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991.
Pryjomska I Bartosz-Bechowski H Ciunik Z Trzeciak AM Ziółkowski JJ 《Dalton transactions (Cambridge, England : 2003)》2006,(1):213-220
The new phosphinite and phosphonite complexes (1-8) are very efficient catalysts for the methoxycarbonylation of iodobenzene and Heck cross-coupling of bromobenzene with butyl acrylate. High catalytic activity of these complexes can be explained by their in situ transformations during the reaction, stimulated by the presence of water, acid (HCl) or base (NEt(3)). Hydrolysis of phosphinite palladium complexes of the form trans-PdCl(2)[PPh(2)(OR)](2) (R = C(6)F(5), 2, (t)Bu 3, or O-menthyl 4) results in the formation of the dimeric complex [mu-ClPd(PPh(2)OH)(PPh(2)O)](2) 5, which is deprotonated by NEt(3), producing a polymeric complex of formula [Pd(P(O)PPh(2))(2)](n) 8. The reverse reaction, protonolysis of 8 with HCl, leads back to 5 and the monomeric complex 5a. The phosphinite complex PdCl(2)[PPh(2)(OBu)](2)1 with a more lipophilic ligand, PPh(2)(OBu), does not undergo hydrolysis under the same conditions. In the reaction of PdCl(2)(cod) with P(OPh)(2)(OH), the new dimer [mu-ClPd(P(OPh)(2)OH)(P(OPh)(2)O)](2) 6 was obtained, whereas reaction of Pd(OAc)(2) with P(OPh)(2)(OH) leads to the polymeric complex [Pd[P(O)(OPh)(2)](2)](n) 7. Protonolysis of 7 with HCl results in the formation of 6. 相似文献
992.
The air stable asarone-derived Ru carbene 16, a robust olefin metathesis catalyst, can be easily separated after reaction by deposition on silica gel and reused up to nine times. This procedure provides products of excellent purity with low Ru content. 相似文献
993.
Summary Carbon deposits on the surface ofRu/Fe2O3 catalysts used in the water-gas shift reaction have been investigated by Auger Electron Spectrometry. A correlation has been
found between the thickness of the carbon deposit and the catalytic activity in WGSR. The carbon deposit covers the metallic
active centers and blocks their contact with reagents. The dotting of the iron oxide support with sodium has been found to
reduce the amount of carbon deposit. . 相似文献
994.
leg . Varzatskii Yan Z. Voloshin Sergey V. Korobko Sergey V. Shulga Roland Krmer Alexander S. Belov Anna V. Vologzhanina Yurii N. Bubnov 《Polyhedron》2009,28(16):553
The nucleophilic substitution of the reactive halogen atoms of clathrochelate precursors with soft nucleophilic agents was promoted by cadmium(II) ion using various types of cadmium-containing compounds. Cadmium(II) activates the C–Hal bond both by the coordination of halogen substituents to this ion and the formation of anionic forms of a nucleophilic agent with cadmium amides, that increase the electron density on a reactive site of this agent. The cadmium-promoted substitution reactions of the reactive chlorine ribbed substituents in the di- and hexachlorine-containing clathrochelate precursors afforded the clathrochelate ribbed-functionalized derivatives of soft nucleophiles [alcohols (including fluorinated ones) and aromatic amines (including the nucleophiles with electron-withdrawing substituents)] by efficient one-pot procedures in high yields under mild conditions with generated in situ low-basic cadmium(II) alcoholates and amides. The complexes obtained were characterized using elemental analysis, MALDI-TOF mass spectrometry, IR, UV–Vis, 57Fe Mössbauer, and NMR spectroscopies, and X-ray crystallography. The potential of cadmium-promoted reactions for synthesis of different types of organic and coordination compounds is discussed. 相似文献
995.
