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961.
Bhattacharya T Pal SK Misra T Saini RD Ganguly T 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2004,60(8-9):1957-1966
Electrochemical measurements by cyclic voltammetry predict the possibility of occurrence of photoinduced electron-transfer (PET) reactions between the ground state of 2-phenylindole (2PI) (electron donor) and the excited singlet of 9-cyanoanthracene (9CNA) molecule acting as an electron acceptor. However, 2PI should be expected to behave as a relatively weaker electron donating agent than the structurally related donor 2-methylindole (2MI) as it possesses higher oxidation potential value. Both steady-state and time-resolved spectroscopic measurements in the polar acetonitrile (ACN) and ethanol (EtOH) solvents show that the fluorescence quenching phenomenon of 9CNA in presence of 2PI is primarily due to the involvement of dynamic process which in high probability should be PET. Nevertheless, in less polar tetrahydrofuran (THF) medium, the quenching of 9CNA results from the combined effect of dynamic and static modes. The transient absorption spectra, measured by using nanosecond laser flash photolysis, of 9CNA in presence of 2PI exhibit the signature of the bands of the anionic species of 9CNA, cation of the donor 2PI and the contact neutral radical. Observations of the transient absorption at the different delays infer that ion-recombination mechanism is responsible for production of the monomeric triplets of both 9CNA and 2PI. From the transient absorption decays in ACN medium, it has been demonstrated that the diffusional separation of ions from geminate ion-pair is facilitated in the case of 2MI-9CNA pair whereas for 2PI-9CNA system the energy wasting charge recombination dominates over the process of charge dissociation. From the above observations, the possibility of developing much potential photosynthetic model compounds with the donor 2MI, rather than with the other donor 2PI molecule has been hinted. 相似文献
962.
Sujan Chatterjee Paltu Banerjee Smritimoy Pramanik Attreyee Mukherjee Kumar K. Mahalanabis Subhash Chandra Bhattacharya 《Chemical physics letters》2007,440(4-6):313-320
S0 → S1 and S0 → S2 electronic transitions have been observed in UV–Visible absorption spectroscopy of 3-pyrazolyl-2-pyrazoline (PZ) in different homogeneous solvents. Radiative emissions and relaxation processes from S1 and S2 states of PZ have been resolved in water, ethylene glycol and glycerol whereas in polar aprotic and protic solvents the radiative transitions have been observed from S1 state. The S2–S1 electronic energy spacing has been calculated from the absorption maxima of the S0 → S2 transitions and fluorescence maxima of the S1 → S0 transitions. Solute–solvent interactions have been established to rationalize the photophysical modification of PZ in H-bonding solvents. 相似文献
963.
Bhattacharya S Nayak SK Chattopadhyay S Banerjee M Mukherjee AK 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(1-2):321-329
[60]- and [70]fullerenes have been shown to form 1:1 supramolecular complexes with (i) 24,26-dimethoxy-25,27-dihydroxy-5,11,17,23-tetra(4-tert-butyl)calix[4]arene (1) and (ii) 37,39,41-trimethoxy-38,40,42-trihydroxy-5,11,17,23,29,35-hexa(4-tert-butyl)calix[6]arene (2) in CCl(4) medium by absorption spectroscopy. Charge transfer absorption bands of the complexes have been located in each of the cases (except [70]fullerene-2 complex) studied from which the vertical ionisation potential of 1 has been obtained. Formation constants of the complexes have been determined at four different temperatures from which the enthalpies and entropies of formation of the complexes have been obtained. Moreover, the formation constant of [70]fullerene-2 complex is higher than that of the [60]fullerene-1 and [60]fullerene-2 complexes at all the four temperatures studied. This has been accounted in terms of greater cavity size of 2 which is a calix[6]arene compared to 1 which is a calix[4]arene and also by the fact that a high degree of preorganisation takes place in case of 2 through intramolecular H-bonding at its lower rim. 相似文献
964.
965.
966.
967.
Utso Bhattacharya Sayak Dasgupta Amit Dutta 《The European Physical Journal B - Condensed Matter and Complex Systems》2016,89(10):216
We study the effect of a half wave rectified sinusoidal electromagnetic (EM) wave on the Kitaev honeycomb model with an additional magneto-electric coupling term arising due to induced polarization of the bonds. Within the framework of Floquet analysis, we show that merging of a pair of Dirac points in the gapless region of the Kitaev model leading to a semi-Dirac spectrum is indeed possible by externally varying the amplitude and the phase of the EM field. 相似文献
968.
A bis(μ-NN′-tetrazolate)-bridged centrosymmetric dinuclear zinc(II) Schiff base complex, [Zn2(L)2(PZTZ)2] (HL is a tridentate Schiff base, 2-(2-(dimethylamino)ethyliminomethyl)-6-ethoxyphenol and HPZTZ is 2-pyrazinyltetrazole), has been synthesized via [3 + 2] cycloaddition of 2-cyanopyrazine and sodium azide in the presence of zinc(II) acetate dihydrate and HL. The structure of the complex is confirmed by single-crystal X-ray diffraction analysis. The complex shows fluorescence. 相似文献
969.
970.
Paltiel Y Zeldov E Myasoedov Y Rappaport ML Jung G Bhattacharya S Higgins MJ Xiao ZL Andrei EY Gammel PL Bishop DJ 《Physical review letters》2000,85(17):3712-3715
Transport studies in a Corbino disk suggest that the Bragg glass phase undergoes a first-order transition into a disordered solid. This transition shows sharp reentrant behavior at low fields. In contrast, in the conventional strip configuration, the phase transition is obscured by the injection of the disordered vortices through the sample edges, which results in the commonly observed vortex instabilities and smearing of the peak effect in NbSe2 crystals. These features are found to be absent in the Corbino geometry in which the circulating vortices do not cross the sample edges. 相似文献