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71.
Swapnil S.Sonar Sandip A.Sadaphal Shivaji S.Pawar Bapurao B.Shingate Murlidhar S.Shingare 《中国化学快报》2009,20(5):557-561
A convenient synthesis of quino[2,3-b][1,5]benzoxazepines from substituted 2-chloroquinoline-3-carbaldehyde and 2-hydroxy-aniline by using stable,non-toxic and inexpensive catalyst 1,8-diazabicyclo-undecan-7-ene (DBU)/silica gel is described.This method affords the quino[2,3-b][1,5]benzoxazepines under the influence of microwave irradiation (360 W) in solvent-free conditions within short reaction times (2-3 min),giving high yields of products (93-96%). 相似文献
72.
We prove existence and uniqueness of positive solutions for the boundary value problem
(rN−1φ(u′))′=−λrN−1f(u),u′(0)=u(1)=0, 相似文献
73.
Shobha Oruganti Junping Shi Ratnasingham Shivaji 《Transactions of the American Mathematical Society》2002,354(9):3601-3619
We consider a reaction-diffusion equation which models the constant yield harvesting to a spatially heterogeneous population which satisfies a logistic growth. We prove the existence, uniqueness and stability of the maximal steady state solutions under certain conditions, and we also classify all steady state solutions under more restricted conditions. Exact global bifurcation diagrams are obtained in the latter case. Our method is a combination of comparison arguments and bifurcation theory.
74.
We consider the non-linear two point boundary value problem where λ > 0,f ∈ C2, f′ ≥ 0, f(0) < 0 and limu → ∞ f(u) > 0. By considering the non-negative as well as all sign changing solutions, we establish the existence of infinitely many non-trivial bifurcation points. Further, when f is superlinear, we prove that there exists a constant λ* > 0, such that for each λ ∈ (0, λ*) there are exactly two solutions with m interior zeros for every m = 1,2, …We apply our results to the case when f(u) = u 3 - k; k > 0, and also discuss the evolution of the bifurcation diagram as k → 0. 相似文献
75.
Sharma KS Rodgers C Palepu RM Rakshit AK 《Journal of colloid and interface science》2003,268(2):482-488
The interaction between the alkanediyl-alpha,omega-type cationic gemini surfactant, [(C(16)H(33)N(+)(CH(3))(2)(CH(2))(4)N(+)(CH(3))(2)C(16)H(33))2Br(-)], 16-4-16 and the conventional nonionic surfactant [CH(3)(CH(2))(10)CH(2)(OCH(2)CH(2))(6)OH], C(12)E(6) in aqueous medium has been investigated. The critical micelle concentrations of different mixtures have been measured by surface tension using a du Nouy tensiometer in aqueous solution at different temperatures (303, 308, and 313 K). Maximum surface excess (Gamma(max)) and minimum area per molecule (A(min)) were evaluated from a surface tension vs log(10)C (C is concentration) plot. The cmc value of the mixture was used to compute beta(m), the interaction parameter. The beta(sigma), the interaction parameter at the monolayer air-water interface, was also calculated. We observed synergism in 16-4-16/C(12)E(6) system at all concentration ratios. The micelle aggregation number (N(agg)) has been measured using a steady state fluorescence quenching method at a total surfactant concentration approximately 2 mM at 25 degrees C. The micropolarity and the binding constant (K(sv)) of mixed systems were determined from the ratio of intensity of peaks (I(1)/I(3)) of the pyrene fluorescence emission spectrum. The micellar interiors were found to be reasonably polar. We also found, using Maeda's concept, that the chain-chain interactions are very important in this system. 相似文献
76.
Systematic analysis of the persulfonylation of branched aromatic oligoamines with different arylsulfonyl chlorides allowed optimization of the repetitive steps involved in the synthesis of the sulfonimide-based dendrimers. The optimized procedures afforded the fourth generation N- and pentaphenylene-centered dendrimers with 16 and 32 peripheral groups, respectively. Analysis of products of incomplete substitution showed that the amino groups in aromatic oligoamines are persulfonylated consecutively. 相似文献
77.
Shivaji S. Pawar Deepak V. Dekhane Murlidhar S. Shingare Shivaji N. Thore 《中国化学快报》2008,19(9):1055-1058
Glyoxylic acid (5 mol%) performs as a novel highly water-soluble catalyst for the synthesis of 2-aryl-l-arylmethyl-lH- benzimidazoles from a wide range of substituted o-phenylenediamines and various substituted aldehydes in good to excellent isolated yields (85-95%) using water as solvent at ambient temperature. The remarkable advantages offered by this method are easily and inexpensive available catalyst, simple procedure, mild conditions, much faster (20--40 rain) reactions and excellent yields of products. 相似文献
78.
79.
Synthesis and Antifungal Screening of 2‐(2‐Aryl‐4‐methyl‐thiazol‐5‐yl)‐5‐((2‐aryl/benzylthiazol‐4‐yl)methyl)‐1,3,4‐oxadiazole Derivatives
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Pravin C. Mhaske Shivaji H. Shelke Kisan Gadge Abhijit Shinde 《Journal of heterocyclic chemistry》2016,53(1):129-134
A new series of synthesis and biological screening of 2‐(2‐aryl‐4‐methyl‐thiazol‐5‐yl)‐5‐((2‐aryl/benzylthiazol‐4‐yl)methyl)‐1,3,4‐oxadiazole derivatives 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i was achieved by condensation of 2‐(2‐aryl/benzylthiazol‐4‐yl)acetohydrazide 2a , 2b , 2c with 4‐methyl‐2‐arylthiazole‐5‐carbaldehyde 3a , 3b , 3c followed by oxidative cyclization of N'‐((4‐methyl‐2‐arylthiazol‐5‐yl)methylene)‐2‐(2‐aryl/benzylthiazol‐4‐yl)acetohydrazide 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i using iodobenzene diacetate as oxidizing agent. All the synthesized compounds were screened for their in vitro antifungal activity against Candida albicans, Candida tropicalis, Aspergillus niger, and Aspergillus flavus. Some of the synthesized compounds showed good antifungal activity. 相似文献
80.
Srinivasa Rao Vidadala Shivaji A. Thadke Srinivas Hotha Sudhir Kashyap 《Journal of carbohydrate chemistry》2013,32(3):241-251
Various thioglycosides were synthesized from stable propargyl glycosides using catalytic quantity of AuBr3 and various thiol aglycons. The current protocol enables preparation of thioglycosides from propargyl glycosides in an efficient and simple manner. The reaction is fast, catalytic, and mild. Supplemental materials are available for this article. Go to the publisher's online edition of Journal of Carbohydrate Chemistry to view the free supplemental file. 相似文献