收费全文 | 30026篇 |
免费 | 1567篇 |
国内免费 | 645篇 |
耳鼻咽喉 | 104篇 |
儿科学 | 149篇 |
妇产科学 | 144篇 |
基础医学 | 2081篇 |
口腔科学 | 512篇 |
临床医学 | 2370篇 |
内科学 | 1533篇 |
皮肤病学 | 90篇 |
神经病学 | 876篇 |
特种医学 | 3110篇 |
外国民族医学 | 5篇 |
外科学 | 11423篇 |
综合类 | 5293篇 |
现状与发展 | 2篇 |
预防医学 | 702篇 |
眼科学 | 431篇 |
药学 | 2031篇 |
33篇 | |
中国医学 | 701篇 |
肿瘤学 | 648篇 |
2024年 | 66篇 |
2023年 | 346篇 |
2022年 | 651篇 |
2021年 | 889篇 |
2020年 | 1023篇 |
2019年 | 765篇 |
2018年 | 659篇 |
2017年 | 904篇 |
2016年 | 1023篇 |
2015年 | 979篇 |
2014年 | 2023篇 |
2013年 | 2029篇 |
2012年 | 2003篇 |
2011年 | 2166篇 |
2010年 | 1819篇 |
2009年 | 1847篇 |
2008年 | 1681篇 |
2007年 | 1690篇 |
2006年 | 1557篇 |
2005年 | 1417篇 |
2004年 | 1225篇 |
2003年 | 919篇 |
2002年 | 664篇 |
2001年 | 617篇 |
2000年 | 463篇 |
1999年 | 390篇 |
1998年 | 272篇 |
1997年 | 294篇 |
1996年 | 225篇 |
1995年 | 198篇 |
1994年 | 165篇 |
1993年 | 133篇 |
1992年 | 118篇 |
1991年 | 78篇 |
1990年 | 89篇 |
1989年 | 77篇 |
1988年 | 76篇 |
1987年 | 63篇 |
1986年 | 57篇 |
1985年 | 89篇 |
1984年 | 66篇 |
1983年 | 51篇 |
1982年 | 64篇 |
1981年 | 62篇 |
1980年 | 43篇 |
1979年 | 40篇 |
1978年 | 29篇 |
1977年 | 39篇 |
1976年 | 25篇 |
1975年 | 30篇 |
Methods: Tumour and surrounding tissue were modeled by elliptical two- and three-dimensional computational phantoms having six different nanoparticle distributions. Nanoparticles were modeled as point heat sources having amplitude-dependent loss power. The total number of nanoparticles was fixed, and their spatial distribution and heat output were varied. Heat transfer was computed by solving the Pennes’ bioheat equation using finite element methods (FEM) with temperature-dependent blood perfusion. Local temperature was regulated using a proportional-integral-derivative (PID) controller. Tissue temperature, thermal dose and tissue damage were calculated. The required minimum thermal dose delivered to the tumor was kept constant, and heating power was adjusted for comparison of both the heating methods.
Results: Modulated power heating produced lower and more homogeneous temperature distributions than did constant power heating for all studied nanoparticle distributions. For a concentrated nanoparticle distribution, located off-center within the tumor, the maximum temperatures inside the tumor were 16% lower for modulated power heating when compared to constant power heating. This resulted in less damage to surrounding normal tissue. Modulated power heating reached target thermal doses up to nine-fold more rapidly when compared to constant power heating.
Conclusions: Controlling the temperature at the tumor-healthy tissue boundary by modulating the heating power of magnetic nanoparticles demonstrably compensates for a variable nanoparticle distribution to deliver effective treatment. 相似文献
We preserved rat livers either by cold storage (UW) for 10 h, or by perfusion for 3 h (oxygenated modified UW) after 10 h cold storage. We assessed viability of livers after preservation and after ischemic rewarming + normothermic reperfusion ex vivo . Ten hour cold storage reduced mitochondrial cytochrome oxidase and metabolically depleted the livers. Oxygenated perfusion after cold storage resulted in uploaded cellular energy charge and oxidized mitochondrial cytochrome oxidase. Reperfusion after 10 h cold storage increased formation of superoxid anions, release of cytosolic LDH, lipid peroxidation, caspase activities and led to disruption of sinusoidal endothelial cells. In contrast, reperfusion after 10 h cold storage + 3 h hypothermic oxygenated perfusion resulted in no changes of lipid peroxidation, bile flow, energy charge, total glutathione, LDH release and of caspase activation, as compared to fresh resected livers.
This study demonstrates, that a metabolically depleted liver due to cold storage can be energy recharged by short-termed cold machine perfusion. The machine perfused graft exhibited improved viability and functional integrity. 相似文献