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41.
Monika Müllerová Karol Holý Pavol Blahušiak Martin Bulko 《Journal of Radioanalytical and Nuclear Chemistry》2018,315(2):237-241
The influence of meteorological parameters on radon exhalation rate was analyzed. The analyses show a significant influence of precipitation on radon exhalation rate. The highest exhalation rate was found during dry periods and the lowest during the periods of strong precipitation. We also tested two different types of detectors for the measurement of radon exhalation rate—the ionization chamber (AlphaGUARD) and the scintillation chamber of Lucas type. The exhalation rates measured by these detectors were in a good agreement. Likewise, there was an agreement in radon exhalation rates determined from short term and long term increases in radon activity concentration. 相似文献
42.
Hydrolysis of Amides of Phospholinic Acid The acid catalysed hydrolysis of (= OAP, R = organic substituent) has been investigated kinetically. Provided the pH remains constant, the hydrolysis is a first order reaction. From the temperature dependance of the rate constant the activation energy Ea as well as the thermodynamic data ΔH* and ΔS* have been calculated. In comparison to the compound with R = H aromatic substituents and additional the t-butyl group enhance Ea whilst aliphatic substituents included the benzyl group diminish Ea. The first step of the reaction is a protonation at the oxygen or nitrogen resulting in the formation of an equilibrium. After the determination of the basicity constant KA of some OAPs it was possible to calculate the respective rate constants of the rate determining step of the reactions and the corresponding thermodynamic data EF, ΔH and ΔS. It is assumed that the mechanism of the hydrolysis takes place according to the same scheme which has been assumed for the hydrolysis of cyclic esters of the phosphinic acid by Ugi [1] and colaborators. 相似文献
43.
Secondary ion mass spectrometry and alpha-spectrometry of electrodeposited thorium films 总被引:1,自引:0,他引:1
Jozef Kuruc Jana Strišovská Dušan Galanda Silvia Dulanská Ľubomír Mátel Monika Jerigová Dušan Velič 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(3):973-981
The main aim of this work was the preparation of samples with thorium content on the steel discs by electrodeposition for determination of natural thorium isotope by alpha spectrometry and secondary ion mass spectrometry and finding out their possible linear correlation between these methods. The analysis of the composition of surface was other aim of study. Discs were measured by alpha spectrometer. After that, alpha spectrometry discs were analyzed by TOF-SIMS IV, which is installed in the International Laser Centre in Bratislava. The integral and normalized intensities of isotope of 232Th and intensities of ions of ThO+, ThOH+, ThO2H+, Th2O4H+, ThO2 ?, ThO3H?, ThH3O3 ? a ThN2O5H? were measured. The linear correlation is between surface’s weights of Th and intensities of ions of Th+ from identified in SIMS spectra. We found out the chemical binding between thorium and oxygen and hydrogen on the surface of samples by SIMS method. Obtained intensities of ions 232ThO+, 232ThOH+, 232ThO2H+ prove the presence of oxidized forms of thorium in the upper layers of surface. The oxidized ions predominate in univalent form of thorium up to deep about 3,000 nm. 相似文献
44.
Helicenophyrins: Expanded Carbaporphyrins Incorporating Aza[5]helicene and Heptacyclic S‐Shaped Aza[5]helicene Motifs 下载免费PDF全文
Dr. Bartosz Szyszko Monika Przewoźnik Dr. Michał J. Białek Dr. Agata Białońska Prof. Dr. Piotr J. Chmielewski Dr. Jakub Cichos Prof. Dr. Lechosław Latos‐Grażyński 《Angewandte Chemie (International ed. in English)》2018,57(15):4030-4034
Incorporation of phenanthrene into a hexaphyrin(1.1.1.1.1.0) frame resulted in intramolecular ring fusion, thus giving rise to chiral helicenophyrins. These molecules contain helicene and porphyrin features by incorporating either an aza[5]helicene or heptacyclic S‐shaped aza[5]helicene. 相似文献
45.
