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51.
A. M. Demchenko N. A. Shtil A. P. Andrushko A. N. Krasovsky A. N. Chernega E. B. Rusanov V. V. Pirozhenko M. O. Lozinskii 《Chemistry of Heterocyclic Compounds》2003,39(8):1084-1089
It has been established that the condensation of 3-(4-methoxyphenylamino)-5,6-dihydro-2H-1,4-oxazine with substituted phenacyl bromides occurs at the exocyclic nitrogen atom with formation of 3-aryl-3-hydroxy-1-(4-methoxyphenyl)-2,5,6,8-tetrahydro-3H-imidazo[2,1-c]-1,4-oxazinium bromides. By treatment of the latter with acetic anhydride 3-aryl-1-(4-methoxyphenyl)-5,6-dihydro-8H-imidazo[2,1-c]-1,4-oxazinium bromides are formed. The structures of the compounds synthesized were determined via
1H NMR spectroscopy and X-ray diffraction. 相似文献
52.
Tuning Pore Size in Square‐Lattice Coordination Networks for Size‐Selective Sieving of CO2 下载免费PDF全文
Dr. Kai‐Jie Chen Dr. David G. Madden Dr. Tony Pham Katherine A. Forrest Amrit Kumar Dr. Qing‐Yuan Yang Dr. Wei Xue Prof. Dr. Brian Space Dr. John J. Perry IV Prof. Dr. Jie‐Peng Zhang Prof. Dr. Xiao‐Ming Chen Prof. Dr. Michael J. Zaworotko 《Angewandte Chemie (International ed. in English)》2016,55(35):10268-10272
Porous materials capable of selectively capturing CO2 from flue‐gases or natural gas are of interest in terms of rising atmospheric CO2 levels and methane purification. Size‐exclusive sieving of CO2 over CH4 and N2 has rarely been achieved. Herein we show that a crystal engineering approach to tuning of pore‐size in a coordination network, [Cu(quinoline‐5‐carboxyate)2]n ( Qc‐5‐Cu ) ena+bles ultra‐high selectivity for CO2 over N2 (SCN≈40 000) and CH4 (SCM≈3300). Qc‐5‐Cu‐sql‐β , a narrow pore polymorph of the square lattice ( sql ) coordination network Qc‐5‐Cu‐sql‐α, adsorbs CO2 while excluding both CH4 and N2. Experimental measurements and molecular modeling validate and explain the performance. Qc‐5‐Cu‐sql‐β is stable to moisture and its separation performance is unaffected by humidity. 相似文献
53.
K. G. W. Inn E. Hall J. T. Woodward IV B. Stewart R. Pollanen L. Selvig S. Turner I. Outola S. Nour H. Kurosaki J. LaRosa M. Schultz Z. Lin Z. Yu C. McMahon 《Journal of Radioanalytical and Nuclear Chemistry》2008,276(2):385-390
Recoil ions from alpha-particle emission can contaminate surface-barrier detection systems. This contamination results in
increased measurement uncertainty, and may require the replacement of expensive detectors. Disposable thin Collodion films
are easily prepared and effectively retard the recoil ions when either directly applied to the surface of alpha-sources or
as catcher foils between the source and the detector. The thin films are particularly effective for relatively low-level sources,
but can sustain structural damage when exposed to high levels of recoil ions (tens of thousands per second) over extended
periods of time. 相似文献
54.
A. N. Krasovsky A. P. Andrushko A. M. Demchenko 《Chemistry of Heterocyclic Compounds》2001,37(4):496-499
5-Aryl(hetaryl)-2-aroylmethylthio-1,3,4-oxadiazoles behave as CH acids and readily react with aryldiazonium tetrafluoroborates at the active methylene group to give azo coupling products. The spectroscopic properties of the compounds synthesized have been studied. 相似文献
55.
