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991.
992.
The pilot issue of the data collection of the All-Russian Institute of Scientific and Technical Information of the Russian Academy of Sciences “Industry of Nanosystems and Nanomaterials” gives an approximate view of the state of this field of science at the beginning of 2007. The topics of articles in the pilot issue are analyzed. The directions of development of nanotechnologies are shown. The basic types of nanomaterials, the methods of their production, and their properties and applications are given.  相似文献   
993.
994.
995.
The theoretical and experimental quantitative relationships between the dot diameter, dot area, and density of a halftone are given. Experimental results do not agree exactly with the theoretical relationships except for screen negatives and positives with sharp dots.For accurate rendering, highlight dots in a reproduction must increase extremely rapidly in size for small density increments in the highlights of an original. A “emi-dark-field” densitometer is described which eliminates the effect of dot fringe in measuring densities of screen positives. The relationship between density of screen positive and density of proof is briefly discussed.  相似文献   
996.
    
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997.
Previous comparisons of the activity differences of individually and group-housed rats have produced inconsistent findings; therefore, we examined activity using three measures: open-field ambulation, nonspecific circadian activity, and rearing behavior. Open-field ambulation in two 5-day tests confirmed our prediction that isolates would be initially less active but later more active than group-housed rats. Isolates habituated more slowly to the activity monitor and tended to be more active during the light half of the 24-h cycle. In the rearing test, isolates showed elevated and more persistent activity than group-housed rats. All these activity differences were prevalent in both male and female rats. The results are interpreted in terms of the influence of differential housing on “fear responses,” exploration of a novel environment, and differences in habituation/adaptation processes.  相似文献   
998.
In this article we deal with the classical problem of estimating the domain of attraction (DOA) of autonomous dynamical systems. We propose a new LMI estimation method based on recent results from the mathematical theory of moments. In contrast to previous works we exploit the advantages of rational Lyapunov functions to enhance the estimates. Several examples illustrate the estimation method.  相似文献   
999.
The propagation of elastic waves in a heterogeneous bar of variable cross-sectional area is investigated via use of the method of characteristics andthe Laplace transform technique. The Young's modulus and density are assumed to be representable as either power law or exponential distributions in the axial coordinate. The transform method is used to establish an infinite number of multi-parameter solutions in closed form for either a stress, velocity or displacement type boundary condition. The numerical characteristic computations show excellent agreement when compared to the transform solutions, and are then used to obtain additional solutions not attainable by the transform method. Detailed results and conclusions for a bar of ogival cross-section are given for a wide range of inhomogeneity.  相似文献   
1000.
The foregoing notes trace the history of the measurement of the propagation times of radio waves as a means for determining distance. While the reader may feel that undue emphasis has been placed upon the KHL height measurements, a survey of the literature will show that only a small proportion of the reported observations have been cited here. Out of the hundreds of published articles on KHL height measurements, the writer has endeavored to select those which present the step-by-step improvements in the methods and apparatus. In the period just prior to the War, the United States Patents offered the principal means for tracing the development of the art. In the war period the notes are necessarily incomplete because of the scarcity of publications; this is no doubt due to secrecy conditions.  相似文献   
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