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11.
12.
通过从一个导数值等式的证明谈起,探讨教师在课堂教学中如何根据教学内容创设能激起学生新异感的问题情景,启发和引导学生发散思考,类比、联想、猜想,探索和发现新问题并给出解答.使学生思维不断攀升,丰富教学内容,激发学生兴趣,培养学生科学思维方法和创新能力. 相似文献
13.
《合成通讯》2012,42(24):3536-3545
AbstractA novel two-step amine persulfonylation method described here results in significantly higher yields of sulfonimide-based dendrimers as compared with formerly available procedures. This allowed the preparation of the fifth-generation sulfonimide-based dendrimer for the first time, on a 2?g scale. Dendrimers of fourth and fifth generations decorated with naphthyl groups after being spin-coated on a glass substrate were shown to form stable hydrophobic films as revealed by contact angle measurements. 相似文献
14.
在白噪声分析的框架中,我们给出了广义Weiner泛函空间上的梯度算子和散度算子的定义与公式,并利用梯度和散度算子以及适应投影建立了广义泛函的表示公式.也证明了积分核算子可用梯度与散度算子表出. 相似文献
15.
Andrea Kühl Dietrich Bergner Hans-J. Ullrich Matthias Schlaubitz Peter Karduck 《Mikrochimica acta》1992,107(3-6):295-302
Parameters of the diffusion of N (up to 0.3 wt.%) in austenitic stainless steels (12 to 19 wt.% Cr, 12 to 16 wt.% Ni, up to 2 wt.% Mo) were determined within the temperature range of 1283–1573K. The small concentration gradients of N were successfully investigated using (1) mechanical serial sectioning technique in combination with either chemical N analysis or X-ray precision lattice parameter determination, and (2) measurements on microsections by means of either electron probe microanalysis or Kossel technique.The diffusion coefficients of N were found to be independent of its concentration. The alloying elements Cr and Mo reduce the N diffusivity in austenitic stainless steels which on the other hand is increased by Ni. 相似文献
16.
Herbert H.H. Homeier 《Numerical Algorithms》1998,17(3-4):223-239
The stability of a large class of nonlinear sequence transformations is analyzed. Considered are variants of the J transformation [17]. Suitable variants of this transformation belong to the most successful extrapolation algorithms that
are known [20]. Similar to recent results of Sidi, it is proved that the
p
{J} transformations, the Weniger S transformation, the Levin transformation and a special case of the generalized Richardson extrapolation process of Sidi are
S-stable. An efficient algorithm for the calculation of stability indices is presented. A numerical example demonstrates the
validity of the approach.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
17.
18.
This paper presents results of a theoretical and experimental study of Bragg anisotropic diffraction. The diffraction may be used for filtration of optical radiation and processing of images. Special attention is devoted to the investigation of diffraction, which provides spectral filtration simultaneously with polarization analysis of divergent optical beams. A tunable tellurium dioxide acousto-optical filter for processing of optical images is described in the paper. Some experimental results of the image analysis in visible light and in the near-infrared region of the spectrum are discussed. 相似文献
19.
The well-known nodal point method has been employed with some modification to measure the focal lengths of divergent lenses. In this modification, a telescope was used to locate precisely the nodal/principal point of the lens under test, and a travelling microscope was employed to locate precisely the focal point of the lens as well as to measure the focal distance. The accuracy of the measurement was found to be ± 0.5%, with the focal length of the order of about 10 cm. 相似文献
20.