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51.
An observation of radiation continua produced in heavy ion-atom collisions is reported which cannot be explained, in its entirety, as molecular orbital (MO) X-rays. Beams of 12C, 16O, 35Cl and 79Br incident on gold targets yielded very similar spectra. 相似文献
52.
D. E. Appelbe R. A. E. Austin G. C. Ball J. A. Cameron B. Djerroud T. E. Drake S. Flibotte C. D. O’Leary A. Melarangi C. E. Svensson J. C. Waddington D. Ward 《The European Physical Journal A - Hadrons and Nuclei》2000,8(2):153-155
The decays of 2557Mn32 and 2558Mn33 have been studied with the 8π Spectrometer following the reaction 48Ca(13C,pxn)60 − x
Mn at a beam energy of 40 MeV. The level schemes of these two nuclei have been extended, and the multipolarities of the observed
transitions have been determined. 相似文献
53.
This paper describes field measurements to assess innovative correlation techniques for the study of meteorological and topographical effects on sound propagation. To take advantage of the properties of coded signals in a time-varying system, the correlation signal is produced by the modulation of a code sequence onto an acoustic carrier. An established method of increasing signal-to-noise ratio is to use correlation techniques with maximum length sequences. However, this standard method is restricted in its use outdoors because of the time-variant nature of the atmosphere. On the other hand, the correlation properties of a directly carrier-modulated code sequence modulation signal may be exploited in a time-varying environment. An experiment is described in which the correlation properties of the spread spectrum signal are demonstrated and are used to calculate accurate times of flight that compare well with sonic anemometer measurements of speed of sound. The results illustrate that an acoustical spread spectrum system can provide significantly improved ways of measuring sound propagation outdoors. 相似文献
54.
M. A. Schumaker D. Cline G. Hackman C. Pearson C. E. Svensson C. Y. Wu A. Andreyev R. A. E. Austin G. C. Ball D. Bandyopadhyay J. A. Becker A. J. Boston H. C. Boston L. Buchmann R. Churchman F. Cifarelli R. J. Cooper D. S. Cross D. Dashdorj G. A. Demand M. R. Dimmock T. E. Drake P. Finlay A. T. Gallant P. E. Garrett K. L. Green A. N. Grint G. F. Grinyer L. J. Harkness A. B. Hayes R. Kanungo A. F. Lisetskiy K. G. Leach G. Lee R. Maharaj J-P. Martin F. Moisan A. C. Morton S. Mythili L. Nelson O. Newman P. J. Nolan J. N. Orce E. Padilla-Rodal A. A. Phillips M. Porter-Peden J. J. Ressler R. Roy C. Ruiz F. Sarazin D. P. Scraggs J. C. Waddington J. M. Wan A. Whitbeck S. J. Williams J. Wong 《The European Physical Journal A - Hadrons and Nuclei》2009,42(3):477-484
The low-energy structures of the radioactive nuclei 20, 21Na have been examined using Coulomb excitation at the TRIUMF-ISAC radioactive ion beam facility. Beams of ~ 5×106 ions/s were accelerated to 1.7MeV/A and Coulomb excited in a 0.5mg/cm^2 natTi target. Two TIGRESS HPGe clover detectors perpendicular to the beam axis were used for $ \gamma$ -ray detection, while scattered nuclei were observed by the Si detector BAMBINO. For 21Na , Coulomb excitation from the 3/2+ ground state to the first excited 5/2+ state was observed, while for 20Na , Coulomb excitation was observed from the 2+ ground state to the first excited 3+ and 4+ states. For both beams, B ( $ \lambda$ L) values were determined using the 2+ $ \rightarrow$ 0+ de-excitation in 48Ti as a reference. The resulting B(E2) ↓ value for 21Na is 137±9 e^2fm^4, while the resulting B( $ \lambda$ L) ↓ values for 20Na are 55±6 e^2fm^4 for the 3+ $ \rightarrow$ 2+ , 35.7±5.7 e^2 fm^4 for the 4+ $ \rightarrow$ 2+ , and 0.154±0.030 μ_N^2 for the 4+ $ \rightarrow$ 3+ transitions. This analysis significantly improves the measurement of the 21Na B(E2) value, and provides the first experimental determination of B( $ \lambda$ L) values for the proton dripline nucleus 20Na .-1 相似文献
55.
