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981.
GS Kim SH Kim JK Cho JY Park MJ Shin YK Shong KU Lee H Han TG Kim SL Teitelbaum WR Reinus MP Whyte 《Canadian Metallurgical Quarterly》1997,76(3):157-169
Pancreatic cancer is an aggressive disease with a dismal prognosis. It has long been regarded as one of the most difficult cancers to accurately diagnose and stage preoperatively. The purpose of this review is to provide an update of the state-of-the-art for early detection, diagnosis, and staging of pancreatic cancer. These methods include spiral CT scans, magnetic resonance imaging, positron emission tomography (PET) imaging, laparoscopy, endoscopic ultrasound, CA 19-9 serology, fine needle aspiration cytology, ERCP brush cytology, and screening for p53 and ras oncogenes. These advanced techniques should help us to detect pancreatic cancers in high-risk populations at a curative stage and to decrease pancreaticoduodenectomies for benign disease which could otherwise be treated with less morbid procedures. In addition, these tests will help reliably diagnose pancreatic cancer preoperatively. 相似文献
982.
Single-phase operation of a three-phase induction generator with the Smith connection (SMIG) is analyzed using the method of symmetrical components. It is shown that, despite the asymmetrical nature of the winding connection, balanced currents can be made to flow in the three-phase stator winding. The conditions for achieving perfect phase balance are carefully deduced. With the aid of a phasor diagram, expressions for the line power factor and line current under perfect phase balance are also obtained. The effect of the phase-balancing capacitances on the generator performance is investigated. A simple dual-mode control scheme is also proposed with a view of minimizing the phase imbalance over the practical operating speed range. Experiments conducted on a 2.2 kW induction machine confirm the validity of the theoretical analysis and feasibility of the control method 相似文献
983.
984.
巴中,地处四川盆周山区,既是一个农业主产区,也是一个连片旱山区,水利发展相对滞后,工程性缺水矛盾突出。同时,由于多年来形成的传统习惯和思维定式,水利工程运行管理较差,在一定程度上阻碍了水利事业的快速发展,阻碍了全面建设小康社会及构建和谐社会的进程。因此,强力推进水利管理体制改革,尽快建立起维护已成水利工程生命健康的长效机制已迫在眉睫。 相似文献
985.
OBJECTIVE: To describe the occurrence of endometriosis in monozygotic twins. DESIGN: Postal questionnaire plus confirmation of disease status. SETTING: Twins were recruited via the American Endometriosis Association and the National Endometriosis Society of Great Britain and via British gynecologists. RESULT(S): Fourteen twin pairs were concordant for endometriosis, and two were discordant. Nine pairs of twins had moderate-severe endometriosis. CONCLUSION(S): These findings contribute to the growing body of literature that suggests endometriosis has a genetic basis. 相似文献
986.
Unidirectional wetting surfaces can cause liquid droplets to flow/move in one direction while pinning them in the other directions, a feature that is useful for biosensing, adhesives, thermal management, and microfluidics. Such surfaces can be fabricated by employing structurally or chemically asymmetric nanostructures. While unidirectional wetting in the hydrophobic Wenzel regime had previously been observed on surfaces decorated with chemically asymmetric nanostructures, it has yet to be demonstrated on structurally asymmetric nanostructures. Based on the current understanding of the phenomenon, this can only be achieved using highly bent nanowires. Here, evidence to the contrary is provided by showing that mildly bent nanowires can also bring about unidirectional wetting in the hydrophobic Wenzel regime, even for contact angles beyond the superhydrophobic limit. Using NaCl precipitation, the unidirectional wetting mechanism is analyzed on a nanoscale level and it is found that the criteria for unidirectional wetting to take place in the hydrophobic Wenzel regime are different from that in the hydrophilic Wenzel regime. Moreover, it is revealed that slight wetting in the pinned direction can be caused by large scale deformation of high aspect ratio nanostructures during droplet spreading, which may be part of the reason behind previous observations of near‐unidirectional wetting on bent nanowires with high aspect ratios. 相似文献
987.
Hongqiang Li Xiaokang Ren Xuejun Lai Xingrong Zeng 《Journal of Coatings Technology and Research》2014,11(6):959-966
The effects of the type and amount of the surfactant and cosurfactant on the miniemulsion polymerization of acrylate monomers were studied, and the comparison of the kinetics between miniemulsion polymerization and conventional emulsion polymerization was discussed in the presence of reactive surfactant allyloxy nonylphenol propyl polyoxyethylene (10), ether sulfate (DNS-86), and reactive cosurfactant stearyl methacrylate (SMA). The results showed that the obtained polyacrylate miniemulsion had a high monomer conversion rate and a low coagulum fraction, which were affected little by the surfactant and cosurfactant type. When the surfactant and cosurfactant amounts were all 2 wt%, the contact angle of the prepared polyacrylate miniemulsion with DNS-86/SMA and the water absorption fraction of the latex film were 39° and 8.3 wt%, respectively. FTIR results confirmed that DNS-86 and SMA took part in the polymerization of acrylate monomers. In the miniemulsion polymerization of acrylate monomers with DNS-86/SMA, monomer droplet nucleation was the main nucleation style. 相似文献
988.
989.
采用一种简单的低温固相法制备了YF3∶Yb,Er纳米晶,重点探究了烧结温度、烧结时间对纳米晶微结构及发光性能的影响。通过XRD、SEM和FA对样品进行了表征。XRD结果表明:烧结温度达到400℃,烧结时间达到1h,即可获得正交相的YF3∶Yb,Er纳米晶;SEM分析表明:制备的YF3∶Yb,Er纳米晶呈现光滑的类球形,粒径随烧结温度升高及烧结时间增加而变大;FA结果显示:在980nm红外激光激发下,样品的可见光发射峰分别位于波长409、524、547和657nm处,其强度与烧结温度、烧结时间正相关。 相似文献
990.
介绍了汽车行驶模式实验室模拟的重要性,分析了控制对象的一些特性,提出了基于这些特性的智能控制方法,设计了一套测试,控制和管理的软硬件系统,实现了几种典型的汽车行驶模式模拟。 相似文献