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131.
132.
El Khoury L Journel L Guillemin R Carniato S Stolte WC Marin T Lindle DW Simon M 《The Journal of chemical physics》2012,136(2):024319
We present a combined experimental and theoretical study of isolated CH(3)Cl molecules using resonant inelastic x-ray scattering (RIXS). The high-resolution spectra allow extraction of information about nuclear dynamics in the core-excited molecule. Polarization-resolved RIXS spectra exhibit linear dichroism in the spin-orbit intensities, a result interpreted as due to chemical environment and singlet-triplet exchange in the molecular core levels. From analysis of the polarization-resolved data, Cl 2p(x, y) and 2p(z) electronic populations can be determined. 相似文献
133.
S Carniato P Selles L Journel R Guillemin WC Stolte L El Khoury T Marin F Gel'mukhanov DW Lindle M Simon 《The Journal of chemical physics》2012,137(9):094311
We experimentally observed interference effects in elastic x-ray scattering from gas-phase HCl in the vicinity of the Cl K edge. Comparison to theory identifies these effects as interference effects between non-resonant elastic Thomson scattering and resonant Raman scattering. The results indicate the non-resonant Thomson and resonant Raman contributions are of comparable strength. The measurements also exhibit strong polarization dependence, allowing an easy identification of the resonant and non-resonant contributions. 相似文献
134.
Greenbaum DC Arnold WD Lu F Hayrapetian L Baruch A Krumrine J Toba S Chehade K Brömme D Kuntz ID Bogyo M 《Chemistry & biology》2002,9(10):1085-1094
Classifying proteins into functionally distinct families based only on primary sequence information remains a difficult task. We describe here a method to generate a large data set of small molecule affinity fingerprints for a group of closely related enzymes, the papain family of cysteine proteases. Binding data was generated for a library of inhibitors based on the ability of each compound to block active-site labeling of the target proteases by a covalent activity based probe (ABP). Clustering algorithms were used to automatically classify a reference group of proteases into subfamilies based on their small molecule affinity fingerprints. This approach was also used to identify cysteine protease targets modified by the ABP in complex proteomes by direct comparison of target affinity fingerprints with those of the reference library of proteases. Finally, experimental data were used to guide the development of a computational method that predicts small molecule inhibitors based on reported crystal structures. This method could ultimately be used with large enzyme families to aid in the design of selective inhibitors of targets based on limited structural/function information. 相似文献
135.
Kei Ohkubo Dr. Rachel Garcia Paul J. Sintic Dr. Tony Khoury Dr. Maxwell J. Crossley Prof. Dr. Karl M. Kadish Prof. Dr. Shunichi Fukuzumi Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(40):10493-10503
The site of electron‐transfer reduction of AuPQ+ (PQ=5,10,15,20‐tetrakis(3,5‐di‐tert‐butylphenyl)quino‐xalino[2, 3?b′]porphyrin) and AuQPQ+ (QPQ=5,10,15,20‐tetrakis(3,5‐di‐tert‐butylphenyl)bisquinoxalino[2,3‐b′:12,13‐b′′]porphyrin) is changed from the AuIII center to the quinoxaline part of the PQ macrocycle in the presence of Sc3+ in benzonitrile because of strong binding of Sc3+ to the two nitrogen atoms of the quinoxaline moiety. Strong binding of Sc3+ to the corresponding nitrogen atoms on the quinoxaline unit of ZnPQ also occurs for the neutral form. The effects of Sc3+ on the photodynamics of an electron donor–acceptor compound containing a linked ZnII and AuIII porphyrin ([ZnPQ–AuPQ]PF6) have been examined by femto‐ and nanosecond laser flash photolysis measurements. The observed transient absorption bands at 630 and 670 nm after laser pulse irradiation in the absence of Sc3+ in benzonitrile are assigned to the charge‐shifted (CS) state (ZnPQ . +–AuPQ). The CS state decays through back electron transfer (BET) to the ground state rather than to the triplet excited state. The BET rate was determined from the disappearance of the absorption band due to the CS state. The decay of the CS state obeys first‐order kinetics. The CS lifetime was determined to be 250 ps in benzonitrile. Addition of Sc3+ to a solution of ZnPQ–AuPQ+ in benzonitrile caused a drastic lengthening of the CS lifetime that was determined to be 430 ns, a value 1700 times longer than the 250 ps lifetime measured in the absence of Sc3+. Such remarkable prolongation of the CS lifetime in the presence of Sc3+ results from a change in the site of electron transfer from the AuIII center to the quinoxaline part of the PQ macrocycle when Sc3+ binds to the quinoxaline moiety, which decelerate BET due to a large reorganization energy of electron transfer. The change in the site of electron transfer was confirmed by ESR measurements, redox potentials, and UV/Vis spectra of the singly reduced products. 相似文献
136.
Ribeiro PH Caetano DP Almeida MP Huguenin JA dos Santos BC Khoury AZ 《Physical review letters》2001,87(13):133602
We observe experimentally the transfer of angular spectrum and image formation in the process of stimulated parametric down-conversion. Images and interference patterns can be transferred from either the pump or the auxiliary laser beams to the stimulated down-converted one. The stimulated field propagates as the complex conjugate of the auxiliary laser. The phase conjugation is observed through intensity pattern measurements. 相似文献
137.
138.
Peter Kovacic Russell F. Howe Issam Khoury 《Journal of polymer science. Part A, Polymer chemistry》1982,20(12):3305-3312
The second moments of the ESR signals obtained from poly(p-phenylene) (PPP) and deuterated PPP were measured at 9.5 and 35 GHz. The theoretical and experimental contributions to the second moments were considered. It is shown that for deuterated PPP, deuteron hyperfine splitting makes a negligible contribution to the observed second moment. The proton hyperfine contributions to the second moments of the radical species in PPP and p-sexiphenyl were estimated and it was concluded that the unpaired electron was delocalized over only 2-4 phenylene units. A rationale is offered in terms of polarons present as defects in the PPP chains. 相似文献
139.
140.
Shamim Ahmad Khan Shahnawaz Ahmad Bhat Shahab A.A. Nami Abdul Kareem Nahid Nishat 《Comptes Rendus Chimie》2018,21(9):872-879
Coordination polymers were obtained by the reaction of metal acetates, M(CH3COO)2·xH2O {where M = Mn(II), Co(II), Ni(II) and Cu(II)} with AFP ligand (AFP = 5,5'-(piperazine-1,4-diylbis(methylene))bis(2-aminobenzoic acid). The AFP ligand was prepared by the one-pot, two-step reaction of formaldehyde, 2-aminobenzoic acid, and piperazine. Structural and spectroscopic properties have been studied by elemental, spectral (FT-IR, 1H NMR, 13C NMR, and UV–vis), and thermogravimetric analysis. UV–vis spectra and magnetic moment values indicate that Mn(II), Co(II), and Ni(II) polymer–metal complexes are octahedral, while Cu(II) and Zn(II) polymer–metal complexes are distorted octahedral and tetrahedral, respectively. The analytical data confirmed that the coordination polymers of Mn(II), Co(II), Ni(II), and Cu(II) are coordinated with two water molecules, which are further supported by infrared spectra and thermogravimetric analysis data. The prepared polymer–metal complexes showed good antibacterial activities against all tested microorganisms; however, the AFP ligand was also found to be effective, but relatively less than their polymer–metal complexes. Along with antibacterial activity, all the polymer–metal complexes exhibit significant antifungal activity against most of the tested fungal strains. The results of antimicrobial activity reveals that the AFP–Cu(II) showed the highest antibacterial and antifungal activity than other polymer–metal complexes. 相似文献