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101.
Quintela O Cruz A Concheiro M de Castro A López-Rivadulla M 《Rapid communications in mass spectrometry : RCM》2004,18(24):2976-2982
A rapid, sensitive and selective liquid chromatography/electrospray mass spectrometry (LC/ES-MS) method was developed for the quantitative determination of the anaesthetic benzodiazepine midazolam (MID) in human saliva and plasma from patients undergoing anesthesia procedures. Biological samples spiked with diazepam-d5, the internal standard, were extracted into diethyl ether. Compounds were separated on a Xterra RP18 column using a mobile phase of acetonitrile/formic acid 0.1% at a flow rate of 0.25 mL/min under a linear gradient. Column effluents were analyzed using MS with an ES source in the positive ionization mode. Calibration curves were linear in the concentration ranges of 1-250 and 0.2-25 ng/mL in plasma and saliva, respectively. The limits of detection were 0.5 ng/mL in plasma and 0.1 ng/mL in saliva, using a 0.5-mL sample volume. The recoveries of the spiked samples were above 65%. The method was applied to ten real samples from patients undergoing midazolam treatment. 相似文献
102.
A simple reverse flow-injection (rFIA) manifold for the direct determination of aluminum in drinking water is proposed. This rapid and sensitive method is based on the formation of an Al(3+) complex with salicylaldehyde picolinoylhydrazone (SAPH), which shows a maximum blue-green fluorescence (lambda(ex)=384 nm, lambda(em)= 468 nm) at pH 5.4. Operative conditions both for batch and rFIA procedures were investigated including reagent concentration, buffer solutions, injection loop, reacting coil and wavelengths used for the fluorimetric detection. The tolerance limits of foreign ions have been also evaluated, before and after the addition of masking agents. The reverse flow-injection procedure allows determination of Al(3+) at ppb level (LOD: 1.9 mug l(-1)) within a working range of 5-30 mug l(-1). The proposed method was successfully employed for the determination of Al(3+) in several commercial drinking, soft drinking (as certified reference material), and tap water samples. 相似文献
103.
Marta Catellani Sara Deledda Françoise Hénin Jacques Muzart 《Journal of organometallic chemistry》2003,687(2):473-482
A novel reaction sequence leading to the synthesis of substituted biphenyls containing a carbonyl group in an aliphatic chain has been achieved in one-pot reaction starting from iodoarenes and allylic alcohols under the catalytic action of palladium and norbornene. The latter is temporarily incorporated into a palladacycle, which directs the reaction towards the selective formation of an arylaryl bond. Norbornene spontaneously deinserts to allow the biphenylylpalladium bond thus formed to react in its turn with the allylic alcohol. 相似文献
104.
We present extensive molecular dynamics simulations of the motion of a single linear rigid molecule in a two-dimensional random array of fixed overlapping disklike obstacles. The diffusion constants for the center of mass translation, D(CM), and for rotation, D(R), are calculated for a wide range of the molecular length, L, and the density of obstacles, rho. The obtained results follow a master curve Drho(micro) approximately (L(2)rho)(-nu) with an exponent micro=-3/4 and 1/4 for D(R) and D(CM), respectively, that can be deduced from simple scaling and kinematic arguments. The nontrivial positive exponent nu shows an abrupt crossover at L(2)rho=zeta(1). For D(CM) we find a second crossover at L(2)rho=zeta(2). The values of zeta(1) and zeta(2) correspond to the average minor and major axis of the elliptic holes that characterize the random configuration of the obstacles. A violation of the Stokes-Einstein-Debye relation is observed for L(2)rho>zeta(1), in analogy with the phenomenon of enhanced translational diffusion observed in supercooled liquids close to the glass transition temperature. 相似文献
105.
A. Blanco J. M. Campelo A. Garcia D. Luna J. M. Marinas M. S. Moreno 《Reaction Kinetics and Catalysis Letters》1989,38(2):223-228
The effects of surface dehydration on textural properties, crystallinity and the structure of AlPO4–ZrO2 (weight ratio AlPO4/ZrO2=3) systems precipitated with ethylene oxide have been studied by N2 adsorption and XRD measurements. The increase in calcination temperature in the range 773–1273 K decreases the textural parameters as a consequence of AlPO4 crystallization to the tridymite form.
, AlPO4–ZrO2 ( AlPO4/ZrO2=3), , N2 - . 773 1273 , AlPO4 .相似文献
106.
