全文获取类型
收费全文 | 1947篇 |
免费 | 133篇 |
国内免费 | 12篇 |
专业分类
耳鼻咽喉 | 22篇 |
儿科学 | 75篇 |
妇产科学 | 43篇 |
基础医学 | 213篇 |
口腔科学 | 190篇 |
临床医学 | 142篇 |
内科学 | 415篇 |
皮肤病学 | 40篇 |
神经病学 | 131篇 |
特种医学 | 46篇 |
外科学 | 200篇 |
综合类 | 6篇 |
预防医学 | 282篇 |
眼科学 | 29篇 |
药学 | 136篇 |
中国医学 | 13篇 |
肿瘤学 | 109篇 |
出版年
2023年 | 34篇 |
2022年 | 61篇 |
2021年 | 95篇 |
2020年 | 57篇 |
2019年 | 64篇 |
2018年 | 71篇 |
2017年 | 56篇 |
2016年 | 54篇 |
2015年 | 65篇 |
2014年 | 85篇 |
2013年 | 94篇 |
2012年 | 171篇 |
2011年 | 151篇 |
2010年 | 85篇 |
2009年 | 57篇 |
2008年 | 124篇 |
2007年 | 89篇 |
2006年 | 103篇 |
2005年 | 86篇 |
2004年 | 69篇 |
2003年 | 53篇 |
2002年 | 63篇 |
2001年 | 35篇 |
2000年 | 37篇 |
1999年 | 39篇 |
1998年 | 16篇 |
1997年 | 8篇 |
1996年 | 4篇 |
1994年 | 7篇 |
1993年 | 3篇 |
1992年 | 17篇 |
1991年 | 15篇 |
1990年 | 20篇 |
1989年 | 19篇 |
1988年 | 15篇 |
1987年 | 5篇 |
1986年 | 8篇 |
1984年 | 8篇 |
1983年 | 4篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1976年 | 5篇 |
1974年 | 3篇 |
1971年 | 3篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1968年 | 3篇 |
1967年 | 2篇 |
1965年 | 3篇 |
排序方式: 共有2092条查询结果,搜索用时 15 毫秒
81.
Auricelio Batista Cezar-Junior Igor Vilela Faquini Jos Laercio Junior Silva Eduardo Vieira de Carvalho Junior Luiz Euripedes Almondes Santana Lemos Joo Batista Monte Freire Filho Hetevaldo Tavares de Lira Filho Erton Cesar de Albuquerque Pontes Nivaldo Sena Almeida Hildo Rocha Cirne Azevedo-Filho 《Medicine》2020,99(51)
Some evidences suggest the involvement of the central nervous system in patients infected with SARS-CoV-2. We aim to analyze possible associations between coronavirus disease 2019 (COVID-19) pandemic and spontaneous subarachnoid hemorrhage (SAH), in a comprehensive neurological center.We conducted a retrospective case series of 4 patients infected by COVID-19, who developed spontaneous SAH. Clinical data were extracted from electronic medical records.Between March 24, 2020, and May 22, 2020, 4 cases (3 females; 1 male) of SAH were identified in patients infected with SARS-CoV-2, in a comprehensive neurological center in Brazil. The median age was 55.25 years (range 36 -71). COVID-19-related pneumonia was severe in 3 out of 4 cases, and all patients required critical care support during hospitalization. The patients developed Fisher grade III and IV SAH. Digital subtraction angiography (DSA) was performed in 3 of the 4 patients. However, in only 1 case, an aneurysm was identified. Inflammatory blood tests were elevated in all cases, with an average D-dimer of 2336 μg/L and mean C-reactive protein (CRP) of 3835 mg/dl The outcome was poor in the majority of the patients, with 1 death (25%); 2 (50%) remained severely neurologically affected (mRS:4); and 1 (25%) had slight disability (mRS:2).This study shows a series of 4 rare cases of SHA associated with COVID-19. The possible mechanisms underlying the involvement of SARSCoV-2 and SHA is yet to be fully understood. Therefore, SHA should be included in severe neurological manifestations in patients infected by this virus. 相似文献
82.
