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排序方式: 共有76条查询结果,搜索用时 15 毫秒
1.
The fourth-generation centrifugal blood pump 总被引:1,自引:0,他引:1
The NEDO Gyro permanently implantable (PI) centrifugal blood pump has been developed as a simple, durable, centrifugal blood
pump without a complex magnetic suspension system. In vitro studies were performed using a Gyro PI pump with the transparent
pump housing in a mock circuit. These studies revealed that the impeller transfers to a floating or a top contact condition,
which was dependent on the revolutions per minute (RPM). This pump can be easily converted from a left ventricular assist
device (LVAD) to a right ventricular assist device (RVAD) by simply adding a spacer between the pump and the actuator. In
order to optimize the impeller suspension for the LVAD and RVAD, spacers of the proper thickness are inserted between both
of the pumps and the actuators to regulate the magnetic force. Two Gyro PI pumps were implanted in a bovine model in a 3-month
biventricular assist device (BVAD) animal study. This experiment was electively terminated 90 days after implantation. All
of the parameters, including pump flow rate, power consumption, and plasma free hemoglobin, were in acceptable ranges. No
thrombus formation was observed in either pump. Antithrombogenesis and effectiveness were demonstrated in this animal study.
The NEDO Gyro PI pump is ready to move on to the 3-month preclinical system evaluation.
Received: February 28, 2002 / Accepted: May 30, 2002
Acknowledgment The New Energy and Industrial Technology Development Organization (NEDO) under the Ministry of Economy, Trade and Industry
of Japan financially supported this project.
Correspondence to:S. Ichikawa 相似文献
2.
旋转叶轮血泵的发展与展望 总被引:7,自引:0,他引:7
主要从结构设计、轴承密封设计、控制系统设计三个方面介绍了旋转叶轮血泵技术的最新发展 ,并对其发展趋势做出了展望。 相似文献
3.
Wataru Hijikata Takuro Maruyama Tomotaka Murashige Daisuke Sakota Osamu Maruyama 《Artificial organs》2020,44(6):594-603
The use of contactless support technology for the impeller has led to an increase in the durability of ventricular assist devices (VADs), and these have been in clinical use worldwide. However, pump thrombosis and stroke are still issues to be solved. We have developed a method for detecting the thrombosis in a magnetically levitated blood pump without the need for additional sensors or other equipment. In the proposed method, a sinusoidal current is applied to the electromagnets used for the magnetic bearing, resulting in vibration of the impeller. The phase difference between the current and displacement of the impeller increases with pump thrombosis. First, we describe the principle by which the pump thrombosis is detected. Pump thrombosis reduces the narrowest fluid gap in the pump and this gives rise to a change in the phase difference. Second, we report on experiments in which we changed the narrowest fluid gap using oriented polypropylene tape and showed that decreasing the narrowest fluid gap resulted in an increase in phase difference. For these experiments, the measurements were repeated three times for each condition. Third, we examine the relationship between the pump thrombosis and the phase difference evaluated by observations of the underside of the impeller when operating the pump with porcine blood. Since light was unable to penetrate the blood layer, the erythrocytes were removed for this observation. Only one observation was made. The results showed the phase difference rapidly increased at the same moment when the pump thrombosis was observed. This implies the proposed method has the potential to detect the early stages of pump thrombosis. Finally, in vitro experiments to detect thrombosis when using whole porcine blood in the pump were conducted. The experiment was carried out five times. To intentionally form a thrombus inside the pump, the activated clotting time was controlled to be less than 200 s. In every case, the phase difference increased by more than one degree after tens of minutes. Then, the pump was disassembled and a small amount of pump thrombosis was observed. We conclude that real-time diagnosis of pump thrombosis may be realized by measuring the phase difference without the need for additional sensors. 相似文献
4.