Rajesh S. Murthy Sivaramakrishnan Muthukrishnan Sridhar Rajam Sarah M. Mandel Bruce S. Ault Anna D. Gudmundsdottir 《Journal of photochemistry and photobiology. A, Chemistry》2009,201(2-3):157-167
Photolysis of azides 1–4 in methanol, which have a built-in intramolecular triplet sensitizer, yields mainly carbamates 5–8. Laser flash photolysis of 1–4 shows formation of their triplet-excited ketone, which decays by intramolecular energy transfer to form triplet nitrenes 1n–4n. Irradiating 1–3 in matrices yields isocyanic acid, whereas photolysis of 4 forms isocyanate 4i. The depletion rate of the azide bands between 2100 and 2200 cm?1 is different than the rate of formation for the isocyanic acid bands at ~2265 cm?1; thus, the formation of isocyanic acid is a stepwise process. Irradiating 1 in matrices produces an absorption band due to nitrene 1n (λmax ~ 343 nm), which is depleted upon further irradiation, whereas the absorption due to 4-acetyl benzaldehyde (λmax ~ 280 nm) increases with prolonged irradiation. We propose that formation of isocyanic acid in matrices must come from secondary photolysis of nitrenes 1n–3n. This mechanism is further supported by calculation, which show that the estimated transition state for 1n–4n to fall apart to yield alkoxy and cyanato radicals is only ~34 kcal/mol above the ground state of the triplet nitrenes and thus the cleavage can take place photochemically. Thus, nitrenes 1n–4n can be formed selectively, but these intermediates are highly photosensitive and undergo secondary photolysis in matrices. 相似文献
996.
Anna Michta Maria Nowak Joachim Kusz 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(2):o66-o69
The title compound, C9H7NO, has two symmetry‐independent molecules in the asymmetric unit, which have different conformations of the hydroxy group with respect to the quinoline ring. One of the molecules adopts a cis conformation, while the other shows a trans conformation. Each type of independent molecule links into a separate infinite O—H...N hydrogen‐bonded chain with the graph‐set notation C(7). These chains are perpendicular in the unit cell, one extended in the a‐axis direction and the other in the b‐axis direction. There is also a weak C—H...O hydrogen bond with graph‐set notation D(2), which runs in the c‐axis direction and joins the two separate O—H...N chains. The significance of this study lies in the comparison drawn between the experimental and calculated data of the crystal structure of the title compound and the data of several other derivatives possessing the hydroxy group or the quinoline ring. The correlation between the IR spectrum of this compound and the hydrogen‐bond energy is also discussed. 相似文献
997.
Umaporn Paiphansiri Julia Dausend Anna Musyanovych Volker Mailänder Katharina Landfester 《Macromolecular bioscience》2009,9(6):575-584
The functionalization of well‐defined PU nanocapsules with an aqueous core prepared by performing a polyaddition at the interface of inverse (water‐in‐oil) miniemulsion droplets is demonstrated. The miniemulsion technique involving the nanoreactor concept allows one to obtain an encapsulation efficiency as high as 90% within the nanocapsules. A pH independent fluorescent dye is used as a model system for the aqueous core. By varying the molar ratio of the diol to the diisocyanate at a fixed surfactant concentration, the shell thickness of the nanocapsules can be finely tuned. The carboxy‐ and amino‐functionalized surface of the nanocapsules can be tailored by an in‐situ carboxymethylation reaction and by physical adsorption of a cationic polyelectrolyte, i.e. PAEMA or PEI. The increased uptake of amino‐functionalized fluorescent nanocapsules by HeLa cells clearly demonstrates the potential of the functionalized nanocapsules to be successfully exploited as biocarriers.
998.
999.
Transition metal‐based drugs exhibit high affinity to the soft donors of human serum proteins, especially of the high‐abundance protein HSA and of transferrin (Tf), whereas Ga(III) salts are known to bind to Tf and other iron‐containing metalloproteins, thereby interfering with the iron metabolism. Herein, the utilization of CE‐MS methods for studying the binding behavior of a therapeutic gallium nitrate formulation and the anticancer drug candidate Tris(8‐oxyquinolinato)gallium(III) to Tf and HSA under simulated physiological conditions is described. Both the Ga(III) salt and the complex were found to bind to Tf exclusively in the presence of carbonate, however, at different kinetics and to a different extent. Fe(III) induces the release of the Ga ions due to the higher affinity constant and also prevents the Ga(III) species from accessing the iron‐binding pockets of Tf. In contrast, only low affinity to HSA was observed and even when present at ca. 20‐fold excess, the majority of the Ga was attached to Tf. 相似文献
1000.
This article reports on the calulation of 12 low lying states of the nitrogen molecule along its dissociation using the multi-reference exponential wavefunction ansatz (Hanrath in J Chem Phys 123:84102, 2005), the single-reference formalism multi-reference coupled cluster (Oliphant and Adamowicz in J Chem Phys 94:1229, 1991), and MRCI methods. Spin projection errors and state overlap errors are calculated and allow an analysis of the wavefunction with respect to properties different from correlation energies. Both criteria are very sensitive to errors in the wavefunction. Due to its lack of Fermi vacuum invariance the errors are more significant for the single-reference formalism based approach. 相似文献