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1.
Krishnakumar V Balachandran V 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(8):1811-1819
The FTIR and FT-Raman spectra of 2,6-dibromo-4-nitroaniline (2,6-DB4NA) in solid phase and 2-(methylthio)aniline (2-MTA) in liquid phase were measured. The geometry and normal vibrations have been obtained from the density functional theory (DFT) with the B3LYP method employing the 6-31G* basis set. Scale factors, which bring computational frequencies in closer agreement with the experimental data, have been calculated for predominant vibrational motions of the normal modes. The effects of the amino, bromine, nitro, thio and methyl substituents on vibrational frequencies have been investigated. The infrared and Raman spectra were also predicted from the calculated intensities. The observed and the calculated spectra were found to be in good agreement. 相似文献
2.
Balakumar A Lysenko AB Carcel C Malinovskii VL Gryko DT Schweikart KH Loewe RS Yasseri AA Liu Z Bocian DF Lindsey JS 《The Journal of organic chemistry》2004,69(5):1435-1443
A molecular approach to information storage employs redox-active molecules tethered to an electroactive surface. Attachment of the molecules to electroactive surfaces requires control over the nature of the tether (linker and surface attachment group). We have synthesized a collection of redox-active molecules bearing different linkers and surface anchor groups in free or protected form (hydroxy, mercapto, S-acetylthio, and Se-acetylseleno) for attachment to surfaces such as silicon, germanium, and gold. The molecules exhibit a number of cationic oxidation states, including one (ferrocene), two [zinc(II)porphyrin], three [cobalt(II)porphyrin], or four (lanthanide triple-decker sandwich compound). Electrochemical studies of monolayers of a variety of the redox-active molecules attached to Si(100) electrodes indicate that molecules exhibit a regular mode of attachment (via a Si-X bond, X = O, S, or Se), relatively homogeneous surface organization, and robust reversible electrochemical behavior. The acetyl protecting group undergoes cleavage during the surface deposition process, enabling attachment to silicon via thio or seleno groups without handling free thiols or selenols. 相似文献
3.
Hwu JR Jain ML Tsai FY Tsay SC Balakumar A Hakimelahi GH 《The Journal of organic chemistry》2000,65(17):5077-5088
Silica gel-supported ceric ammonium nitrate (CAN-SiO2) was found effective for rapid and selective cleavage of trityl (Tr), monomethoxytrityl (MMTr), and dimethoxytrityl (DMTr) groups from protected nucleosides and nucleotides under mild conditions. Efficiency of deprotections depended upon the stability of the resultant carbocationic species: DMTr+ > MMTr+ > Tr+. Use of a catalytic amount of this solid-supported reagent can also efficiently and selectively remove the tert-butyldimethylsilyl or the triisopropylsilyl group from a primary hydroxyl functionality in di- or trisilyl ethers of ribonucleosides. A comparative study of deprotection reactions by utilization of CAN alone or CAN-SiO2 indicates a remarkable increase in the rate of the reactions involving a solid support. The mechanism of electron-transfer processes is proposed for the use of CAN-SiO2 in the removal of these protective groups from organic molecules. 相似文献
4.
J. P. Dauer K. Balachandran P. Balasubramaniam 《Journal of Optimization Theory and Applications》1994,83(1):167-179
In this paper, sufficient conditions are obtained for the asymptotic null controllability of the system $$\dot x(t) = g(t,x(t)) + B(t,x(t))u(t) + f(t,x(t),u(t)).$$ The results are obtained by using the Leray-Schauder fixed-point theorem. 相似文献
5.
The Raman spectrum of the compound TiNb2O7 prepared by a liquid mix technique was recorded at room temperature using the 530.98-nm line from a krypton-ion laser as exciter. The bands observed at 998 and 884 cm?1 are assigned to the edge-shared and corner-shared NbO6 octahedra, respectively. The relative intensities of these two bands are consistent with the structure of TiNb2O7 worked out by earlier investigators using X-ray and neutron diffraction. The strong band observed at 647 cm?1 is assigned to the vibration of the TiO6 octahedra. The octahedral coordination for both cations based on the results of the Raman spectrum measurements is in essential agreement with the available structural data for the compound TiNb2O7. The weak band observed at 840 cm?1 is suggestive of the presence of NbO4 tetrahedra in small concentrations in TiNb2O7. 相似文献
6.
Thasan Raju Sankar Manivasagan Balachandran Revathy Kumarasamy Kulangiappar Arunachalam Muthukumaran 《Tetrahedron letters》2007,48(21):3681-3684
Electrochemical oxidation of benzylic and substituted benzylic alcohols by two-phase electrolysis yields the corresponding aldehydes as products. The reaction was carried out in a single compartment cell with platinum electrodes at room temperature in chloroform using an aqueous sodium bromide solution (25%) containing a catalytic amount of HBr. The two-phase electrolysis resulted in high yields (74-96%) of benzaldehyde from primary alcohols and secondary alcohols were oxidized to the corresponding ketone but only in low yields under these conditions. 相似文献
7.
Kanthimathi Mookandi Unni Nair Balachandran Ramasami Thirumalachari Jeyakanthan Jeyaraman Velmurugan Devadasan 《Transition Metal Chemistry》2000,25(2):145-149
A new chromium(III) Schiff base complex, [Cr(3-methoxysalen)(H2O)2]ClO4, where salen=N,N-ethylenebis- (salicylideneimine), has been synthesized and characterized by spectroscopic techniques. Single crystal X-ray data reveals that the complex assumes a trans-diaquo structure with formulation [Cr(C18H22N2O6)]ClO4 but, unlike in Cr (salen)(H2O)2
+, the two trans-water molecules are equidistant from CrIII. The effect of the substituent on the phenyl ring in respect of redox reactivity has been investigated. The kinetics of the oxidation of [Cr(Schiff base)- (H2O)2]ClO4, where Schiff base=salen, (1) and 3-OMe-salen, (2) by PhOI has been studied. The bimolecular rate constant for the formation of the O=Crv Schiff base in case of (2) was four times faster than that of (1). The introduction of the OMe group substituent on the phenyl ring influences not only the structure and crystal packing, but also the reactivity of the complex and the electronic environment around the metal ion. 相似文献
8.
First-order Raman spectra have been recorded at room temperature for the anatase and rutile phases of polycrystalline titanium dioxide using an argon ion laser as exciter. The high-temperature rutile phase was found to be stabilized at temperatures below 450°C. Anatase transforms to rutile phase at ~750°C. All the Raman active fundamentals predicted by group theory are observed. 相似文献
9.
Tetraalkylammonium borohydride reduces carboxylic acids to the corresponding alcohols in good yields utilizing only stoichiometric quantities of hydride and also in the absence of any Lewis acids. 相似文献
10.