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21.
Room-temperature ionic liquids, particularly those based on substituted imidazolium cations, are currently being extensively studied for a variety of applications. Herein, we explore the suitability of several imidazolium salts in optical applications by carefully examining the electronic absorption and fluorescence behavior of these substances, generally believed to be transparent in most of the UV region and fully transparent in the visible region. It is shown that all imidazolium ionic liquids are characterized by significant absorption in the entire UV region and a long absorption tail that extends into the visible region. These absorption characteristics are attributed to the imidazolium moiety and its various associated structures. When excited in the UV or early part of the visible region, these liquids exhibit fluorescence, which covers a large part of the visible region and shows dramatic excitation wavelength dependence. The excitation wavelength dependent shift of the fluorescence maximum has been rationalized taking into consideration the existence of the various associated structures of the ionic liquids and the inefficiency of the excitation energy-transfer process between them. The results imply that these liquids may have serious drawbacks in some of the optical studies. 相似文献
22.
A new chelating resin was synthesised by the modification of styrene-divinylbenzene (2%) copolymer and incorporation of dithiocarbamate groups. The polydithiocarbamate resin was characterised by elemental analysis, thermal studies and IR studies. The analytical characteristics of the sorbent were established and optimum sorption conditions for Cu, Ni, Pb, Fe, As and Mn determined. The total sorption capacity of the resin was 37 mg g−1 for Ni(II), 35 mg g−1 for Cu(II), 29 mg g−1 for Fe(III) and 23 mg g−1 for Pb(II). The optimum pH for the removal of metal ions was 3-5 for Ni(II), 5 for Cu(II), 4 for Fe(III) and 4-5 for Pb(II). High sorption capacity was observed when compared with other conventional chelating polymers. The sorption kinetics was fairly rapid, as apparent from the loading half time t1/2 values, indicating a better accessibility of the chelating sites. 相似文献
23.
S. Pramanik S. S. Bhattacharyya P. Chattopadhyay 《Journal of Radioanalytical and Nuclear Chemistry》2007,274(2):237-243
A new stable chelating resin was synthesized by incorporating 2-aminothiophenol into Merrifield polymer through C-N covalent
bond and characterized by elemental analysis, IR and thermal study. The sorption capacity of the newly formed resin for Hg2+ as a function of pH has been studied using 203Hg radioisotope. The resin exhibits no affinity to alkali or alkaline earth metal ions and common anions. The separation of
mercury(II) in presence of different alkali and alkaline earth metal ions (Na+, K+, Mg2+, Ca2+, Sr2+, Ba2+), common anions (ClO4
−, SO4
2−) and other diverse ions (Ag+, Cu2+, Pb2+, Fe3+, Ni2+ and Zn2+) has been checked. In column operation it has been observed that Hg2+ content of the waste water can be removed at usual pH of natural water. Mercury was determined by isotope dilution method
and the concentration of Hg2+ in the waste water spiked with 203Hg was found to be 0.05 to 0.09 μg/ml. 相似文献
24.
Debprasad Patra Poulami Pattanayak Jahar Lal Pratihar Surajit Chattopadhyay 《Polyhedron》2007,26(18):5484-5490
The reactions of HL 1 [where HL is 1N-(2-pyridyl-2-methyl)-2-arylazoaniline and is formulated as ArN = NC6H4N(H)(CH2C5H4N); Ar = C6H5 (for HL1) or p-MeC6H4 (for HL2) or p-ClC6H4 (for HL3)] with K2PtCl4 and Co(ClO4)3 · 6H2O afforded the (L)PtCl and [(L)2Co]ClO4 complexes, respectively. The HL ligands bind the platinum(II) and cobalt(III) centres in a tridentate (N,N,N) fashion, forming new diazoketiminato chelates upon dissociating the amino proton. The X-ray structures of (L3)PtCl and [(L3)2Co]ClO4 were determined. Redox properties of the new complexes have been examined. 相似文献
25.
