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991.
The knowledge about the adsorption and diffusion properties (specially about diffusion) of aluminophosphate molecular sieves is very scarce in the literature. These materials offer interesting properties as adsorbents as they have a polar framework and do not contain charge-balancing cations. In this work, the adsorption isotherms of nitrogen, methane and carbon dioxide over an AlPO4-11 sample synthesized in our laboratories have been measured with a volumetric method at 25, 35, 50 and 65 °C over a pressure range up to 110 kPa. The adsorption capacities of each gas are determined by the strength of interaction with the pore surface (carbon dioxide > methane > nitrogen). The equilibrium selectivity to carbon dioxide is quite high with respect to other adsorbents without cations due to the polarity of the aluminophosphate framework. The adsorption Henry’s law constants and diffusion time constants of nitrogen, methane and carbon dioxide in the synthesized AlPO4-11 material have been measured from pulse experiments. A pressure swing adsorption (PSA) process for recovering methane from a carbon dioxide/methane mixture (resembling biogas) has been designed using a dynamic model where the measured adsorption equilibrium and kinetic information has been incorporated. The simulation results show that the proposed process could be simpler than other PSA processes for biogas upgrading based on cation-containing molecular sieves such as 13X zeolite, as it can treat the biogas at atmospheric pressure, and it requires a lower pressure ratio, to produce high purity methane with high recovery. 相似文献
992.
Dr. Moritz Modl Dr. Sebastian Heinl Dr. Gabor Balázs Dr. Fuencisla Delgado Calvo Dr. Maria Caporali Dr. Gabriele Manca Martin Keilwerth Prof. Dr. Karsten Meyer Prof. Dr. Maurizio Peruzzini Prof. Dr. Manfred Scheer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(25):6300-6305
The reactivity of ruthenium and manganese complexes bearing intact white phosphorus in the coordination sphere was investigated towards the low-valent transition-metal species [Cp′′′Co] (Cp′′′=η5-C5H2-1,2,4-tBu3) and [L0M] (L0=CH[CHN(2,6-Me2C6H3)]2; M=Fe, Co). Remarkably, and irrespective of the metal species, the reaction proceeds by the selective cleavage of two P–P edges and the formation of a square-planar cyclo-P4 ligand. The reaction products [{CpRu(PPh3)2}{CoCp′′′}(μ,η1:4-P4)][CF3SO3] ( 5 ), [{CpBIGMn(CO)2}2{CoCp′′′}(μ,η1:1:4-P4)] ( 6 ) and [{CpBIGMn(CO)2}2{ML0}(μ,η1:1:4-P4)] (CpBIG=C5(C6H4nBu)5; L0=CH[CHN(2,6-Me2C6H3)]2; M=Fe ( 7 a ), Co ( 7 b )), respectively, were fully characterized by single-crystal X-ray diffraction and spectroscopic methods. The electronic structure of the cyclo-P4 ligand in the complexes 5 – 7 is best described as a π-delocalized P42− system, which is further stabilized by two and three metal moieties, respectively. DFT calculations envisaged a potential intermediate in the reaction to form 5 , in which a quasi-butterfly-shaped P4 moiety bridges the two metals and behaves as an η3-coordinated ligand towards the cobalt center. 相似文献
993.
Dicopper(II) Metallacyclophanes with Electroswitchable Polymethyl‐Substituted para‐Phenylene Spacers
Dr. Jesús Ferrando‐Soria María Castellano Dr. Rafael Ruiz‐García Dr. Joan Cano Prof. Dr. Miguel Julve Prof. Dr. Francesc Lloret Prof. Dr. Catalina Ruiz‐Pérez Dr. Jorge Pasán Dr. Laura Cañadillas‐Delgado Dr. Donatella Armentano Dr. Yves Journaux Dr. Emilio Pardo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(36):12124-12137
994.
If a hexacyclic graph G represents a benzenoid, a perfect matching corresponds to a configuration of π-bonds. We present an algorithm for counting the number of configurations of π-bonds for parallelogram-like benzenoids with parallelogram-like holes by counting descending paths in a corresponding rectangular
mesh with rectangular holes. 相似文献
995.