Jakub Hrubý Vinicius T. Santana Dmytro Kostiuk Martin Bou
ek Samuel Lenz Michal Kern Peter iffalovi
Joris van Slageren Petr Neugebauer 《RSC advances》2019,9(42):24066
The scalability and stability of molecular qubits deposited on surfaces is a crucial step for incorporating them into upcoming electronic devices. Herein, we report on the preparation and characterisation of a molecular quantum bit, copper(ii)dibenzoylmethane [Cu(dbm)2], deposited by a modified Langmuir–Schaefer (LS) technique onto a graphene-based substrate. A double LS deposition was used for the preparation of a few-layer-graphene (FLG) on a Si/SiO2 substrate with subsequent deposition of the molecules. Magnetic properties were probed by high-frequency electron spin resonance (HF-ESR) spectroscopy and found maintained after deposition. Additional spectroscopic and imaging techniques, such as Raman spectroscopy (RS), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and scanning electron microscopy (SEM) were performed to characterise the deposited sample. Our approach demonstrated the possibility to utilise a controlled wet-chemistry protocol to prepare an array of potential quantum bits on a disordered graphene-based substrate. The deployed spectroscopic techniques showed unambiguously the robustness of our studied system with a potential to fabricate large-scale, intact, and stable quantum bits.Graphene-based hybrid material with array of copper(ii)-based quantum bits was prepared by a wet-chemistry protocol and characterised by HF-ESR, XPS, Raman, and AFM. 相似文献
83.
84.
Giorgio SilvaSantana Juliet Cunha Bax Dbora Cristina Silva Fernandes Daniela Tendler Leibel Bacellar Cleber Hooper Alexandre Alves Souza Oliveira Dias Cristina Barbosa Silva Aline Moreira de Souza Simone Ramos Ricardo Alexandre Santos Thainara Ramos Pinto Mariana Antunes Ramo Ana Luíza MattosGuaraldi 《动物模型与实验医学(英文)》2020,3(4):304
BackgroundAnimal models are widely used in scientific research in order to obtain information from a whole organism under a specific set of experimental conditions. Various lineages of mice have been used to investigate diseases and new therapeutic strategies, and, consequently, hematological and biochemical tests in these laboratory animals are essential to validate scientific studies. Our study seeks to establish reference values for hematological and biochemical parameters of four lineages of mice.MethodsWe evaluated the hematological and biochemical profiles of 20 males and 20 females from the lineages Swiss (heterogeneous), BALB/c and C57BL/6 (isogenic), and B6D2F1 (hybrid), totaling 160 mice. Analysis were standardized using the systems pocH‐100iV Diff™ for 19 hematological parameters and VITROS® 350 for 12 biochemical parameters.ResultsResults are shown as means and standard deviation, grouped by lineage and genre. Comparing the values obtained in this study with the values from previous studies, some variations were detected, which could be explained by differences in methodologies or individual variability.ConclusionThus our study shows that knowledge and disclosure of the values of physiological parameters of laboratory animals is necessary, and emphasises the importance of considering variations influenced by gender, lineage and genotype in the choice of the best experimental model. 相似文献
85.
