全文获取类型
收费全文 | 7982篇 |
免费 | 442篇 |
国内免费 | 44篇 |
专业分类
耳鼻咽喉 | 89篇 |
儿科学 | 184篇 |
妇产科学 | 135篇 |
基础医学 | 1011篇 |
口腔科学 | 187篇 |
临床医学 | 673篇 |
内科学 | 2041篇 |
皮肤病学 | 149篇 |
神经病学 | 685篇 |
特种医学 | 230篇 |
外科学 | 1320篇 |
综合类 | 57篇 |
一般理论 | 6篇 |
预防医学 | 503篇 |
眼科学 | 229篇 |
药学 | 432篇 |
中国医学 | 50篇 |
肿瘤学 | 487篇 |
出版年
2024年 | 8篇 |
2023年 | 83篇 |
2022年 | 229篇 |
2021年 | 401篇 |
2020年 | 200篇 |
2019年 | 288篇 |
2018年 | 353篇 |
2017年 | 221篇 |
2016年 | 214篇 |
2015年 | 228篇 |
2014年 | 383篇 |
2013年 | 428篇 |
2012年 | 712篇 |
2011年 | 679篇 |
2010年 | 387篇 |
2009年 | 320篇 |
2008年 | 510篇 |
2007年 | 508篇 |
2006年 | 452篇 |
2005年 | 434篇 |
2004年 | 362篇 |
2003年 | 354篇 |
2002年 | 300篇 |
2001年 | 37篇 |
2000年 | 25篇 |
1999年 | 38篇 |
1998年 | 46篇 |
1997年 | 33篇 |
1996年 | 25篇 |
1995年 | 21篇 |
1994年 | 11篇 |
1993年 | 17篇 |
1992年 | 14篇 |
1991年 | 14篇 |
1990年 | 9篇 |
1989年 | 6篇 |
1988年 | 12篇 |
1987年 | 8篇 |
1986年 | 6篇 |
1985年 | 8篇 |
1984年 | 6篇 |
1983年 | 7篇 |
1982年 | 5篇 |
1981年 | 12篇 |
1980年 | 7篇 |
1979年 | 9篇 |
1976年 | 7篇 |
1975年 | 5篇 |
1974年 | 4篇 |
1972年 | 4篇 |
排序方式: 共有8468条查询结果,搜索用时 31 毫秒
991.
Ulises Garza-Ramos Humberto Barrios Fernando Reyna-Flores Alejandro Sánchez-Pérez Elsa Tamayo-Legorreta Alvaro Ibarra-Pacheco Juana Salazar-Salinas Ricardo Núñez-Ceballos Jesus Silva-Sanchez 《Diagnostic microbiology and infectious disease》2014
The KPC-producing Klebsiella pneumoniae sequence type 258 (ST258) is an important pathogen widely spread in nosocomial infections. In this study, we identified the KPC-2–producing K. pneumoniae clinical isolates of 2 unrelated outbreaks that corresponded to pandemic strain ST258. The isolates showed high resistance to cephalosporins, carbapenems, quinolones, and colistin. The KPC-2–producing K. pneumoniae isolates were compared to the previously studied KPC-3–producing K. pneumoniae isolates from an outbreak in Mexico; they showed an unrelated pulsed-field gel electrophoresis fingerprinting pattern and a different plasmid profile. The KPC-2 carbapenemase gene was identified in two 230- and 270-kb non-conjugative plasmids; however, 1 isolate transferred the KPC-2 gene onto an 80-kb plasmid. These findings endorse the need of carrying out a continuous molecular epidemiological surveillance of carbapenem-resistant isolates in hospitals in Mexico. 相似文献
992.
