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1.
Molecular Diversity - Nowadays, one of the principal causes of death in the world is cancer. A series of 2-azetidinones containing anthraquinone moiety with various substituents were synthesized...  相似文献   
2.
The H-point standard addition method (HPSAM), based on a spectrophotometric measurement for the simultaneous determination of hydrazine and acetylhydrazine, is described. This method is based on the difference between the rates of their reactions with N,N-dimethylaminobenzaldehyde (DAB) in the presence of sodium dodecyl sulfate (SDS) in acidic media. The results showed that hydrazine and acetylhydrazine could be determined simultaneously in the range of 0.020 - 0.70 and 0.20 - 5.0 mg L(-1), respectively. Under the working conditions, the proposed method was successfully applied to the simultaneous determination of hydrazine and acetylhydrazine in several synthetic mixtures and plasma and water samples.  相似文献   
3.
Quark-condensate contributions to triangle amplitudes arising from the nonperturbative content of the QCD vacuum are shown to uphold the anomalous axial Ward identity to leading and next-to-leading order in both the expansion parameter [m quark/momentum]2, as well as in the expansion parameter [m π/m quark]2 appropriate forπ 0→ kinematics.  相似文献   
4.
The decay rates for the exclusiveB decaysBK c andBK* c are calculated in the context of the heavy quark effective theory. We obtain(BK c )/ (BK)=1.6±0.2 and(BK* c )/ (K*)=0.39±0.04. These results lead to estimates BR(BK c )=(0.11±0.02)% and BR(BK* c )=(0.05±0.01)% if we use the central current experimental values forB(K, K *) branching ratios.  相似文献   
5.
Charge-transfer complexes of N,N-dimethylaniline (DMA) and triethylamine (TEA) with chloranil have been investigated as inhibitors for the sensitized polymerization of methyl methacrylate (MMA) in bulk and in solution. Complete inhibition is achieved by the complexes of both amines followed by retardation only in case of DMA. The higher inhibiting efficiency of the TEA complexes is attributed to their greater stability. The polymers formed in the presence of chloranil alone or its complexes with both amines are quinonoid and contain no combined nitrogen. The results support the idea that inhibition reaction involve electron transfer from the growing chains to the quinone, with formation of molecular complexes of polymeric cations and semiquinone anions. The latter are the actual inhibiting species, so that the efficiency of inhibiting depends on their concentration, which is determined by the stability of the molecular complexes formed. The inhibition reactions should accordingly be considered as oxidation–reduction processes in which the growing chains are the electron donors. The suggested mechanism affords an explanation for the great differences in the inhibiting power of a particular quinone for the polymerization of different monomers.  相似文献   
6.
7.
The polymeric p-benzoquinone-tin derivatives obtained from the reaction of p-benzoquinone with tin tetrachloride in the absence of solvent have been investigated as thermal stabilizers for rigid PVC at 200°C by measuring the rate of dehydrochlorination. The results reveal the greater stabilizing efficiency of the investigated products in relation to dibutyltin maleate and the basic lead stabilizers commonly used in industry. Evidence has been accumulated that the quinone and metallic elements (Sn? Sn bonds) of the stabilizer participate in the stabilization process by trapping the radical intermediates of degradation and blocking the odd electron sites formed on the polymer chains. Although stabilizers with high quinone content provide greater stabilization in the early stages of degradation, their efficiency sharply decreases in subsequent stages. On the other hand, stabilizers of high tin content effectively prohibit the dehydrochlorination reaction at all stages of degradation. On an equivalent basis of metal content, the results clearly demonstrate the greater stabilizing efficiency of tin atoms when found in direct contact in the stabilizer molecule. The mechanism of stabilization suggested to account for the results obtained may be considered as additional evidence in support of the radical nature of the dehydrochlorination reaction.  相似文献   
8.
We report in this article the design and calculated molecular properties of 18 new mono-cyclic β-lactams 4–21, on the basis of one hypothetical antibacterial pharmacophore structure designed to interact with both of Gram-positive bacteria and Gram-negative bacteria. The in vitro biological evaluation of these compounds allowed us to point out new potential non-nucleoside hits, with MIC values in the range of 2–8 μg/mL active against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa. A correlation structure/antibacterial activities relationship of these monocyclic β-lactams is described.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.  相似文献   
9.
Abstract

Novel derivatives of diethyl (4-oxo-2-phenylchroman-3-yl) methyl phosphonate have been synthesized under optimal conditions using domino-Knoevenagel-phospha-Michael reaction catalyzed by nano-zinc oxide. The combination of recovery and reusability of catalyst, simple and applicable approach, good reaction time and good yields of products make this method as a suitable route for this purpose. The structures of the products were determined by FT-IR, 1H-, 13C- and 31P- Nuclear Magnetic Resonance spectroscopies, and elemental analysis.  相似文献   
10.
The widely utilization of phenol and its derivatives such as 3-nitrophenol (3-NP) has led to the worldwide pollution in the environment. In this study, Ti/TiO2 photoelectrode was prepared with anodic oxidation of Ti foil electrode and then the photoelectrocatalytic (PEC) degradation of 3-NP was performed via this electrode, comparing with photocatalytic (PC), electrooxidation and direct photolysis by ultraviolet light. A significant photoelectrochemical synergetic effect in 3-NP degradation was observed on the Ti/TiO2 electrode and rate constant for the PEC process of Ti/TiO2 electrode was about three times as high as its PC degradation process. 3-NP concentration monitoring was carried out with differential pulse voltammetry. Results showed that PEC degradation has highest effect on concentration decreasing of 3-NP at solution and degraded it about 38 %, while other processes degradation efficiencies were about 4, 7, and 12 % for electrooxidation, direct photolysis and photocatalytic degradation, respectively. Finally, effects of solution pH and applied potential on degradation efficiency were studied and results showed that optimum pH for degradation is equal 4.00 and optimum potential is 1.2 V vs. Ag|AgCl|KCl (3M) reference electrode.  相似文献   
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