Wataru Hijikata Hideo Sobajima Tadahiko Shinshi Yasuyuki Nagamine Suguru Wada Setsuo Takatani Akira Shimokohbe 《Artificial organs》2010,34(8):669-677
To enhance the durability and reduce the blood trauma of a conventional blood pump with a cone‐shaped impeller, a magnetically levitated (MagLev) technology has been applied to the BioPump BPX‐80 (Medtronic Biomedicus, Inc., Minneapolis, MN, USA), whose impeller is supported by a mechanical bearing. The MagLev BioPump (MagLev BP), which we have developed, has a cone‐shaped impeller, the same as that used in the BPX‐80. The suspension and driving system, which is comprised of two degrees of freedom, radial‐controlled magnetic bearing, and a simply structured magnetic coupling, eliminates any physical contact between the impeller and the housing. To reduce both oscillation of the impeller and current in the coils, the magnetic bearing system utilizes repetitive and zero‐power compensators. In this article, we present the design of the MagLev mechanism, measure the levitational accuracy of the impeller and pressure‐flow curves (head‐quantity [HQ] characteristics), and describe in vitro experiments designed to measure hemolysis. For the flow‐induced hemolysis of the initial design to be reduced, the blood damage index was estimated by using computational fluid dynamics (CFD) analysis. Stable rotation of the impeller in a prototype MagLev BP from 0 to 2750 rpm was obtained, yielding a flow rate of 5 L/min against a head pressure in excess of 250 mm Hg. Because the impeller of the prototype MagLev BP is levitated without contact, the normalized index of hemolysis was 10% less than the equivalent value with the BPX‐80. The results of the CFD analysis showed that the shape of the outlet and the width of the fluid clearances have a large effect on blood damage. The prototype MagLev BP satisfied the required HQ characteristics (5 L/min, 250 mm Hg) for extracorporeal circulation support with stable levitation of the impeller and showed an acceptable level of hemolysis. The simulation results of the CFD analysis indicated the possibility of further reducing the blood damage of the prototype MagLev BP. 相似文献
5.
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8.
Purpose The United States Pharmacopoeia (USP) imposes strict requirements on the geometry and operating conditions of the USP Dissolution
Testing Apparatus II. A previously validated Computational Fluid Dynamics (CFD) approach was used here to study the hydrodynamics
of USP Apparatus II when the impeller was placed at four different locations, all within the limits specified by USP.
Method CFD was used to predict the velocity profiles, energy dissipation rates, and strain rates when the impeller was placed in
the reference location (centrally mounted, 25 mm off the vessel bottom), 2 mm off-center, 2 mm higher, and 2 mm lower than
the reference location.
Results Small changes in impeller location, especially if associated with loss of symmetry, produced extensive changes in velocity
profiles and shear rates. Centrally located impellers, irrespective of their off-bottom clearance, produced non-uniform but
nearly symmetric strain rates. The off-center impeller produced a more uniform but slightly asymmetric strain rate distribution.
Conclusions The system hydrodynamics depends strongly on small differences in equipment configurations and operating conditions, which
are likely to affect significantly the flow field and shear rate experienced by the oral dosage form being tested, and hence
the solid–liquid mass transfer and dissolution rate. 相似文献
9.
血栓的产生会影响血泵运转,同时也可能给患者带来栓塞或卒中等不良并发症。新一代叶轮式连续型血泵体积小、各部件之间间隙小,这些特点使其更易形成血栓,从而导致设备故障。因此血栓评价对考察叶轮式连续型血泵的安全性和有效性具有重要意义。本文从血泵运转中血栓形成的过程及血栓的种类入手,首先对比了研发过程中血栓评价的3种方法,即数值模拟、体外试验、体内试验,分析发现体内试验评价血栓更具有说服力。然后从血泵设计、材料选择及加工、抗凝三大主要因素分析对血栓形成的影响。血泵设计决定血液流场分布,材料选择及加工影响其抗凝血程度,抗凝不足或过度也将产生不良影响。最后对叶轮式连续型血泵血栓评价方法进行了总结和展望。 相似文献
10.
Mechanical circulatory support devices have been used clinically for patients with heart failure for over 10 years. However, thrombus formation inside blood pumps remains a risk to patient life, causing pump failure and contributing to neurological damage through embolization. In this article, we propose a method for preventing thrombus formation by applying vibrational excitation to the impeller. We evaluate the ability of this method to enhance the antithrombogenic properties of a magnetically levitated centrifugal blood pump and ensure that the impeller vibration does not cause undue hemolysis. First, 3 vibrational conditions were compared using an isolated pump without a mock circulation loop; the vibrational excitation frequencies and amplitudes for the impeller were set to (a) 0 Hz‐0 μm, (b) 70 Hz‐10 μm, and (c) 300 Hz‐2.5 μm. The motor torque was measured to detect thrombus formation and obtain blood coagulation time by calculating the derivative of the torque. Upon thrombus detection, the pump was stopped and thrombi size were evaluated. The results showed an increase in the blood coagulation time and a decrease in the rate of thrombus formation in pumps with the impeller vibration. Second, an in vitro hemolysis test was performed for each vibrational condition to determine the effect of impeller vibration on hemolysis. The results revealed that there was no significant difference in hemolysis levels between each condition. Finally, the selected vibration based on the above test results and the non‐vibration as control were compared to investigate antithrombogenic properties under the continuous flow condition. The blood coagulation time and thrombi size were investigated. As a result, vibrational excitation of the impeller at a frequency of 300 Hz and amplitude of 2.5 μm was found to significantly lengthen clotting time, decreasing the rate of pump thrombus compared to the non‐vibration condition. We indicate the potential of impeller vibration as a novel mechanical antithrombogenic mechanism for rotary blood pumps. 相似文献