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131.
Jacquet O Das Neves Gomes C Ephritikhine M Cantat T 《Journal of the American Chemical Society》2012,134(6):2934-2937
A highly active organocatalytic system based on N-heterocyclic carbenes has been designed for the formylation of N-H bonds in a large variety of nitrogen molecules and heterocycles, using two chemical wastes: CO(2) and polymethylhydrosiloxane (PMHS). 相似文献
132.
We consider the problem of optimal management of energy contracts, with bounds on the local (time step) amounts and global (whole period) amounts to be traded, integer constraint on the decision variables and uncertainty on prices only. After building a finite state Markov chain by using vectorial quantization tree method, we rely on the stochastic dual dynamic programming (SDDP) method to solve the continuous relaxation of this stochastic optimization problem. An heuristic for computing sub optimal solutions to the integer optimization problem, based on the Bellman values of the continuous relaxation, is provided. Combining the previous techniques, we are able to deal with high-dimensional state variables problems. Numerical tests applied to realistic energy markets problems have been performed. 相似文献
133.
Deeb Taher Prof. Dr. Michelle E. Thibault Domenico Di Mondo Michael Jennings Marcel Schlaf Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(39):10132-10143
The ruthenium aqua complexes [Ru(H2O)2(bipy)2](OTf)2, [cis‐Ru(6,6′‐Cl2‐bipy)2(OH2)2](OTf)2, [Ru(H2O)2(phen)2](OTf)2, [Ru(H2O)3(2,2′:6′,2′′‐terpy)](OTf)2 and [Ru(H2O)3(Phterpy)](OTf)2 (bipy=2,2′‐bipyridine; OTf?=triflate; phen=phenanthroline; terpy= terpyridine; Phterpy=4′‐phenyl‐2,2′:6′,2′′‐terpyridine) are water‐ and acid‐stable catalysts for the hydrogenation of aldehydes and ketones in sulfolane solution. In the presence of HOS(O)2CF3 (triflic acid) as a dehydration co‐catalyst they directly convert 1,2‐hexanediol to n‐hexanol and hexane. The terpyridine complexes are stable and active as catalysts at temperatures ≥250 °C and in either aqueous sulfolane solution or pure water convert glycerol into n‐propanol and ultimately propane as the final reaction product in up to quantitative yield. For the terpy complexes the active catalyst is postulated to be a carbonyl species [(4′‐R‐2,2′:6′,2′′‐terpy)Ru(CO)(H2O)2](OTf)2 (R=H, Ph) formed by the decarbonylation of aldehydes (hexanal for 1,2‐hexanediol and 3‐hydroxypropanal for glycerol) generated in the reaction mixture through acid‐catalyzed dehydration. The structure of the dimeric complex [{(4′‐phenyl‐2,2′:6′,2′′‐terpy)Ru(CO)}2(μ‐OCH3)2](OTf)2 has been determined by single crystal X‐ray crystallography (Space group P (a=8.2532(17); b=12.858(3); c=14.363(3) Å; α=64.38(3); β=77.26(3); γ = 87.12(3)°, R=4.36 %). 相似文献
134.
We prove in the general setting of lower semicontinuous functions on Banach spaces the relation between the Rockafellar directional derivative and the mixed lower limit of the lower Dini derivatives. As a byproduct we derive the famous inclusions of tangent cones of closed sets in Banach spaces. The results are established using as principal tool multidirectional mean value inequalities [Aussel et al., SIAM J Optim 9(3), 690–706 (1999)]. 相似文献
135.
Kenji Hirai Hiroto Ishikawa Thibault Chervy James A. Hutchison Hiroshi Uji-i 《Chemical science》2021,12(36):11986
The coupling of (photo)chemical processes to optical cavity vacuum fields is an emerging method for modulating molecular and material properties. Recent reports have shown that strong coupling of the vibrational modes of solvents to cavity vacuum fields can influence the chemical reaction kinetics of dissolved solutes. This suggests that vibrational strong coupling might also effect other important solution-based processes, such as crystallization from solution. Here we test this hitherto unexplored notion, investigating pseudopolymorphism in the crystallization from water of ZIF metal–organic frameworks inside optical microcavities. We find that ZIF-8 crystals are selectively obtained from solution inside optical microcavities, where the OH stretching vibration of water is strongly coupled to cavity vacuum fields, whereas mixtures of ZIF-8 and ZIF-L are obtained otherwise. Moreover, ZIF crystallization is accelerated by solvent vibrational strong coupling. This work suggests that cavity vacuum fields might become a tool for materials synthesis, biasing molecular self-assembly and driving macroscopic material outcomes.Strong coupling of optical cavity vacuum fields and solvent vibrations leads to selective crystallization in a pseudo-polymorphic MOF system. 相似文献
136.
Dr. Raul Pereira Dr. Thibault Gendron Chandan Sanghera Hannah E. Greenwood Joseph Newcombe Dr. Patrick N. McCormick Dr. Kerstin Sander Prof. Dr. Maya Topf Prof. Dr. Erik Årstad Dr. Timothy H. Witney 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(9):2345-2351
Aldehyde dehydrogenases (ALDHs) catalyze the oxidation of aldehydes to carboxylic acids. Elevated ALDH expression in human cancers is linked to metastases and poor overall survival. Despite ALDH being a poor prognostic factor, the non-invasive assessment of ALDH activity in vivo has not been possible due to a lack of sensitive and translational imaging agents. Presented in this report are the synthesis and biological evaluation of ALDH1A1-selective chemical probes composed of an aromatic aldehyde derived from N,N-diethylamino benzaldehyde (DEAB) linked to a fluorinated pyridine ring either via an amide or amine linkage. Of the focused library of compounds evaluated, N-ethyl-6-(fluoro)-N-(4-formylbenzyl)nicotinamide 4 b was found to have excellent affinity and isozyme selectivity for ALDH1A1 in vitro. Following 18F-fluorination, [18F] 4 b was taken up by colorectal tumor cells and trapped through the conversion to its 18F-labeled carboxylate product under the action of ALDH. In vivo positron emission tomography revealed high uptake of [18F] 4 b in the lungs and liver, with radioactivity cleared through the urinary tract. Oxidation of [18F] 4 b , however, was observed in vivo, which may limit the tissue penetration of this first-in-class radiotracer. 相似文献
137.
