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1.
Margaret S. Cheney und Ellen Swallow Richards 《Fresenius' Journal of Analytical Chemistry》1878,17(1):214-216
Ohne Zusammenfassung 相似文献
2.
Let be a univariant function, and letg(x) be the average of (x,u) asu runs over the unit sphere in
n
. We give a necessary and sufficient condition forg to be a kernel function, i.e., thatg be inL
1 (
n
) and have integral 1. The result is used to give a constructive proof of the density of the ridge functions based upon the function . 相似文献
3.
We establish a result related to a theorem of de Boor and Jia [1]. Their theorem, in turn, corrected and extended a result of Fix and Strang [5] concerning controlled approximation. In our result, the approximating functions are not required to have compact support, but satisfy instead conditions on their behavior at . Our theorem includes some recent results of Jackson [6] and is closely related to the work of Buhmann [2].Communicated by Carl de Boor 相似文献
4.
Fischer J Hammerschmidt K Cheney DL Seyfarth RM 《The Journal of the Acoustical Society of America》2002,111(3):1465-1474
The acoustic structure of loud calls ("wahoos") recorded from free-ranging male baboons (Papio cynocephalus ursinus) in the Moremi Game Reserve, Botswana, was examined for differences between and within contexts, using calls given in response to predators (alarm wahoos), during male contests (contest wahoos), and when a male had become separated from the group (contact wahoos). Calls were recorded from adolescent, subadult, and adult males. In addition, male alarm calls were compared with those recorded from females. Despite their superficial acoustic similarity, the analysis revealed a number of significant differences between alarm, contest, and contact wahoos. Contest wahoos are given at a much higher rate, exhibit lower frequency characteristics, have a longer "hoo" duration, and a relatively louder "hoo" portion than alarm wahoos. Contact wahoos are acoustically similar to contest wahoos, but are given at a much lower rate. Both alarm and contest wahoos also exhibit significant differences among individuals. Some of the acoustic features that vary in relation to age and sex presumably reflect differences in body size, whereas others are possibly related to male stamina and endurance. The finding that calls serving markedly different functions constitute variants of the same general call type suggests that the vocal production in nonhuman primates is evolutionarily constrained. 相似文献
5.
A method for the determination of ethanol in vodka by phase-sensitive a.c. tensammetry is described; the only prior treatment of the sample is dilution with water and addition of KCl The positive wave of the tensammetric response was used. Ethanol concentrations in the range 2–10% can be determined with a relative imprecision of 0.5%. Other species having surfactant properties, such as the fusel oils found in most distilled liquors, interfere. 相似文献
6.
Background
Growth hormone (GH) plays an incompletely understood role in the development of the central nervous system (CNS). In this study, we use transgenic mice expressing a growth hormone antagonist (GHA) to explore the role of GH in regulating postnatal brain, spinal cord and body growth into adulthood. The GHA transgene encodes a protein that inhibits the binding of GH to its receptor, specifically antagonizing the trophic effects of endogenous GH. 相似文献7.
Budde M Bech Nielsen B Parks Cheney C Tolk NH Feldman LC 《Physical review letters》2000,85(14):2965-2968
Two distinct isolated hydrogen defects are observed in crystalline Ge by in situ infrared absorption spectroscopy. Implantation of protons into Ge at cryogenic temperatures gives rise to two intense absorption lines at 745 and 1794 cm(-1). The lines originate from distinct defects, each of which contains one H atom located on a <111> axis. The 1794-cm(-1) line is assigned to bond center H in the positive charge state, whereas the 745-cm(-1) line is ascribed to negatively charged H located on a <111> axis close to the tetrahedral site. 相似文献
8.
A dedicated general purpose digital computer has been built on the principle of a sampled-data system to run an ultrasonic subsystem under programmed control. A most significant application is the ability to extract a signal from an interfering background. As illustrated in the paper, a 1 mm diameter transducer was used to measure the diameter of a 2.5 mm OD plastics tube with 0.4 mm wall thickness. Echoes from all four surfaces were displayed and the measurements indicated an uncertainty of less than 0.1 mm. 相似文献
9.
Amorphous Fe67?xC10B9Mo7+xCr4W3 (x = 1–7 at.%) plates with 0.64 mm thickness were prepared by copper mold casting. The thermal properties and microstructural development during heat treatments were investigated by a combination of differential scanning calorimetry, differential thermal analysis, and X-ray diffraction. The glass forming ability (GFA) and activation energy for crystallization have a distinct dependence on Mo content. Fe62C10B9Mo12Cr4W3 was the best glass former in this study, demonstrating a supercooled liquid region, ΔTx = 51 K, and an activation energy for crystallization, Q = 453 kJ/mol. The GFA of alloys in this system was governed by elastic strain optimization resulting directly from the variation in Mo content. Heat treatments were performed to demonstrate resistance to crystallization under typical processing conditions. Alloys in this system exhibited a three phased evolution during crystallization. A second set of heat treatments was performed to identify each phase. An analysis of phase evolution revealed a distinct dependence of phase evolution with stepwise substitution of Mo for Fe in this system. 相似文献
10.
P. Hari C. Cheney G. Luepke S. Singh N. Tolk J. S. Sanghera I. D. Aggarwal 《Journal of Non》2000,270(1-3):265-268
In this study we report first measurements of wavelength-selective infrared-induced materials modification of bulk As2S3 and As2Se3. These materials are currently being considered as candidate materials for infrared optical fiber transmission in the range of 1–10 μm. Our study is aimed at modifying oxygen, hydrogen and carbon impurities bound to chalcogenide constituent elements in the materials to reduce absorption. Tunable infrared radiation from the W.M. Keck Free Electron Laser (FEL) at Vanderbilt was used to excite specific vibrational modes, S–O–H and CHx modes in bulk As2S3 and Se–H, CHx and S–H2 modes in bulk As2Se3. Changes in vibrational mode amplitudes are monitored by measuring the intensity of the Fourier transform infrared (FTIR) spectra before and after irradiation at appropriate wavelengths. By tuning wavelengths to hydrogen vibrational modes, we find evidence that hydrogen is released and/or redistributed athermally. In particular, following irradiation at specific resonant wavelengths, vibrational mode amplitudes as monitored by FTIR associated with CHx are significantly reduced in bulk As2S3 and As2Se3 samples. In As2S3, the changes in CHx modes are reversed by heat treatment at 115°C for 35 min in nitrogen atmosphere. 相似文献