A. G. Vendilo H. Rönkkömäki M. Hannu-Kuure M. Lajunen J. Asikkala V. G. Krasovsky E. A. Chernikova P. Oksman L. H. J. Lajunen T. Tuomi K. I. Popov 《Journal of inclusion phenomena and macrocyclic chemistry》2010,66(3-4):223-230
Thermodynamic data for cesium complexes formation with 18-crown-6 (18C6, L) [Cs(18C6)]+ in N-butyl-4-methyl-pyridinium tetrafluoroborate ([BMPy][BF4], I), in 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4], II) and in 1-butyl-3-methylimidazolium dicyanamide ([BMIM][N(CN)2], III) were measured with NMR 133Cs technique at 23–50 °C. The stability of cesium complex in RTILs is estimated to be in the range between water and DMFA. Stability constants for [Cs(18C6)]+ are found to decrease as temperature is increasing. The following values for lgK(Cs+L) and ΔH(Cs+L) at 23 °C are determined: 2.6 (0.3), ?47(1) kJ/mol (RTIL I); 2.8(0.3), ?80(3) kJ/mol (RTIL II) and 3.03 (0.08), ?47(2) kJ/mol (RTIL III). It is demonstrated that enthalpy change promotes complex formation while the corresponding change of entropy is negative and provides decomposition of [Cs(18C6)]+. 相似文献
56.
Ashley Ringer McDonald Jessica A. Nash Paul S. Nerenberg K. Aurelia Ball Olaseni Sode Jonathon J. Foley IV Theresa L. Windus T. Daniel Crawford 《International journal of quantum chemistry》2020,120(20):e26359
The Molecular Sciences Software Institute (MolSSI) is an National Science Foundation (NSF) funded institute that focuses on improving software, education, and training in the computational molecular sciences. Through a collaboration with the Molecular Education and Research Consortium in Undergraduate computational chemistRY (MERCURY), the MolSSI has developed resources for undergraduate and other early career students to lay an educational foundation for the next generation of computational molecular scientists. The resources focus on introducing best practices in software engineering to students from the very start to make their software more useable, maintainable, and reproducible. 相似文献
57.
The spectrum of Harper's equation is determined by the discriminant, which is a certain polynomial of degree Q if the commensurability parameter of Harper's equation is P/Q, where P, Q are coprime positive integers. A simple expression is indicated for the derivative of the discriminant at zero energy for odd Q. Three dominant terms of the asymptotics of this derivative are calculated for the case of an arbitrary P as Q increases. The result gives a lower bound on the width of the centermost band of Harper's equation and shows the effects of band clustering. 相似文献
58.
59.
William T. Farrar IV Guy C. Van Orden 《Nonlinear dynamics, psychology, and life sciences》2001,5(3):223-265
Five simulations mimicked benchmark phenomena of intact and dyslexic word naming. Initially, an iterative map was tuned to simulate the frequency × consistency interaction in skilled naming. Subsequently, two model parameters were changed, in turn, to produce the regularization error of surface dyslexia (PINT pronounced to rhyme with /mint/), absent pseudoword (BINT) naming of phonological dyslexia (words are named correctly; pseudowords are not), the semantic error of deep dyslexia (BUSH named as /tree/), and a dissociation in picture naming of spoken versus written responses (the spoken response to a picture of a bush is /tree/, but the written response is BUSH). All errors, except absent pseudoword naming, were simulated as transcritical bifurcations. 相似文献
60.
Francis Delano IV Ernesto Castellanos John McCracken Selvan Demir 《Chemical science》2021,12(46):15219
Introducing spin onto organic ligands that are coordinated to rare earth metal ions allows direct exchange with metal spin centres. This is particularly relevant for the deeply buried 4f-orbitals of the lanthanide ions that can give rise to unparalleled magnetic properties. For efficacy of exchange coupling, the donor atoms of the radical ligand require high-spin density. Such molecules are extremely rare owing to their reactive nature that renders isolation and purification difficult. Here, we demonstrate that a 2,2′-azopyridyl (abpy) radical (S = 1/2) bound to the rare earth metal yttrium can be realized. This molecule represents the first rare earth metal complex containing an abpy radical and is unambigously characterized by X-ray crystallography, NMR, UV-Vis-NIR, and IR spectroscopy. In addition, the most stable isotope 89Y with a natural abundance of 100% and a nuclear spin of ½ allows an in-depth analysis of the yttrium–radical complex via EPR and HYSCORE spectroscopy. Further insight into the electronic ground state of the radical azobispyridine-coordinated metal complex was realized through unrestricted DFT calculations, which suggests that the unpaired spin density of the SOMO is heavily localized on the azo and pyridyl nitrogen atoms. The experimental results are supported by NBO calculations and give a comprehensive picture of the spin density of the azopyridyl ancillary ligand. This unexplored azopyridyl radical anion in heavy element chemistry bears crucial implications for the design of molecule-based magnets particularly comprising anisotropic lanthanide ions.Unambiguous characterization of the first 2,2′-azobispyridine radical-containing rare earth metal complex through X-ray crystallography, DFT computations, EPR and HYSCORE spectroscopy. 相似文献