P. E. Wolf F. Bonnet L. Guyon T. Lambert S. Perraud L. Puech B. Rousset P. Thibault 《The European physical journal. E, Soft matter》2009,28(2):183-198
We have investigated the formation of helium droplets in two physical situations. In the first one, droplets are atomised
from superfluid or normal liquid by a fast helium vapour flow. In the second, droplets of normal liquid are formed inside
porous glasses during the process of helium condensation. The context, aims, and results of these experiments are reviewed,
with focus on the specificity of light scattering by helium. In particular, we discuss how, for different reasons, the closeness
to unity of the index of refraction of helium allows in both cases to minimise the problem of multiple scattering and obtain
results which it would not be possible to get using other fluids. 相似文献
138.
N. Bernier F. Bocquet A. Allouche W. Saikaly C. Brosset J. Thibault A. Charaï 《Journal of Electron Spectroscopy and Related Phenomena》2008,164(1-3):34-43
A methodology is presented to select a consistent method, using electron energy loss spectroscopy (EELS), to extract the fraction of sp2-bonded carbon atoms in carbonaceous materials. According to this methodology, a reliable method has to conjointly fulfill two criteria. The first one consists in verifying, on a perfect graphite sample, that the experimental evolution of R = Iπ*/(Iπ* + Iσ*)-ratios is in good agreement with the one theoretically predicted as a function of experimental settings. The second criterion consists in measuring sp2 fractions in amorphous carbon samples with a minimum of fluctuation. We test three commonly used R-extraction techniques, and we show that they exhibit some failures. We thus implement a more accurate R-extraction process that accounts for the predicted graphite R-evolution and exhibits a low intrinsic 4%-noise, as determined from the sp2 fraction fluctuation. Moreover, we check the transferability of our method on a wide range of EELS spectra, acquired with different experimental resolutions on samples exhibiting various sp2 contents. 相似文献
139.
Thibault Cantat 《Journal of organometallic chemistry》2003,687(2):365-376
Addition of ligands to [Pd(η3-RCHCHCH2)(μ-Cl)]2 or chloride ions to cationic [(η3-RCHCHCH2)PdL2]+BF4− induces the formation of neutral complexes η1-RCHCHCH2PdClL2 (R=H with L=(4-ClC6H4)3P, (4-CH3C6H4)3P, (4-CF3C6H4)3P or L2=1,2-bis(diphenylphosphino)butane (dppb), 1,1′-bis(diphenylphosphino)ferrocene (dppf); R=Ph with L=(4-ClC6H4)3P), instead of the expected cationic complexes [(η3-RCHCHCH2)PdL2]+Cl−. In the presence of chloride ions, the reaction of morpholine with the cationic complexes [(η3-allyl)Pd(PAr3)2]+BF4− (Ar=4-ClC6H4, 4-CH3C6H4) goes slower and involves both cationic [(η3-allyl)Pd(PAr3)2]+ and neutral η1-allyl-PdCl(PAr3)2 complexes as reactive species in equilibrium with Cl−. The cationic complex is more reactive than the neutral one. However, their relative contribution in the reaction strongly depends on the chloride concentration, which controls their relative concentration. The neutral η1-allyl-PdCl(PAr3)2 may become the major reactive species at high chloride concentration. Consequently, [Pd(η3-allyl)(μ-Cl)]2 associated with ligands or cationic [(η3-allyl)PdL2]+BF4−, used indifferently as precursors in palladium-catalyzed allylic substitutions, are not equivalent. In both situations, the mechanism of the Pd-catalyzed allylic substitution depends on the concentration of the chloride ions, delivered by the precursor or purposely added, that determines which species, [(η3-allyl)PdL2]+ or/and η1-allyl-PdClL2 are involved in the nucleophilic attack with consequences on the rate of the reaction and probably on its regioselectivity. Consequently, the chloride ions of the catalytic precursors [Pd(η3-allyl)(μ-Cl)]2 must not be considered as ‘innocent’ ligands. 相似文献
140.
Baillie RA Tran T Thibault ME Legzdins P 《Journal of the American Chemical Society》2010,132(43):15160-15161
C-H activation of benzene at 26 °C by (η(5)-C(5)Me(5))W(NO)(CH(2)CMe(3))(η(3)-CH(2)CHCHMe) results after 4 h in the production of five new organometallic complexes, only two of which are isomers of the desired (η(5)-C(5)Me(5))W(NO)(C(6)H(5))(η(3)-CH(2)CHCHMe) compound. In contrast, the identical reaction involving the η(5)-C(5)Me(4)H analogue affords only the phenyl complexes during the first 24 h, thereby facilitating their isolation in good yields. This striking difference in reactivity can be attributed to the lesser steric demands of the η(5)-C(5)Me(4)H ligand that result in its complexes reacting at a significantly slower rate. 相似文献