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庾晋 《大科技．科学之谜》2003,(4):44-46
古细菌是一类生活在今天的生物，被称为“活化石”细菌，它们不是细菌，因为它们有着与细菌不同的遗传基因。它们是独立的一类生物。我们的生物界被划分为真核生物（细胞中含有细胞核）、细菌和古细菌三大类。古细菌之所以被称为古细菌，只是因为它们是地球上最早出现的生物并且在形态上跟细菌差不了多少。古细菌的生命沉浮 古细菌出现于38亿年以前的生命诞生之初。那时的地球，大气中充满了有毒气体（比如硫化氢），完全没有氧气（即使有那么一点，也会与其他物质反应而被消耗），大气的化学性质是呈还原性的。在这样奇特的环境影响… 相似文献
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人体生物摩擦学的基础科学问题 总被引：2，自引：0，他引：2
人体的生物摩擦副包含头发、皮肤、眼睛、味觉、牙齿、关节、心脏
、血液等,它们
对人体健康和康复质量具有重要影响。本文对人体生物摩擦学的特点、生物摩擦学行为对人
体生命质量的影响、人体生物摩擦学的科学问题进行了探讨,提出了人体内植物“少磨损、
低危害”的生物摩擦学质量概念,以及实现这个目标所需要的NBIC摩擦学融合技术,即Nano
tribology,Biotribology,Implants materials, Coating technology四方面相互交叉融
合产生的摩擦学新技术。 相似文献
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是什么在为我们的生命负责？是生物大分子。生物大分子是指生命体内一些组织结构复杂的高分子，它们是生命活动的主要物质基础，从细菌到动植物等一切生命，都由生物大分子主宰，可以说，生命的本质归根结底在于生物在分子水平上的微观运动。生物大分子的主要类型有蛋白质、核酸（包括DNA和RNA）、多糖类、脂类，其中又以蛋白质特别重要。 “看清”它们的真面目曾经是科学家的梦想，如今这一梦想已成为现实。2002年诺贝尔化学奖表彰的就是这一领域的两项成果。生物分子革命性的解析法 在过去几年中，越来越多的生物有机体的基… 相似文献
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长链多不饱满和脂肪酸是指链长在十八个碳原子以上并含有多个顺型烯式键的脂肪酸，包括：花生四烯酸（二十碳四烯酸，AA，n-6）、二十碳五烯酸（EPA，n-3）和二十二碳六烯酸（DHA，n-3）等。n-6和n-3分别是指这些脂肪酸链的末端第6位和第3位的碳原子上为烯式键。介绍了长链多不饱和脂肪酸对人体生命早期所起到的重要作用以及合理补充的方法。 相似文献
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《大科技．科学之谜》2010,(10):55-57
2010年第08期宛超读者问：假如人类乘坐一艘接近光速的飞船,那么在船上．时间相对于处于普通速度的人来说,就应该是静止的．飞船上的人就应该是长生不老的．可是人体的细胞分裂次数是有限的（除癌细胞外）,人即使在飞船上也应该有正常的生理功能,这样的话,飞船上的人照样会衰老．这两者是不是相互矛盾的？ 相似文献
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《大科技．科学之谜》2010,(8):55-55
以下是读者提出的问题,欢迎广大读者对此各抒己见。
假如人类乘坐一艘接近光速的飞船,那么在船上,时间相对于处于普通速度的人来说,就应该是静止的,飞船上的人就应该是长生不老的,可是人体的细胞分裂次数是有限的（除癌细胞外）,人即使在飞船上也应该有正常的生理功能,这样的的话,飞船上的人照样会衰老,这两者是不是相互矛盾的？ 相似文献
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Blood analysis plays a major role in medical and science applications and white blood cells (WBCs) are an important target of analysis. We proposed an integrated microfluidic chip for direct and rapid trapping WBCs from whole blood. The microfluidic chip consists of two basic functional units: a winding channel to mix and arrays of two-layer trapping structures to trap WBCs. Red blood cells (RBCs) were eliminated through moving the winding channel and then WBCs were trapped by the arrays of trapping structures. We fabricated the PDMS (polydimethylsiloxane) chip using soft lithography and determined the critical flow velocities of tartrazine and brilliant blue water mixing and whole blood and red blood cell lysis buffer mixing in the winding channel. They are 0.25 μl/min and 0.05 μl/min, respectively. The critical flow velocity of the whole blood and red blood cell lysis buffer is lower due to larger volume of the RBCs and higher kinematic viscosity of the whole blood. The time taken for complete lysis of whole blood was about 85 s under the flow velocity 0.05 μl/min. The RBCs were lysed completely by mixing and the WBCs were trapped by the trapping structures. The chip trapped about 2.0 × 103 from 3.3 × 103 WBCs. 相似文献
