全文获取类型
收费全文 | 22548篇 |
免费 | 560篇 |
国内免费 | 47篇 |
专业分类
耳鼻咽喉 | 356篇 |
儿科学 | 637篇 |
妇产科学 | 765篇 |
基础医学 | 3069篇 |
口腔科学 | 1243篇 |
临床医学 | 1539篇 |
内科学 | 4676篇 |
皮肤病学 | 758篇 |
神经病学 | 2034篇 |
特种医学 | 573篇 |
外国民族医学 | 1篇 |
外科学 | 3318篇 |
综合类 | 107篇 |
一般理论 | 8篇 |
预防医学 | 1504篇 |
眼科学 | 351篇 |
药学 | 1099篇 |
中国医学 | 88篇 |
肿瘤学 | 1029篇 |
出版年
2024年 | 151篇 |
2023年 | 170篇 |
2022年 | 388篇 |
2021年 | 691篇 |
2020年 | 472篇 |
2019年 | 620篇 |
2018年 | 731篇 |
2017年 | 504篇 |
2016年 | 534篇 |
2015年 | 671篇 |
2014年 | 890篇 |
2013年 | 1022篇 |
2012年 | 1537篇 |
2011年 | 1633篇 |
2010年 | 987篇 |
2009年 | 856篇 |
2008年 | 1375篇 |
2007年 | 1368篇 |
2006年 | 1290篇 |
2005年 | 1232篇 |
2004年 | 979篇 |
2003年 | 877篇 |
2002年 | 789篇 |
2001年 | 289篇 |
2000年 | 285篇 |
1999年 | 286篇 |
1998年 | 162篇 |
1997年 | 178篇 |
1996年 | 139篇 |
1995年 | 131篇 |
1994年 | 101篇 |
1993年 | 93篇 |
1992年 | 157篇 |
1991年 | 154篇 |
1990年 | 138篇 |
1989年 | 121篇 |
1988年 | 151篇 |
1987年 | 109篇 |
1986年 | 114篇 |
1985年 | 77篇 |
1984年 | 78篇 |
1983年 | 58篇 |
1982年 | 49篇 |
1981年 | 49篇 |
1980年 | 39篇 |
1979年 | 47篇 |
1978年 | 33篇 |
1977年 | 37篇 |
1976年 | 43篇 |
1974年 | 50篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Anna Chang Brian S. Schwartz Elizabeth Harleman Meshell Johnson Louise C. Walter Alicia Fernandez 《Journal of general internal medicine》2021,36(10):3113
Department chairs and division chiefs at research-intensive academic medical centers often find mentoring clinician educators challenging. These faculty constitute the majority of academic physicians. Supporting excellent clinician educators is key to ensuring high-quality patient care and developing tomorrow’s physicians. Little has been written for leaders on strategies to advance academic clinician educators’ career success. We present a framework to guide chairs, chiefs, and mentors seeking to address clinician educator retention and satisfaction in academic medical centers.KEY WORDS: clinician educator, academic medicine, mentoring 相似文献
992.
Sarah V Williams Amoolya Vusirikala Shamez N Ladhani Elena Fernandez Ruiz De Olano Nalini Iyanger Felicity Aiano Kelly Stoker Guduru Gopal Rao Laurence John Bharat Patel Nick Andrews Gavin Dabrera Mary Ramsay Kevin E Brown Jamie Lopez Bernal Vanessa Saliba 《Euro surveillance : bulletin européen sur les maladies transmissibles = European communicable disease bulletin》2021,26(27)
We investigated a COVID-19 outbreak of the SARS-CoV-2 Delta variant of concern in a London care home, where 8/21 residents and 14/21 staff had received a single dose of Vaxzevria (ChAdOx1-S; AstraZeneca) vaccine. We identified 24 SARS-CoV-2 infections (16 residents, 8 staff) among 40 individuals (19 residents, 21 staff); four (3 residents, 1 staff) were hospitalised, and none died. The attack rate after one vaccine dose was 35.7% (5/14) for staff and 81.3% (13/16) for residents. 相似文献
993.
