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991.
A flotation spectrophotometric method for the determination of germanium with isochromatic dye ion-pairs is described. The molar ratio of germanium to rhodamine 6G to tetrabromofluorescein is 1:5:5. The apparent molar absorptivity is 5.8 x 10(5) l mol(-1) cm(-1) at 531 nm. Beer's law is obeyed over the concentration range of 5.0 x 10(-8)-1.25 x 10(-6) mol l(-1). The proposed method is sensitive and accuracy and can be applied satisfactorily to the determination of germanium in vegetables. 相似文献
992.
J. Planinić Z. Faj B. Šuveljak V. Radolić J. Vaupotič I. Kobal 《Journal of Radioanalytical and Nuclear Chemistry》1996,210(1):227-231
The radon concentration in the air and water of the Bizovac spa was measured by the Radhome silicon detector and the average values were obtained as 70 Bq/m3 in the indoor pool, 40 Bq/m3 in the hotel room, 135 Bq/m3 in the closed therapeutic bathroom, but the geothermal water had a Rn concentration of 25.3 kBq/m3 and the potable one 2.7 kBq/m3. The Rn transfer factor (f) from water to air in the indoor pool and therapeutic bathroom was 10 and 40 times higher than for normal dwellings (f
n=10–4), respectively. The effective equivalent dose of inhaled radon for permanent personnel under the worst conditions in the spa was 5.4 mSv/y, but visitors spending two weeks in the spa could receive the dose of 77 Sv. 相似文献
993.
Application of magdala red as a fluorescence probe in the determination of nucleic acids 总被引:3,自引:0,他引:3
A fluorescence quenching method was developed for the rapid determination of DNA and RNA using magdala red as fluorescence probe. In weakly acidic medium, the fluorescence of magdala red (lambdaex/lambdaem = 540/555 nm) can be largely quenched by DNA or RNA. The calibration graphs are linear over the range 0.01-1.2 microg/mL for both calf thymus DNA (CT DNA) and salmon DNA (SM DNA), and 0.015-1.0 microg/mL for yeast RNA, respectively. The corresponding detection limits are 6.0 ng/mL for CT DNA, 7.0 ng/mL for SM DNA and 15.0 ng/mL for yeast RNA, respectively. CT DNA could be determined in the presence of 20% (w/w) yeast RNA, and the relative standard deviation of six replicate measurements is 3.18% for 400 ng/mL of CT DNA. Interference from coexisting substances in the determination of DNA was also examined. Real samples were determined with satisfactory results. 相似文献
994.
V. B. Novikov D. I. Abaidullina N. Z. Gainutdinova M. A. Varfalomeev B. N. Solomonov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2006,80(11):1790-1794
Calorimetry was used to measure the enthalpies of solution of chloroform in various proton-acceptor solvents and, vice versa, proton-acceptors in chloroform. Based on a previously proposed equation, the enthalpies of specific interaction were calculated and compared with the published data on the enthalpy of hydrogen bonding of chloroform with various proton-acceptor solvents. The composition of the H-bonded complexes mainly formed during the dissolution of proton-acceptor solutes in chloroform was established. It was demonstrated that the dissolution of ethers in chloroform is predominantly accompanied by the formation of 1: 1 complexes, while the dissolution of acetone, dimethylformamide, and dimethyl sulfoxide in chloroform gives rise to more complex associates. 相似文献
995.
M. G. Voronkov S. N. Adamovich V. A. Potapov V. I. Rakhlin B. Z. Shterenberg R. G. Mirskov S. V. Amosova 《Russian Chemical Bulletin》1987,36(8):1723-1724
Conclusions Transetherification of methylvinyldialkoxyslianes by diols (HOCH2CH2)2M (M=O, S, Se, and Te) gave 2-methyl-2-vinyl-1,3-dioxa-6-chalcogena-2-silacyclooctanes CH3 (CH2=CH)Si(OCH2· CH2)2M. The IR, NMR, and mass spectra of these compounds were studied.29Si NMR spectroscopy indicated that there is a transannular interaction in such heterocycles only in the case of M=Te.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1859–1861, August, 1987. 相似文献
996.
