全文获取类型
收费全文 | 128940篇 |
免费 | 7751篇 |
国内免费 | 684篇 |
专业分类
耳鼻咽喉 | 1543篇 |
儿科学 | 4052篇 |
妇产科学 | 2830篇 |
基础医学 | 18127篇 |
口腔科学 | 4234篇 |
临床医学 | 12458篇 |
内科学 | 28155篇 |
皮肤病学 | 3125篇 |
神经病学 | 12397篇 |
特种医学 | 3411篇 |
外国民族医学 | 1篇 |
外科学 | 12996篇 |
综合类 | 805篇 |
一般理论 | 68篇 |
预防医学 | 12669篇 |
眼科学 | 2140篇 |
药学 | 8878篇 |
中国医学 | 431篇 |
肿瘤学 | 9055篇 |
出版年
2024年 | 140篇 |
2023年 | 1267篇 |
2022年 | 2578篇 |
2021年 | 4548篇 |
2020年 | 2806篇 |
2019年 | 3885篇 |
2018年 | 4423篇 |
2017年 | 3247篇 |
2016年 | 3688篇 |
2015年 | 4093篇 |
2014年 | 5412篇 |
2013年 | 7277篇 |
2012年 | 10576篇 |
2011年 | 10846篇 |
2010年 | 5897篇 |
2009年 | 4949篇 |
2008年 | 8459篇 |
2007年 | 8480篇 |
2006年 | 7761篇 |
2005年 | 7153篇 |
2004年 | 6521篇 |
2003年 | 5696篇 |
2002年 | 5142篇 |
2001年 | 896篇 |
2000年 | 782篇 |
1999年 | 917篇 |
1998年 | 934篇 |
1997年 | 764篇 |
1996年 | 653篇 |
1995年 | 541篇 |
1994年 | 514篇 |
1993年 | 437篇 |
1992年 | 537篇 |
1991年 | 402篇 |
1990年 | 409篇 |
1989年 | 400篇 |
1988年 | 389篇 |
1987年 | 332篇 |
1986年 | 408篇 |
1985年 | 275篇 |
1984年 | 283篇 |
1983年 | 251篇 |
1982年 | 244篇 |
1981年 | 199篇 |
1980年 | 209篇 |
1979年 | 227篇 |
1978年 | 169篇 |
1977年 | 135篇 |
1976年 | 132篇 |
1975年 | 122篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
?ngela S. Inácio Gabriel N. Costa Neuza S. Domingues Maria S. Santos António J. M. Moreno Winchil L. C. Vaz Otília V. Vieira 《Antimicrobial agents and chemotherapy》2013,57(6):2631-2639
Surfactants have long been known to have microbicidal action and have been extensively used as antiseptics and disinfectants for a variety of general hygiene and clinical purposes. Among surfactants, quaternary ammonium compounds (QAC) are known to be the most useful antiseptics and disinfectants. However, our previous toxicological studies showed that QAC are also the most toxic surfactants for mammalian cells. An understanding of the mechanisms that underlie QAC toxicity is a crucial first step in their rational use and in the design and development of more effective and safer molecules. We show that QAC-induced toxicity is mediated primarily through mitochondrial dysfunction in mammalian columnar epithelial cell cultures in vitro. Toxic effects begin at sublethal concentrations and are characterized by mitochondrial fragmentation accompanied by decreased cellular energy charge. At very low concentrations, several QAC act on mitochondrial bioenergetics through a common mechanism of action, primarily by inhibiting mitochondrial respiration initiated at complex I and, to a lesser extent, by slowing down coupled ADP phosphorylation. The result is a reduction of cellular energy charge which, when reduced below 50% of its original value, induces apoptosis. The lethal effects are shown to be primarily a result of this process. At higher doses (closer to the critical micellar concentration), QAC induce the complete breakdown of cellular energy charge and necrotic cell death. 相似文献
992.
993.
994.
996.
997.
Milena de Paiva Cavalcanti Filipe Dantas-Torres Suênia da Cunha Gonçalves de Albuquerque Rayana Carla Silva de Morais Maria Edileuza Felinto de Brito Domenico Otranto Sinval Pinto Brandão-Filho 《Molecular and cellular probes》2013,27(3-4):122-128
American cutaneous leishmaniasis (ACL) caused by Leishmania (Viannia) braziliensis is a neglected disease of humans in the New World that may also cause irreversible skin and eventually mucocutaneous lesions. This parasite can also infect dogs and represents a diagnostic challenge for veterinarians. Methods currently available for the diagnosis of ACL have a low sensitivity and may be time-consuming, representing a limit for treatment expedition of ACL. Quantitative real time PCR assays (qPCR) for the detection of L. (V.) braziliensis in canine blood samples were developed herein, and the detection limit and specificity of different molecular targets (kDNA and rDNA) evaluated. Of the protocols assessed, two qPCR assays, one targeting the kDNA and other the SSU rDNA of L. (V.) braziliensis, performed better, with detection limits of 100 fg and 10 pg, respectively. These assays were also used to test skin samples from humans with suspected ACL. The results indicate that the qPCR protocols developed represent an advance for the diagnosis of ACL in dogs and humans from this region, and provide a rapid and non-invasive diagnosis of the infection by L. (V.) braziliensis. Considering the quantitative nature of the assays, they will also be useful for monitoring treatment efficacy and preventing relapses in human patients in Brazil, although further studies are needed to critically evaluate the specificity of the qPCRs for their capacity to distinguish different Leishmania species and subspecies (represented by zymodemes) in other countries. Finally, molecular assays established may represent new tools for future basic and applied research focused on species identification, host–parasite associations, and infection dynamics in host and vector populations. 相似文献
998.
