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171.
172.
Muonium-radicals resulting from insertion into the benzene ring are found to be much more prevalent in allyl benzene (C6H5CH2CH=CH2) than in styrene (C6H5CH=CH2). The salient implication of this comparison is that intramolecular rearrangements preceeded the μSR observation for the
case of styrene. In turn, this suggests that muonium-containing free radicals, as seen directly by kilogauss transverse field
μSR, are not necessarily theprimary radicals. Therefore, the elucidation of mechanism (and identification of the precursor) of Mu-radical formation is further
complicated by the fact that the observations may refer to thermodynamically more stable secondary radicals-those resulting
from a variety of intra-or inter-molecular relaxations or exchanges. Primary kinetic selectivities of thermalized muonium
atom addition reactions can be determined, however, through the substituent effect on the Hammett linear free energy parameter
in dilute solution. Results have been obtained for substituted benzenes and benzoic acids. Muonium apparently has a mild nucleophilic
character. And, most interestingly, this is opposite to that of its heavy isotope hydrogen. 相似文献
173.
J. Nemeth M. Barranco C. Ngô E. Tomasi 《Zeitschrift für Physik A Hadrons and Nuclei》1986,323(4):419-435
A hydrodynamical approach and the Thomas Fermi approximation have been used to study the evolution of hot and compressed nuclei. Spherical symmetry was assumed in the calculation. The dynamical equations have been transformed into “Schrödinger like” equations (using the Madelung transformation) and were solved numerically. Dissipation was simulated in the same way as in the Navier-Stokes equation by introducing shear and bulk viscosities. Global as well as local thermal equilibrium have been studied. The model has been applied to small amplitude oscillations (the breathing mode) and to the stability of hot and compressed nuclei. It was found that compression is more efficient to break nuclei than thermal excitation. The relaxation time for global equilibrium was estimated to be of the order of 10?22 s. It was found that the results obtained in the case of global and local thermal equilibrium are very similar. 相似文献
174.
V. M. Murukeshan Ng Chee Keong Krishnakumar. V Ong Lin Seng A. Asundi 《Optics & Laser Technology》2001,33(5):919
This paper presents a double shearographic configuration based on the optical method by using two Michelson interferometers in tandem. The problems associated with the extraction of second order derivatives by optical means and a comparison with the proposed novel approach by digital means are discussed in this paper. 相似文献
175.
H. Luo D.Y. Tang G.Q. Xie H.J. Zhang L.J. Qin H.H. Yu L.Y. Ng L.J. Qian 《Optics Communications》2008,281(21):5382-5384
Passive mode-locking of a diode pumped Yb-doped GdVO4 crystal laser was demonstrated for the first time to our knowledge. The laser was mode-locked at the wavelength of 1019.1 nm and had an average output power of 1.01 W. The mode-locked pulse duration was 3.1 ps. The laser was end-pumped by a high-power fiber pigtailed laser diode bar and the mode-locking was enabled by a semiconductor saturable absorber mirror (SESAM). 相似文献
176.
177.
J. B. Natowitz S. Leray R. Lucas C. Ngô E. Tomasi C. Volant 《Zeitschrift für Physik A Hadrons and Nuclei》1986,325(4):467-474
A simple formula based on leading particle models of nucleon-nucleon collisions is used to evaluate the average momentum transfer in central heavy ion collisions at energies from 20 to 150 MeV/u. This formula, which reproduces a number of the features of the observed systematics, offers a straightforward explanation for the approximate universality of fractional linear momentum transfer as a function of velocity, the dependence of fractional momentum transfer on target mass and the greater fractional momentum transfer of the proton as compared to heavy ion projectiles. 相似文献
178.
Alan Man-Ching Ng Kai-Hang Tam Wai-Kin Chan Kok-Wai Cheah Jesse Chan 《Optics Communications》2008,281(9):2498-2503
Ultraviolet organic light emitting diodes with 3,4,9,10-perylenetetracarboxylicdiimide (PTCDI) interlayer have been achieved. The emission spectrum and intensity were strongly dependent on the thickness of PTCDI interlayer, in spite of the fact that PTCDI has neither much lower HOMO nor much higher LUMO level, which is considered necessary for efficient charge blocking layers. The influence of PTCDI layer was investigated in three different device configurations and obtained results are discussed. For optimal device configuration, OLED with emission centered at 370 nm and turn-on voltage of 4.5 V is obtained. 相似文献
179.
May Lee Low Cheang Wei Chan Pei Ying Ng Ing Hong Ooi Mohd Jamil Maah Soi Moi Chye 《Journal of Coordination Chemistry》2017,70(2):223-241
Three ternary copper(II) complexes, [Cu(phen)(L-phe)Cl]·2H2O, [Cu(phen)(L-leu)Cl]·4½H2O, and [Cu(phen)(L-tyr)Cl]·3H2O, and four binary copper(II) complexes, [Cu(phen)Cl2], Cu(L-phe)2·½H2O, Cu(L-leu)2·½H2O, and Cu(L-tyr)2·H2O (where phen = 110-phenanthroline, L-phe = L-phenylalanine, L-tyr = L-tyrosine, L-leu = L-leucine and Cl- = chloride), were synthesized and characterized by elemental analysis, spectroscopic techniques (FTIR, UV–visible, fluorescence spectroscopy), magnetic susceptibility, molar conductivity, and lipophilicity measurement. X-ray diffraction determination of a single crystal of [Cu(phen)(L-tyr)Cl] showed two independent molecules in the asymmetric unit, each with the same distorted square pyramidal geometry about copper(II). p-Nitrosodimethylaniline assay revealed that the three ternary complexes were better inducers of reactive oxygen species over time than binary complexes, CuCl2, and free ligands. All the copper(II) complexes in this series inhibited the three proteolytic activities in the order Trypsin-like > Caspase-like > Chymotrypsin-like. In terms of anticancer properties, the copper(II)-phen complexes had GI50 values of less than 4 μM against MCF-7, HepG2, CNE1 and A549 cancer cell lines, more potent than cisplatin. 相似文献
180.
M.?A.?Subhan S.?W.?Ng C.-S.?Lee J.-H.?ChoiEmail author 《Journal of Structural Chemistry》2017,58(4):742-749
A new complex [Cu(L1)(NCS)]SCN, where L1 = 3,14-dimethyl-2,6,13,17-tetraazatricyclo( 16.4.0.07,12)docosane is prepared and characterized by single crystal X-ray crystallographic analysis. The complex crystallizes in the triclinic space group P1? with two mononuclear formula units in a cell of dimensions a = 7.9681(2) Å, b = 8.8644(2) Å, c = 18.8165(5) Å, α = 76.758(70)°, β = 78.490(2)° and γ = 77.679(2)°. The Cu(II) ion is five-coordinate in an axially elongated square pyramidal environment, with the four amine N atoms at the equatorial positions and the N atom of one thiocyanate at an apical site. The macrocyclic cyclam moiety adopts a stable trans-III configuration. The Cu–N basal plane bond length has a mean value of 2.037(2) Å. The coordinated Cu–NCS bond length is 2.322(3) Å. The N atom of the thiocyanate anion is connected to the macrocyclic ligand of the cation via an NH…N(CS) hydrogen bond. The UV-visible absorption and IR spectral properties are also discussed. 相似文献