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排序方式: 共有73条查询结果,搜索用时 31 毫秒
1.
Cellulose catalyzed oxidative hydroxylation of aryl and hetero-arylboronic acids to the corresponding phenols under metal and base free strategy has been demonstrated. The sustainable ipso-hydroxylation takes place using hydrogen peroxide as an oxidant in water under mild condition in shorter period of time. Interestingly, easy recovery and reusability of heterogeneous catalyst without significant loss in catalytic yield makes the protocol environmentally benign. 相似文献
2.
JPC – Journal of Planar Chromatography – Modern TLC - The four new spray reagents (Benzoic acid and some of its parahaloderivatives) have been introduced. These reagents enable... 相似文献
3.
Research on Chemical Intermediates - The discharge of hexavalent chromium [Cr(VI)] has resulted in significant pollution because of the presence of Cr(VI) oxyanions. They are highly water-soluble,... 相似文献
4.
Renu Laskar 《Discrete Applied Mathematics》2009,157(2):330-338
The question of whether a graph can be partitioned into k independent dominating sets, which is the same as having a fallk-colouring, is considered. For k=3, it is shown that a graph G can be partitioned into three independent dominating sets if and only if the cartesian product G□K2 can be partitioned into three independent dominating sets. The graph K2 can be replaced by any graph H such that there is a mapping f:Qn→H, where f is a type-II graph homomorphism.The cartesian product of two trees is considered, as well as the complexity of partitioning a bipartite graph into three independent dominating sets, which is shown to be NP-complete. For other values of k, iterated cartesian products are considered, leading to a result that shows for what values of k the hypercubes can be partitioned into k independent dominating sets. 相似文献
5.
JPC – Journal of Planar Chromatography – Modern TLC - 相似文献
6.
It is shown by Rao and Rao that certain geometric properties characterize the line graph of a BIB design with parameters b, v, r, k, 1, provided r - 2k + 1 < 0. If r = k + 1, and , a characterization of the line graph of a finite affine plane is obtained. If r - 2k + 1 = 0, the only possible value for k is 2 and consequently r = k + 1 resulting in the case of the line graph of a finite affine plane. It is shown here that if r = k + 1 and k = 2, there are exactly seven other non-isomorphic graphs with those properties which are not the line graph of a finite affine plane and these are the only cubic graphs on twelve vertices with no quadrilaterals. 相似文献
7.
Masihhur R. Laskar Tapas Ganguli A. A. Rahman A. P. Shah M. R. Gokhale Arnab Bhattacharya 《固体物理学:研究快报》2010,4(7):163-165
We report the metal organic vapor phase epitaxy (MOVPE) growth and characterization of non‐polar (11 0) a ‐plane Alx Ga1–xN on (1 02) r ‐plane sapphire substrates over the entire composition range. Alx Ga1–xN samples with ~0.8 μm thick layers and with x = 0, 0.18, 0.38, 0.46, 0.66, and 1.0 have been grown on r ‐plane sapphire substrates. The layer quality can be improved by using a 3‐stage AlN nucleation layer and appropriate V/III ratio switching following nucleation. All a ‐plane AlGaN epilayers show an anisotropic in‐plane mosaicity, strongly influenced by Al incorporation and growth conditions. Careful lattice parameter measurements show anisotropic in‐plane strain that results in an orthorhombic distortion of the hexagonal unit cell, making Al composition determination from X‐ray diffraction difficult. In general lower Al incorporation is seen in a ‐plane epilayers compared to c ‐plane samples grown under the same conditions. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
8.
B. Mukhopadhyay M. Nag S. Laskar S. Lahiri 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(2):415-418
Pleurotus citrinopileatus, a species of edible mushrooms, is widely accepted food component, especially in Indian subcontinent. The accumulating susceptibility
of this edible mushroom species towards long-lived radioisotopes of cesium was studied in controlled laboratory condition
using the 134Cs (T
1/2 = 2.06 y) radioisotope. It was observed that the experimental mushroom species accumulated 134Cs and maximum accumulation took place in the cap portion. The pileus (cap)/stipes (stem) ratio of each 134Cs accumulated mushroom sample was determined and found 2.22±0.74. The protein and fat fractions of the experimental mushroom
species were extracted separately after accumulation of radiocesium and it was found that most of the radiocesium accumulation
occurred in the protein fraction of the mushroom. The mushroom Pleurotus citrinopileatus which is white in color, turned completely black after radiocesium accumulation. The black mushroom so obtained was produced
upto fourth generation by tissue culture method without using any radiocesium further. All the successors were found to be
black indicating a permanent mutation of the mushroom species. 相似文献
9.
T. Datta Samanta S. Laskar D. Nayak S. Lahiri 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(2):323-325
Binding ability of mercury, thallium, lead and bismuth with Erythrina variegata seed protein have been investigated using tracer packet technique. Due to the lack of standard methods, inter-comparisons
have been made among three different approaches, like trichloroacetic acid (TCA) precipitation, isoelectric precipitation
and dialysis of protein after incubation with the metals. Good agreement was observed for all the cases except that of lead. 相似文献
10.
Bhattacharya S Chattopadhyay S Laskar S Banerjee M 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2006,63(2):313-319
Electron donor-acceptor (EDA) complexes of tri-n-octylamine (TOA) with [60]- and [70]fullerenes and some other electron acceptors have been studied in chloroform medium by absorption spectrophotometric technique. Charge transfer (CT) absorption bands are observed in the visible region. Vertical ionization potential of TOA was determined utilizing CT transition energy. Oscillator strengths, transition dipole strengths and resonance energies for all the complexes have been calculated. [60]Fullerene/TOA and [70]fullerene/TOA complexes are found to decay slowly with time. Kinetics of these reactions have been studied and activation energies for such processes have been estimated. Ab initio calculations suggest that complexation of [70]fullerene with TOA is enthalpy favoured. 相似文献