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101.
Dr. Stepas Toliautas Dr. Jelena Dodonova Audrius Žvirblis Ignas Čiplys Artūras Polita Dr. Andrius Devižis Prof. Sigitas Tumkevičius Prof. Juozas Šulskus Dr. Aurimas Vyšniauskas 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(44):10342-10349
Molecular rotors are a class of fluorophores that enable convenient imaging of viscosity inside microscopic samples such as lipid vesicles or live cells. Currently, rotor compounds containing a boron-dipyrromethene (BODIPY) group are among the most promising viscosity probes. In this work, it is reported that by adding heavy-electron-withdrawing −NO2 groups, the viscosity-sensitive range of a BODIPY probe is drastically expanded from 5–1500 cP to 0.5–50 000 cP. The improved range makes it, to our knowledge, the first hydrophobic molecular rotor applicable not only at moderate viscosities but also for viscosity measurements in highly viscous samples. Furthermore, the photophysical mechanism of the BODIPY molecular rotors under study has been determined by performing quantum chemical calculations and transient absorption experiments. This mechanism demonstrates how BODIPY molecular rotors work in general, why the −NO2 group causes such an improvement, and why BODIPY molecular rotors suffer from undesirable sensitivity to temperature. Overall, besides reporting a viscosity probe with remarkable properties, the results obtained expand the general understanding of molecular rotors and show a way to use the knowledge of their molecular action mechanism for augmenting their viscosity-sensing properties. 相似文献
102.
J. Mareš R. Baltramiejúnas V. Narkevičius J. Vaitkus 《Czechoslovak Journal of Physics》1975,25(8):934-942
Luminescent properties of powder AlN∶Eu2+ phosphors were studied by excitation of 2-nd harmonic of ruby laser (hv=3·56 eV). It was shown that emission spectra of AlN∶Eu2+ phosphors consist of five or two overlapping bands according to the concentration of europium and the intensity of excitation. Decay times of luminescence of Eu2+ centres in different peaks lie between 0·9 and 1·5 μsec which is in agreement with the value of decay time of 4f6 5d→477 transition of Eu2+ ions. It is evident from the decomposition of emission spectra of Eu2+ centres that there exist several types of Eu2+ centres in AlN as was already demonstrated in the case of oxygen centres in AlN. 相似文献
103.
Rūta Araminaitė Rasa Garjonytė Albertas Malinauskas 《Central European Journal of Chemistry》2008,6(2):175-179
Kinetic study on the decomposition of Prussian Blue electrocatalytic layer during electrochemical reduction of hydrogen peroxide
has been studied in relation to biosensor application of this electrocatalyst. The decomposition has been shown to proceed
as a nearly exponential decay process and the corresponding first-order rate coefficients were determined. It has been shown
that the decomposition proceeds about 10 times faster in pH 7.3 buffer solution as compared to pH 5.5 buffer. A linear dependence
of the decomposition rate on the concentration of hydrogen peroxide has been found.
相似文献
104.
Oyamada H Naito T Miyamoto S Akiyama R Hagio H Kobayashi S 《Organic & biomolecular chemistry》2008,6(1):61-65
Novel immobilized Pd catalysts, polysilane-supported palladium/alumina hybrid catalysts, have been developed. The catalysts showed high catalytic activity for hydrogenation, and could be used in an organic solvent or under solvent-free conditions. 相似文献
105.
Povilas Virbickas Gerda Ziziunaite Arunas Ramanavicius Aušra Valiūnienė 《Electroanalysis》2023,35(4):e202200230
In this research a Hg2+ ion biosensor was developed by combining Prussian blue (PB) with glucose oxidase (GOx) – an enzyme that can be inhibited by Hg2+ ions. An application of PB in the design of Hg2+ ion biosensor enabled detecting changes in hydrogen peroxide reduction current at low operational potential of 0.2 vs Ag|AgCl,KClsat. The described Hg2+ ion biosensor exhibited wide linear range from 27 μM to 247 μM of Hg2+ and higher maximal detectable concentration of Hg2+ than other GOx inhibition-based biosensors, making it convenient for the analysis of samples with high concentration of Hg2+ ions. 相似文献
106.
