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31.
Carla Gasbarri Maurizio Ronci Antonio Aceto Roshan Vasani Gianluca Iezzi Tullio Florio Federica Barbieri Guido Angelini Luca Scotti 《Molecules (Basel, Switzerland)》2021,26(17)
The aim of this work was to deeply investigate the structure and properties of electrochemically synthesized silver nanoparticles (AgNPs) through high-resolution techniques such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), Zeta Potential measurements, and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS). Strong brightness, tendency to generate nanoclusters containing an odd number of atoms, and absence of the free silver ions in solution were observed. The research also highlighted that the chemical and physical properties of the AgNPs seemed to be related to their peculiar oxidative state as suggested by X-ray photoelectron spectroscopy (XPS) and X-ray powder diffraction (XRPD) analyses. Finally, the MTT assay tested the low cytotoxicity of the investigated AgNPs. 相似文献
32.
Filippi A Speranza M Paladini A De Carolis R Guidoni AG Laganà A Satta M 《Journal of mass spectrometry : JMS》2006,41(1):98-102
Diastereomeric clusters of general formula [MAB(2)](+) and [MA(2)B](+) (M = Li(I), Na(I), Ag(I), Ni(II)-H, or Cu(II)-H; A = (R)-(-)- and (S)-(+)-(1-aminopropyl)phosphonic acid; B = (1R)-(-)- and (1S)-(+)-(1-aminohexyl)phosphonic acid) have been readily generated in the electrospray ionization (ESI) source of a triple-quadrupole mass spectrometer and their collision-induced dissociation (CID) investigated. CID of diastereomeric complexes, e.g. [MA(S)(B(S))(2)](+) and [MA(R)(B(S))(2)](+), leads to fragmentation patterns characterized by R(homo) = [MA(S)B(S)](+)/[M(B(S))(2)](+) and R(hetero) = [MA(R)B(S)](+)/[M(B(S))(2)](+) abundance ratios, which depend upon the relative stability of the diastereomeric [MA(S)B(S)](+) and [MA(R)B(S)](+) complexes in the gas phase. The chiral resolution factor R(chiral) = R(homo)/R(hetero) is found to depend not only on the nature of the M ion but also on that of the fragmenting species, whether [MAB(2)](+) or [MA(2)B](+). The origin of this behavior is discussed. 相似文献
33.
Guldi DM Rahman GM Qin S Tchoul M Ford WT Marcaccio M Paolucci D Paolucci F Campidelli S Prato M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(8):2152-2161
Dispersible single-walled carbon nanotubes grafted with poly(4-vinylpyridine), SWNT-PVP, were tested in coordination assays with zinc tetraphenylporphyrin (ZnP). Kinetic and spectroscopic evidence corroborates the successful formation of a SWNT-PVPZnP nanohybrid. Within this SWNT-PVPZnP nanohybrid, static electron-transfer quenching (2.0+/-0.1) x 10(9) s(-1) converts the photoexcited-ZnP chromophore into a radical-ion-pair state with a microsecond lifetime, namely one-electron oxidized-ZnP and reduced-SWNT. 相似文献
34.
Barone V Casarin M Forrer D Pavone M Sambi M Vittadini A 《Journal of computational chemistry》2009,30(6):934-939
A semiempirical addition of dispersive forces to conventional density functionals (DFT-D) has been implemented into a pseudopotential plane-wave code. Test calculations on the benzene dimer reproduced the results obtained by using localized basis set, provided that the latter are corrected for the basis set superposition error. By applying the DFT-D/plane-wave approach a substantial agreement with experiments is found for the structure and energetics of polyethylene and graphite, two typical solids that are badly described by standard local and semilocal density functionals. 相似文献
35.
Chryssostomos Chatgilialoglu Dr. Mila D'Angelantonio Dr. Maurizio Guerra Dr. Panagiotis Kaloudis Quinto G. Mulazzani Dr. 《Angewandte Chemie (International ed. in English)》2009,48(12):2214-2217
Radically different : Contrary to previous proposals, the main reaction of the HO. radical with guanosine or 2′‐deoxyguanosine is the hydrogen abstraction from the NH2 moiety to give a guanyl radical. This radical, characterized by a broad band in the visible region (around 610 nm), undergoes tautomerization to the most stable isomer.
36.
Benfatto M Della Longa S Hatada K Hayakawa K Gawelda W Bressler C Chergui M 《The journal of physical chemistry. B》2006,110(29):14035-14039
A full multiple theoretical model (MXAN) is applied to fit picosecond difference X-ray absorption spectra at the ruthenium L(3) edge upon photoexcitation of aqueous [RuII(bpy)3]2+. We show that fitting difference spectra allows an increase in sensitivity, such that slight structural changes can be retrieved, which are not detected in fitting full spectra. The Ru-N bond distances of the excited complex in the (3)MLCT state are in good agreement with recently published values. The implementation of the present approach to L-edge spectra and its high sensitivity opens opportunities for its extension to a large class of experiments where difference X-ray absorption spectra are recorded. 相似文献
37.
