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近年来,可用于昆虫迁飞研究且可自动运行的垂直波束雷达(vertical-looking radar,VLR)的发展使得对迁飞性害虫的周年长期自动监测成为可能。本文提供了我们对能否将这种雷达应用于中国的褐飞虱和其他水稻害虫的监测与预测体系以改善其综合治理的可行性研究结果。以往的研究已经表明,这些害虫一般在300—2000m高度迁飞;而我们根据褐飞虱的雷达和射有效截面的计算结果表明,目前使用的3.2cm波长的VLR对褐飞虱个体目标的最大可检测高度仅约240m;虽然建造一部8.8mm波长的VLR即可覆盖褐飞虱迁飞高度的绝大部分,但其造价和维护费用均过于昂贵。为此,一个更可行的解决方案是,以3.2cm波长的VLR作为包括大多数水稻害虫在内的个体较大的迁飞性害虫的监测工具。  相似文献   
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Evaluation of facial movement, including distance and direction, is essential for anyone interested in facial paralysis reconstruction. The authors' goal was to develop a measurement system that is simple, uses commercially available equipment, takes little time, and provides meaningful and accurate measurements. This technique is called the facial reanimation measurement system. It involves placing dots around the patient's mouth and video recording the patient performing maximal effort smiles. Using a video editing program, one frame showing the patient at rest is overlaid with a second frame showing the patient's smile. This overlaid image is imported into Adobe PhotoShop, where measurements are obtained using tools available in the program. Twenty patients were used to test interrater and intrarater reliability of the facial reanimation measurement system. The accuracy of the measurement process was tested by comparing 10 known distances and angles with those obtained using the facial reanimation measurement system. Both intrarater and interrater reliability of the distance and angle measurements are highly accurate, with intraclass correlations greater than 0.9. The facial reanimation measurement system is accurate to within 0.6 mm and 2.0 degrees when compared with a "known" distance and angle. The facial reanimation measurement system has been used to measure smile movements of more than 200 patients and has been demonstrated to be valuable for detecting changes of facial movements over time. This system is simple and economical and only requires 20 minutes to perform. Although the authors demonstrated evaluation of smile movement, the system may be used to evaluate other movements, such as mouth puckering, eye closure, and forehead elevation.  相似文献   
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Quaternary climatic fluctuations have left contrasting historical footprints on the neutral genetic diversity patterns of existing populations of different tree species. We should expect the demography, and consequently the neutral genetic structure, of taxa less tolerant to particular climatic extremes to be more sensitive to long‐term climate fluctuations. We explore this hypothesis here by sampling all six pine species found in the Iberian Peninsula (2464 individuals, 105 populations), using a common set of chloroplast microsatellite markers, and by looking at the association between neutral genetic diversity and species‐specific climatic requirements. We found large variation in neutral genetic diversity and structure among Iberian pines, with cold‐enduring mountain species (Pinus uncinata, P. sylvestris and P. nigra) showing substantially greater diversity than thermophilous taxa (P. pinea and P. halepensis). Within species, we observed a significant positive correlation between population genetic diversity and summer precipitation for some of the mountain pines. The observed pattern is consistent with the hypotheses that: (i) more thermophilous species have been subjected to stronger demographic fluctuations in the past, as a consequence of their maladaptation to recurrent glacial cold stages; and (ii) altitudinal migrations have allowed the maintenance of large effective population sizes and genetic variation in cold‐tolerant species, especially in more humid regions. In the light of these results and hypotheses, we discuss some potential genetic consequences of impending climate change.  相似文献   
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Abstract: An early Cenozoic shark fauna, comprising at least 16 taxa, is described from Paleocene sedimentary rocks on the South Island of New Zealand. Although representing a remote Southern Hemisphere location, the fauna includes forms closely comparable to contemporary species from the Northern Hemisphere, in addition to the new species Chlamydoselachus keyesi and Centroselachus goordi. Comparison with closely related extant species suggests the fauna may be interpreted as a deep water one, typical of the outer continental shelf and upper slope. However, after palaeogeography, sedimentology and mineralogy of the enclosing rock, and the nature of similar faunas from elsewhere are taken into consideration, the fauna is interpreted to have occupied a mid‐shelf environment.  相似文献   
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The final activity of the alcohol dehydrogenase (E.C.1.1.1.1, abbreviated ADH) from germinating pea, isolated by fractionating with ammonium sulphate, chromatography on DEAE cellulose and gel filtration, was 80,000, from bean 25,000 and from lentil 13,500 units per mg protein. Molecular weights of the ADHs are close to each other: pea and bean ADH 60,000, lentil ADH 70,000. The Km values are mutually similar with three enzymes, i.e. of the order of 10−4M for NAD and 10−2M for ethanol. The pH optima lie in the alkaline region. These enzymes catalyse oxidation of a number of monovalent alcohols. At temperatures above 60°C the enzymes are thermally unstable. Stability is enhanced slowly by ethanol but not by NAD. Pyrazol, imidazol and pyridine inhibit plant ADH similarly to the enzyme from horse liver. There is a similarity between plant alcohol dehydrogenases and animal and yeast enzymes.  相似文献   
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Thirty male adult Wistar rats (300-/+10 g body weight) underwent either 5/6 nephrectomy (Nx, n=20) or sham operation (SHAM, n=10) to determine olpadronate effects in an experimental model of uremic bone disease. For a 38-day period, 10 rats received olpadronate (16microg/100g bw) once a week (Nx+OPD) and the other vehicle (Nx). SHAM received vehicle. At baseline, treatment onset (t=7 days) and end of study (t=45 days) calcium, phosphorus, creatinine, bone alkaline phosphatase (b-ALP) and deoxypyridinoline crosslinks (DPyr) were determined. At t=0 and t=45 bone mineral density (BMD) was measured by DXA. At t=45 the right tibia was removed for bone histology. There were no differences in serum calcium. Phosphorus increased in Nx and Nx+OPD compared to SHAM (p相似文献   
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