Víctor Segura-Jiménez Inmaculada C. Álvarez-Gallardo Alejandro Romero-Zurita Daniel Camiletti-Moirón Diego Munguía-Izquierdo Ana Carbonell-Baeza Jonatan R. Ruiz 《Archives of physical medicine and rehabilitation》2014
Objective
To compare the levels of physical activity (PA) assessed with questionnaires (Leisure Time Physical Activity Instrument [LTPAI], Physical Activity at Home and Work Instrument [PAHWI]) and accelerometry in patients with fibromyalgia; and to analyze the test-retest reliability of these questionnaires.Design
Cross-sectional study.Setting
Local fibromyalgia association.Participants
Participants (N=99; 5 men) with fibromyalgia with a mean age of 50.2±9.5 years.Interventions
Not applicable.Main Outcome Measures
Participants carried an accelerometer for 1 week and completed the LTPAI and PAHWI twice (separated by a 1-wk interval). The LTPAI and PAHWI were summed to obtain overall values of PA.Results
Time spent in total, moderate, and moderate-vigorous PA was higher (P<.01) when assessed by the LTPAI and PAHWI compared with accelerometry. The Bland-Altman method showed an absence of agreement between the LTPAI and PAHWI and the accelerometer for moderate, moderate-vigorous, and total PA. The test-retest reliability for the workplace subscale and total score of the PAHWI showed high and moderate intraclass correlation coefficients (ICCs), respectively, but also manifested high SE of measurements (up to 179min/d). The LTPAI showed low to moderate ICCs and high SE of measurements (up to 79min/d). For the LTPAI and PAHWI, the ICCs for total activity across the population were low to moderate, and the Bland-Altman method confirmed this lack of agreement.Conclusions
The LTPAI and PAHWI and the accelerometer differ greatly when assessing PA. Furthermore, the LTPAI and PAHWI did not show good levels of test-retest reliability. Therefore, the self-administered LTPAI and PAHWI show questionable usefulness to assess PA in populations with fibromyalgia. 相似文献993.
Alejandro Gutierrez Li Pan Richard W.J. Groen Frederic Baleydier Alex Kentsis Jason Marineau Ruta Grebliunaite Elena Kozakewich Casie Reed Francoise Pflumio Sandrine Poglio Benjamin Uzan Paul Clemons Lynn VerPlank Frank An Jason Burbank Stephanie Norton Nicola Tolliday Hanno Steen Andrew P. Weng Huipin Yuan James E. Bradner Constantine Mitsiades A. Thomas Look Jon C. Aster 《The Journal of clinical investigation》2014,124(2):644-655
T cell acute lymphoblastic leukemia (T-ALL) is an aggressive cancer that is frequently associated with activating mutations in NOTCH1 and dysregulation of MYC. Here, we performed 2 complementary screens to identify FDA-approved drugs and drug-like small molecules with activity against T-ALL. We developed a zebrafish system to screen small molecules for toxic activity toward MYC-overexpressing thymocytes and used a human T-ALL cell line to screen for small molecules that synergize with Notch inhibitors. We identified the antipsychotic drug perphenazine in both screens due to its ability to induce apoptosis in fish, mouse, and human T-ALL cells. Using ligand-affinity chromatography coupled with mass spectrometry, we identified protein phosphatase 2A (PP2A) as a perphenazine target. T-ALL cell lines treated with perphenazine exhibited rapid dephosphorylation of multiple PP2A substrates and subsequent apoptosis. Moreover, shRNA knockdown of specific PP2A subunits attenuated perphenazine activity, indicating that PP2A mediates the drug’s antileukemic activity. Finally, human T-ALLs treated with perphenazine exhibited suppressed cell growth and dephosphorylation of PP2A targets in vitro and in vivo. Our findings provide a mechanistic explanation for the recurring identification of phenothiazines as a class of drugs with anticancer effects. Furthermore, these data suggest that pharmacologic PP2A activation in T-ALL and other cancers driven by hyperphosphorylated PP2A substrates has therapeutic potential. 相似文献
994.
Tiffany L Stallings Alejandro Riefkohl Lisci Nathan L McCray Daniel E Weiner James S Kaufman Ann Aschengrau Yan Ma Michael P LaValley Oriana Ramírez-Rubio Juan Jose Amador Damaris Lpez-Pilarte Rebecca L Laws Michael Winter V Eloesa McSorley Daniel R Brooks Katie M Applebaum 《Scandinavian journal of work, environment & health》2021,47(5):377
Objectives:Nicaraguan sugarcane workers, particularly cane cutters, have an elevated prevalence of chronic kidney disease of unknown origin, also referred to as Mesoamerican nephropathy (MeN). The pathogenesis of MeN may include recurrent heat stress, crystalluria, and muscle injury with subsequent kidney injury. Yet, studies examining the frequency of such events in long-term, longitudinal studies are limited.Methods:Using employment and medical data for male workers at a Nicaraguan sugarcane company, we classified months of active work as either work as a cane cutter or other sugarcane job and determined occurrence of dysuria, heat events and muscle events. Work months and events occurred January 1997 to June 2010. Associations between cane cutting and each outcome were analyzed using logistic regression based on generalized estimating equations for repeated events, controlling for age.Results:Among 242 workers with 7257 active work months, 19.5% of person-months were as a cane cutter. There were 160, 21, and 16 episodes of dysuria, heat events, and muscle events, respectively. Compared with work months in other jobs, cane cutting was associated with an elevated odds of dysuria [odds ratio 2.40 (95% confidence interval 1.56–3.68)]. The number of heat and muscle events by cane cutter and other job were limited.Conclusions:Working as a cane cutter compared with other jobs in the sugarcane industry was associated with increased dysuria, supporting the hypothesis that cane cutters are at increased risk of events suspected of inducing or presaging clinically evident kidney injury. 相似文献
995.