Chaudhuri RK Freed KF Hose G Piecuch P Kowalski K Włoch M Chattopadhyay S Mukherjee D Rolik Z Szabados A Tóth G Surján PR 《The Journal of chemical physics》2005,122(13):134105
Tests have been made to benchmark and assess the relative accuracies of low-order multireference perturbation theories as compared to coupled cluster (CC) and full configuration interaction (FCI) methods. Test calculations include the ground and some excited states of the Be, H(2), BeH(2), CH(2), and SiH(2) systems. Comparisons with FCI and CC calculations show that in most cases the effective valence shell Hamiltonian (H(v)) method is more accurate than other low-order multireference perturbation theories, although none of the perturbative methods is as accurate as the CC approximations. We also briefly discuss some of the basic differences among the multireference perturbation theories considered in this work. 相似文献
26.
27.
The anisotropy of the magnetic susceptibility of CuO has been measured. In both, the paramagnetic and the antiferromagnetic state the susceptibility can be described to a good approximation by
相似文献
28.
Sumanta Bhattacharya Sandip K. Nayak Subrata Chattopadhyay Manas Banerjee 《Journal of solution chemistry》2006,35(4):485-506
Supramolecular complexes of [60]- and [70]fullerenes with various meso-tetraphenylporphyrins in toluene solutions have been studied by electronic absorption spectroscopy. Charge transfer (CT) absorption bands are observed in the visible region. Vertical ionization potentials (I
D
V) of the meso-tetraphenylporphyrins are reported from a study of EDA interaction of these porphyrins with a number of electron acceptors like o-chloranil, p-chloranil, 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) and vitamin K. The dependence of the CT transition energy on the donor ionization potential has been utilized to estimate the vertical electron affinities (E
A
V) of [60]- and [70]fullerenes in solution. The value of E
A
V for [60]fullerene is found to be 0.10 eV lower in magnitude than that of [70]fullerene. We have extracted degrees of CT, and oscillator and transition dipole strengths of the fullerenes/meso-tetraphenylporphyrins complexes. The experimental results show that the CT complexes studied here have a neutral character in their ground states. Electronic coupling elements have been determined for fullerene/meso-tetraphenylporphyrin complexes. Values of the solvent reorganization energy indicate that the electron transfer process takes place at a faster rate in the case of [70]fullerene/meso-tetraphenylporphyrin complexes. 相似文献
29.
Abstract— Triplet-and singlet-related photoprocesses of pyrene-1-aldehyde (PA) in various solvents have been investigated in detail using 337.1 and 355 nm laser flash photolysis in conjunction with time-correlated determination of fluorescence lifetimes (τ
30.
Mallick A Haldar B Maiti S Chattopadhyay N 《Journal of colloid and interface science》2004,278(1):215-223
Photophysical properties of 3-acetyl-4-oxo-6,7-dihydro-12H indolo-[2,3-a] quinolizine (AODIQ) have been studied in different aqueous micellar environments using steady-state and time-resolved emission spectroscopy. The charge transfer (CT) fluorescence exhibits appreciable hypsochromic shift, along with an enhancement in the fluorescence intensity in all the micellar media. This is associated with an increase in the fluorescence anisotropy (r), which suggests that the fluorophore molecule experiences motionally restricted environments upon binding with the micelles. Fluorescence spectral position and fluorescence quenching studies suggest that the fluorescing moiety does not penetrate into the core of the micellar units; rather it binds at the micelle-water interfacial region. The binding constant and free energy change during probe-micelle binding have been evaluated from relevant fluorescence data. Light has been thrown on the mode of action of urea on micelle bound probes. The results are interpreted in terms of the model that urea displaces water molecules from the micellar interface and the consequent destabilization leads to the expulsion of the probe molecules from the interfacial region. Polarity and viscosity of the microenvironments around the probe have been determined in the micellar systems. 相似文献
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