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961.
Wojciech Ostrowski Błażej Gierczyk Marcin Hoffmann Rafał Frański 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):1141-1150
Abstract The complexes of 2-phenyl-1,3,4-selena(thia/oxa)diazole with a palladium cation were studied by using electrospray ionization mass spectrometry. Palladium chloride was used as a source of palladium cations. The complexes of ligand:metal stoichiometry of 3:1 (ions [L3+PdCl]+) were formed for selenadiazoles and thiadiazoles. Quantum mechanical calculations performed indicated that ligand molecules are attached to palladium cation by the N-4 atom. The fragment ions formed [L2–H+Pd]+ may be regarded as organometallic species. Selenadiazoles were found more prone to form the palladium complexes than thiadiazoles. Oxadiazoles did not yield the respective palladium complexes. For comparison, the nickel cation was also included in the study but only 1:1, and less abundant 2:1 complexes were observed. Exchange of selenium into oxygen does not affect the abilities of the ligands to form nickel complexes. 相似文献
962.
Abstract X-ray structures of ternary complexes composed of small dipeptides, i.e. glycylglycine or L-α-alanyl-L-α-alanine, 18-crown-6 and water molecules are determined based on single-crystal studies. It has been concluded that both dipeptides exist in the complex as zwitterions and are bonded to the 18-crown-6 macrocycle by the -NH+ 3 end group through N-H…O hydrogen bonds. The carboxylic groups at the opposite side of the peptide molecules take part in hydrogen bonding with water molecules. This scheme of water-peptide hydrogen bonding is particularly interesting in the glycylglycine compound where the water content is rather high (approximately 16 moles per mole of crown/dipeptide, 6 of which are found in the X-ray study) and may have interesting relevance with respect to the structure of gel solutions which easily form in these systems. The DSC and TGA thermograms of different hydrated forms of the complexes were obtained. Two types of water, i.e. weakly and strongly bonded, were observed upon heating of the hydrated complex. On further heating the anhydrous complexes have at least two transitions in the range 320–470 K: melting of complexes at 373–383 K and decomposition above 410 K. 相似文献
963.
Malgorzata Herman Agnieszka Przybylowicz Ewa Florek Wojciech Piekoszewski 《Journal of Analytical Chemistry》2013,68(4):360-367
A graphite furnace atomic absorption spectrometry (GF-AAS) method was developed for the determination of copper in selected alternative materials. The method is characterised by a low limit of detection, good accuracy and satisfactory precision, while the duration of a single measurement is approximately 80 s. It allowed an application of the developed method to determine copper in small samples of hair and nails with equipment available in most analytical laboratories. The developed GF-AAS method was successfully applied to routine analyses using samples collected from healthy humans. The study has shown similar concentration of copper in fingernails and toenails collected from women and men, which was 2–3 times lower than concentration of this element in hair of both genders. The correlation between concentration of copper in nails and hair allows one to use hair, fingernails and toenails as invariable materials for the evaluation of chronic exposure to copper. 相似文献
964.
Dominika Bukalak Izabela Majchrzak-Kucęba Wojciech Nowak 《Journal of Thermal Analysis and Calorimetry》2013,113(1):157-160
Adsorption methods using solid sorbents are an alternative to the absorption technology in the processes of purification gases from carbon dioxide. There is a need to rapidly assess the suitability of sorbents for use it in PSA, TSA, or VPSA installations. Important parameters which determine the quality of the sorbent are the sorption capacity of sorbent, selectivity to CO2 and the possibility of regeneration. This paper presents the results of sorption/desorption of CO2 study on the impregnated porous materials using thermogravimetric methods. Thermogravimetry allows for rapid assessment of sorption capacity and regeneration of the sorbents. Specially selected temperature program allowed to determine the sorption capacity of sorbents depending on the concentration of CO2 in the gas mixture and temperature. Degree of sorbent purification was determined in desorption process. 相似文献
965.
Prof. Jiří Kulhánek Prof. Filip Bureš Dr. Wojciech Kuznik Prof. Iwan V. Kityk Dr. Tomáš Mikysek Prof. Aleš Růžička 《化学:亚洲杂志》2013,8(2):465-475
A series of new nonlinear optical chromophores ( 1 – 15 ) that were comprised of ferrocene‐donor and 4,5‐dicyanoimidazole‐acceptor moieties and various π linkers of different length were synthesized. Support for the presence of significant D ? A interactions in these NLO‐phores was obtained from the evaluation of the quinoid character of the 1,4‐phenylene moieties and their electronic absorption spectra, which featured intense high‐energy (HE) bands that were accompanied by less‐intense low‐energy (LE) bands. The redox behavior of these compounds was investigated by cyclic voltammetry (CV) and by rotating‐disc voltammetry (RDV); their electrochemical gaps decreased steadily from 2.64 to 2.09 V. In addition to the experimentally obtained data, DFT calculations of their absorption spectra, HOMO/LUMO levels, and second‐order polarizabilities (β) (?2ω,ω,ω) were performed. A structure–property relationship study that was performed by systematically altering the π linker revealed that the intramolecular charge‐transfer and nonlinear optical properties of these inorganic–organic hybrid D? π? A systems ( 1 – 15 ) were primarily affected by: 1) The presence of olefinic/acetylenic subunits; 2) the length of the π linker; and 3) the spatial arrangement (planarity) of the π linker. 相似文献
966.
967.
968.
Studies on the catalysis of the reaction of organotin phenoxides with diethyl acetylenedicarboxylate
Different organotin phenoxides react at room temperature with diethyl acetylenedicarboxylate in diethyl ether, in the presence of lithium perchlorate to give a mixture of corresponding phenyl vinyl ethers and ring ethenylated phenols. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
969.
Bogdan Marciniec Hieronim Maciejewski Wojciech Duczmal Ryszard Fiedorow Dariusz Kityski 《应用有机金属化学》2003,17(2):127-134
The kinetics of substrate conversions in the commercially important hydrosilylation of allyl chloride with trichlorosilane, catalyzed by active carbon‐supported platinum, as well as the yields of the main product (3‐chloropropyltrichlorosilane) and by‐products (tetrachlorosilane, propyltrichlorosilane) have been studied. On the basis of the measurements performed, the pseudo first‐order rate constants (kobs, k1 and k2 from the model of competitive reactions) and activation energy (Ea = 11 kcal mol?1 (46.2 kJ mol?1)) were determined. The data obtained point to a non‐linear dependence of kobs on the catalyst amount. From the kinetic relationships, the kinetic equation was deduced. All the results of kinetic, IR spectroscopic and thermogravimetric measurements, as well as the derived kinetic equation, have confirmed the general model of consecutive–competitive reaction involving the formation of a surface complex C1 which can decompose in two directions according to the Chalk–Harrod mechanism. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
970.