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91.
Andrzej Królikowski Ewelina Płońska Andrzej Ostrowski Mikołaj Donten Zbigniew Stojek 《Journal of Solid State Electrochemistry》2009,13(2):263-275
Ni–W alloys were electrodeposited onto copper foil from citrate solution. Coatings containing from 11 to 21 at.% W and having
7–52 μm in thickness were obtained. The structure of these alloys was analyzed by X-ray diffraction and by using electron
and light microscopy techniques. Alloys with 11 and 15% W are composed of two phases: solid solution of W in fcc Ni and solid
solution of Ni in bcc W. An increase in W content in the Ni–W alloys to ca. 18–19% of W resulted in the grain refinement and
the transition to amorphous structure. The corrosion behavior of obtained Ni–W and unalloyed Ni coatings was studied in 0.5 M
NaCl solution by means of electrochemical impedance spectroscopy, potentiodynamic polarization and light microscopy. Comparing
to pure Ni, the obtained Ni–W coatings exhibited a clearly decreased corrosion resistance (in terms of corrosion current density
and polarization or charge transfer resistance at the open circuit potential). Despite of the quite wide range of composition
of the alloys under test, the related grain refinement, and the transition to the amorphous structure, no clear relation between
the corrosion rate and W content was detected. This behavior can be a result of the interplay of the activating effect of
grain refinement or preferential dissolution of W from one side and diffusion barrier action or inhibition provided by the
surface film of W oxidation products from the other side. The differences observed in the corrosion resistance of Ni–W coatings
are more related to their morphological imperfections arising from various deposition conditions than to the W content. Some
samples showed a rather non-uniform nature of corrosion (pronounced attack along cracks). An inversion in the dissolution
behavior of Ni–W and unalloyed Ni was observed with increasing anodic potential. Contrary to pure Ni, Ni–W coatings were resistant
to pitting corrosion in NaCl solution.
Contribution to the Fall Meeting of the European Materials Research Society, Symposium D: 9th International Symposium on Electrochemical/Chemical
Reactivity of Metastable Materials, Warsaw, 17th–21st September, 2007. 相似文献
92.
Wiktor Beker Karol M. Langner Edyta Dyguda‐Kazimierowicz Mikołaj Feliks W. Andrzej Sokalski 《Journal of computational chemistry》2013,34(21):1797-1799
The relative stability of biologically relevant, hydrogen bonded complexes with shortened distances can be assessed at low cost by the electrostatic multipole term alone more successfully than by ab initio methods. These results imply that atomic multipole moments may help improve ligand–receptor ranking predictions, particularly in cases where accurate structural data are not available. © 2013 Wiley Periodicals, Inc. 相似文献
93.
Jerzy Krysiak Wanda H. Midura Wanda Wieczorek Lesław Sieroń Marian Mikołajczyk 《Tetrahedron: Asymmetry》2010,21(11-12):1486-1493
A new stereocontrolled synthesis of (+)-2-aminobicyclo[3.1.0]hexane-2.6-dicarboxylic acid (LY354740) 1, a potent and selective 2mGluR agonist, has been accomplished in four steps with an overall yield of 27% starting from the enantiopure (+)-(R)-2-(p-tolylsulfinyl)cyclopent-2-enone 3. The key steps include asymmetric cyclopropanation of 3 with (dimethylsulfuranylidene)acetate (EDSA) and removal of the chiral p-tolylsulfinyl auxiliary from the cycloadduct ent-4c upon treatment with iso-propylmagnesium chloride. The stereoselective hydantoin formation from the bicyclic ketone 6 formed (Bucherer–Bergs reaction) and subsequent hydrolysis completed the synthesis of 1. The same reaction sequence has been applied in the first synthesis of enantiopure (+)-2-amino-6-phosphonobicyclo[3.0.1]hexane-2-carboxylic acid 2, a structural 6-phosphono analogue of 1. The starting bicyclic ketophosphonates 9–11 have been obtained by asymmetric cyclopropanation of (?)-(S)-3 with phosphoryl sulfonium ylides, producing only two endo-isomers. The major endo-isomer (+)-11a containing the 6-diisopropoxyphosphoryl group has been converted in three steps into (+)-endo-2 in 46% overall yield. 相似文献
94.
Mikołaj Kisielewicz 《Physics letters. A》1985,109(4):183-186
The effects of H+, C+, N+, Ne+, Al+, P+, Cl+, Ar+, Ga+, As+, Kr+, Sb+, Xe+, Au+ and Tl+ ion implantation on the anodic oxidation of Si have been investigated as a function of dose and energy, in the as-implanted stage and after heat treatment at temperatures up to 1050°C. It is speculated that the location, in the formed oxide, of agglomerates containing the dopant, and the influence of these agglomerates on oxygen diffusion in SiO2 and/or oxygen evaluation at the oxide/solution interface are factors which account for the enhancement/retardation of the anodic oxidation. 相似文献
95.
