篇 |
2007年 | 1808篇 |
2006年 | 1735篇 |
2005年 | 1497篇 |
2004年 | 1471篇 |
2003年 | 1279篇 |
2002年 | 1105篇 |
2001年 | 732篇 |
2000年 | 412篇 |
1999年 | 515篇 |
1998年 | 530篇 |
1997年 | 458篇 |
1996年 | 466篇 |
1995年 | 338篇 |
1994年 | 240篇 |
1993年 | 264篇 |
1992年 | 245篇 |
1991年 | 216篇 |
1990年 | 147篇 |
1989年 | 173篇 |
1988年 | 160篇 |
1987年 | 107篇 |
1986年 | 139篇 |
1985年 | 108篇 |
1984年 | 93篇 |
1983年 | 88篇 |
1982年 | 88篇 |
1981年 | 78篇 |
1980年 | 79篇 |
1979年 | 63篇 |
1978年 | 71篇 |
1977年 | 59篇 |
1975年 | 51篇 |
1973年 | 58篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
991.
992.
993.
Passos CP Santos PR Aguiar MC Cangussu MC Toralles MB da Silva MC Nascimento RJ Campos MI 《Special care in dentistry》2012,32(2):55-60
This study investigated the prevalence of dental caries and periodontal condition in a population with sickle cell disease (SCD), analyzing some associations with disease severity. The Decayed, Missing and Filled Teeth index (DMFT) and Community Periodontal Index (CPI) were recorded for 99 individuals with SCD and 91 matched controls. Socio-demographic status, oral health behaviors, and history of clinical severity of SCD were assessed. Statistical comparisons were performed between the group with SCD and the control group, as well as multivariate logistic regression analyses with DMFT index and CPI as the dependent variables. The mean number of decayed teeth was significantly higher in individuals with HbSS. Older age, female gender, and daily smoking were identified as risk factors for higher DMFT, while older age and absence of daily use of dental floss were risk factors for the development of periodontal disease. In conclusion, risk factors known to cause caries and periodontal disease had more influence on oral health than the direct impact of SCD. 相似文献
994.
995.
996.
997.
998.
Zahra Elyasi Javad Safaei Ghomi Gholam Reza Najafi Mohammad Reza Zand Monfared 《RSC advances》2020,10(72):44159
Although poly (ionic liquids) (PILs) have attracted great research interest owing to their various applications, the performance of nanoporous PILs has been rarely developed in the catalysis field. To this end, a micro–mesoporous PIL with acid–base bifunctional active sites was designed and fabricated by two different polymerization protocols including hydrothermal and classical precipitation polymerization in this paper. Based on our observations, hydrothermal conditions (high temperature and pressure) enabled the proposed sonocatalyst to possess a great porous structure with a high specific surface area (SBET: 315 m2 g−1) and thermal stability (around 450 °C for 45% weight loss) through strengthening cross-linking. In a comparative study, the preferred nanoporous PIL was selected and utilized as the sonocatalyst in a multicomponent reaction of isatins, primary amines, and thioglycolic acid. In the following, a variety of new and known pharmaceutical spiro-4-thiazolidinone derivatives were synthesized at room temperature and obtained excellent yields (>90%) within short reaction times (4–12 min) owing to the substantial synergistic effect between ultrasound irradiation and magnetically separable catalyst.Sustainable synthesize of a new mesoporous poly (ionic liquid) as acid–base bifunctional catalyst for environmental being preparation of monospiro derivatives has been developed. 相似文献
999.
Somayeh Tajik Hadi Beitollahi Fariba Garkani Nejad Iran Sheikh Shoaie Mohammad A. Khalilzadeh Mehdi Shahedi Asl Quyet Van Le Kaiqiang Zhang Ho Won Jang Mohammadreza Shokouhimehr 《RSC advances》2020,10(62):37834
Scientists have categorized conductive polymers as materials having strongly reversible redox behavior and uncommon combined features of plastics and metal. Because of their multifunctional characteristics, e.g., simplistic synthesis, acceptable environmental stability, beneficial optical, electronic, and mechanical features, researchers have largely considered them for diverse applications. Therefore, their capability of catalyzing several electrode reactions has been introduced as one of their significant features. A thin layer of the conducting polymer deposited on the substrate electrode surface can augment the electrode process kinetics of several solution species. Such electrocatalytic procedures with modified conducting polymer electrodes can create beneficial utilization in diverse fields of applied electrochemistry. This review article explores typical recent applications of conductive polymers (2016–2020) as active electrode materials for energy storage applications, electrochemical sensing, and conversion fields such as electrochemical supercapacitors, lithium-ion batteries, fuel cells, and solar cells.Scientists have categorized conductive polymers as materials having strongly reversible redox behavior and uncommon combined features of plastics and metal. 相似文献
1000.
The aim of this study was to immobilize a Co(ii) salen complex on KCC-1 as a catalyst that can be recovered (Co(ii) salen complex@KCC-1). Field-emission transmission electron microscopy, FT-IR spectroscopy, thermogravimetric analysis, elemental analysis, atomic absorption spectroscopy, and XRD were used to confirm the structure and chemical nature of Co(ii) salen complex@KCC-1. The oxidation efficiency was obtained for an extensive range of sulfides and alcohols using this sustainable catalyst, alongside O2 as an oxygen source and isobutyraldehyde (IBA) as an oxygen acceptor, with superior selectivity and conversion for the relevant oxidation products (sulfoxides and ketones or aldehydes) under moderate conditions. The μ-oxo and peroxo groups on the ligands of the Co complex appeared to be responsible for the superior activity of the catalyst. Essential factors behind the oxidation of alcohol and sulfoxides were investigated, including the catalyst, solvent, and temperature. In this paper, molecular oxygen (O2) was used as a green oxidant. Furthermore, kinetic studies were conducted, revealing a first-order reaction for the oxidation of both benzyl alcohol and sulfide. The reaction progressed at mild temperature, and the catalyst could be easily recovered and reused for numerous consecutive runs under the reaction conditions, without any substantial reduction in the functionality of the catalytic system.The aim of this study was to immobilize a Co(ii) salen complex on KCC-1 as a catalyst that can be recovered (Co(ii) salen complex@KCC-1). 相似文献