Two CrIII–picolinato complexes were obtained and characterized in solution. The [Cr(C2O4)(pyac)2]– and [Cr(C2O4)2(pyac)]2– ions (pyac = picolinic acid anion) in acidic solutions undergo a reversible one-end CrIII–picolinato chelate ring opening via CrIII—N bond breaking. The reaction rate was determined spectrophotometrically in the 0.1–1.0 M HClO4 range at I = 1.0 M. The observed pseudo-first order rate constant depends on [H+] according to the equation: k
obs = a + b[H+] + c/[H+]. A reaction mechanism, which assumes participation of the protonated and unprotonated forms of the reactants, has been proposed. The kinetic parameters a, b, c have been defined as a = k
1, b = k
2
Q
1, c = k
–1/Q
2, where k
1, k
–1,k
2 are rate constants for the forward and reverse processes and Q
1, Q
2 are the protolytic equilibrium constants in the term of the proposed mechanism. The activation parameters have been determined and discussed. 相似文献
46.
The first attempts to use ethynylsiloxysilsesquioxanes as reagents for hydrosilylation in the presence of Pt‐ and Ru‐based catalysts are reported. The results obtained strongly depend on the catalytic system used. The catalysts are proved to promote regioselective introduction of β‐(E)‐ and α‐fragments of the alkenylsilane group to the silsesquioxane core. The favourable features of these catalytic systems are their high selectivity and the requirement for relatively mild conditions. This methodology was also successfully applied to dihydro‐substituted organosilicon compounds to obtain a new class of silsesquioxane‐based compounds. 相似文献
47.
48.
Monika Skowron Robert Zakrzewski Witold Ciesielski 《International journal of environmental analytical chemistry》2018,98(3):286-294
A simple and convenient thin-layer chromatography (TLC) method combined with image analysis technique was developed to determine thiophanate methyl. The detection of pesticide was based on iodine–azide reaction. Digital images of TLC plate chromatograms were analysed using TLSee software, and quantitative analysis was conducted. The linearity (0.3–3.0 µg per spot), sensitivity, accuracy and precision of the system were investigated. 相似文献
49.
Sourav Adak Luke L. Daemen Monika Hartl Darrick Williams Jennifer Summerhill Heinz Nakotte 《Journal of solid state chemistry》2011,184(11):2854-2861
We present a comprehensive study of the structural properties and the thermal expansion behavior of 17 different Prussian Blue Analogs (PBAs) with compositions MII3[(M′)III(CN)6]2·nH2O and MII2[FeII(CN)6]·nH2O, where MII=Mn, Fe, Co, Ni, Cu and Zn, (M′)III=Co, Fe and n is the number of water molecules, which range from 5 to 18 for these compounds. The PBAs were synthesized via standard chemical precipitation methods, and temperature-dependent X-ray diffraction studies were performed in the temperature range between −150 °C (123 K) and room-temperature. The vast majority of the studied PBAs were found to crystallize in cubic structures of space groups Fm3?m, F4?3m and Pm3?m. The temperature dependence of the lattice parameters was taken to compute an average coefficient of linear thermal expansion in the studied temperature range. Of the 17 compounds, 9 display negative values for the average coefficient of linear thermal expansion, which can be as large as 39.7×10−6 K−1 for Co3[Co(CN)6]2·12H2O. All of the MII3[CoIII(CN)6]2·nH2O compounds show negative thermal expansion behavior, which correlates with the Irving–Williams series for metal complex stability. The thermal expansion behavior for the PBAs of the MII3[FeIII(CN)6]2·nH2O family are found to switch between positive (for M=Mn, Co, Ni) and negative (M=Cu, Zn) behavior, depending on the choice of the metal cation (M). On the other hand, all of the MII2[FeII(CN)6]·nH2O compounds show positive thermal expansion behavior. 相似文献
50.