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21.
22.
OK Yoon WG Hwang JC Choe MS Kim 《Rapid communications in mass spectrometry : RCM》1999,13(14):1515-1521
A technique to investigate photodissociation kinetics on a nanosecond time scale has been devised for molecular ions generated by multiphoton ionization (MPI) using mass-analyzed ion kinetic energy spectrometry. The branching ratio or rate constant has been determined for the photodissociation of the n-butylbenzene, bromobenzene, iodobenzene, and aniline molecular ions generated by MPI at 266 nm. The ion internal energies have been estimated by comparing the measured kinetic data with the previous energy dependence data. The analysis has shown that only those molecular ions generated by two-photon ionization contribute to the photodissociation signals. Around half of the available energy has been found to remain as molecular ion internal energy in the two-photon ionization process. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
23.
N.Yu. Agafonova M. Aglietta P. Antonioli G. Bari A. Bonardi V.V. Boyarkin G. Bruno W. Fulgione P. Galeotti M. Garbini P.L. Ghia P. Giusti E. Kemp V.V. Kuznetsov V.A. Kuznetsov A.S. Malguin H. Menghetti R. Persiani A. Pesci I.A. Pless A. Porta V.G. Ryasny O.G. Ryazhskaya O. Saavedra G. Sartorelli M. Selvi C. Vigorito L. Votano V.F. Yakushev G.T. Zatsepin A. Zichichi 《The European Physical Journal C - Particles and Fields》2007,52(4):849-855
The CERN Neutrino to Gran Sasso (CNGS) project aims to produce a high energy, wide band νμ beam at CERN and send it toward the INFN Gran Sasso National Laboratory (LNGS), 732 km away. Its main goal is the observation
of the ντ appearance, through neutrino flavour oscillation. The beam started its operation in August 2006 for about 12 days: a total
amount of 7.6×1017 protons were delivered to the target. The LVD detector, installed in hall A of the LNGS and mainly dedicated to the study
of supernova neutrinos, was fully operating during the whole CNGS running time. A total number of 569 events were detected
in coincidence with the beam spill time. This is in good agreement with the expected number of events from Monte Carlo simulations.
PACS 14.60.Pq; 29.27.Fh; 29.40.Mc; 95.55.Vj 相似文献
24.
Ivanildo A. Brito Fernanda Thevenard Thais A. Costa-Silva Samuel S. Oliveira Rodrigo L. O. R. Cunha Emerson A. de Oliveira Patricia Sartorelli Rafael C. Guadagnin Maiara M. Romanelli Andre G. Tempone Joo Henrique G. Lago 《Molecules (Basel, Switzerland)》2022,27(3)
As part of our continuous studies involving the prospection of natural products from Brazilian flora aiming at the discovery of prototypes for the development of new antiparasitic drugs, the present study describes the isolation of two natural acetylene acetogenins, (2S,3R,4R)-3-hydroxy-4-methyl-2-(n-eicos-11′-yn-19′-enyl)butanolide (1) and (2S,3R,4R)-3-hydroxy-4-methyl-2-(n-eicos-11′-ynyl)butanolide (2), from the seeds of Porcelia macrocarpa (Warm.) R.E. Fries (Annonaceae). Using an ex-vivo assay, compound 1 showed an IC50 value of 29.9 μM against the intracellular amastigote forms of Leishmania (L.) infantum, whereas compound 2 was inactive. These results suggested that the terminal double bond plays an important role in the activity. This effect was also observed for the semisynthetic acetylated (1a and 2a) and eliminated (1b and 2b) derivatives, since only compounds containing a double bond at C-19 displayed activity, resulting in IC50 values of 43.3 μM (1a) and 23.1 μM (1b). In order to evaluate the effect of the triple bond in the antileishmanial potential, the mixture of compounds 1 + 2 was subjected to catalytic hydrogenation to afford a compound 3 containing a saturated side chain. The antiparasitic assays performed with compound 3, acetylated (3a), and eliminated (3b) derivatives confirmed the lack of activity. Furthermore, an in-silico study using the SwissADME online platform was performed to bioactive compounds 1, 1a, and 1b in order to investigate their physicochemical parameters, pharmacokinetics, and drug-likeness. Despite the reduced effect against amastigote forms of the parasite to the purified compounds, different mixtures of compounds 1 + 2, 1a + 2a, and 1b + 2b were prepared and exhibited IC50 values ranging from 7.9 to 38.4 μM, with no toxicity for NCTC mammalian cells (CC50 > 200 μM). Selectivity indexes to these mixtures ranged from >5.2 to >25.3. The obtained results indicate that seeds of Porcelia macrocarpa are a promising source of interesting prototypes for further modifications aiming at the discovery of new antileishmanial drugs. 相似文献
25.