Janina Karolak-Wojciechowska Marian Mikołajczyk Andrzej Zatorski Katarzyna Kiec-Kononowicz Alfred Zejc 《Tetrahedron》1985,41(20):4593-4602
The crystal and molecular structures of the title isomeric compounds and , obtained by intramolecular N,S--dialkylation of 5,5-diphenyl-2-thiohydantoin with 1,2-dibro-moethane, have been determined from X-ray diffractometer data. 2,3-Dihydro-6,6-diphenylimidazo-[2,1-b]-thiazol-5(6H)-one crystallizes in space group P212121 with a=11.376(3), b=12,255(5), c=8.434(3) Å and Z=4. Crystals of , containing one molecule of benzene, are monoclinic,space group P21/c with a=11.539(6), b=10.242(3), c=16.353(5) Å, β=95.45(5)° and Z=4. In both cases a planar geometry of the two fused five-membered heterocyclic rings was found. The selected bond lengths in and , as well as those analogous imidazothiazinones and , were used to calculate EHOSE (Harmonic Oscillation Stabilization Energy). The problem of stability and chemical reactivity of compounds to is also discussed. 相似文献
96.
M Kowalik CM Gothard AM Drews NA Gothard A Weckiewicz PE Fuller BA Grzybowski KJ Bishop 《Angewandte Chemie (International ed. in English)》2012,51(32):7928-7932
Finding a needle in a haystack: The number of possible synthetic pathways leading to the desired target of a synthesis can be astronomical (10(19) within five synthetic steps). Algorithms are described that navigate through the entire known chemical-synthetic knowledge to identify optimal synthetic pathways. Examples are provided to illustrate single-target optimization and parallel optimization of syntheses leading to multiple targets. 相似文献
97.
Gawroński J Grajewski J Drabowicz J Mikołajczyk M 《The Journal of organic chemistry》2003,68(25):9821-9822
A simple nonempirical method for the assignment of absolute configuration of N-phthalimidosulfoximines and related S-chiral sulfoxides, based on exciton-coupled circular dichroism, is presented. 相似文献
98.
The thermal decompositions of K2[Fe(CN)4
L]·4 H2O, H2[Fe(CN)4
L] and H[Fe(CN)L](L=1,1-bipyridine, of 1,10-phenanthroline) were studied. The experimental results showed that the protonated ferrous complexes decompose with formation of HCN at lower temperature than the corresponding potassium salts. The decomposition of K2[Fe(CN)4
L] starts by removal of the ligand L. HCN elimination is followed by a redox reaction with formation of cyanogen in the case of H[FeIII(CN)4
L].
XIV. A. Hantshmann, J. Salvetter, H. Hennig and B. Mohai, Thermochim. Acta. 25 (1978) 341
The authors thank I. Ötvös for mass-spectroscopic investigations, and Mrs. Csukás, Mrs. Csiszár and Mrs. Haeffner for experimental assistance. 相似文献
Zusammenfassung Die thermische Zersetzung von K2 [Fe(CN)4 Z]·4H2O, H2[Fe(CN)4 L] und H[Fe(CN)4 L] (L=1,1'-Dipyridin, 1,10-Phenantrolin) wurde untersucht. Die Versuchsergebnisse zeigten, dass die protonierten Ferrokomplexe unter Bildung von HCN bei niedrigeren Temperaturen zersetzt werden, als die entsprechenden Kaliumsalze. Die Zersetzung von K2 [Fe(CN)4 L] beginnt durch die Abspaltung des LigandenL. Nach Eliminierung des HCN folgt eine Redox-Reaktion unter Bildung von Dizyan im Falle von H[FeIII(CN)4 Z].
K2[Fe(CN)4 L]·42, H2[Fe(CN)4 L] H[Fe(CN)4 L] L=1,1- 1.10-. , , . K2[Fe(CN)4 L] L. H[Fe111(CN)4 L] HCN - .
XIV. A. Hantshmann, J. Salvetter, H. Hennig and B. Mohai, Thermochim. Acta. 25 (1978) 341
The authors thank I. Ötvös for mass-spectroscopic investigations, and Mrs. Csukás, Mrs. Csiszár and Mrs. Haeffner for experimental assistance. 相似文献
99.
Oxidation of the α-alkylthio-substituted phosphonate carbanions was found to give the corresponding carbonyl compounds. A new synthesis of 1,4-dicarbonyl systems involving the oxygenation of phosphonate carbanions as a key step is described. Total synthesis of dihydrojasmone and allethrone and formal synthesis of methylenomycin B is reported. 相似文献
100.
We report on the intershell electron transport in multiwalled carbon nanotubes (MWNTs). To do this, local and nonlocal four-point measurements are used to study the current path through the different shells of a MWNT. For short electrode separations less, similar 1 mum the current mainly flows through the two outer shells, described by a resistive transmission line with an intershell conductance per length of approximately (10 kOmega)(-1)/microm. The intershell transport is tunnel type and the transmission is consistent with the estimate based on the overlap between pi orbitals of neighboring shells. 相似文献