全文获取类型
收费全文 | 3240篇 |
免费 | 147篇 |
国内免费 | 14篇 |
专业分类
耳鼻咽喉 | 27篇 |
儿科学 | 55篇 |
妇产科学 | 40篇 |
基础医学 | 639篇 |
口腔科学 | 25篇 |
临床医学 | 218篇 |
内科学 | 904篇 |
皮肤病学 | 54篇 |
神经病学 | 238篇 |
特种医学 | 144篇 |
外科学 | 333篇 |
综合类 | 21篇 |
预防医学 | 218篇 |
眼科学 | 19篇 |
药学 | 242篇 |
中国医学 | 8篇 |
肿瘤学 | 216篇 |
出版年
2023年 | 23篇 |
2022年 | 99篇 |
2021年 | 139篇 |
2020年 | 65篇 |
2019年 | 76篇 |
2018年 | 78篇 |
2017年 | 67篇 |
2016年 | 81篇 |
2015年 | 94篇 |
2014年 | 125篇 |
2013年 | 171篇 |
2012年 | 262篇 |
2011年 | 277篇 |
2010年 | 172篇 |
2009年 | 103篇 |
2008年 | 195篇 |
2007年 | 184篇 |
2006年 | 171篇 |
2005年 | 167篇 |
2004年 | 146篇 |
2003年 | 130篇 |
2002年 | 109篇 |
2001年 | 22篇 |
2000年 | 13篇 |
1999年 | 30篇 |
1998年 | 13篇 |
1997年 | 15篇 |
1995年 | 12篇 |
1994年 | 9篇 |
1993年 | 8篇 |
1992年 | 20篇 |
1991年 | 11篇 |
1990年 | 18篇 |
1989年 | 8篇 |
1988年 | 15篇 |
1985年 | 14篇 |
1984年 | 12篇 |
1983年 | 8篇 |
1982年 | 11篇 |
1981年 | 8篇 |
1979年 | 14篇 |
1978年 | 9篇 |
1977年 | 10篇 |
1974年 | 14篇 |
1973年 | 23篇 |
1972年 | 16篇 |
1971年 | 14篇 |
1970年 | 13篇 |
1969年 | 8篇 |
1966年 | 8篇 |
排序方式: 共有3401条查询结果,搜索用时 15 毫秒
31.
Michal Marko Petr Hrubý Martin Jan
a Jakub Kíkala Jan Hajzler Frantiek oukal Jan Vojtíek Martin Doleal 《Materials》2022,15(14)
The possibility of the formation of an alkali–silicate reaction (ASR) is a crucial issue for the service life of concrete. The coexistence of key parameters such as the presence of alkalis, reactive SiO2, humidity, and temperature predetermine the possibility of its formation and application. When an ASR gel forms, it results in the concreting cracking and spalling as well as in the deterioration of its overall properties. The risk of ASR depends on the concentration of alkalis and their mobility, which influence their ability to penetrate the concrete. The objective of this study was to determine the ionic mobility of not only Na+ and K+, but Ca2+ as well, from external sources (0.5 and 1.0 mol/L solutions of Na/K carbonate, nitrate, and hydroxide) to a cementitious matrix as the precursor for ASR. The concentrations of ions in both the immersion solutions (ICP) and the cementitious matrix itself (SEM-EDX) were studied as a function of time, from 0 to 120 days, for leaching, and according to temperature (25 and 40 °C). The reaction products were characterized using SEM-EDX. Different diffusion rates and behavior were observed depending on the anion type of the external alkali source. Both sodium and potassium ions in all the three environments studied, namely carbonate, hydroxide, and nitrate, penetrated into the composite and further into its structure by different mechanisms. The action of hydroxides, in particular, transformed the original hydration products into calcium-silicate-hydrate (CASH) or ASR gel, while nitrates crystallized in pores and did not cause any changes in the hydration product. The driving force was the increased temperature of the experiment as well as the increased concentration of the solution to which the test specimen was exposed. 相似文献
32.
Brazdil Vojtech Kala Petr Hudec Martin Poloczek Martin Kanovsky Jan Stipal Roman Jerabek Petr Bocek Otakar Pail Martin Brazdil Milan 《Clinical autonomic research》2022,32(1):9-17
Clinical Autonomic Research - Takotsubo syndrome (TTS), also known as stress cardiomyopathy or “broken heart” syndrome, is a mysterious condition that often mimics an acute myocardial... 相似文献
33.
34.
Lukasova Vera Buzgo Matej Vocetkova Karolina Kubíkov Tereza Tonar Zbynk Doupnik Miroslav Blahnova Veronika Litvinec Andrej Sovkova Vera Voltrov Barbora Staffa Andrea Svora Petr Kralickova Milena Amler Evzen Filova Eva Rustichelli Franco Rampichova Michala 《RSC advances》2018,8(39):21889
Bone regeneration is a long-term process requiring proper scaffolding and drug delivery systems. The current study delivers a three-dimensional (3D) scaffold prepared by blend centrifugal spinning loaded with the osteogenic supplements (OS) β-glycerol phosphate, ascorbate-2-phosphate and dexamethasone. The OS were successfully encapsulated into a fibrous scaffold and showed sustained release for 30 days. Furthermore, biological testing showed the osteoinductive properties of the scaffolds on a model of human mesenchymal stem cells and stimulatory effect on a model of osteoblasts. The osteoinductive properties were further proved in vivo in critical size defects of rabbits. The amount of bone trabecules was bigger compared to control fibers without OS. The results indicate that due to its long-term drug releasing properties, single step fabrication process and 3D structure, the system shows ideal properties for use as a cell-free bone implant in tissue-engineering.Bone regeneration is a long-term process requiring proper scaffolding and drug delivery systems. 相似文献
35.
