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C. Raab J. Bolle H. Oberst J. Eschner F. Schmidt-Kaler R. Blatt 《Applied physics. B, Lasers and optics》1998,67(6):683-688
+ ions. Frequency doubling of a 100 mW diode laser at 986 nm results in up to 60 mW output power at 493 nm in a bandwidth of
less than 60 kHz with respect to the cavity used for locking. Reference frequencies of 18 spectral lines of Te2 near the 493 nm resonance of Ba+ have been measured using modulation transfer spectroscopy. The fluorescence excitation spectrum of a single Ba+ ion, measured with this laser, exhibits well-resolved dark resonances, which confirms the versatility of the system for quantum
optical experiments.
Received: 12 June 1998 相似文献
33.
Karamertzanis PG Anandamanoharan PR Fernandes P Cains PW Vickers M Tocher DA Florence AJ Price SL 《The journal of physical chemistry. B》2007,111(19):5326-5336
The crystal structures, including two new polymorphs, of three diastereomerically related salt pairs formed by (R)-1-phenylethylammonium (1) with (S&R)-2-phenylpropanoate (2), (S&R)-2-phenylbutyrate (3), and (S&R)-mandelate (4) ions were characterized by low-temperature single crystal or powder X-ray diffraction. Thermal, solubility, and solution calorimetry measurements were used to determine the relative stabilities of the salt pairs and polymorphs. These were qualitatively predicted by lattice energy calculations combining realistic models for the dominant intermolecular electrostatic interactions and ab initio calculations for the ions' conformational energies due to the distortion of their geometries by the crystal packing forces. Crystal structure prediction studies were also performed for the highly polymorphic diastereomeric salt pair (R)-1-phenylethylammonium-(S&R)-2-phenylbutyrate (1-3) in an attempt to predict the separation efficiency without relying on experimental information. This joint experimental and computational investigation provides a stringent test for the reliability of lattice modeling approaches to explain the origins of chiral resolution via diastereomer formation (Pasteurian resolution). The further developments required for the computational screening of single-enantiomer resolving agents to achieve optimal chiral separation are discussed. 相似文献
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Garcia B Salome M Lemelle L Bridot JL Gillet P Perriat P Roux S Tillement O 《Chemical communications (Cambridge, England)》2005,(3):369-371
Dihydrolipoic acid (DHLA) capped gold nanoparticles (Au@DHLA) are characterized in solid and liquid states by sulfur K-edge XANES spectroscopy; it clearly shows that DHLA is anchored to gold thanks to both sulfur ends. 相似文献
35.
Phillipe A. Guy Robert J. Anderegg Amareth Lim Matthew J. Saderholm Yibing Yan Bruce W. Erickson 《Journal of the American Society for Mass Spectrometry》1999,10(10):969-974
Betabellin 15D is a 64-residue, disulfide-bridged homodimer. When folded into a beta structure, the protein is predicted to have two clusters of three histidine residues, each cluster able to bind a divalent metal ion. When the protein was incubated with Cu2+, Zn2+, Co2+, or Mn2+, metal complexes of betabellin 15D were observed by electrospray-ionization mass spectrometry. The relative abundances of the ionic complexes suggested an order of affinities of Cu2+ > Zn2+ > Co2+ > Mn2+, consistent with solution-phase affinities for nitrogen- or sulfur-containing ligands. Limited proteolysis of betabellin 15D by immobilized pepsin, as measured by nanoelectrospray-ionization mass spectrometry, showed that the Phe12-Ser13 peptide bond of betabellin 15D was cleaved more slowly in the presence of Cu2+ than in its absence. Because Cu2+ has little or no effect on the catalytic rate of pepsin, the slower cleavage of the Phe12-Ser13 peptide bond may be due to its decreased accessibility caused by Cu(2+)-induced folding of betabellin 15D. 相似文献
36.
Hulme AT Johnston A Florence AJ Fernandes P Shankland K Bedford CT Welch GW Sadiq G Haynes DA Motherwell WD Tocher DA Price SL 《Journal of the American Chemical Society》2007,129(12):3649-3657
The predictions of the crystal structure of 3-azabicyclo[3.3.1]nonane-2,4-dione submitted in the 2001 international blind test of crystal structure prediction (CSP2001) led to the conclusion that crystal structures containing an alternative hydrogen bonded dimer motif were energetically competitive with the known catemer-based structure. Here we report an extensive search for a dimer-based crystal structure. Using an automated polymorph screen a new catemer-based metastable polymorph (form 2) and two new catemer-based solvates were found, and concurrent thermal studies reproduced form 2 and identified a plastic phase (form 3), whose powder X-ray diffraction pattern was consistent with the cubic space group I23 (a = 7.5856(1) A). Computational studies on the monomer showed that the imide N-H was a weak hydrogen bond donor, rationalizing the occurrence of the plastic phase which involved the breaking of all hydrogen bonds, and modeling of small clusters showed that dimers could easily reorganize to give the catemer. FTIR spectra confirmed the weakness of the hydrogen bond, with the solute showing no self-assembly in solution. It is concluded that the weakness of the N-H donor, coupled with the globular shape of the molecule, allows unusually facile transformation between alternative hydrogen bonding motifs during aggregation and nucleation. 相似文献
37.
Mulki H BhatAnne Miura Phillipe VinatierAlain Levasseur Kalya J Rao 《Solid State Communications》2003,125(10):557-562
A microwave method has been developed for the preparation and sintering of lithium lanthanum titanate (LLTO) of the formula Li0.35La0.55TiO3. The method is fast, clean, economical and gives phase pure product of high conductivity. 相似文献
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