Avelina Arnanz Salomé Delgado Consuelo Moreno 《Journal of organometallic chemistry》2008,693(23):3457-3470
A large number of Co2(CO)6- and Co2(CO)4(L-L)-substituted alkyne complexes (L-L = dppa and dmpm) have been prepared, characterized and studied by cyclic and square-wave voltammetry. In this paper we report a comparative electrochemical study of 2,5-, 2,4-, 3,4- and 2,3-bis(trimethylsilylethynyl)thiophene dicobalt substituted alkyne complexes, in order to evaluate the extent of the electronic interaction between the “Co2C2” redox centres depending on the position of the alkynyl substituent on the thiophene ring. 相似文献
996.
Koupanou E Ahualli S Glatter O Delgado A Krumeich F Leontidis E 《Langmuir : the ACS journal of surfaces and colloids》2010,26(22):16909-16920
Lead sulfide (PbS) nanoparticles have been synthesized in aqueous solutions by a reaction between inorganic lead salts and sodium sulfide and stabilized using the cationic polyelectrolytes branched poly(ethylenimine) (PEI), poly(allylamine hydrochloride) (PAH), and poly(diallyldimethylammonium chloride) (PDDA). The structures of the polyamine-stabilized nanoparticle dispersions were examined in detail using UV-vis spectroscopy, small-angle X-ray scattering (SAXS), static and dynamic electrophoretic mobility measurements, and transmission electron microscopy (TEM). Considerable differences were found between the stabilizing efficiencies of these polyelectrolytes, which cannot be attributed to their charge densities or their persistence lengths. Small monodisperse nanoparticles of PbS with a tight stabilizing shell were consistently found only when PEI was used as a stabilizer even at high pH values, although its charge density is then very low. The excellence of PEI as a stabilizer is mainly due to the extensive branching of the chains and the presence of uncharged secondary and tertiary amine groups, which apparently serve as good anchoring points at the nanoparticle surfaces. None of the polyelectrolytes examined here provide long-term protection of the nanoparticles toward oxidation by air, showing that a need for more complex multipurpose stabilizers exists for aqueous PbS dispersions. 相似文献
997.
Esther Delgado Elisa Hernández Avelino Martín 《Journal of organometallic chemistry》2010,695(3):446-11252
The multifunctional ligands [(Z)-FcCCSC(H)C(H)XR] [X = O, R = Me (2a); X = O, R = Et (2b); X = S, R = Ph (3); X = S, R = C6F5 (5)] and [(Z,Z)-Fc(SR)CC(H)SC(H)C(H)SR] [R = Ph (4), C6F5 (6)] have been prepared through hydroalkoxylation and hydrothiolation processes of the alkyne groups in the compound FcCCSCCH 1. Reactions between compound 3 and the carbonyl metals Co2(CO)8, Os3(CO)10(NCMe)2 and Fe2(CO)9 have allowed the synthesis of the polynuclear compounds [(Z)-{Co2(CO)6}(μ-η2-FcCCSC(H)C(H)SPh)] 9, [(Z)-Os3(CO)9(μ-CO){μ3-η2-FcCCSC(H)C(H)(SPh)}] 10 and [(Z)-{Fe3(CO)9}[μ3,η3-(CCS)-FcCCSC(H)C(H)(SPh)] 11. All the compounds have been characterized by elemental analysis, 1H and 13C{1H} NMR spectroscopy, mass spectrometry and the crystal structure of compounds [(Z)-FcCCSC(H)C(H)OMe] 2a and [{Co2(CO)6}2(μ-η2:η2-FcCCSCCSiMe3)] 7 have been solved by X ray diffraction analysis. 相似文献
998.
