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121.
During 6 months of post-natal development in the laboratory, the weight of the adrenal gland relative to body weight decreases exponentially. In the 3 day-old duckling a single intravenous dose of labelled corticosterone becomes distributed in a very large apparent volume and an "extracellular" pool that is greater than the extracellular fluid volume and the pattern of disappearance of labelled hormone from plasma is biphasic. Later during development the volumes of distribution decrease and the biphasic pattern of disappearance becomes less distinct until at 6 months only one phase of disappearance can be detected with confidence. No significant change in plasma corticosterone concentration occurs during this period of development in the laboratory. Estimations of the corticosterone secretory rates, however, indicate that whereas the adrenal weight-specific rate os secretion increases during the first 3 weeks and declines therafter, the bodyf weight-specific secretory rate continues to decline throughtout the period of increasing body weight.  相似文献   
122.
123.
在一次系统故障过程中。输电线路的两套高频保护装置CSL-101B型和LFP-901B型动作行为不一致。本文就此展开分析,以达到正确理解两种保护动作行为的目的。并对加强高频保护的现场管理提出意见。  相似文献   
124.
This paper uses two large databases, one of given names and one of family names, to categorise the names of researchers from Italy, Sweden, the UK and the USA whose papers in astronomy and oncology were published in 2006–2007 and in 2011–2012 by sex (gender) and ethnicity or national origin. For all the countries, there were relatively many more females publishing papers in oncology than in astronomy, but their share of contributions was lower than the percentage of researchers. Sweden and the UK had much higher percentages of both other European and Rest of the World researchers than Italy did. US researchers with non-European names were categorised in six main country groups. The ones with the greatest presence were Chinese (mainly Mandarin) and South Asians (mainly Indians). The method could be adapted to investigate the progress of women in research in many other countries, and the role played by non-national researchers in their scientific output.  相似文献   
125.
Liquid marbles may be traditionally formed by rolling a droplet on a bed of non-wetting particles resulting in encapsulation and stabilisation. Particles used in this process may range from nanometre to millimetre if handled with sufficient care. This method, however, runs the risk of droplet coalescence and is limited to non-wetting particles. Currently there exist some alternative methods of formulation including using electrostatics to either deliver a particle bed to the droplet or pull the droplet to the particles. The former has shown some promise in potential batch processes but is hindered by interparticle forces. Additional production methods include a form of blender, but this has shown to be unable to produce marbles of a narrow size distribution. Once formed, liquid marbles have demonstrated value as potential blood typing devices, as micro-reaction vessels due to the inherent barrier between the internal phase and the substrate whilst maintaining gas permeability, and as contaminant sensors. Liquid marbles also demonstrate a remarkable level of elasticity under compressive force and reduced evaporation rates when compared to bare water droplets, a function of the size and composition of the stabilising particles. In addition to this, liquid marbles have been proposed as actuators. Locomotion may easily be induced in these structures, using electrostatics, sound, magnetism or light depending on the particle/liquid combinations used in formation, and the environment of deployment. This review seeks to present and summarise recent advances in the field of liquid marble manufacture and methods for actuation. We also aim to highlight potential future avenues of further study within this arena.  相似文献   
126.
This paper describes a tool to aid the development of computer vision applications for pixel-level diagnosis. A conceptual framework for constructing pixel processors is described. The proposed tool is based on two domains: one deals with numerical images, named features, and the other deals with symbolic images, named classes. A reduced set of image and operator types is defined. Based on it, an object-oriented language is described. The main objects define features and classes and their associated operators, namely procedures, classifiers, and rules. All system control is goal oriented and is designed to provide symbolic images as results when a request is received from a higher level of the image understanding system. Some knowledge engineering concepts, such as certainty control and instances, are also included.  相似文献   
127.
128.
The temperature dependence of piezoelectric properties (direct piezoelectric coefficient d33, converse piezoelectric coefficient d33(E = 0), strain S and electromechanical coupling coefficient kp) for two niobate‐based lead‐free piezoceramics have been contrasted. 0.92(Na0.5K0.5)NbO3–0.02(Bi1/2Li1/2)TiO3–0.06BaZrO3 (6BZ/2BLT/92NKN) has a morphotropic phase boundary (MPB) between rhombohedral and tetragonal at room temperature and 0.92(Na0.5K0.5)NbO3–0.03(Bi1/2Li1/2)TiO3–0.05BaZrO3 (5BZ/3BLT/92NKN) features an MPB engineered to be located below room temperature. At 30°C, d33d33(E = 0), S (at 2 kV/mm), and kp are 252 pC/N, 230 pm/V, 0.069%, 0.51 for 5BZ/3BLT/92NKN; and 348 pC/N, 380 pm/V, 0.106%, 0.57 for 6BZ/2BLT/92NKN, respectively. With increasing temperature, the piezoelectric properties decrease. At 200°C, d33, d33(E = 0), S (at 2 kV/mm), and kp are 170 pC/N, 160 pm/V, 0.059%, 0.36 for 5BZ/3BLT/92NKN; and 181 pC/N, 190 pm/V, 0.061%, 0.39 for 6BZ/2BLT/92NKN. It is found that the electromechanical coupling coefficient has a better temperature stability than the piezoelectric coefficient in the studied system due to a large temperature‐dependent compliance change. The results demonstrate that engineering an MPB is highly effective in tailoring temperature stability of piezoceramics.  相似文献   
129.
Piezoelectric multilayer actuators are technologically important devices used in numerous positioning and force generation applications. During operation, the actuator displacement and force are nonlinearly coupled to the applied electric field, which is often ignored during material characterization. In this study, a novel experimental arrangement is presented that acts like a virtual linear spring, allowing for characterization of the full operational range as a function of applied electric field as well as the true blocking force and impedance matching system stiffness. The macroscopic measurements are contrasted to previous experimental techniques, providing insight into the effect of path dependence on the blocking force.  相似文献   
130.
综述了近年来以环己烯、环己酮、环己醇或环己烷等作原料,以过氧化氢或氧气等为氧源,采用不同的催化体系清洁合成己二酸的新进展.指出:在这些方法中,改性的分子筛及负载型催化剂-双氧水体系将是今后己二酸清洁合成的重点研究方向.  相似文献   
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