全文获取类型
收费全文 | 13334篇 |
免费 | 705篇 |
国内免费 | 95篇 |
专业分类
耳鼻咽喉 | 116篇 |
儿科学 | 315篇 |
妇产科学 | 232篇 |
基础医学 | 1865篇 |
口腔科学 | 354篇 |
临床医学 | 1179篇 |
内科学 | 3663篇 |
皮肤病学 | 224篇 |
神经病学 | 1253篇 |
特种医学 | 397篇 |
外科学 | 1898篇 |
综合类 | 42篇 |
一般理论 | 4篇 |
预防医学 | 645篇 |
眼科学 | 190篇 |
药学 | 734篇 |
1篇 | |
中国医学 | 28篇 |
肿瘤学 | 994篇 |
出版年
2024年 | 24篇 |
2023年 | 107篇 |
2022年 | 217篇 |
2021年 | 365篇 |
2020年 | 267篇 |
2019年 | 296篇 |
2018年 | 384篇 |
2017年 | 285篇 |
2016年 | 330篇 |
2015年 | 394篇 |
2014年 | 535篇 |
2013年 | 688篇 |
2012年 | 1093篇 |
2011年 | 1072篇 |
2010年 | 626篇 |
2009年 | 554篇 |
2008年 | 917篇 |
2007年 | 921篇 |
2006年 | 877篇 |
2005年 | 845篇 |
2004年 | 789篇 |
2003年 | 650篇 |
2002年 | 619篇 |
2001年 | 97篇 |
2000年 | 81篇 |
1999年 | 109篇 |
1998年 | 115篇 |
1997年 | 99篇 |
1996年 | 103篇 |
1995年 | 72篇 |
1994年 | 66篇 |
1993年 | 51篇 |
1992年 | 46篇 |
1991年 | 49篇 |
1990年 | 36篇 |
1989年 | 33篇 |
1988年 | 30篇 |
1987年 | 24篇 |
1986年 | 23篇 |
1985年 | 21篇 |
1984年 | 37篇 |
1983年 | 30篇 |
1982年 | 26篇 |
1981年 | 25篇 |
1980年 | 12篇 |
1979年 | 10篇 |
1977年 | 9篇 |
1976年 | 12篇 |
1975年 | 10篇 |
1974年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
The study of intra and interlayer excitons in 2D semiconducting vdW heterostructures is a very hot topic not only from a fundamental but also an applicative point of view. Due to their strong light–matter interaction, Transition Metal Dichalcogenides (TMD) and group-III nitrides are particularly attractive in the field of opto-electronic applications such as photo-catalytic and photo-voltaic ultra-thin and flexible devices. Using first-principles ground and excited-state simulations, we investigate here the electronic and excitonic properties of a representative nitride/TMD heterobilayer, the . We demonstrate that the band alignment is of type I, and low energy intralayer excitons are similar to those of a pristine monolayer. Further, we disentangle the role of strain and AlN dielectric screening on the electronic and optical gaps. These results, although they do not favor the possible use of AlN/ in photo-catalysis, as envisaged in the previous literature, can boost the recently started experimental studies of 2D hexagonal aluminum nitride as a good low screening substrate for TMD-based electronic and opto-electronic devices. Importantly, our work shows how the inclusion of both spin-orbit and many-body interactions is compulsory for the correct prediction of the electronic and optical properties of TMD/nitride heterobilayers. 相似文献
92.
Claudio Ferdeghini Andrea Mezzetta Felicia DAndrea Christian Silvio Pomelli Lorenzo Guazzelli Luca Guglielmero 《Materials》2022,15(23)
Two couples of dicationic ionic liquids, featuring pyrrolidinium and piperidinium cations and different linker chains, were prepared and characterized. 1,1′-(propane-1,3-diyl)bis(1-methylpyrrolidinium) bromide, 1,1′-(octane-1,8-diyl)bis(1-methylpyrrolidinium) bromide, 1,1′-(propane-1,3-diyl)bis(1-methylpiperidinium) bromide, and 1,1′-(octane-1,8-diyl)bis(1-methylpiperidinium) bromide were synthesized in quantitative yields and high purity and thermally characterized through TGA and DSC analysis. In this study, we propose a preliminary comparative evaluation of the effect of the linker chain length and of the size of the aliphatic ammonium ring on the thermal and solubility properties of bromide dicationic ionic liquids. 相似文献
93.
