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71.
Excitation functions for 12C(6Li, 6Li)12C (gs, 4.43 MeV) have been measured at 10 angles (40° ? θcm ? 160°) over the energy range 20 MeV < Elab < 36 MeV. A single anomaly of width Γ ≈ 800 keV is observed at Elab = 22.8 MeV. The results casts doubts on the resonant two-step α-exchange mechanism suggested to occur in this system. 相似文献
72.
Certain finite-voltage current steps appearing in zero magnetic field in Josephson tunnel junctions are interpreted as arising from a novel process involving the inertial motion of one or more vortices in the junction. 相似文献
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75.
Fulton JR Sklenak S Bouwkamp MW Bergman RG 《Journal of the American Chemical Society》2002,124(17):4722-4737
trans-(DMPE)(2)Ru(H)(NH(2)) (1) dehydrogenates cyclohexadiene and 9,10-dihydroanthracene to yield benzene (or anthracene), (DMPE)(2)Ru(H)(2), and ammonia. Addition of fluorene to 1 results in the formation of the ion pair [trans-(DMPE)(2)Ru(H)(NH(3))(+)][A(-)] (A(-) = fluorenide, 4a). Complex 1 also reacts with weak acids A-H (A-H = phenylacetylene, 1,2-propadiene, phenylacetonitrile, 4-(alpha,alpha,alpha-trifluoromethyl)phenylacetonitrile, cyclobutanone, phenol, p-cresol, aniline) to form ammonia and trans-(DMPE)(2)Ru(H)(A) (7, 8, 9a, 9b, 10, 11b, 11c, 12, respectively). In the cases where A-H = phenylacetylene, cyclobutanone, aniline, phenol, and p-cresol, the reaction was observed to proceed via ion pairs analogous to 4a. Compound 1 is reactive toward even weaker acids such as toluene, propylene, ammonia, cycloheptatriene, and dihydrogen, but in these cases deuterium labeling studies revealed that only H/D exchange between A-H and the ND(2) group is observed, rather than detectable formation of ion pairs or displacement products. Addition of triphenylmethane to 1 results in the formation of an equilibrium mixture of 1, triphenylmethane, and the ruthenium/triphenylmethide ion pair 4h. If the energetics of ion-pair association are ignored, this result indicates that the basicity of 1 is similar to that of triphenylmethide. All these observations support the conclusion that the NH(2) group in amido complex 1 is exceptionally basic and as a result prefers to abstract a proton rather than a hydrogen atom from a reactive C-H bond. The energetics and mechanism of these proton-transfer and -exchange reactions are analyzed with the help of DFT calculations. 相似文献
76.
W. Stepp R. Fricke W. Ponndorf S. L. Langedijk S. M. Auld A. Hantzsch Joachim Wagner C. Neuberg A. Gottschalk Y. Tomoda R. D. Barnard M. V. Jonescu C. Bodea H. Leffmann Ch. C. Pines F. Auerbach H. Barschall R. Signer J. Bicskei Maria E. Alessandrini Ch. C. Fulton P. N. van Eck G. W. Ellis W. Smith M. J. Veibel E. Stojciechowska-Struszyńska V. Villaveechia 《Analytical and bioanalytical chemistry》1932,89(11-12):451-458
77.
Thompson AL Parker D Fulton DA Howard JA Pandya SU Puschmann H Senanayake K Stenson PA Badari A Botta M Avedano S Aime S 《Dalton transactions (Cambridge, England : 2003)》2006,(47):5605-5616
The crystal structures of the hydrated salts of [Gd.DOTAM]3+ and its more hydrophobic derivative [Gd.]3+, bearing 4 alpha-phenylethyl groups, (both Gd and Yb salts) are reported and compared. The nature of the anion determines the degree of ordering in the lattice and the extent of hydration. These effects are correlated with the results of 17O and 1H NMR measurements of water exchange dynamics in solution. With [Gd.DOTAM]3+, structural ordering or the extent of hydration in the hydrated lattice follows the sequence Cl->Br->I- and this order also defines the water exchange rate in solution: 7.3, 19.5, 33.3x10(4) s-1 (298 K), respectively. For [Gd.]3+ salts, the measured relaxivity is determined purely by the outer sphere term and the water exchange rate at 298 K is very similar (typically 1x10(4) s-1) for chloride, bromide, iodide, acetate, triflate and nitrate salts, notwithstanding the different nature and extent of hydration found in the crystalline lattice. 相似文献
78.
Dr. Patrick L. Higgs Jordan L. Appleton Prof. Dr. W. Bruce Turnbull Dr. David A. Fulton 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(70):17647-17654
There is growing interest in developing methods to ‘wrap’ nano- and micron-sized biological objects within films that may offer protection, enhance their stability or improve performance. We describe the successful ‘wrapping’ of lectin-decorated microspheres, which serve as appealing model micron-sized objects, within cross-linked polymer film. This approach utilizes polymer chains able to undergo a structural metamorphosis, from being intramolecularly cross-linked to intermolecularly cross-linked, a process that is triggered by polymer concentration upon the particle surface. Experiments demonstrate that both complementary molecular recognition and the dynamic covalent nature of the crosslinker are required for successful ‘wrapping’ to occur. This work is significant as it suggests that nano- and micron-sized biological objects such as virus-like particles, bacteria or mammalian cells—all of which may benefit from additional environmental protection or stabilization in emerging applications—may also be ‘wrapped’ by this approach. 相似文献
79.
80.
B. R. Fulton 《Zeitschrift für Physik A Hadrons and Nuclei》1994,349(3-4):227-232
The idea that clusters of nucleons might exist in the nucleus has a long history and dates back to the earliest days of nuclear physics. Recently there have been significant advances in our theoretical treatment of clustering and in the experimental methods available to identify cluster structure in nuclei. These developments are reviewed with particular reference to the24Mg nucleus where a rich variety of cluster configurations is observed. 相似文献