全文获取类型
收费全文 | 5846篇 |
免费 | 352篇 |
国内免费 | 40篇 |
专业分类
耳鼻咽喉 | 54篇 |
儿科学 | 79篇 |
妇产科学 | 114篇 |
基础医学 | 788篇 |
口腔科学 | 364篇 |
临床医学 | 418篇 |
内科学 | 1662篇 |
皮肤病学 | 130篇 |
神经病学 | 444篇 |
特种医学 | 120篇 |
外科学 | 835篇 |
综合类 | 25篇 |
一般理论 | 1篇 |
预防医学 | 337篇 |
眼科学 | 224篇 |
药学 | 291篇 |
中国医学 | 24篇 |
肿瘤学 | 328篇 |
出版年
2024年 | 7篇 |
2023年 | 52篇 |
2022年 | 149篇 |
2021年 | 290篇 |
2020年 | 168篇 |
2019年 | 233篇 |
2018年 | 243篇 |
2017年 | 164篇 |
2016年 | 180篇 |
2015年 | 227篇 |
2014年 | 308篇 |
2013年 | 328篇 |
2012年 | 461篇 |
2011年 | 539篇 |
2010年 | 261篇 |
2009年 | 205篇 |
2008年 | 335篇 |
2007年 | 360篇 |
2006年 | 313篇 |
2005年 | 302篇 |
2004年 | 240篇 |
2003年 | 205篇 |
2002年 | 193篇 |
2001年 | 58篇 |
2000年 | 48篇 |
1999年 | 43篇 |
1998年 | 15篇 |
1997年 | 24篇 |
1996年 | 18篇 |
1995年 | 11篇 |
1994年 | 14篇 |
1993年 | 10篇 |
1992年 | 13篇 |
1991年 | 22篇 |
1990年 | 15篇 |
1989年 | 13篇 |
1988年 | 20篇 |
1987年 | 10篇 |
1986年 | 12篇 |
1985年 | 16篇 |
1984年 | 12篇 |
1983年 | 12篇 |
1982年 | 7篇 |
1981年 | 9篇 |
1978年 | 5篇 |
1976年 | 5篇 |
1975年 | 9篇 |
1974年 | 9篇 |
1973年 | 7篇 |
1970年 | 5篇 |
排序方式: 共有6238条查询结果,搜索用时 46 毫秒
131.
Gabriel Felipe de Bragança Júlia Dantas Mazão Antheunis Versluis Carlos José Soares 《The Journal of prosthetic dentistry》2021,125(5):778-787
Statement of problemHow the polymerization shrinkage, loading, and mechanical properties of luting materials affect the shrinkage and functional stresses in ceramic laminate veneers (CLVs) with and without tooth preparation is unclear.PurposeThe purpose of this finite element analysis (FEA) study was to evaluate the effect of the polymerization shrinkage, functional loading, and mechanical properties of different luting materials on the stresses in ultrathin 0.3-mm CLVs with and without tooth preparation.Material and methodsThree resin cements, RelyX Veneer (RV), Allcem Veneer APS (AV), Variolink Esthetic LC (VE), and 1 flowable composite resin, Tetric N-Flow (TF), were tested for post-gel shrinkage (Shr), Knoop hardness (KHN), elastic modulus (E), compressive strength (CS), and diametral tensile strength (DTS). IPS e.max CAD disks of 0.3-mm thickness were made for simulating the effects of light attenuation. Eight 2-dimensional finite element models (Marc-Mentat) of a maxillary central incisor were generated to evaluate the polymerization shrinkage stress of different materials for luting 0.3-mm CLVs with or without tooth preparation and the stress during functional loading by using a modified von Mises criterion (mvm). Collected data from Shr, KHN, and E were submitted to 2-way ANOVA and the Tukey HSD test (α=.05).ResultsLight attenuation by the 0.3-mm ceramic disk did not significantly affect the E values, but Shr was significantly lower in VE (26%) and TF (35%). TF had lower volumetric Shr (%) when interposing a ceramic disk (0.31%). Both tested tooth preparation options showed similar stress distributions from polymerization shrinkage or functional loading, with higher stress concentration on the incisal edge and also on the cervical surface. The model featuring tooth preparation and RV resin cement had the highest and VE the lowest stress levels.ConclusionsThe flowable composite resin had similar mechanical properties as the resin cements. The stress distribution from shrinkage and functional loading was similar for both techniques with or without tooth preparation. 相似文献
132.