The C(60)-gamma-cyclodextrin and Nafion chemically modified electrode exhibits two redox waves by cyclic voltammetry. Such an electrode will effect reduction and oxidation of cytochrome c and be capable of mediating the electron transfer to cytochrome c. 相似文献
997.
Vostrikov N. S. Abutkov A. V. Vasikov V. Z. Miftakhov M. S. 《Russian Journal of Organic Chemistry》2003,39(5):650-653
(1S,4R)-7,7-Dimethyl-1-vinylbicyclo[2.2.1]heptan-2-one oxime in the system (CF3CO)2O-CF3COOH and (1S,4R)-1-(1,2-dibromoethyl)-7,7-dimethylbicyclo[2.2.1]heptan-2-one in the system MeONa-MeOH undergo fragmentation to give exo-alkylidenecyclopentane derivatives, (4R)-4-cyanomethyl-5,5-dimethyl-1-[(1E)-trifluoroacetoxyethylidene]cyclopentane and isomeric (4R)-4-carboxymethyl-1-[(1ZE)-2-methoxyethylidene]-5,5-dimethylcyclopentanes, respectively. The trifluoroacetate derivative undergoes unusual rearrangement, yielding an equilibrium mixture of two isomers with endo- and exocyclic double bond. 相似文献
998.
G. Montavon G. Duplâtre Z. Asfari J. Vicens 《Journal of Radioanalytical and Nuclear Chemistry》1996,210(1):87-103
The solvent extraction of uranium(VI) with a di-carboxylated calix[4]arne (LH2) in chloroform and 1,2-dichloroethane has been studied in the presence or absence of alkali ions (M=Na+,K+). For UO
2
2+
when studied alone, a 12 (metal: ligand) extracted species is evidenced, with a rather low associated extraction equilibrium constant. The efficiency of extraction increases drastically in the presence of alkali ions, due to the formation of heteronuclear complexes. In all cases, the extracted species are found to be both 122 and 112 (UO
2
2+
MLH2) mixed complexes, except in chloroform with K+, where only the latter is formed. In the case of Na+, mass spectrometry spectra confirm the existence of both homo and heteronuclear complexes as determined in the extraction studies. 相似文献
999.
U. M. Dzhemilev R. I. Khusnutdinov Z. S. Muslimov O. M. Nefedov G. A. Tolstikov 《Russian Chemical Bulletin》1988,37(11):2337-2343
Conclusions The homodimerization of spiro{bicyclo[2.2.1]hepta-2,5-diene-7,1-cyclopropane} (I) has been investigated in the presence of Ni-, Fe-, Co-, Rh-, and Ir-based metal complex catalysts. Depending on the nature of the metal and its ligand environment cyclodimerization of (I) can take place via [2+2]-, [2+2+2]-, and [4+4]-cycloaddition schemes, to give high yields of hepta-, octa-, and nonacyclic strained hydrocarbons.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2592–2599, November, 1988. 相似文献
1000.
Z. Řanda M. Vobecký J. Kuncír J. Benada 《Journal of Radioanalytical and Nuclear Chemistry》1978,46(1):95-107
The application of multielement standards (MES) in routine neutron activation analysis brings a whole range of advantages.
This paper deals with the experience obtained during many years of application of these MES. Nine of these MES contain a total
of 50 elements in suitable combinations and concentrations; thus, the determination of most of the common elements by NAA
can be carried out simultaneously. This refers to the following elements: Na, Mg, Al, Cl, K, Ca, Sc, V, Cr, Mn, Fe, Co, Ni,
Cu, Zn, Ga, As, Se, Br, Rb, Sr, Mo, Ag, Cd, In, Sb, Te, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf,
W, Re, Au, Hg, Th and U. For the determination of the remaining elements such as Zr, Ta, Ir etc., single element standards
(SES) are used. 相似文献