Pedro Henrique Campanini Candido Luciana de Souza Nunes Elizabeth Andrade Marques Tania Wrobel Folescu Fábrice Santana Coelho Vinicius Calado Nogueira de Moura Marlei Gomes da Silva Karen Machado Gomes Maria Cristina da Silva Louren?o Fábio Silva Aguiar Fernanda Chitolina Derek T. Armstrong Sylvia Cardoso Le?o Felipe Piedade Gon?alves Neves Fernanda Carvalho de Queiroz Mello Rafael Silva Duarte 《Journal of clinical microbiology》2014,52(8):2990-2997
Worldwide, nontuberculous mycobacteria (NTM) have become emergent pathogens of pulmonary infections in cystic fibrosis (CF) patients, with an estimated prevalence ranging from 5 to 20%. This work investigated the presence of NTM in sputum samples of 129 CF patients (2 to 18 years old) submitted to longitudinal clinical supervision at a regional reference center in Rio de Janeiro, Brazil. From June 2009 to March 2012, 36 NTM isolates recovered from 10 (7.75%) out of 129 children were obtained. Molecular identification of NTM was performed by using PCR restriction analysis targeting the hsp65 gene (PRA-hsp65) and sequencing of the rpoB gene, and susceptibility tests were performed that followed Clinical and Laboratory Standards Institute recommendations. For evaluating the genotypic diversity, pulsed-field gel electrophoresis (PFGE) and/or enterobacterial repetitive intergenic consensus sequence PCR (ERIC-PCR) was performed. The species identified were Mycobacterium abscessus subsp. bolletii (n = 24), M. abscessus subsp. abscessus (n = 6), Mycobacterium fortuitum (n = 3), Mycobacterium marseillense (n = 2), and Mycobacterium timonense (n = 1). Most of the isolates presented resistance to five or more of the antimicrobials tested. Typing profiles were mainly patient specific. The PFGE profiles indicated the presence of two clonal groups for M. abscessus subsp. abscessus and five clonal groups for M. abscesssus subsp. bolletii, with just one clone detected in two patients. Given the observed multidrug resistance patterns and the possibility of transmission between patients, we suggest the implementation of continuous and routine investigation of NTM infection or colonization in CF patients, including countries with a high burden of tuberculosis disease. 相似文献
86.
Steven M. Santana Marc A. Antonyak Richard A. Cerione Brian J. Kirby 《Biomedical microdevices》2014,16(6):869-877
Extracellular shed vesicles, including exosomes and microvesicles, are disseminated throughout the body and represent an important conduit of cell communication. Cancer-cell-derived microvesicles have potential as a cancer biomarker as they help shape the tumor microenvironment to promote the growth of the primary tumor and prime the metastatic niche. It is likely that, in cancer cell cultures, the two constituent extracellular shed vesicle subpopulations, observed in dynamic light scattering, represent an exosome population and a cancer-cell-specific microvesicle population and that extracellular shed vesicle size provides information about provenance and cargo. We have designed and implemented a novel microfluidic technology that separates microvesicles, as a function of diameter, from heterogeneous populations of cancer-cell-derived extracellular shed vesicles. We measured cargo carried by the microvesicle subpopulation processed through this microfluidic platform. Such analyses could enable future investigations to more accurately and reliably determine provenance, functional activity, and mechanisms of transformation in cancer. 相似文献
87.
Maristela Soares Swerts Pereira Marcos A. Rossi Cristina Ribeiro Cardoso João Santana da Silva Léa Assed Bezerra da Silva Milton Carlos Kuga Gisele Faria 《Journal of endodontics》2014
Introduction
The aim of this study was to characterize the response of mouse subcutaneous tissue to triple antibiotic paste (TAP) using conventional light microscopy and real-time PCR (qRT-PCR).Methods
Polyethylene tubes containing TAP or calcium hydroxide (CH) (ie, the control group) were implanted in mouse subcutaneous tissue. Animals that received empty tubes or no tubes were used as additional controls. After periods of 7, 21, and 63 days postimplantation, the specimens were removed and subjected to histologic processing. The number of inflammatory cells and vessels, vessel areas, vascular density, and relative percentage of collagen were evaluated. Gene expression of proinflammatory (interleukin-1 beta, tumor necrosis factor alpha, and interleukin 17) and anti-inflammatory (transforming growth factor beta) cytokines and angiogenic factors (vascular endothelial growth factor and hypoxia-inducible factor-1 alpha) was quantified by 7 and 21 days postimplantation. Results were analyzed using the Student t test, analysis of variance, and the Tukey test (α = 0.05).Results
TAP induced an exuberant inflammatory and angiogenic response, with higher numbers of inflammatory cells, higher vascular area and density, and lower relative percentage of collagen compared with CH. In general, the expression of genes involved in inflammation and angiogenesis was higher in the TAP group compared with animals that received CH or empty tubes.Conclusions
The response of mouse subcutaneous tissue to TAP was characterized by exuberant and persistent inflammatory and angiogenic responses with no repair and high gene expression of biomarkers associated with inflammation and angiogenesis. 相似文献88.
89.