Antonio V. Herrera‐Herrera Javier Hernández‐Borges Teresa M. Borges‐Miquel Miguel Á. Rodríguez‐Delgado 《Electrophoresis》2010,31(20):3457-3465
Dispersive liquid–liquid microextraction (DLLME) was combined for the first time with NACE‐UV for the selective determination of eight fluoroquinolone antibiotics (lomefloxacin, levofloxacin, marbofloxacin, ciprofloxacin, sarafloxacin, enrofloxacin, danofloxacin and difloxacin) in mineral and run‐off waters. Field‐enhanced sample injection was carried out in order to improve the sensitivity, whereas pipemidic acid was used as internal standard. The BGE that provided complete separation of the eight analytes and the internal standard was composed of 3 M acetic acid, 49 mM ammonium acetate in 55:45 v/v methanol:ACN. Optimum DLLME conditions (extraction of 5 mL of water at pH 7.6 with 685 μL of CHCl3 and 1250 μL of ACN, extractant and disperser solvents, respectively) were achieved by means of experimental design methodology. Calibration curves of the whole method were obtained with correlation coefficients (R) higher than 0.994 in all cases. An accuracy and precision study was carried out at different levels of concentration, finding that there were no significant differences (Student's t‐test) between real and spiked concentrations. 相似文献
999.
Delgado JL de la Cruz P López-Arza V Langa F Kimball DB Haley MM Araki Y Ito O 《The Journal of organic chemistry》2004,69(8):2661-2668
A series of isoindazole-C(60) dyads 4a-c based on pyrazolino[60]fullerene have been prepared by 1,3-dipolar cycloadditions of the nitrile imines, generated in situ from hydrazones 3a-c, to C(60). Molecular orbital calculations for 4b revealed that the electron distribution of the HOMO is located on the isoindazole moiety, while the electron distribution of the LUMO is located on the C(60) moiety. Electrochemical properties of the new dyads 4a-c show a similar electron affinity with respect to C(60). Charge-transfer interactions in the ground state between the isoindazole ring and the fullerene cage are predicted by the molecular orbital calculations and confirmed by electrochemical studies in 4a,b. Steady-state fluorescence emission spectra of dyads 4a-c show that fluorescence intensities in polar benzonitrile solvent decrease with increasing electron-donating ability of the substituent attached on the isoindazole group. This was confirmed by the shortening of fluorescence lifetimes, from which intramolecular charge-separation rates and efficiencies via the excited singlet states of the fullerene moiety were evaluated. The yields of the triplet states in polar solvent decrease with the electron-donating ability, supporting the competitive formation of the charge-separated state with the intersystem crossing from the excited states. Thus, isoindazole[60]fullerene 4b can be considered a molecular switch with an AND logic gate. 相似文献
1000.
Evaluation of two molecularly imprinted polymers for the solid‐phase extraction of natural,synthetic and mycoestrogens from environmental water samples before liquid chromatography with mass spectrometry 下载免费PDF全文
Javier González‐Sálamo Bárbara Socas‐Rodríguez Javier Hernández‐Borges María del Mar Afonso Miguel Ángel Rodríguez‐Delgado 《Journal of separation science》2015,38(15):2692-2699
In this work, we have compared the selectivity of two commercial molecularly imprinted polymers (AFFINIMIP®SPE Estrogens and AFFINIMIP®SPE Zearalenone) for the extraction of 12 estrogenic compounds of interest (i.e. 17α‐estradiol, 17β‐estradiol, estrone, hexestrol, 17α‐ethynylestradiol, diethylstibestrol, dienestrol, zearalenone, α‐zearalanol, β‐zearalanol, α‐zearalenol and β‐zearalenol) from different water samples. High‐performance liquid chromatography coupled with ion trap mass spectrometry with electrospray ionization was used for their determination. Results showed that although both molecularly imprinted polymeric cartridges were specifically designed for different groups of analytes (natural estrogens like estradiol in the first case and zearalenone derivatives in the second) they nearly have the same extraction performance (with recovery values in the range 65–101%) for the same analytes in Milli‐Q water because of the cross‐reactivity of the polymer. However, when more complex water samples were analyzed, it was clear that the behavior was different and that the AFFINIMIP®SPE Estrogens showed less cross‐reactivity than the other cartridge. Validation of the proposed methodology with both cartridges revealed that the extraction was reproducible and that the final limits of detection of the proposed method were in the low ng/L range. 相似文献