全文获取类型
收费全文 | 3185篇 |
免费 | 179篇 |
国内免费 | 19篇 |
学科分类
医药卫生 | 3383篇 |
出版年
2024年 | 8篇 |
2023年 | 66篇 |
2022年 | 106篇 |
2021年 | 173篇 |
2020年 | 83篇 |
2019年 | 110篇 |
2018年 | 147篇 |
2017年 | 107篇 |
2016年 | 132篇 |
2015年 | 123篇 |
2014年 | 157篇 |
2013年 | 173篇 |
2012年 | 281篇 |
2011年 | 261篇 |
2010年 | 136篇 |
2009年 | 113篇 |
2008年 | 175篇 |
2007年 | 179篇 |
2006年 | 147篇 |
2005年 | 115篇 |
2004年 | 81篇 |
2003年 | 81篇 |
2002年 | 100篇 |
2001年 | 26篇 |
2000年 | 15篇 |
1999年 | 19篇 |
1998年 | 16篇 |
1997年 | 13篇 |
1996年 | 15篇 |
1995年 | 10篇 |
1994年 | 6篇 |
1993年 | 7篇 |
1992年 | 8篇 |
1991年 | 15篇 |
1990年 | 15篇 |
1989年 | 9篇 |
1988年 | 8篇 |
1987年 | 4篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1980年 | 6篇 |
1977年 | 5篇 |
1968年 | 4篇 |
1931年 | 5篇 |
1928年 | 6篇 |
1927年 | 4篇 |
1923年 | 4篇 |
1902年 | 3篇 |
1896年 | 3篇 |
1893年 | 5篇 |
排序方式: 共有3383条查询结果,搜索用时 15 毫秒
61.
62.
63.
Stoecklein Veit Michael Kellert Lars Patzig Maximilian Küpper Clemens Giese Armin Ruf Viktoria Weller Jonathan Kreth Friedrich-Wilhelm Schöberl Florian 《Journal of neurology》2021,268(1):367-376
Journal of Neurology - To evaluate the diagnostic accuracy and safety of extended stereotactic brain biopsy (ESBB) in a single center cohort with suspected primary angiitis of the central nervous... 相似文献
64.
65.
Michael Zech MD Robert Jech MD PhD Sylvia Boesch MD Matej Škorvánek MD PhD Ján Necpál MD Jana Švantnerová MD Matias Wagner MD Ariane Sadr-Nabavi PhD Felix Distelmaier MD Martin Krenn MD PhD Tereza Serranová MD PhD Irena Rektorová MD PhD Petra Havránková MD PhD Alexandra Mosejová MD Iva Příhodová MD PhD Jana Šarláková MD Kristína Kulcsarová MD Olga Ulmanová MD PhD Karel Bechyně MD Miriam Ostrozovičová MD Vladimír Haň MD PhD Joaquim Ribeiro Ventosa MD Theresa Brunet MD Riccardo Berutti PhD Mohammad Shariati MD Ali Shoeibi MD Susanne A. Schneider MD Alice Kuster MD Matthias Baumann MD David Weise MD Friederike Wilbert MD Wibke G. Janzarik MD Matthias Eckenweiler MD Volker Mall MD Bernhard Haslinger MD Steffen Berweck MD Juliane Winkelmann MD Konrad Oexle MD 《Movement disorders》2021,36(8):1959-1964
66.
ObjectiveTo predict the clinically relevant transmitted irradiance that is available for luting when a CAD/CAM restoration is inserted. The influence of irradiance, exposure distance, light curing unit (LCU) angulation and direction of polymerization is analyzed when curing through crowns of different thicknesses.MethodsThree modern CAD/CAM resin-based composites (RBCs) were used to produce 45 crown-shaped specimens. The distance between fissure and crown base was set at 1.0, 1.5 and 2.0 mm (n = 5). Transmitted irradiance, while using a violet-blue LCU, was measured with a photo-spectrometer. 180 exposure conditions per specimen were investigated by variation in LCU curing mode, angulation, exposure distance and direction. Data was analyzed using univariate ANOVA followed by Tukey HSD (α = 0.05) and comparison of 95% confidence intervals.ResultsThe CAD/CAM-RBC’s decadic absorption coefficient ranges from 0.317 mm?1 to 0.387 mm?1 and the reflection correcting factor for crowns ranges from 0.305 to 0.337. Transmitted irradiance decreases significantly with increasing exposure distance and decreasing incident irradiance. For tilt angles greater than 10°, transmitted irradiances are significantly reduced (?11% for 20°, ?23% for 30°). Significantly lowest transmitted irradiances were measured for vestibular curing direction (up to ?15%).SignificanceA calculation model can predict the transmitted irradiance through a CAD/CAM restoration in dependence of restoration thickness and radiant emittance. The practitioner can be supported by this model to adapt material choice of dental restoration and adhesive system to the individual situation. Variation in exposure conditions shows negative effect on the transmission of light and should be limited. 相似文献
67.
68.