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This study proposes a capillary dielectrophoretic chip to separate blood cells from a drop of whole blood (approximately 1 μl) sample using negative dielectrophoretic force. The separating efficiency was evaluated by analyzing the image before and after dielectrophoretic force manipulation. Blood samples with various hematocrits (10%–60%) were tested with varied separating voltages and chip designs. In this study, a chip with 50 μm gap design achieved a separation efficiency of approximately 90% within 30 s when the hematocrit was in the range of 10%–50%. Furthermore, glucose concentration was electrochemically measured by separating electrodes following manipulation. The current response increased significantly (8.8-fold) after blood cell separation, which was attributed not only to the blood cell separation but also to sample disturbance by the dielectrophoretic force. 相似文献
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Homsy A van der Wal PD Doll W Schaller R Korsatko S Ratzer M Ellmerer M Pieber TR Nicol A de Rooij NF 《Biomicrofluidics》2012,6(1):12804-128049
Clinical point of care testing often needs plasma instead of whole blood. As centrifugation is labor intensive and not always accessible, filtration is a more appropriate separation technique. The complexity of whole blood is such that there is still no commercially available filtration system capable of separating small sample volumes (10-100 μl) at the point of care. The microfluidics research in blood filtration is very active but to date nobody has validated a low cost device that simultaneously filtrates small samples of whole blood and reproducibly recovers clinically relevant biomarkers, and all this in a limited amount of time with undiluted raw samples. In this paper, we show first that plasma filtration from undiluted whole blood is feasible and reproducible in a low-cost microfluidic device. This novel microfluidic blood filtration element (BFE) extracts 12 μl of plasma from 100 μl of whole blood in less than 10 min. Then, we demonstrate that our device is valid for clinical studies by measuring the adsorption of interleukins through our system. This adsorption is reproducible for interleukins IL6, IL8, and IL10 but not for TNFα. Hence, our BFE is valid for clinical diagnostics with simple calibration prior to performing any measurement. 相似文献
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Laura Campo-Dea?o Roel P. A. Dullens Dirk G. A. L. Aarts Fernando T. Pinho Mónica S. N. Oliveira 《Biomicrofluidics》2013,7(3)
The non-Newtonian properties of blood are of great importance since they are closely related with incident cardiovascular diseases. A good understanding of the hemodynamics through the main vessels of the human circulatory system is thus fundamental in the detection and especially in the treatment of these diseases. Very often such studies take place in vitro for convenience and better flow control and these generally require blood analogue solutions that not only adequately mimic the viscoelastic properties of blood but also minimize undesirable optical distortions arising from vessel curvature that could interfere in flow visualizations or particle image velocimetry measurements. In this work, we present the viscoelastic moduli of whole human blood obtained by means of passive microrheology experiments. These results and existing shear and extensional rheological data for whole human blood in the literature enabled us to develop solutions with rheological behavior analogous to real whole blood and with a refractive index suited for PDMS (polydymethylsiloxane) micro- and milli-channels. In addition, these blood analogues can be modified in order to obtain a larger range of refractive indices from 1.38 to 1.43 to match the refractive index of several materials other than PDMS. 相似文献