133.
Juan Venegas Felipe Díaz Tamara Rojas Sandra Miranda M. I. Jercic Christian González William Coñoepán Alex Vargas Sergio Pichuantes Marta Gajardo Jorge Rodríguez Gittith Sánchez 《Acta parasitologica / Witold Stefański Institute of Parasitology, Warszawa, Poland》2013,58(2):139-148
The objective of this study was to investigate if there is specific host-parasite association in Chilean populations of Trypanosoma cruzi. For this purpose, two groups of parasites were analyzed, one from chronic chagasic patients, and the other from Triatoma infestans triatomines in three regions of the country. The first group consisted of four types of samples: parasites from peripheral blood of non-cardiopathic T. cruzi infected patients (NB); parasites from their corresponding xenodiagnosis (NX); parasites from peripheral blood of T. cruzi infected cardiopathic patients (CB) and parasites from their xenodiagnostics (CX). The T. infestans sample in turn was from three regions: III, V and M (Metropolitan). The genetic differentiation by the Fisher exact method, the lineage distribution of the samples, the molecular phylogeny and the frequency of multiclonality were analysed. The results show that not only are the groups of T. cruzi clones from Chagas disease patients and vectors genetically differentiated, but also all the sub-groups (NB, NX, CB and CX) from the III, V and M regions. The analysis of lineage distribution was concordant with the above results, because significant differences among the percentages of TcI, TcIII and hybrids (TcV or TcVI) were observed. The phylogenetic reconstruction with these Chilean T. cruzi samples was coherent with the above results because the four chagasic samples clustered together in a node with high bootstrap support, whereas the three triatomine samples (III, V and M) were located apart from that node. The topology of the tree including published T. cruzi clones and isolates was concordant with the known topology, which confirmed that the results presented here are correct and are not biased by experimental error. Taken together the results presented here are concordant with a specific host-parasite association between some Chilean T. cruzi populations. 相似文献
134.
135.
136.
Felipe Lipsky Luis Henrique da Silveira Lacerda Srgio Ricardo de Lazaro Elson Longo Juan Andrs Miguel Angel San-Miguel 《RSC advances》2020,10(51):30640
Over the years, the possibility of using solar radiation in photocatalysis or photodegradation processes has attracted remarkable interest from scientists around the world. In such processes, due to its electronic properties, Ag3PO4 is one of the most important semiconductors. This work delves into the photocatalytic activity, stability, and reactivity of Ag3PO4 surfaces by comparing plane waves with projector augmented wave and localized Gaussian basis set simulations, at the atomic level. The results indicate that the (110) surface, in agreement with previous experimental reports, displays the most suitable characteristics for photocatalytic activity due to its high reactivity, i.e. the presence of a large amount of undercoordinated Ag cations and a high value work function. Beyond the innovative results, this work shows a good synergy between both kinds of DFT approaches.Over the years, the possibility of using solar radiation in photocatalysis or photodegradation processes has attracted remarkable interest from scientists around the world. 相似文献
137.
138.
139.
Bordini Ester Alves Ferreira Cassiano Fernanda Balestrero Silva Isabela Sanches Pompeo Usberti Felipe Rochelle Anovazzi Giovana Pacheco Leandro Edgar Pansani Tasa Nogueira Leite Maria Lusa Hebling Josimeri de Souza Costa Carlos Alberto Soares Diana Gabriela 《Clinical oral investigations》2020,24(2):663-674
Clinical Oral Investigations - This study aimed to develop a porous chitosan–calcium–aluminate scaffold (CH-AlCa) in combination with a bioactive dosage of 1α,25-dihydroxyvitamin... 相似文献
140.
Machado Felipe Paiva Khoury Rayana Duarte Toia Cassia Cestari Flores Orozco Esteban Isai de Oliveira Felipe Eduardo de Oliveira Luciane Dias da Rosa Cardoso Flávia Goulart Valera Marcia Carneiro 《Clinical oral investigations》2020,24(9):3169-3179
Clinical Oral Investigations - To compare the microbial load and composition and to determine the lipopolysaccharides (LPS) and lipoteichoic acid (LTA) concentrations found in primary apical... 相似文献