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611.
Liposomes incorporating fluorescent, metal-chelating lipids find applications in molecular recognition of peptides, 2D protein recrystallization, protein targeting, and biological sensing. It would be advantageous to combine the usefulness of polymerizable, metal-chelating lipids and fluorescent lipids. Herein, we report the synthesis and fluorescence properties of several fluorescent, polymerizable, metal-chelating lipids. They have been successfully incorporated into liposomes and then polymerized. These lipids can be used as membrane probes to study the polymerizable liposomes in the unpolymerized state and to investigate lipid redistribution during polymerization. In addition, if a luminescent metal ion (e.g., Eu(3+), Tb(3+), etc.) is used to complex the headgroup, the lipids can probe the membrane interior and exterior simultaneously. 相似文献
612.
An original montmorillonite K-10 clay catalysed cycloisomerisation of salicylaldehyde 4-arylthiosemicarbazones yields 3,4-dihydro-4-hydrazino-2H-benz[e]-1,3-oxazine-2-thiones, which on reductive dehydrazination on alumina-supported copper(II) sulfate readily furnish 3,4-dihydro-2H-benz[e]-1,3-oxazine-2-thiones under solvent-free microwave irradiation. Under the same conditions salicylaldehyde thiosemicarbazones undergo cyclodehydrazination to yield 2H-benz[e]-1,3-oxazine-2-thiones. 相似文献
613.
In an effort to develop a dielectric screening function for molecular dynamics simulations of biomolecules in implicit solvent, effective dielectric constants (D(eff)) for a large number of atom pairs in a typical globular protein are calculated by continuum electrostatics. Plots of D(eff) versus the intercharge distance are in general sigmoidal with the characteristics of the curve depending on the distance of the two charges from the dielectric boundary and, secondarily, on the extent to which the area surrounding each charge is occupied by solvent (the "exposure"). The D(eff) values were fitted to an empirical, analytical function of these parameters that reproduces the data reasonably well, although considerable scatter exists in the range of D(eff) from 30 to 80. In the system used for parameterization, the mean square deviation of electrostatic interaction energies with this function is 0.48 kcal/mol, compared to 1.45 for an analytical Generalized Born model and 1.52 for the linear distance-dependent dielectric model. When tested in other proteins of varying size and compactness, the present function is superior to both of the above models, except for a fully unfolded polypeptide chain, where the Generalized Born model is superior. 相似文献
614.
Ghosh D Mukhopadhyay S Samanta S Choi KY Endo A Chaudhury M 《Inorganic chemistry》2003,42(22):7189-7199
Nickel(II) complexes of three new heterodonor ligands (HL(1), H(2)L(2), and H(3)L(3)) based on 2-aminocyclopent-1-ene-1-dithiocarboxylate have been synthesized, and their crystallographic characterizations are reported. With the pentacoordinating ligands HL(1) and H(3)L(3), the products obtained (1 and 2) are both mononuclear square planar compounds in which one of the pyrazolyl arms of ligand HL(1) and the bridgehead alkoxy oxygen of H(3)L(3) are staying away from coordination in 1 and 2, respectively. The saturated three carbon alkanyl chain in the ligand H(3)L(3) provides enough flexibility to generate tetrahedral distortion (dihedral angle, 22.7 degrees ) in the planarity of 2. Compound 1 displays paramagnetic line-broadening in its (1)H NMR spectrum due to oligomerization in solution. With the unsymmetrical binucleating ligand H(2)L(2), two mixed-spin homodinuclear complexes (3 and 4) have been synthesized using pyrazole and 2-mercaptopyridine as ancillary mu(2)-bridging ligands. Both these complexes have square planar low-spin and spin-triplet nickel(II) centers which display both coordination number and donor set asymmetry in tandem. The compounds have been characterized by (1)H NMR, electronic spectroscopy, and electrochemical studies. 相似文献
615.
Vasant R. Choudhary Suman K. Jana 《Journal of molecular catalysis. A, Chemical》2002,180(1-2):267-276
Liquid phase benzylation of benzene by benzyl chloride to diphenyl methane over InCl3, GaCl3, FeCl3 and ZnCl2 supported on commercial clays (viz. Montmorillonite-K10, Montmorillonite-KSF and Kaolin) or on high silica mesoporous MCM-41 (at 60, 70 and 80 °C) has been investigated. The supported InCl3, GaCl3 and FeCl3 showed high activity for the benzylation of benzene. The redox function created due to the impregnation of the clays or Si-MCM-41 by InCl3, GaCl3, FeCl3 or ZnCl2 seems to play a very important role in the benzylation process. Among the catalysts, the InCl3/Mont.-K10 showed both high activity and high selectivity for the benzylation. The activity of this catalyst for the benzylation of different aromatic compounds is in the following order: benzene>toluene>mesitylene>anisole. The InCl3 (or GaCl3)/Mont.-K10 (or Si-MCM-41) catalyst showed high benzene benzylation activity even in the presence of moisture in the reaction mixture. The catalyst can also be reused in the benzylation for several times. Kinetics of the benzene benzylation (using excess of benzene) over the supported metal chloride catalysts have also been thoroughly investigated. A plausible reaction mechanism for the benzylation over the supported metal chloride catalysts is proposed. 相似文献
616.
Adler J Bai Z Blaylock GT Bolton T Brient J Browder TE Brown JS Bunnell KO Burchell M Burnett TH Cassell RE Coffman D Cook V Coward DH DeJongh F Dorfan DE Drinkard J Dubois GP Eigen G Einsweiler KF Eisenstein BI Freese T Gatto C Gladding G Grab C Hauser J Heusch CA Hitlin DG Izen JM Kim PC Köpke L Labs J Li A Lockman WS Mallik U Matthews CG Mincer AI Mir R Mockett PM Nemati B Odian A Parrish L Partridge R Pitman D Plaetzer SA Richman JD Roco M Sadrozinski HF Scarlatella M Schalk TL Schindler RH 《Physical review letters》1990,64(2):169-171
617.
618.
Suman Mandal Krishnakumar S. R. Menon 《The European Physical Journal B - Condensed Matter and Complex Systems》2012,85(1):2
The role of interfacial disorder and roughness has been pointed out several times in ferromagnetic-antiferromagnetic exchange coupled systems. However, effect of surface morphology on magnetic properties of bare antiferromagnetic material has been mostly ignored. Here we report our experimental observations of magnetic instabilities on high temperature air annealed NiO(100) surfaces through treatment of successive vacuum and oxygen annealing above Néel temperature. Preferential spin-orientations are found to be governed by surface morphology with enhanced roughness and oxygen diffusion process. Stable domain distribution has been observed on smoother surfaces, which are found to be mostly inactive to these annealing treatments. 相似文献
619.