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381.
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383.
Kamal Tahseen Khan Sher Bahadar Bakhsh Esraa M. Anwar Yasir 《Cellulose (London, England)》2021,28(17):11067-11080
Cellulose - In this research work, we present a synthesis of silver and cobalt bimetal nanoparticles stabilized by a carboxymethyl cellulose biopolymer (CMC-AgCo) and its coating on a cellulose... 相似文献
384.
Gul Melek Elemes Yiannis Pelit Emel Dernektsi Eleni Georgiou Dimitra Oikonomou Kosmas Lis Tadeusz Szafert Sławomir 《Research on Chemical Intermediates》2017,43(2):1031-1045
Research on Chemical Intermediates - Stereospecific α-amination has been accomplished via addition of N-phenyltriazolinedione (PhTAD) to the allylic position of dihydropyrroles. The aim of... 相似文献
385.
E. N. Sher 《Journal of Applied Mechanics and Technical Physics》1969,10(3):507-511
The plane problem of the theory of elasticity is considered. It is assumed that in the neighborhood of the tip of an arbitrarily moving crack the stresses have a singularity of order r–1/2. On this assumption a general expression is obtained for the distribution of the stresstensor components in the given neighborhood. This distribution is determined by the two parameters N and P. In the case of stresses symmetrical about the line of the crack (P=0) the angular distribution does not depend on the intensity coefficient N and is determined only by the velocity of the crack at the given instant and the transverse and longitudinal wave velocities. On the same assumptions it is shown that the energy condition obtained by Craggs for the particular case of steady-state motion is a necessary condition for the arbitrarily moving crack. Irwin [1] and Cherepanov [2] have studied these questions in the quasi-static approximation.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, Vol. 10, No. 3, pp. 175–178, May–June, 1969. 相似文献
386.
Rhodium‐Catalyzed Intramolecular [3+2+2] Cycloadditions between Alkylidenecyclopropanes,Alkynes, and Alkenes 下载免费PDF全文
Marisel Araya Moisés Gulías Dr. Israel Fernández Dr. Gaurav Bhargava Prof. Luis Castedo Prof. José Luis Mascareñas Dr. Fernando López 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(33):10255-10259
A Rh‐catalyzed intramolecular [3+2+2] cycloaddition is reported. The cycloaddition affords synthetically relevant 5,7,5‐fused tricyclic systems of type 2 from readily available dienyne precursors. The transformation takes place with moderate or good yields, high diastereoselectivity, and total chemoselectivity. 相似文献
387.
Song Guo Liang Xu Kejing Xu Jianzhang Zhao Betül Kü?ük?z Ahmet Karatay Halime Gul Yaglioglu Mustafa Hayvali Ayhan Elmali 《Chemical science》2015,6(7):3724-3737
Supramolecular triplet photosensitizers based on hydrogen bonding-mediated molecular assemblies were prepared. Three thymine-containing visible light-harvesting Bodipy derivatives (B-1, B-2 and B-3, which show absorption at 505 nm, 630 nm and 593 nm, respectively) were used as H-bonding modules, and 1,6-diaminopyridine-appended C60 was used as the complementary hydrogen bonding module (C-1), in which the C60 part acts as a spin converter for triplet formation. Visible light-harvesting antennae with methylated thymine were prepared as references (B-1-Me, B-2-Me and B-3-Me), which are unable to form strong H-bonds with C-1. Triple H-bonds are formed between each Bodipy antenna (B-1, B-2 and B-3) and the C60 module (C-1). The photophysical properties of the H-bonding assemblies and the reference non-hydrogen bond-forming mixtures were studied using steady state UV/vis absorption spectroscopy, fluorescence emission spectroscopy, electrochemical characterization, and nanosecond transient absorption spectroscopy. Singlet energy transfer from the Bodipy antenna to the C60 module was confirmed by fluorescence quenching studies. The intersystem crossing of the latter produced the triplet excited state. The nanosecond transient absorption spectroscopy showed that the triplet state is either localized on the C60 module (for assembly B-1·C-1), or on the styryl-Bodipy antenna (for assemblies B-2·C-1 and B-3·C-1). Intra-assembly forward–backward (ping-pong) singlet/triplet energy transfer was proposed. In contrast to the H-bonding assemblies, slow triplet energy transfer was observed for the non-hydrogen bonding mixtures. As a proof of concept, these supramolecular assemblies were used as triplet photosensitizers for triplet–triplet annihilation upconversion. 相似文献
388.
V. M. Kuznetsov B. A. Lugovtsov E. I. Sher 《Journal of Applied Mechanics and Technical Physics》1966,7(1):88-89
This study deals with the motion of a gas bubble developing under the influence of surface-tension forces in an imponderable viscous liquid with a temperature gradient. A theory of steady-state motion of a bubble in a field with constant temperature gradient is given for the case of small Reynolds numbers. Experimental results that show qualitative agreement with the theory are presented.The authors wish to thank M. A. Lavrent'ev for formulating the problem and giving constant attention to their work. 相似文献
389.
The effect of the biaxial field of external rock pressure on the deformation of the fracture zone formed by radial cracks
in an elastic-brittle medium is studied. We consider cylindrical charges that are rather thin compared to the diameter of
the explosive borehole. This allows one to exclude the grinding zone from consideration. At the initial moment of time, the
system of emerging cracks originating at the boundary of the circular hole is assumed to be symmetric. To solve the problem,
we use singular integral equations and the fracture criterion σϑ. The propagation trajectories of the system cracks are calculated in the quasistatic approximation in a step-by-step manner
in relation to the parameters of the external compressive stress field. Two ideal variants of loading of the crack system
are analyzed. In the first variant, gaseous detonation products penetrate into cracks, and the pressure in the explosion cavity
and the cracks instantaneously equalizes. In the second variant, gases do not penetrate into the cracks of the system. The
fracture zone is shown to become an ellipse whose long axis is oriented in the direction of the largest compressive stress
in magnitude acting at infinity. The effect of the variants of loading of the crack system on the shape and dimensions of
the deformed fracture zone is evaluated.
Mining Institute, Siberian Division, Russian Academy of Sciences, Novosibirsk 630091. Translated from Prikladnaya Mekhanika
i Tekhnicheskaya Fizika, Vol. 39, No. 1, pp. 129–137, January–February, 1998. 相似文献
390.