Charlotte Martin Edith Oyen Yannick Van Wanseele Tanila Ben Haddou Helmut Schmidhammer Jessica Andrade Lynne Waddington Ann Van Eeckhaut Bruno Van Mele James Gardiner Richard Hoogenboom Annemieke Madder Mariana Spetea Steven Ballet 《Materials Today Chemistry》2017
To overcome drawbacks related to repeated opioid administration during the treatment of chronic pain, several controlled-drug delivery systems of opioids have been designed. In order to address some of the limitations of the existing systems, injectable peptide-based hydrogels represent a promising alternative. This work reports on the design and synthesis of short amphipathic peptide-based hydrogels as controlled-drug delivery systems for opioids. Based on the lead sequence H-FEFQFK-NH2, a new set of peptide hydrogelators was designed including β-homo and d-amino acids, mainly aiming at enhancing proteolytic resistance of the peptides, and which hypothetically allows an extension of the drug release period. After self-assembly in aqueous media, the resulting hydrogels were characterized by dynamic rheometry, cryogenic transmission electronic microscopy and their cytotoxicity was assessed. The cryoTEM images of drug loaded hydrogels show the association of microcrystals of the loaded drug along the axes of the fibres, suggesting that the peptide fibres play a key-role as nucleating site for the drug crystals. Hydrogelators devoid of cytotoxicity were considered for further in vivo evaluation. Upon encapsulation of morphine and 14-methoxymetopon, two opioid analgesics, the applicability of the peptide hydrogels as controlled-drug delivery platforms was validated in vivo using the mouse tail-flick test. A sustained antinociceptive effect was observed after subcutaneous injection of the drug loaded gels and, in comparison with the lead sequence H-FEFQFK-NH2, novel sequences revealed extension of the in vivo antinociception up to 72–96 h post injection. 相似文献
56.
Two new isostructural two-dimensional (2D) coordination polymers exhibiting spin crossover (SCO) behavior of formulation [Fe(4,4'-bipy)(2)(NCX)(2)]·4CHCl(3) (4,4'-bipy = 4,4'-bipyridine; X = S [1·4CHCl(3)], Se [2·4CHCl(3)]) have been synthesized and characterized, and both undergo cooperative spin transitions (ST). For 1·4CHCl(3) the ST takes place in two steps with critical temperatures of T(c1)(down) = 143.1 K, T(c2)(down) = 91.2 K, T(c1)(up) = 150.7 K, and T(c2)(up) = 112.2 K. 2·4CHCl(3) displays half ST characterized by T(c)(down) = 161.7 K and T(c)(up) = 168.3 K. The average enthalpy and entropy variations and cooperativity parameters associated with the ST have been estimated to be ΔH(1)(av) = 5.18 kJ mol(-1), ΔS(1)(av) = 35 J K(-1) mol(-1), and Γ(1) = 2.8 kJ mol(-1) and ΔH(2)(av) = 3.55 kJ mol(-1), ΔS(2)(av) = 35 J K(-1) mol(-1), and Γ(2) = 2.6 kJ mol(-1) for 1·4CHCl(3), and ΔH(av) = 6.25 kJ mol(-1), ΔS(av) = 38.1 J K(-1) mol(-1), and Γ = 3.2 kJ mol(-1) for 2·4CHCl(3). At T > [T(c1) (1·4CHCl(3)); T(c) (2·4CHCl(3))], both compounds are in the space group P2/c while at T < [T(c1) (1·4CHCl(3)); T(c) (2·4CHCl(3))] they change to the C2/c space group and display an ordered checkerboard-like arrangement of iron(II) sites where the high- and low-spin states coexist at 50%. 相似文献
57.
Ohne ZusammenfassungMit 1 Abbildung und 1 Tabelle 相似文献
59.
60.
A unified analysis for a class of long-step primal-dual path-following interior-point algorithms for semidefinite programming 总被引:1,自引:0,他引:1
We present a unified analysis for a class of long-step primal-dual path-following algorithms for semidefinite programming whose search directions are obtained through linearization of the symmetrized equation of the central pathH
P
(XS) [PXSP
–1 + (PXSP
–1)
T
]/2 = I, introduced by Zhang. At an iterate (X,S), we choose a scaling matrixP from the class of nonsingular matricesP such thatPXSP
–1 is symmetric. This class of matrices includes the three well-known choices, namely:P = S
1/2 andP = X
–1/2 proposed by Monteiro, and the matrixP corresponding to the Nesterov—Todd direction. We show that within the class of algorithms studied in this paper, the one based on the Nesterov—Todd direction has the lowest possible iteration-complexity bound that can provably be derived from our analysis. More specifically, its iteration-complexity bound is of the same order as that of the corresponding long-step primal-dual path-following algorithm for linear programming introduced by Kojima, Mizuno and Yoshise. © 1998 The Mathematical Programming Society, Inc. Published by Elsevier Science B.V.Corresponding author.This author's research is supported in part by the National Science Foundation under grants INT-9600343 and CCR-9700448 and the Office of Naval Research under grant N00014-94-1-0340.This author's research was supported in part by DOE DE-FG02-93ER25171-A001. 相似文献