A method is proposed for the treatment of data from a kinetic system of first order consecutive reactions by using an optimization procedure which converges to the correct solution of the two mathematically possible solutions and which does not need initial estimates of the parameters close to those to be determined.
, , , .相似文献
107.
C. Díaz M. L. Valenzuela E. Spodine Y. Moreno O. Peña 《Journal of Cluster Science》2007,18(4):831-844
Pyrolysis of the organometallic polymer: {{[N=P(R1)]0.8[N=P(OC6H4CH2CN[Ru])2]0.15[N=P((OC6H5)(OC6H4CH2CN[Ru]]0.05}{Cl}0.31}
n
, [Ru]=CpRu(PPh3)2, R1 = O2C12H8 (1) as well of the cyclic specie {N3P3 (OC6H5)5(OC6H4CH2CN[Ru])}{PF6} (2) under a flow of air at 800°C affords nanostructured RuO2. Nanoparticles near to 10 nm were observed. The differences in the use of cyclic or polymeric phosphazenes, as solid state
template, influence strongly the morphology and slightly the composition of the pyrolytic product. Temperature variable (SQUID)
measurements in the range of 5–300 K of the material obtained from the polymer, indicate an antiferromagnetic interaction
between the Ru atoms, although lower than that found for the crystalline ruthenium oxide, probably due to some amorphous product
present in the pyrolytic material. The possible formation mechanism is discussed and the differences in using the cyclic or
the polymeric compound as precursor is analyzed in terms of the relative content of Ru to P, N. A general formation method
of nanostructured metal oxides is proposed. 相似文献
108.
Brown SP Pérez-Torralba M Sanz D Claramunt RM Emsley L 《Journal of the American Chemical Society》2002,124(7):1152-1153
A new method for detecting hydrogen bonds in the solid state is presented. Using two-dimensional NMR correlation experiments, it is shown that a hydrogen-bond mediated J coupling can be observed in a powder under magic-angle spinning conditions, even though the J coupling is 2 orders of magnitude smaller than the dominant anisotropic interactions encountered in solid-state NMR. Specifically, the observation of a pair of peaks in a two-dimensional 15N-15N solid-state INADEQUATE experiment due to two nitrogens that have no covalent connectivity is attributed to the presence of a J coupling across a linking hydrogen bond. 相似文献
109.
Marta Catellani Gian Paolo Chiusoli Mirco Costa 《Journal of organometallic chemistry》1995,500(1-2):69-80
Chelating or metallacycle-forming substrates are very useful for directing organometallic reactions. This review covers the more recent research that has been carried out in the authors' laboratory. Rhodium(I)- and (III)-catalysed reactions of C---C coupling of butadiene with N-allylamides or N-alkylbutenamides are described. These reactions are controlled by the size and strength of the chelate ring formed by double-bond insertion into the crotyl-rhodium bond (formed from butadiene) and their regioselectivity can change with the oxidation state of the metal. Rhodium(I)-catalysed reactions of butadiene with enamides are also chelation controlled and lead to different products, depending on the substituents at nitrogen. Cobalt(II) metallacycles have been utilized for promoting some organic reactions. It has been shown that alkenes can be catalytically incorporated into cobaltacyclopentadiene rings, that spirocycles can be obtained from diynes, carbon monoxide and acrylic esters and that a Pauson-Khand-type reaction can be combined with a Michael-type reaction to prepare catalytically new cyclopentenones. The use of palladacycles, derived from norbornene insertion into aryl-palladium bonds, followed by cyclization, has allowed the selective functionalization of either end of the metallacycle and the formation of condensed rings. Conversion of a palladium(II) into a palladium(IV) metallacycle, and catalytic processes involving these intermediates, have been achieved. The formation of alkylaromatic palladacycles has also been exploited for the selective meta functionalization of the aromatic moiety by means of alkyl groups, accompanied by expulsion of the norbornene molecule. 相似文献
110.
M. A. Aramendía V. Borau C. Jiménez J. M. Marinas A. Moreno F. J. Urbano 《Reaction Kinetics and Catalysis Letters》1995,56(1):87-96
We have studied the activity of Pd/sepiolite and Pd/SiO2–AlPO4 catalysts in cyclohexane aromatization. The catalysts were characterized by H2 chemisorption measurements. The influence of support and reduction temperature on the metal surface properties and activity of the catalysts is discussed. 相似文献