Jani Rankinen Petri Haataja Leo&#x;Pekka Lyytikinen Heini Huhtala Terho Lehtimki Mika Khnen Markku Eskola Andrs Ricardo Prez&#x;Riera Antti Jula Harri Rissanen Kjell Nikus Jussi Hernesniemi 《Annals of noninvasive electrocardiology》2021,26(1)
BackgroundPrevious population studies have presented conflicting results regarding the prognostic impact of intraventricular conduction delays (IVCD).MethodsWe studied long‐term prognostic impact and the association with comorbidities of eight IVCDs in a random sample of 6,299 Finnish subjects (2,857 men and 3,442 women, mean age 52.8, SD 14.9 years) aged 30 or over who participated in the health examination including 12‐lead ECG. For left bundle branch block (LBBB) and non‐specific IVCD (NSIVCD), two different definitions were used.ResultsDuring 16.5 years’ follow‐up, 1,309 of the 6,299 subjects (20.8%) died and of these 655 (10.4%) were cardiovascular (CV) deaths. After controlling for known clinical risk factors, the hazard ratio for CV death, compared with individuals without IVCD, was 1.55 for the Minnesota definition of LBBB (95% confidence interval 1.04–2.31, p = .032) and 1.27 (95% confidence interval 0.80–2.02, p = .308) for the Strauss’ definition of LBBB. Subjects with NSIVCD were associated with twofold to threefold increase in CV mortality depending on the definition. While right bundle branch block, left anterior fascicular block and incomplete bundle branch blocks were associated with seemingly higher mortality, this was no longer the case after adjustment for age and sex. The presence of R‐R’ pattern was not associated with any adverse outcome.ConclusionsIn a population study with long‐term follow‐up, NSIVCD and Minnesota definition of LBBB were independently associated with CV mortality. Other IVCDs had no significant impact on prognosis. The prognostic impact of LBBB and NSIVCD was affected by the definition of the conduction disorder. 相似文献
994.
995.
Lucian Zweifel Igor Zhilyaev Christian Brauner Martin Rheme Gregor Eckhard Valentin Bersier Slobodan Glava&#x;ki Ricardo Pfeiffer 《Materials》2021,14(20)
Creating connection points for sandwich-structured composites without losing technical performance is key to realising optimal lightweight structures. The patented LiteWWeight® technology presents cost-effective connections on sandwich panels in a fraction of a few seconds without predrilling. Ultrasonic equipment is used to insert a thermoplastic fastener into the substrate material and partially melt it into the porous internal structure. This creates a highly interlocked connection (connection strength is above 500 N) suitable for semi-structural applications. This study focused on the simulation and experimental validation of this process, mainly on the interaction between the pin and the substrate material during the joining process. The dynamic thermo-mechanical model showed reasonable agreement with experimental methods such as process data, high-speed camera monitoring or computed tomography and allowed the prediction of the connection quality by evaluation of the degree of interlock. The connection strength prediction by the developed model was validated within several various process setups, resulting in a prediction accuracy between 94–99% depending on the setup. 相似文献
996.
Benjamin Valdez-Salas Ramiro Vazquez-Delgado Jorge Salvador-Carlos Ernesto Beltran-Partida Ricardo Salinas-Martinez Nelson Cheng Mario Curiel-Alvarez 《Materials》2021,14(12)
The construction industry has extensively demanded novel green inhibition strategies for the conservation and protection of carbon steel-reinforced concrete structures. For the first time, the effect of Azadirachta indica leaf extract (Neem) as a potential corrosion inhibitor of carbon steel in reinforced concrete under corrosion in saline simulated media was evaluated. To assess the corrosion inhibition behavior of the Neem natural organic extract, three inorganic commercial inhibitors were tested to compare following the criteria established by Stratful for half-cell potential under a simulated chloride environment. Moreover, the effect of concrete integrity by the Neem treatment was recorded after different temperature conditions, slump, weight alteration, air content, compressive strength, and chloride-ions penetration. The results suggested that the Neem treatments did not alter the concrete integrity and the physicochemical parameters. We reached a promoted long-term corrosion protection of 95% after 182 days of evaluation. Thus far, our current results open up a new promising “green” road to the conservation of carbon steel in reinforced concrete for the construction industry. 相似文献
997.
Shabbir Memon Dariusz Fydrych Aintzane Conde Fernandez Hamed Aghajani Derazkola Hesamoddin Aghajani Derazkola 《Materials》2021,14(16)
One of the main challenging issues in friction stir welding (FSW) of stiffened structures is maximizing skin and flange mixing. Among the various parameters in FSW that can affect the quality of mixing between skin and flange is tool plunge depth (TPD). In this research, the effects of TPD during FSW of an Al-Mg-Si alloy T-joint are investigated. The computational fluid dynamics (CFD) method can help understand TPD effects on FSW of the T-joint structure. For this reason, the CFD method is employed in the simulation of heat generation, heat distribution, material flow, and defect formation during welding processes at various TPD. CFD is a powerful method that can simulate phenomena during the mixing of flange and skin that are hard to assess experimentally. For the evaluation of FSW joints, macrostructure visualization is carried out. Simulation results showed that at higher TPD, more frictional heat is generated and causes the formation of a bigger stir zone. The temperature distribution is antisymmetric to the welding line, and the concentration of heat on the advancing side (AS) is more than the retreating side (RS). Simulation results from viscosity changes and material velocity study on the stir zone indicated that the possibility of the formation of a tunnel defect on the skin–flange interface at the RS is very high. Material flow and defect formation are very sensitive to TPD. Low TPD creates internal defects with incomplete mixing of skin and flange, and high TPD forms surface flash. Higher TPD increases frictional heat and axial force that diminish the mixing of skin and flange in this joint. The optimum TPD was selected due to the best materials flow and final mechanical properties of joints. 相似文献
998.
