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1.
Katarina D. Karljiković Branislava S. Stanković Emil B. Milosavljević Zlatko J. Binenfeld 《Monatshefte für Chemie / Chemical Monthly》1986,117(5):661-670
Mixed acidic constants (pK
a
) of quinolinium oximes [1-(2-phenyl-2-hydroxyiminoethyl)-1-quinolinium chloride (F-1), 1-(2-phenyl-2-hydroxyiminoethyl)-1-isoquinolinium chloride (F-2), 1-(2-phenyl-2-hydroxyiminoethyl)-1-(4-methyl)-quinolinium chloride (F-3), and 1-(2-phenyl-2-hydroxyiminoethyl)-1-(6-methyl)-quinolinium chloride (F-4)] have been determined via their UV absorption spectra recorded in the series ofBritton-Robinson's buffer solutions in thepH region 8.74–11.28 (t=25±0.5°C, =0.2). The obtainedpK
a
values are in good agreement with those achieved by applying graphical methods. The followingpK
a
values have been obtained: 9.93 forF-1, 9.90 forF-2, and 10.02 forF-3 andF-4.On the basis of potentiometric titrations thermodynamic acidic constants (pK
a
) of compoundsF-1,F-2,F-3, andF-4 have been determined and they were found to be 9.82, 9.71, 9.91, and 9.86, respectively. The values obtained by transferringpK
a
intopK
a
are in good agreement with the values obtained spectrophotometrically.
Bestimmung der Aciditätskonstanten einiger Phenyl-hydroxyiminoethylchinolin-Verbindungen
Zusammenfassung Die Mischaciditätskonstanten (pK a ) der Chinolin-Oxime 1-(2-Phenyl-2-hydroxyiminoethyl)-1-chinolinium chlorid (F-1), 1-(2-Phenyl-2-hydroxyiminoethyl)-1-isochinolium chlorid (F-2), 1-(2-Phenyl-2-hydroxyiminoethyl)-1-(4-methyl)-chinolinium chlorid (F-3) und 1-(2-Phenyl-2-hydroxyiminoethyl)-1-(6-methyl)-chinolinium chlorid (F-4) wurden durch ihre UV-Absorptionspektren in einer Reihe vonBritton-Robinson-Pufferlösungen impH-Intervall 8.74–11.28 (t=25±0.5°C; =0.2) bestimmt. Die berechnetenpK a -Werte stimmen mit den über graphische Methoden erhaltenen Ergebnissen überein. DerpK a -Wert beträgt 9.93 für die VerbindungF-1 und 9.90 fürF-2, sowie 10.02 fürF-3 andF-4.Auf Grund der potentiometrischen Titration wurden auch die thermodynamischen Aciditätskonstanten (pK a ) berechnet: 9.82 fürF-1, 9.71 fürF-2, 9.91 fürF-3 und 9.86 fürF-4. Wenn man diese Konstanten in Mischaciditätskonstanten überträgt, erhält man Werte, die mit den durch spektrophotometrischen Bestimmungen erhaltenen Werten gut übereinstimmen.相似文献
2.
Jan Kameník Henrieta Dulaiova Ferdinand Šebesta Kamila Šťastná 《Journal of Radioanalytical and Nuclear Chemistry》2013,296(2):841-846
The method developed for cesium concentration from large freshwater samples was tested and adapted for analysis of cesium radionuclides in seawater. Concentration of dissolved forms of cesium in large seawater samples (about 100 L) was performed using composite absorbers AMP-PAN and KNiFC-PAN with ammonium molybdophosphate and potassium–nickel hexacyanoferrate(II) as active components, respectively, and polyacrylonitrile as a binding polymer. A specially designed chromatography column with bed volume (BV) 25 mL allowed fast flow rates of seawater (up to 1,200 BV h?1). The recovery yields were determined by ICP-MS analysis of stable cesium added to seawater sample. Both absorbers proved usability for cesium concentration from large seawater samples. KNiFC-PAN material was slightly more effective in cesium concentration from acidified seawater (recovery yield around 93 % for 700 BV h?1). This material showed similar efficiency in cesium concentration also from natural seawater. The activity concentrations of 137Cs determined in seawater from the central Pacific Ocean were 1.5 ± 0.1 and 1.4 ± 0.1 Bq m?3 for an offshore (January 2012) and a coastal (February 2012) locality, respectively, 134Cs activities were below detection limit (<0.2 Bq m?3). 相似文献
3.