Geraldo Capannesi Alberto Rosada Maurizio Manigrasso Pasquale Avino 《Journal of Radioanalytical and Nuclear Chemistry》2012,291(1):163-168
In geochemistry, the distribution of the Rare Earth Elements (REEs) in earth crust and mantle allows to understand geochemical
cycles and origin and age of igneous rocks. In this article REEs (Ce, Dy, Eu, La, Nd, Sm, Tb, and Yb), Th and U in ores of
the North-Latium (Bracciano area, Ceriti Mt., Fate Mt., Sabatini Mt., Vulsini Mt., Acqua Rossa basin), have been investigated
for evaluating the extraction feasibility for industrial applications. 107 samples were irradiated in the rotating rack of
the TRIGA Mark II reactor of the R.C. Casaccia (ENEA) at neutron flux of 2.6 × 1012
n × cm−2 × s−1 for 12 h together with primary and secondary standards. The gamma spectrometry measurements were performed after 8 h, 3 and
30 days of decay by means of HPGe detector (FWHM 1.75 keV at 1332.5 keV, peak/Compton ratio 55.1, relative efficiency of 22%)
connected to a multi-channel analyzer. The total REE mean content is 105 μg g−1, ranging widely between 2.23 and 410.5 μg g−1 (average coefficient of variation 112%). A similar behavior is found for Th and U: their average levels are 13.5 and 6.0 μg g−1, respectively. A quite good correlation between REEs and Th (and U) is found for Ceriti Mt. (r
2 > 0.8) whereas for the other areas the correlation is <0.7. The results obtained evidence the low U content in the investigated
locations. 相似文献
38.
Golub IE Filippov OA Gutsul EI Belkova NV Epstein LM Rossin A Peruzzini M Shubina ES 《Inorganic chemistry》2012,51(12):6486-6497
The mechanism of transition-metal tetrahydroborate dimerization was established for the first time on the example of (Ph(3)P)(2)Cu(η(2)-BH(4)) interaction with different proton donors [MeOH, CH(2)FCH(2)OH, CF(3)CH(2)OH, (CF(3))(2)CHOH, (CF(3))(3)CHOH, p-NO(2)C(6)H(4)OH, p-NO(2)C(6)H(4)N═NC(6)H(4)OH, p-NO(2)C(6)H(4)NH(2)] using the combination of experimental (IR, 190-300 K) and quantum-chemical (DFT/M06) methods. The formation of dihydrogen-bonded complexes as the first reaction step was established experimentally. Their structural, electronic, energetic, and spectroscopic features were thoroughly analyzed by means of quantum-chemical calculations. Bifurcate complexes involving both bridging and terminal hydride hydrogen atoms become thermodynamically preferred for strong proton donors. Their formation was found to be a prerequisite for the subsequent proton transfer and dimerization to occur. Reaction kinetics was studied at variable temperature, showing that proton transfer is the rate-determining step. This result is in agreement with the computed potential energy profile of (Ph(3)P)(2)Cu(η(2)-BH(4)) dimerization, yielding [{(Ph(3)P)(2)Cu}(2)(μ,η(4)-BH(4))](+). 相似文献
39.
Park K Engelkemier J Persico M Manikandan P Hase WL 《The journal of physical chemistry. A》2011,115(24):6603-6609
Algorithms are presented for sampling quantum microcanonical ensembles for a potential energy minimum and for the conical intersection at the minimum energy crossing point of two coupled electronic states. These ensembles may be used to initialize trajectories for chemical dynamics simulations. The unimolecular dynamics of a microcanonical ensemble about a potential energy minimum may be compared with the dynamics predicted by quantum Rice-Ramsperger-Kassel-Marcus (RRKM) theory. If the dynamics is non-RRKM, it will be of particular interest to determine which states have particularly long lifetimes. Initializing a microcanonical ensemble for the electronically excited state at a conical intersection is a model for electronic nonadiabatic dynamics. The trajectory surface-hopping approach may be used to study the ensuing chemical dynamics. A strength of the model is that zero-point energy conditions are included for the initial nonadiabatic dynamics at the conical intersection. 相似文献
40.
Alberti A Fuochi P Guerra M Macciantelli D Torri G Valerio A Vismara E 《Organic & biomolecular chemistry》2011,9(9):3199-3204
Irradiation of a number of different sutures largely employed in the clinical practice with either high energy electrons or with γ-rays followed by quenching with glycidyl methacrylate (GMA) conveniently led to derivatization through a radical-based process. The radicals involved were detected by means of ESR spectroscopy and were characterized on the basis of their ESR spectral parameters which were also found to be consistent with the hfs constants predicted by DFT calculations. Evidence of the GMA derivatization of the sutures was obtained via(13)C CP-MAS NMR spectroscopy, while its extent was evaluated gravimetrically. 相似文献