Brian T. Heaton Luciano Longhetti D. Michael P. Mingos Clive E. Briant Peter C. Minshall Brian R.C. Theobald Luigi Garlaschelli Ugo Sartorelli 《Journal of organometallic chemistry》1981,213(1):333-350
The crystal structures of Rh4(CO)10(PPh3)2 and Rh4(CO)9P(OPh)33 are reported. 31P-1H NMR studies on Rh4(CO)12-x {P(OPh)3}x(X 1, 2 and 3) show that each derivative exists as only one isomer in solution whereas the analogous triphenylphosphine derivatives can exist as different isomers. A quantitative redistribution of triphenylphosphites occurs on mixing Rh4-(CO)12-xLx with Rh4(CO)12-yLy (L P(OPh)3; x 0, 1, 2, y x + 2; x 0, y x + 4) to give Rh4(CO)12-zLz[z (x + y)]; a related rapid intermolecular randomisation of carbonyls occurs on mixing Rh4(12CO)12 with Rh4(13CO)12. 相似文献
26.
α-Haloketones and -dibromides are converted to the corresponding ketones and alkenes respectively with nickel boride generated from sodium borohydride and nickel chloride. 相似文献
27.
B.T. Heaton L. Longhetti L. Garleschelli U. Sartorelli 《Journal of organometallic chemistry》1980,192(3):431-435
Variable temperature 13C-{31P, 1H} NMR studies on Rh4(CO)8 {P(OPh)3}4 show that the solid state structure is maintained in solution at low temperature; at higher temperatures carbonyl migration occurs around the metal polyhedron with the lowest energy migration occurring via a Cotton type mechanism which also involves a rocking motion about the unique rhodium in the basal plane. At +82°C, the fast exchange limiting 13C-{31P, 1H} and 31P spectra exhibit a quintet and doublet of quartets, respectively. 相似文献
28.
Casper D Becker-Szendy R Bratton CB Cady DR Claus R Dye ST Gajewski W Goldhaber M Haines TJ Halverson PG Jones TW Kielczewska D Kropp WR Learned JG LoSecco JM McGrew C Matsuno S Matthews J Mudan MS Price L Reines F Schultz J Sinclair D Sobel HW Stone JL Sulak LR Svoboda R Thornton G van der Velde JC 《Physical review letters》1991,66(20):2561-2564
29.
To aid in designing new therapeutic iron chelating agents, the mechanism of iron binding to prototypic heterocyclic carboxaldehyde thiosemicarbazones has been studied. Based on molecular orbital and spectroscopic studies, iron (II) is found to bind in a covalent manner, while iron(III) seems to interact ionically. However, with both iron(II) and iron(III), chelate formation is dependent on charge interaction between the metal and the coordinating atoms of the ligand. 相似文献
30.
Becker-Szendy R Bratton CB Cady DR Casper D Claus R Crouch M Dye ST Gajewski W Goldhaber M Haines TJ Halverson PG Jones TW Kielczewska D Kropp WR Learned JG LoSecco JM McGrew C Matsuno S Mudan MS Price L Reines F Schultz J Sinclair D Sobel HW Stone JL Sulak LR Svoboda R Thornton G van der Velde JC 《Physical review D: Particles and fields》1990,42(9):2974-2976