Fabiana Miraglia Minekazo Matsuo Zenaide Maria Morais Odir Antonio Dellagostin Fabiana Kömmling Seixas Julio César Freitas Rudy Hartskeerl Luisa Zanolli Moreno Bárbara Letícia Costa Gisele Oliveira Souza Silvio Arruda Vasconcellos Andrea Micke Moreno 《Diagnostic microbiology and infectious disease》2013
Leptospira interrogans serogroup Icterohaemorrhagiae is the major serogroup infecting humans worldwide, and rodents and dogs are the most significant transmission sources in urban environments. Knowledge of the prevalent serovars and their maintenance hosts is essential to understand the epidemiology of leptospirosis. In this study, 20 Leptospira isolates were evaluated by pulsed-field gel electrophoresis (PFGE), variable number tandem-repeat analysis (VNTR), serotyping, and determination of antimicrobial resistance profile. Isolates, originated from bovine, canine, human, and rodent sources, were characterized by microscopic agglutination test with polyclonal and monoclonal antibodies and were identified as L. interrogans serogroup Icterohaemorrhagiae serovar Copenhageni. MICs of antimicrobials often used in veterinary medicine were determined by broth microdilution test. Most of tested antibiotics were effective against isolates, including penicillin, ampicillin, and ceftiofur. Higher MIC variability was observed for fluoroquinolones and neomycin; all isolates were resistant to trimethoprim/sulfamethoxazole and sulphadimethoxine. Isolates were genotyped by PFGE and VNTR; both techniques were unable to discriminate between serovars Copenhageni and Icterohaemorrhagiae, as expected. PFGE clustered all isolates in 1 pulsotype, indicating that these serovars can be transmitted between species and that bovine, rodent, and dogs can maintain them in the environment endangering the human population. 相似文献
999.
Ethan J. Halpern Jacob P. Deutsch Maria M. Hannaway Adrian T. Estepa Anand S. Kenia Kenneth J. Neuburger David C. Levin 《The American journal of emergency medicine》2013,31(10):1479-1485
ObjectiveThe objective of the study is to evaluate cardiac risk factors and risk scores for prediction of coronary artery disease (CAD) and adverse outcomes in an emergency department (ED) population judged to be at low to intermediate risk for acute coronary syndrome.MethodsInformed consent was obtained from consecutive ED patients who presented with chest pain and were evaluated with coronary computed tomography angiography (cCTA). Cardiac risk factors, clinical presentation, electrocardiogram, and laboratory studies were recorded; the Thrombolysis in Myocardial Infarction (TIMI) and Global Registry of Acute Coronary Events (GRACE) scores were tabulated. Coronary computed tomography angiography findings were rated on a 6-level plaque burden scale and classified for significant CAD (stenosis ≥ 50%). Adverse cardiovascular outcomes were recorded at 30 days.ResultsAmong 250 patients evaluated by cCTA, 143 (57%) had no CAD, 64 (26%) demonstrated minimal plaque (< 30% stenosis), 26 (10%) demonstrated mild plaque (< 50% stenosis), 9 (4%) demonstrated moderate single vessel disease (50%-70% stenosis), 2 (1%) demonstrated moderate multivessel disease, and 6 (2%) demonstrated severe disease (> 70% stenosis). Six patients developed adverse cardiovascular outcomes. Among traditional cardiac risk factors, only age (older) and sex (male) were significant independent predictors of CAD. Correlation with CAD was poor for the TIMI (r = 0.12) and GRACE (r = 0.09-0.23) scores. The TIMI and GRACE scores were not useful to predict adverse outcomes. Coronary computed tomography angiography identified severe CAD in all subjects with adverse outcomes.ConclusionAmong ED patients who present with chest pain judged to be at low to intermediate risk for acute coronary syndrome, traditional risk factors are not useful to stratify risk for CAD and adverse outcomes. Coronary computed tomography angiography is an excellent predictor of CAD and outcome. 相似文献
1000.