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Hans-Dieter Scharf Jrg Fleischhauer Hans Leismann Ingrid Ressler Wolf-gang Schleker Robert Weitz 《Angewandte Chemie (International ed. in English)》1979,18(9):652-662
The utilization of simple photochemical reactions for the storage of solar energy in the form of chemical energy in energy-rich products has often been considered in the further development and improvement of e. g. simple thermosolar techniques. The hitherto proposed criteria for the qualification of an abiotic photochemical system are, however, mostly of a qualitative nature, so a mutal comparison of the systems is not precise enough. In this article it is shown how a useful correlation on the basis of time-independent experimental data can be achieved and how, from the viewpoint of photochemistry, a comparative classification of known reactions is possible. The following reactions are compared: the [2 + 2]-photocycloadditions of norbornadiene, dimethyl 2,3-norbornadienedicarboxylate, and dicyclopentadienone, the photoisomerization of trans- to cis-diacetylindigo, the photodissociation of nitrosyl chloride as well as a photocatalytic redox reaction. The quantity of material required and storage efficiency are by far the most favorable in the case of trans-diacetylindigo. The main disadvantage of the latter however, is that the energy-rich cis-from rapidly reverts to the stable trans-form at elevated temperatures. 相似文献
236.
Dr. Annika Buchheit Britta Teßmer Dr. Marina Muñoz-Castro Prof. Hartmut Bracht Prof. Hans-Dieter Wiemhöfer 《ChemistryOpen》2021,10(3):340-346
This work examines the proton intercalation in vanadium pentoxide (V2O5) thin films and its optical properties in the near-infrared (near-IR) region. Samples were prepared via direct current magnetron sputter deposition and cyclic voltammetry was used to characterize the insertion and extraction behavior of protons in V2O5 in a trifluoroacetic acid containing electrolyte. With the same setup chronopotentiometry was done to intercalate a well-defined number of protons in the HxV2O5 system in the range of x=0 and x=1. These films were characterized with optical reflectometry in the near-IR region (between 700 and 1700 nm wavelength) and the refractive index n and extinction coefficient k were determined using Cauchy ’s dispersion model. The results show a clear correlation between proton concentration and n and k. 相似文献
237.
Richter F Gatti F Léonard C Le Quéré F Meyer HD 《The Journal of chemical physics》2007,127(16):164315
The present paper is devoted to a full quantum mechanical study of the cis-->trans isomerization of HONO. In contrast to our previous study [Richter et al., J. Chem. Phys. 120, 6072 (2004)], the dynamics is now performed in the presence of an external time-dependent field in order to be closer to experimental conditions. A six-dimensional dipole surface is computed. Using a previously developed potential energy surface [Richter et al., J. Chem. Phys. 120, 1306 (2004)], all eigenstates up to 4000 cm(-1) are calculated. We simulate the dynamics during and after excitation by an electromagnetic pulse whose parameters are chosen to efficiently trigger the isomerization. Our investigations show that there is a selective isomerization pathway. 相似文献
238.
Hu TS Tannert R Arndt HD Waldmann H 《Chemical communications (Cambridge, England)》2007,(38):3942-3944
The synthesis of a focused library of jasplakinolide analogs with a 1,2,3-triazole in place of an E-configured double bond is described, featuring the Cu(I) catalyzed azide-alkyne cycloaddition reaction as an efficient macrocyclization tool. 相似文献
239.
R. Beckhaus M. Wagner V. V. Burlakov W. Baumann N. Peulecke A. Spannenberg R. Kempe U. Rosenthal 《无机化学与普通化学杂志》1998,624(1):129-134
The titanocene acetylene complex [Cp*2Ti(η2-Me3SiC≡CSiMe3)] ( 14 ) reacts with 1-alkynes such as phenylacetylene ( 15 a ), 1-hexyne ( 15 b ), 1-dodecyne ( 15 c ) and trimethylsilylacetylene ( 15 d ) by ligand exchange and proton shift, to yield exclusively the 1-alkenyltitanocene acetylides [Cp*2Ti(CH=CHR)(C≡CR)] ( 21 ) (R = Ph ( 21 a ), CH3(CH2)3 ( 21 b ), CH3(CH2)9 ( 21 c ), SiMe3 ( 21 d )). The X-ray structure of 21 a is presented. In reaction of acetylene HC≡CH ( 15 e ) with 14 other products are formed. However, no intermediates, like [Cp*2Ti(η2-RC≡CH)] ( 17 ), [Cp*2Ti(H)C≡CR] ( 17 ) or [Cp*2Ti=C=CHR] ( 22 ) in reactions of 14 with 15 are detectable. On the other hand, a stable titanocenehydride [Cp*2Ti(H)OCH3] ( 23 ) is obtained by oxidative addition of CH3OH with Cp*2Ti, generated from 14 . 相似文献
240.
D. Thomas N. Peulecke V. V. Burlakov B. Heller W. Baumann A. Spannenberg R. Kempe U. Rosenthal R. Beckhaus 《无机化学与普通化学杂志》1998,624(5):919-924
Desactivation of Catalysts in the Polymerization of Acetylene by Bis(trimethylsilyl)acetylene Complexes of Titanocene or Zirconocene Unexpected inactive byproducts were observed in the catalytic polymerization of acetylene using metallocene alkyne complexes Cp2M(L)(η2-Me3SiC2SiMe3), 1 : M = Ti, without L; 2 : M = Zr, L = thf. The reaction of 1 was investigated in detail by NMR to give quantitatively at –20 °C the titanacyclopentadiene Cp2Ti–CH=CH–C(SiMe3)=C(SiMe3) ( 3 ). Around 0 °C 3 starts to rearrange to yield the dihydroindenyl complex 4 via coupling of one Cp-ligand with the titanacyclopentadiene. In the reaction of 2 under analogous conditions a zirconacyclopentadiene Cp2Zr–CH=CH–C(SiMe3)=C(SiMe3) ( 5 ) and the dimeric complex [Cp2Zr(C(SiMe3)=CH(SiMe3)]2[μ-σ(1,2)-C≡C] ( 6 ) were observed. Whereas 5 decomposes to a mixture of unidentified paramagnetic species, 6 was isolated and investigated by NMR spectroscopy and X-ray analysis. In the reaction of rac-(ebthi)Zr(η2-Me3SiC2SiMe3) (ebthi = ethylenbistetrahydroindenyl) with 2-ethynyl-pyridine the complex rac-(ebthi)ZrC(SiMe3)=CH(SiMe3)](σ-C≡CPy) 7 was obtained, which was investigated by an X-ray analysis. 相似文献