Application of Novel Zn‐Ferrite Modified Glassy Carbon Paste Electrode as a Sensor for Determination of Cd(II) in Waste Water 下载免费PDF全文
Dalibor M. Stanković Sandra Škrivanj Nenad Savić Aleksandar S. Nikolić Predrag Vulić Dragan D. Manojlović 《Electroanalysis》2014,26(7):1536-1543
This paper describes the preparation of a new sensor based on Zn‐ferrite modified glassy carbon paste electrode and its electrochemical application for the determination of trace Cd(II) ions in waste waters using differential pulse anodic stripping voltammetry (DPASV). Different Zn/Ni ferrite nanoparticles were synthesized and characterized using scanning electron microscopy (SEM) and X‐ray powder diffraction (XRPD). The prepared ferrite nanoparticles were used for the preparation of Zn‐ferrite‐modified glassy carbon paste electrode (ZnMGCPE) for determination of Cd(II) at nanomolar levels in waste water at pH 5. The different parameters such as conditions of preparation, Zn2+/Ni2+/Fe2+ ratio and electrochemical parameters, percentage of modifier, accumulation time, pH and accumulation potential were investigated. Besides, interference measurements were also evaluated under optimized parameters. The best voltammetric response was observed for ZnFe2O4 modifier, when the percentage of modifier was 3 %, accumulation time 9 min, pH of supporting electrolyte 5 and accumulation potential ?1.05 V. Thus prepared electrode displays excellent response to Cd(II) with a detection limit of 0.38 ppb, and selective detection toward Cd(II) was achieved. 相似文献
4.
Stanković S Catak S D'hooghe M Goossens H Abbaspour Tehrani K Bogaert P Waroquier M Van Speybroeck V De Kimpe N 《The Journal of organic chemistry》2011,76(7):2157-2167
The synthetic utility of N-alkylidene-(2,3-dibromo-2-methylpropyl)amines and N-(2,3-dibromo-2-methylpropylidene)benzylamines was demonstrated by the unexpected synthesis of 3-methoxy-3-methylazetidines upon treatment with sodium borohydride in methanol under reflux through a rare aziridine to azetidine rearrangement. These findings stand in contrast to the known reactivity of the closely related N-alkylidene-(2,3-dibromopropyl)amines, which are easily converted into 2-(bromomethyl)aziridines under the same reaction conditions. A thorough insight into the reaction mechanism was provided by both experimental study and theoretical rationalization. 相似文献
5.
Hrdlovic P Donovalova J Stankovicova H Gaplovsky A 《Molecules (Basel, Switzerland)》2010,15(12):8915-8932
Absorption and fluorescence spectra of bichromophoric coumarins were investigated in different solvents and in polymer matrices. These bichromophoric coumarins were composed of a coumarin dimethylamino-substituted at position 7 or unsubstituted coumarin and phthalimide or a 1,8-naphthylimide linked with an iminomethyl bridge to the position 3 or 8 of the coumarin ring. Absorption spectra of 7-dimethylamino derivatives in position 3 of coumarin were quite similar, exhibiting broad bands around 430-440 nm like the parent compound 7-dimethylaminocoumarin-3-carbaldehyde. For coumarin derivatives substituted in position 8, the absorption maximum was shifted to shorter wavelength as for derivatives without position 7 dimethylamino substitution. The most intense fluorescence was observed for 7-(N,N-dimethylamino)-3-[(N-phtalimidoyl)iminomethyl]coumarin in polar solvent, while intense fluorescence was observed for 7-(N,N-dimethylamino)-3-[N-(1,3-dioxobenz[de]isoquinolinyl)iminomethyl]-coumarin in non polar solvent (chloroform), comparable with the fluorescence of 7-amino-4-methylcoumarin. Spectral measurements of bichromophoric coumarins in polymer matrices revealed that the maxima lies in between those for chloroform and methanol yielding more intense fluorescence then in solutions. Completely different solvent effects were observed for 7-(N,N-dimethylamino)-3-[N-(1,3-dioxobenz[de]isoquinolinyl)imino-methyl]coumarin and 7-(N,N-dimethylamino)-3-[(N-phtalimidoyl)iminomethyl]coumarin. With addition of polar methanol the intensity of fluorescence decreases, yielding a Stern-Volmer-like constant of 0.54 dm3 mol?1 for 7-(N,N-dimethylamino)-3-[N-(1,3-dioxo-benz[de]isoquinolinyl)iminomethyl]coumarin and an even higher one of 1.08 dm3·mol?1 for 7-dimethylaminocoumarin-3-carbaldehyde compared to the rather low one of 0.024 dm3 mol?1 for 7-amino-4-methylcoumarin. Contrary to this, addition of methanol under identical conditions brings about an increase in fluorescence intensity of 7-(N,N-dimethylamino)-3-[(N-phtalimidoyl)iminomethyl]coumarin (about 60-fold). The reasons for these different solvent effects are discussed. 相似文献
6.