Epicardial RFA to Achieve Electrical PV Isolation. During catheter ablation of atrial fibrillation, ablation within the pulmonary veins is undesirable due to the risk of pulmonary venous stenosis and the possibility of leaving residual cuffs of arrhythmogenic tissue proximal to the ablation lesion set. An extra-ostial pulmonary vein isolation strategy may circumvent these limitations, but achieving electrical isolation can be technically challenging, even with the use of saline-irrigated radiofrequency energy technology. This report describes the successful use of epicardial radiofrequency ablation in a patient in whom endocardial irrigated radiofrequency ablation failed to achieve extra-ostial pulmonary vein isolation. 相似文献
36.
Stanislava Eisová Ondřej Naňka Petr Velemínský Emiliano Bruner 《Journal of anatomy》2021,239(5):1050-1065
Middle meningeal vessels, dural venous sinuses, and emissary veins leave imprints and canals in the endocranium, and thus provide evidence of vascular patterns in osteological samples. This paper investigates whether craniovascular morphology undergoes changes in craniosynostotic human skulls, and if specific alterations may reflect structural and functional relationships in the cranium. The analyzed osteological sample consists of adult individuals with craniosynostoses generally associated with dolichocephalic or brachycephalic proportions, and a control sample of anatomically normal adult skulls. The pattern and dominance of the middle meningeal artery, the morphology of the confluence of the sinuses, and the size and number of the emissary foramina were evaluated. Craniovascular morphology was more diverse in craniosynostotic skulls than in anatomically normal skulls. The craniosynostotic skulls often displayed enlarged occipito-marginal sinuses and more numerous emissary foramina. The craniosynostotic skulls associated with more brachycephalic morphology often presented enlarged emissary foramina, while the craniosynostotic skulls associated with dolichocephalic effects frequently displayed more developed posterior branches of the middle meningeal artery. The course and morphology of the middle meningeal vessels, dural venous sinuses, and emissary veins in craniosynostotic skulls can be related to the redistribution of growth forces, higher intracranial pressure, venous hypertension, or thermal constraints. These functional and structural changes are of interest in both anthropology and medicine, involving epigenetic traits that concern the functional and ontogenetic balance between soft and hard tissues. 相似文献
37.
Jitka Majovska Igor Nestrasil Amy Paulson David Nascene Katarina Jurickova Anna Hlavata Troy Lund Paul J. Orchard Manuela Vaneckova Jiri Zeman Martin Magner Petr Dusek 《Molecular genetics and metabolism》2021,132(3):189-197
ObjectiveDespite profound neurological symptomatology there are only few MRI studies focused on the brain abnormalities in alpha-mannosidosis (AM). Our aim was to characterize brain MRI findings in a large cohort of AM patients along with clinical manifestations.MethodsTwenty-two brain MRIs acquired in 13 untreated AM patients (8 M/5F; median age 17 years) were independently assessed by three experienced readers and compared to 16 controls.ResultsFocal and/or diffuse hyperintense signals in the cerebral white matter were present in most (85%) patients. Cerebellar atrophy was common (62%), present from the age of 5 years. Progression was observed in two out of 6 patients with follow-up scans. Cortical atrophy (62%) and corpus callosum thinning (23%) were already present in a 13-month-old child. The presence of low T2 signal intensity in basal ganglia and thalami was excluded by the normalized signal intensity profiling. The enlargement of perivascular spaces in white matter (38%), widening of perioptic CSF spaces (62%), and enlargement of cisterna magna (85%) were also observed. Diploic space thickening (100%), mucosal thickening (69%) and sinus hypoplasia (54%) were the most frequent non-CNS abnormalities.ConclusionWhite matter changes and cerebellar atrophy are proposed to be the characteristic brain MRI features of AM. The previously reported decreased T2 signal intensity in basal ganglia and thalami was not detected in this quantitative study. Rather, this relative MR appearance seems to be related to the diffuse high T2 signal in the adjacent white matter and not the gray matter iron deposition that has been hypothesized. 相似文献
38.
39.
Partha Sen Romana Gerychova Petr Janku Marta Jezova Iveta Valaskova Colby Navarro Iris Silva Claire Langston Stephen Welty John Belmont Pawel Stankiewicz 《European journal of human genetics : EJHG》2013,21(4):474-477
Alveolar capillary dysplasia with misalignment of pulmonary veins (ACD/MPV) is a rare developmental lung disorder that is uniformly lethal. Affected infants die within the first few weeks of their life despite aggressive treatment, although a few cases of late manifestation and longer survival have been reported. We have shown previously that mutations and deletions in FOXF1 are a cause of this disorder. Although most of the cases of ACD/MPV are sporadic, there have been infrequent reports of familial cases. We present a family with five out of six children affected with ACD/MPV. DNA analysis identified a missense mutation (c.416G>T; p.Arg139Leu) in the FOXF1 gene that segregated in the three affected siblings tested. The same variant is also present as a de novo mutation in the mother and arose on her paternally derived chromosome 16. The two tested affected siblings share the same chromosome 16 haplotype inherited from their maternal grandfather. Their single healthy sibling has a different chromosome 16 haplotype inherited from the maternal grandmother. The results are consistent with paternal imprinting of FOXF1 in human. 相似文献