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51.
J. P. Durand F. Dawans Ph. Teyssie 《Journal of polymer science. Part A, Polymer chemistry》1970,8(4):979-990
In the course of investigations of polymerization of diolefins by transition metal derivatives, we have synthesized various monometallic nickel coordination catalysts. The complexes were prepared by reacting 2,6,10-dodecatriene-1,12-diyl nickel with protonic acids; they were shown to initiate the stereospecific polymerization of 1,3-butadiene. The study of these catalysts showed the strong influence of the nature of the counteranion used on the stereospecificity and the polymerization rate. Moreover, by adding various ligands, we were able to modify the behavior of the catalytic systems and to prepare either pure cis-1,4 or pure trans-1,4 or cis–trans equibinary polybutadienes, starting from the same complex and keeping a high 1,4 specificity. Some of these modifications were shown to be reversible. 相似文献
52.
Studies on Oxide Catalysts. XXIX. Spectroscopic and Catalytic Investigations on Ni2+-, Co2+-, Cr3+-, and Cu2+-exchanged Mordenites NiNaM, CoNaM, CrNaM und CuNaM (M = Mordenite) have been characterized by UV-VIS, EPR and i.r. spectroscopy and the results were compared with the catalytic activity and the activity-time-dependence in the cracking of n-octane and with the shape selectivity in the cracking of a n-octane and isooctane mixture. Water molecules acting as ligands of the exchanged cations are able to dissociate yielding Brönsted acidity. Brönsted sites may be regarded as catalytic active centers in the cracking reaction. Unreduced transition metal cations facilitate the “coking” of the mordenite. The unreduced chromium and cobalt cations for which a position within the main channel is expected, affect the diffusion of the branched paraffin molecule thus increasing shape selectivity. 相似文献
53.
Ph. Albert 《Journal of Radioanalytical and Nuclear Chemistry》1980,55(2):453-462
In this article the research topics dealt with at Research Group for Applications of Nuclear Reactions to Chemical Analysis
(GARNAC) are described. Particular emphasis is laid on the main contribution of the GARNAC to the development and the evolution
of charged particle activation analysis, evolving with the analytical studies performed and with the scientific and technical
progress realized in material and semiconductors science.
相似文献
54.
H. W. Goedde D. Gehring und R. Hofmann 《Fresenius' Journal of Analytical Chemistry》1965,212(1):238-252
Zusammenfassung Es werden verschiedene Methoden zur Differenzierung genetisch bedingter Enzymvarianten der Pseudocholinesterase (spektrophotometrischer Test, Agar-Diffusionstest, Säulenchromatographie), Versuche zur Charakterisierung der verschiedenen Enzymproteine und der in der Stärkegelelektrophorese auftretenden vier Enzymfraktionen mitgeteilt. Ein Reinigungsverfahren für die Pseudocholinesterase wurde ausgearbeitet; nach der Immunisierung von Kaninchen mit dem angereicherten Enzymprotein wurden mit dem gewonnenen Antiserum immunchemische Versuche durchgeführt.
Die in der Literatur am häufigsten zu findende Bezeichnung Pseudocholinesterase wird hier verwendet.
Wir danken der Deutschen Forschungsgemeinschaft, dem Bundesministerium für Wissenschaftliche Forschung und dem Fonds der Chemischen Industrie für ihre Unterstützung. 相似文献
Summary Methods are reported for the differentiation and characterisation of genetically determined enzyme variants and the enzyme fractions occuring in starch-gel electrophoresis of pseudocholinesterase (spectrophotometrical assays, agar diffusion test, column chromatography). A method has been developed to purify the pseudocholinesterase. Rabbits were immunized against a purified enzyme protein. Results of these immuno-chemical assays are given.
Die in der Literatur am häufigsten zu findende Bezeichnung Pseudocholinesterase wird hier verwendet.
Wir danken der Deutschen Forschungsgemeinschaft, dem Bundesministerium für Wissenschaftliche Forschung und dem Fonds der Chemischen Industrie für ihre Unterstützung. 相似文献
55.
56.
Mercury Compounds with Cyancarbanions. II Synthesis and Crystal Structure of Dimercury(I)-bis(1,1,3,3-tetracyanpropenide) The structure of dimercury(I)-bis(1,1,3,3-tetracyanpropenide), Hg2(tcp)2, has been determined by single-crystal X-ray diffraction methods. The crystals are monoclinic, space group P 21/n. The unit cell dimensions are: a = 9.9193(3) Å, b = 5.6912(6) Å, c = 13.3806(4), β = 92.544(4)° and Z = 2. The mercury atoms in the centrosymmetric cation are three-coordinate with Hg? Hg 2.503, Hg? N 2.207, 2.207, 2.560 Å. tcp behaves as a bidentate ligand forming infinite chains running parallel to the a-axis. 相似文献
57.
E. M. Essassi J. P. Lavergne Ph. Viallefont J. Daunis 《Journal of heterocyclic chemistry》1975,12(4):661-663
The condensation of 3,4-diamino 1,2,4-triazole with ethyl aceloacelate gave 6-methyl-8,9-dihydro(7H)-s-triazolo[4,3-b]-1,2,4-triazepin-8-one ( 2 ); 2 has been caracterized by nmr spectroscopy and by comparison with its methylated derivative prepared in an unambigous manner. 相似文献
58.
T. de Beer G. Ph. Hoornweg G. J. Grootendorst N. H. Velthorst C. Gooijer 《Analytica chimica acta》1996,330(2-3):189-197
An explorative study on the compatibility of liquid separation systems, such as (micro) liquid chromatography (LC) and capillary electrophoresis (CE), and forward-scattering degenerate four-wave mixing (F-D4WM) as a detection method is presented. F-D4WM is a laser-based technique showing some analogy with holographic spectroscopy: a signal on a theoretical dark background is observed as a result of light absorption by an analyte. Parameters considered are solvent composition focussing on acetonitrile, methanol and water; mobile phases in LC and CE), detector cell construction, and influences of laser beam powers. A specially designed detector cell has been developed to meet the Brewster condition, both at the air-quartz and the quartz-liquid boundaries. For practical reasons, the tested cell has an optical pathlength of 1 mm; reduction to 100 μm is required to apply the cell in microseparations. The F-D4WM technique has been involved for detection in a conventional-size, reversed-phase LC separation of 1- and 2-aminoanthraquinones. The detection limit obtained (for the 1 mm cell) is 2 × 10−5 absorbance units. The experiments indicate that further reduction of background deserves explicit attention. 相似文献
59.
Contrary to the results of other semi-empirical all-valence electron methods, the main features concerning the conformation of trans-benzylideneaniline are correctly accounted for using the NDDO method. Based on a modified continuum model the influence of solvents on the molecular structure was estimated. 相似文献
60.
Accurate values for the coefficients of the R?6, R?8 and R?10 in the series representation of the dispersion interaction between two helium atoms at distance R are obtained by a simple variation method. 相似文献