Justina Jovaišaitė Sven Kirschner Steponas Raišys Gediminas Kreiza Paulius Baronas Saulius Juršėnas Matthias Wagner 《Angewandte Chemie (International ed. in English)》2023,62(4):e202215071
Organic ultralong room temperature phosphorescence (RTP), or organic afterglow, is a unique phenomenon, gaining widespread attention due to its far-reaching application potential and fundamental interest. Here, two laterally expanded 9,10-dimesityl-dihydro-9,10-diboraanthracene (DBA) derivatives are demonstrated as excellent afterglow materials for red and blue-green light emission, which is traced back to persistent thermally activated delayed fluorescence and RTP. The lateral substitution of polycyclic DBA scaffold, together with weak transversal electron-donating mesityl groups, ensures the optimal molecular properties for (reverse) intersystem crossing and long-lived triplet states in a rigid poly(methyl methacrylate) matrix. The achieved afterglow emission quantum yields of up to 3 % and 15 %, afterglow lifetimes up to 0.8 s and 3.2 s and afterglow durations up to 5 s and 25 s (for red and blue-green emitters, respectively) are attributed to the properties of single molecules. 相似文献
107.
Renata Karpicz Vytautas Getautis Karolis Kazlauskas Saulius Jurnas Vidmantas Gulbinas 《Chemical physics》2008,351(1-3):147-153
Excited state relaxation of indan-1,3-dione derivatives with different substituents attached to the phenyl ring and with the bridged amino group was investigated by means of the steady-state fluorescence and femtosecond time-resolved absorption pump–probe spectroscopy. Bridging of the amino group increases the fluorescence quantum yield and the excited state lifetime. Analysis of the results indicates that the phenyl ring twisting around a single central bond leads to the nonradiative state formation and to subsequent fast relaxation to the ground state. Double bond twisting takes place in molecules with the bridged amino group and causes a large Stokes shift and slightly slower excited state relaxation. 相似文献
108.
We have discovered the unprecedented catalytic use of In(0) for catalytic C-C bond transformations. Remarkably, these general catalytic allylations of ketones proceeded smoothly in water as a sole solvent under mild conditions, and water proved to be essential for these reactions. Both the displayed substrate scope and the functional group tolerance were excellent. Importantly, the In metal catalyst could be easily recovered and reused without loss of catalytic activity. Moreover, when an alpha-substituted allylboronate was used, an unusual constitutional selectivity was observed providing exclusively the formal alpha-adduct. Additionally, the resulting tertiary homoallylic alcohols were obtained with exceptionally high diastereoselectivities. The applicability of this concept to asymmetric catalysis in water by using In(0) combined with a chiral bis(oxazoline) ligand was demonstrated as well. 相似文献
109.
110.
Determination of ten sulfonamides (SAs) in egg and honey has been compared using column liquid chromatography (LC) and ultra-performance liquid chromatography (UPLC) coupled to tandem mass spectrometry (MS–MS). A liquid–liquid extraction with acetonitrile followed by solid-phase extraction on a Strata-X cartridge was developed for sample preparation. The analytical performance of both methods was compared applying the alternative matrix-comprehensive in-house validation approach using specially designed software InterVal?. Using UPLC the separation time was shortened about 30% reducing the run time by 8 min and a better resolution was achieved compared to LC. Due to higher peak efficiency achieved with UPLC, the decision limit values obtained by both techniques were almost equal (6.61–9.43 μg kg?1 and 7.25–11.9 μg kg?1 for UPLC and LC, respectively), despite the fact that in UPLC twice lower sample volumes were injected. Satisfactory and comparable recoveries (80–110%) were obtained by UPLC and LC for all the SAs, except for sulfacetamide by LC and sulfabenzamide by both methods. For a majority of the spiked compounds, UPLC gave significantly better precision. 相似文献