Jacob Abdelfatah Rubn Paz María Elena Alemn-Domínguez Mario Monzn Ricardo Donate Gabriel Winter 《Materials》2021,14(9)
The degradation rate of polycaprolactone (PCL) is a key issue when using this material in Tissue Engineering or eco-friendly packaging sectors. Although different PCL-based composite materials have been suggested in the literature and extensively tested in terms of processability by material extrusion additive manufacturing, little attention has been paid to the influence of the fillers on the mechanical properties of the material during degradation. This work analyses the possibility of tuning the degradation rate of PCL-based filaments by the introduction of microcrystalline cellulose into the polymer matrix. The enzymatic degradation of the composite and pure PCL materials were compared in terms of mass loss, mechanical properties, morphology and infrared spectra. The results showed an increased degradation rate of the composite material due to the presence of the filler (enhanced interaction with the enzymes). Additionally, a new numerical method for the prediction of the degraded geometry was developed. The method, based on the Monte Carlo Method in an iterative process, adjusts the degradation probability according to the exposure of each discretized element to the degradation media. This probability is also amplified depending on the corresponding experimental mass loss, thus allowing a good fit to the experimental data in relatively few iterations. 相似文献
999.
Yue Yuan Caron A. Jacobs Isabel Llorente Garcia Pedro M. Pereira Scott P. Lawrence Romain F. Laine Mark Marsh Ricardo Henriques 《Viruses》2021,13(1)
The first step of cellular entry for the human immunodeficiency virus type-1 (HIV-1) occurs through the binding of its envelope protein (Env) with the plasma membrane receptor CD4 and co-receptor CCR5 or CXCR4 on susceptible cells, primarily CD4+ T cells and macrophages. Although there is considerable knowledge of the molecular interactions between Env and host cell receptors that lead to successful fusion, the precise way in which HIV-1 receptors redistribute to sites of virus binding at the nanoscale remains unknown. Here, we quantitatively examine changes in the nanoscale organisation of CD4 on the surface of CD4+ T cells following HIV-1 binding. Using single-molecule super-resolution imaging, we show that CD4 molecules are distributed mostly as either individual molecules or small clusters of up to 4 molecules. Following virus binding, we observe a local 3-to-10-fold increase in cluster diameter and molecule number for virus-associated CD4 clusters. Moreover, a similar but smaller magnitude reorganisation of CD4 was also observed with recombinant gp120. For one of the first times, our results quantify the nanoscale CD4 reorganisation triggered by HIV-1 on host CD4+ T cells. Our quantitative approach provides a robust methodology for characterising the nanoscale organisation of plasma membrane receptors in general with the potential to link spatial organisation to function. 相似文献
1000.
Jean H. Daugrois Denis Filloux Charlotte Julian Lisa Claude Romain Ferdinand Emmanuel Fernandez Hugo Fontes Philippe C. Rott Philippe Roumagnac 《Viruses》2021,13(5)
Visacane is a sugarcane quarantine station located in the South of France, far away from sugarcane growing areas. Visacane imports up to 100 sugarcane varieties per year, using safe control and confinement measures of plants and their wastes to prevent any risk of pathogen spread outside of the facilities. Viruses hosted by the imported material are either known or unknown to cause disease in cultivated sugarcane. Poaceae viruses occurring in plants surrounding the quarantine glasshouse are currently unknown. These viruses could be considered as a source of new sugarcane infections and potentially cause new sugarcane diseases in cases of confinement barrier failure. The aim of this study was to compare the plant virome inside and outside of the quarantine station to identify potential confinement failures and risks of cross infections. Leaves from quarantined sugarcane varieties and from wild Poaceae growing near the quarantine were collected and processed by a metagenomics approach based on virion-associated nucleic acids extraction and library preparation for Illumina sequencing. While viruses belonging to the same virus genus or family were identified in the sugarcane quarantine and its surroundings, no virus species was detected in both environments. Based on the data obtained in this study, no virus movement between quarantined sugarcane and nearby grassland has occurred so far, and the confinement procedures of Visacane appear to be properly implemented. 相似文献