Mohammad Sirajul Islam Zahid Hayat Mahmud Partha Sarathi Gope Rokon Uz Zaman Zakir Hossain Mohammad Shafiqul Islam Dinesh Mondal Mohammad Abu Yushuf Sharker Khairul Islam Hasin Jahan Abbas Bhuiya Hubert P. Endtz Alejandro Cravioto Valerie Curtis Ousmane Touré Sandy Cairncross 《Tropical medicine & international health : TM & IH》2013,18(3):250-258
996.
Heather L. Forrest Alejandro Garcia Angela Danner Jon P. Seiler Kimberly Friedman Robert G. Webster Jeremy C. Jones 《Influenza and other respiratory viruses》2013,7(6):1194-1201
Background
Despite the use of vaccines, low‐pathogenic (LP) H5N2 influenza viruses have continued to circulate and evolve in chickens in Mexico since 1993, giving rise to multiple genetic variants. Antigenic drift is partially responsible for the failure to control H5N2 influenza by vaccination; the contribution of maternal antibodies to this problem has received less attention.Methods
We investigated the effect of different antisera on the efficacy of vaccination and whether booster doses of vaccine can impact immune suppression.Results
While single doses of inactivated oil emulsion vaccine to currently circulating H5N2 influenza viruses provide partial protection from homologous challenge, chickens that receive high‐titer homologous antisera intraperitoneally before vaccination showed effects ranging from added protection to immunosuppression. Post‐infection antisera were less immunosuppressive than antisera obtained from field‐vaccinated chickens. Homologous, post‐infection chicken antisera provided initial protection from virus challenge, but reduced the induction of detectable antibody responses. Homologous antisera from field‐vaccinated chickens were markedly immunosuppressive, annulling the efficacy of the vaccine and leaving the chickens as susceptible to infection as non‐vaccinated birds. Booster doses of vaccine reduced the immunosuppressive effects of the administered sera.Conclusion
Vaccine efficacy against LP H5N2 in Mexico can be severely reduced by maternal antibodies. Source‐dependent antisera effects offer the possibility of further elucidation of the immunosuppressive components involved. 相似文献997.
998.
999.
1000.
Tristan Whitmarsh Ludovic Humbert Luis M. Del Río Barquero Silvana Di Gregorio Alejandro F. Frangi 《Medical image analysis》2013,17(4):475-487
Current vertebral fracture prevention measures use Dual-energy X-ray Absorptiometry (DXA) to quantify the density of the vertebrae and subsequently determine the risk of fracture. This modality however only provides information about the projected Bone Mineral Density (BMD) while the shape and spatial distribution of the bone determines the strength of the vertebrae. Quantitative Computed Tomography (QCT) allows for the measurement of the vertebral dimensions and volumetric densities, which have been shown to be able to determine the fracture risk more reliably than DXA. However, for the high cost and high radiation dose, QCT is not used in clinical routine for fracture risk assessment. In this work, we therefore propose a method to reconstruct the 3D shape and density volume of lumbar vertebrae from an anteroposterior (AP) and lateral DXA image used in clinical routine. The method is evaluated for the L2, L3 and L4 vertebra. Of these vertebrae a statistical model of the vertebral shape and density distribution is first constructed from a large dataset of QCT scans. All three models are then simultaneously registered onto both AP and lateral DXA image. The shape and volumetric BMD at several regions of the reconstructed vertebrae is then evaluated with respect to the ground truth QCT volumes. For the L2, L3 and L4 vertebrae respectively the shape was reconstructed with a mean (2RMS) point-to-surface distance of 1.00 (2.64) mm, 0.93(2.52) mm and 1.34(3.72) mm and a strong correlation (r > 0.82) was found between the trabecular volumetric BMD extracted from the reconstructions and from the same subject QCT scans. These results indicate that the proposed method is able to accurately reconstruct the 3D shape and density volume of the lumbar vertebrae from AP and lateral DXA, which can potentially improve the fracture risk estimation accuracy with respect to the currently used DXA derived areal BMD measurements. 相似文献