Marco Zuin Giacomo Mugnai Maurizio Anselmi Stefano Bonapace Paolo Bozzini Fabio Chirillo Ada Cutolo Giuseppe Grassi Daniela Mancuso Samuele Meneghin Giulio Molon Antonio Mugnolo Ivan Pantano Angela Polo Paola Purita Loris Roncon Salvatore Sacc Daniele Scarpa Domenico Tavella Sakis Themistoclakis Giovanni Turiano Roberto Valle Maddalena Widmann Edlira Zakja Alberto Zamboni Gianluca Rigatelli Claudio Bilato 《Viruses》2022,14(9)
Background: During the COVID-19 pandemic, the risk of SARS-CoV-2 infection, the public health measures of social distancing, the freedom limitations, quarantine, and the enforced homeworking under the lockdown period, as well as medical causes including COVID-19 infection per se, may have caused major emotional distress, especially in the most vulnerable patients. We aimed to evaluate the variations in the number of admissions due to Takotsubo syndrome (TTS) during the COVID-19 pandemic in the Veneto region. Methods: We retrospectively reviewed and analyzed the number of admissions because of TTS in 13 Divisions of Cardiology located in the Veneto region, the northeastern area of Italy, covering a population of more than 2.5 million inhabitants, during the two major pandemic waves of COVID-19 (the first between 15 March and 30 April 2020 and the second between 15 November and 30 December 2020) that occurred in 2020. Results: In total, 807 acute coronary syndromes were admitted in the 13 enrolling hospitals. Among these, 3.9% had TTS. Compared to the corresponding 2018 and 2019 time periods, we observed a significant increase in the number of TTS cases (+15.6%, p = 0.03 and +12.5%, p = 0.04, comparing 2018 to 2020 and 2019 to 2020, respectively). Geographical distribution of the TTS cases reflected the broad spread of the SARS-CoV-2 infection with a significant direct relationship between TTS incidence and the number of COVID-19 infections according to Pearson’s correlation (r = 0.798, p < 0.001). Conclusions: The higher incidence of TTS during the 2020 COVID-19 pandemic waves, especially in the areas that were hit hardest in terms of morbidity and mortality by the SARS-CoV-2 infection, suggest a strong direct and/or indirect role of COVID-19 in the pathogenesis of TTS. 相似文献
94.
Maria Grazia Amoroso Francesco Serra Gianluca Miletti Lorena Cardillo Claudio de Martinis Luisa Marati Flora Alfano Gianmarco Ferrara Ugo Pagnini Esterina De Carlo Giovanna Fusco Serena Montagnaro 《Viruses》2022,14(11)
From 2019 to 2021, a retrospective molecular study was conducted in the Campania region (southern Italy) to determine the prevalence of viral diseases in domestic cats. A total of 328 dead animals were analyzed by Real-Time PCR for the presence of feline panleukopenia virus (FPV), feline leukemia virus (FeLV), feline enteric coronavirus (FCoV), rotavirus (RVA), feline herpesvirus type 1 (FHV-1), and feline calicivirus (FCV). The possible presence of SARS-CoV-2 was also investigated by Real-Time PCR. The cats included in this study were specifically sourced and referred by local veterinarians and local authorities to the Zooprofilactic Experimental Institute of Southern Italy (IZSM) for pathological evaluation. The samples consisted of owners, catteries, and stray cats. Results revealed: 73.5% positive cats for FPV (189/257), 23.6% for FeLV (21/89), 21.5% for FCoV (56/266), 11.4% for RVA (16/140), 9.05% for FeHV-1 (21/232), and 7.04 for FCV (15/213). In contrast, SARS-CoV-2 was never detected. FPV was more prevalent in winter (p = 0.0027). FCoV FHV-1, FCV, and RVA predominated in autumn, whereas FeLV predominated in summer. As expected, viral infections were found more frequently in outdoor and shelter cats than in indoor ones, although no statistical association was found between animal lifestyle and viral presence. The study showed a high prevalence of FPV, FeLV, and FCoV and a moderate prevalence of RVA, FHV-1, and FCV. Moreover, the prevalence of these pathogens varied among the cat populations investigated. 相似文献
95.
96.
97.
Benedetto Mangiavillano Francesco Auriemma Mario Bianchetti Nicola Mantovani Stefano Pilati Dario Reggio Claudio Barletti Edoardo Forcignan Giuseppe Pentassuglia Alberto Arezzo Elena Cavargini Carlo Fabbri Miriam Mezzanzanica Luca De Luca Rita Conigliaro Alessandro Repici 《Digestive endoscopy》2021,33(1):118-124
98.
99.
Maria Antonia De Francesco Claudio Poiesi Franco Gargiulo Carlo Bonfanti Patrizia Pollara Simona Fiorentini Francesca Caccuri Valentina Carta Lucia Mangeri Simone Pellizzeri Damiano Rizzoni Paolo Malerba Massimo Salvetti Maria Lorenza Muiesan Federico Alberici Francesco Scolari Andrea Pilotto Alessandro Padovani Arnaldo Caruso 《The Journal of infection》2021,82(4):e4-e7