Karolin J. Paprottka Philipp M. Paprottka Maximilian F. Reiser Tobias Waggershauser 《Diagnostic and interventional radiology (Ankara, Turkey)》2015,21(5):403-409
PURPOSE
Clinical cases of stent-fractures show that corrosion behavior might play a role in these fractures. Implanted in vivo, especially in combination with other implanted foreign materials, these metallic products are exposed to special conditions, which can cause a process of corrosion. Here, we aimed to test the corrosion potential of stents made of different materials in an in vitro setting.METHODS
A total of 28 peripheral stents of different materials (nitinol, cobalt-chromium-nickel, tantalum, V4A) and surface treatments (electropolish, mechanical polish, no polish) were tested in vitro. Corrosion was accelerated by applying a constant voltage of 3.5 V and amperage of 1.16 mA in 0.9% NaCl.RESULTS
Nitinol stents showed the lowest susceptibility to corrosion and the longest period without damage. The Memotherm II® (BARD Angiomed®) was the only stent that showed neither macroscopic nor microscopic damages. The worst performing material was cobalt-chromium-nickel, which showed corrosion damages about ten times earlier compared to nitinol. Considering the reasons for termination of the test, nitinol stents primarily showed length deficits, while V4A and tantalum stents showed fractures. Cobalt-chromium-nickel stents had multiple fractures or a complete lysis in equal proportions. When placed in direct contact, nitinol stents showed best corrosion resistance, regardless of what material they were combined with. In terms of polishing treatments, electropolished stents performed the best, mechanical-polished stents and those without polishing treatment followed.CONCLUSION
The analysis of corrosion behavior may be useful to select the right stent fulfilling the individual needs of the patient within a large number of different stents.Congenital stenosis or volume decreasing processes due to accumulation of tissues or by outside pressures are the most common indications for vascular interventional therapies. After the initial “cardiac catheterization” by Forssmann et al. (1) in 1929, percutaneous interventional techniques for treatment of vasoconstricting processes was continued constantly, whereby the use of permanent mechanical stents has gained an increasingly important role.Stents used in clinical practice should fulfill certain conditions to achieve an un-problematic application as well as an optimal result. The following properties apply to this ideal: good biocompatibility, low shortening, high-density in X-ray, high patency rates, low thrombogenicity, rapid endothelialization without excessive intimal hyperplasia, high flexibility and longitudinal elasticity, sufficient pressure stability at high centrifugal force, technical ability to secure application and exact positioning, and good expansion ratio for safe percutaneous application also with larger prostheses (2, 3). With the approval of stents for clinical use in 1986, the use of stents in peripheral vessels was also practiced on human patients. Palmaz et al. (4) published the first results of the clinical use in 1988 in one of the first multicenter trials on the use of stents in stenosed atherosclerotic iliac arteries. After the successful development of Palmaz® stents and Wallstents® as prototypes of balloon-expandable and self-expanding stents, a variety of new stents have been developed.The stents used today are made of different materials. These include nickel titanium alloys (nitinol), surgical stainless steel (V4A), tantalum, and cobalt compounds. Implanted in the human body, especially in combination with other implanted foreign materials, these metallic products are exposed to special conditions causing a process of corrosion. The higher the ionic conductivity of a liquid is, the faster the reaction. For this reason, liquids that contain a high proportion of electrolytes, such as blood with its high proportion of NaCl, cause much faster corrosion of materials (5).We aimed to perform a comparative study regarding the corrosion behavior of peripheral stents, to reffect the behavior of implanted stents in patients and contribute to find a safer indication in the selection of vascular prostheses. Likewise, we tested the hypothesis that the polishing process influences their corrosion behavior. 相似文献69.
Numerical and In Vitro Investigation of a Novel Mechanical Circulatory Support Device Installed in the Descending Aorta 下载免费PDF全文
Mohammad Amin Rezaienia Akbar Rahideh Borhan Alhosseini Hamedani Dawid Emanuel Maximilian Bosak Silviya Zustiak Theodosios Korakianitis 《Artificial organs》2015,39(6):502-513
Traditional implantation techniques of assist devices from the apex of left ventricle to the ascending or descending aorta are highly invasive and carry substantial complications for end‐stage heart failure patients. This study has shown that the descending aorta can be a promising location to install an implantable mechanical circulatory support with minimally invasive surgery. Herein, the hemodynamic effect of an in‐house prototyped pump implanted in the descending aorta was investigated numerically as well as experimentally. The objective of the experimental study is met by using the in‐house simulator of the cardiovascular loop replicating congestive heart failure conditions. The objective of the numerical study was met by using the modified version of the concentrated lumped parameter model developed by the same team. The results show that the pump placement in the descending aorta can lead to an improvement in pulsatility. The pressure drop, generated at the upstream of the pump, facilitates the cardiac output as a result of after‐load reduction, but at the same time, it induces a slight drop in the carotid as well as the coronary perfusion. The pressure rise, generated at the downstream of the pump, improves the blood perfusion in the renal circulation. 相似文献
70.