Marija S. ?iri? Milan Lj. Zlatanovi? Mi?a S. Stankovi? Ljubica S. Velimirovi? 《Applied mathematics and computation》2012,218(12):6648-6655
In this paper geodesic mappings of equidistant generalized Riemannian spaces are discussed. It is proved that each equidistant generalized Riemannian space of basic type admits non-trivial geodesic mapping with preserved equidistant congruence. Especially, there exists non-trivial geodesic mapping of equidistant generalized Riemannian space onto equidistant Riemannian space. An example of geodesic mapping of an equidistant generalized Riemannian spaces is presented. 相似文献
7.
Marija Mirković Drina Janković Sanja Vranješ‐Đurić Magdalena Radović Dragana Stanković Dušan Mijin Nadežda Nikolić 《应用有机金属化学》2012,26(7):347-355
Two novel diamine dioxime ligands, 4,7‐diaza‐3,8‐diethyldecane‐2,9‐dione bis oxime (3) and 4,9‐diaza‐3,10‐diethyldodecane‐2,11‐dione bis oxime (5), were synthesized in order to develop new brain perfusion imaging agents, based on 99mTc(V)‐complexes. The synthesis involved condensation of 2‐hydroxyimino‐3‐pentanone with appropriate diamine in protic solvent which afforded the bis imine adducts. Subsequent reduction of imine functional groups yielded a diastereoisomeric mixture of 3 and 5. UV–visible, IR, 1H NMR, 13C NMR and elemental analysis were used to characterize the structures of the synthesized compounds. 99mTc‐complexes of both diamine dioximes were prepared and radiolabeling conditions optimized to give the maximum yield. Physicochemical parameters of the labeled complexes as well as and their biodistribution in rats were investigated. Both compounds (3 and 5) formed 99mTc‐complexes with a net charge of zero, determined by electrophoresis. The resultant lipophilic 99mTc‐complexes of 3 and 5 were readily formed at pH ~9.0 within 10 min at room temperature with yields of 90% and 95%, respectively. The 99mTc‐3 complex was found to be stable within 1 h, while 99mTc‐5 was stable for a few hours. A significant brain uptake of 99mTc‐3 (2.1% injected dose) and 99mTc‐5 (1.8% injected dose) complexes, 2 min after injection, is in accordance with their lipophilicity. The present study suggests that both ligands are promising candidates as new 99mTc‐based brain‐imaging agents. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
8.
M. Stanković M. Blagojević S. Petrović 《Journal of Thermal Analysis and Calorimetry》1999,56(3):1375-1382
Hexogen can be used pressed only if its crystals are covered by some polymeric material [1], either natural or artificial.
Montan waxes, as natural polymeric materials, were used for the phlegmatization. The melting process of seven types of waxes
was analyzed by differential scanning calorimetry. The thermal decomposition processes of hexogens and phlegmatized hexogens
were investigated by dynamic differential scanning calorimetry and dynamic thermogravimetric analyses. Kinetic parameters
of the decomposition processes of hexogens were evaluated by using data obtained from differential scanning calorimetric curves.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
9.
Predrag M. Rajković Sladjana D. Marinković Miomir S. Stanković 《The Ramanujan Journal》2006,12(2):245-255
We construct the sequence of orthogonal polynomials with respect to an inner product which is defined by q-integrals over a collection of intervals in the complex plane. We prove that they are connected with little q-Jacobi polynomials. For such polynomials we discuss a few representations, a recurrence relation, a difference equation,
a Rodrigues-type formula and a generating function.
2000 Mathematics Subject Classification Primary—33D45, 42C05 相似文献
10.
Simple,Rapid and Sensitive Electrochemical Method for the Determination of the Triketone Herbicide Sulcotrione in River Water Using a Glassy Carbon Electrode 下载免费PDF全文
We report a novel, simple, rapid and sensitive electrochemical method for the determination of sulcotrione, a member of the relatively new class of triketone herbicides, using differential pulse voltammetry on a glassy carbon electrode. Its electrochemical behavior including influences of electrolyte composition, pH and scan rate was studied to select optimal experimental parameters for its determination. In Britton? Robinson buffer at pH 3 sulcotrione provided a well‐defined reduction peak at ?0.84 V (vs. Ag/AgCl electrode), with good repeatability (relative standard deviation of 2.3 % for 8 measurements at 10 µM concentration level). With optimized parameters differential pulse voltammetry rendered two linear concentration ranges from 0.2 to 2 µM and from 2 to 50 µM with a detection limit of 0.05 µM. The proposed procedure was successfully applied to the determination of sulcotrione in spiked river water samples with satisfactory recoveries (93–109 %). The developed method may represent a simple, rapid and sensitive alternative to highly toxic mercury electrodes and chromatographic methods. 相似文献