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951.
Grzelczak M Kulisic N Prato M Mateo-Alonso A 《Chemical communications (Cambridge, England)》2010,46(48):9122-9124
Self-assembled nanohybrids of a 1,10-phenanthroline derivative and Au nanoparticles exhibit different optoelectronic properties, as a consequence of the different arrangements of the nanoparticles on the surface of the different-sized phenanthroline scaffolds. 相似文献
952.
We present a class of consensus protocols over groups of agents with stochastically switching, directed, and weighted communication topologies. In this protocol, an agent’s traits, that is, the cardinality of its neighbor set and the weight assigned to its neighbors in the updating process, are given by two jointly distributed random variables and the neighbors of an agent are selected with equal probability. We provide closed form results for the asymptotic convergence rate and for the steady state mean square deviation in the presence of additive noise. These results are specialized to consensus protocols based on Erd?s–Rényi and numerosity-constrained networks. 相似文献
953.
The question whether large turbulent drag reduction can be achieved at the high values of Re typical of applications is addressed. Answering such question, either by experiments or DNS, is obviously challenging. For DNS, the problem lies in the tremendous increase of the computational cost with Re, that has to be appreciated in view of the need of carrying out an entire parametric study at every Re, owing to the unknown location of the optimal forcing parameters. In this paper we limit ourselves to considering an open-loop technique based on spanwise forcing, the streamwise-traveling waves introduced by [1], and explore via Direct Numerical Simulations (DNS) how the drag reduction varies when the friction Reynolds number is increased from Reτ = 200 to Reτ = 2000. To achieve high Re while keeping the computational cost affordable, computational domains of reduced size are employed. We adopted special care to interpret results that are indeed still box-size dependent, as well as strategies to compute the random errors and give the results an error bar. Our results indicate that still R = 0.29 can be obtained at Reτ = 2000 in the partial region of the parameter space studied. The maximum R is found to decrease as R ˜ Reτ−0.22 in the Reynolds range investigated. As most important outcome, we find that the sensitivity of R to Re becomes smaller when far from the low-Re optimum parameters: in this region, we suggest R ˜ Reτ−0.08. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
954.
We perform 3D numerical simulations, heuristic modeling and microfluidic experiments to demonstrate, for the first time, the presence of a bistability scenario for transversal migration of particles suspended in a viscoelastic liquid flowing in a pipe. Our results show that particle migration, either at the centerline or at the wall, can be controlled by the rheological properties of the suspending liquid and by the relative dimensions of the particle and tube. Proper selection of these parameters can promote strict aligning of particles on a line, i.e., 3-D focusing. Simple design rules are given to rationally control particle focusing under flow in micropipes. 相似文献
955.
Methyl trioctylphosphonium methyl carbonate [P(8881)](+)[MeOCO(2)](-) was prepared by the alkylation of trioctyl phosphine with the non-toxic dimethyl carbonate. This salt was a convenient source to synthesize different ionic liquids where the methyl trioctylphosphonium cation was coupled to weakly basic anions such as bicarbonate, acetate, and phenolate. At 90-220 °C, all these compounds [P(8881)](+)X(-); X = MeOCO(2); HOCO(2); AcO; PhO were excellent organocatalysts for the transesterification of dimethyl and diethyl carbonate with primary and secondary alcohols, including benzyl alcohol, cyclopentanol, cyclohexanol, and the rather sterically hindered menthol. Conditions were optimized to operate with very low catalyst loadings up to 1 mol% and to obtain non-symmetric dialkyl carbonates (ROCO(2)R'; R = Me, Et) with selectivity up to 99% and isolated yields >90%. The catalytic performance of the investigated ionic liquids was discussed through a cooperative mechanism of simultaneous activation of both electrophilic and nucleophilic reactants. 相似文献
956.
Iannazzo D Piperno A Ferlazzo A Pistone A Milone C Lanza M Cimino F Speciale A Trombetta D Saija A Galvagno S 《Organic & biomolecular chemistry》2012,10(5):1025-1031
We report the synthesis and the characterization of different multi-walled carbon nanotubes (MWCNTs) linked to natural molecules, 5,7-coumarins and/or oleic acid, obtained from purified pristine MWCNTs by a cascade of chemical functionalization. The activities of these modified MWCNTs were investigated in vitro on human umbilical vein endothelial cells (HUVECs) by evaluating their ability to influence cell viability and to induce cell apoptosis. Our data showed that pristine MWCNTs are markedly cytotoxic; conversely, the carboxylated carbon nanotubes, much more readily dispersed in aqueous solutions and CNT-Link, the key intermediate designed by us for the drug anchorage, are biocompatible at the tested concentrations (1 and 10 μg ml(-1)). 相似文献
957.
Oliveri V Giuffrida ML Vecchio G Aiello C Viale M 《Dalton transactions (Cambridge, England : 2003)》2012,41(15):4530-4535
8-Hydroxyquinolines are systems of great interest in the field of inorganic and bioinorganic chemistry. They are metal-binding compounds and are known to exhibit a variety of biological activities, such as antibacterial and anticancer activities. Among these systems, clioquinol has been the focus of a renewed interest in recent years. In this scenario, we synthesized and characterized the new clioquinol glucoconjugate, 5-chloro-7-iodo-8-quinolinyl-β-D-glucopyranoside in order to compare this system to that of clioquinol. We also synthesized, 8-quinolinyl-β-D-glucopyranoside, an 8-hydroxyquinoline glucoconjugate. The reason for the development of glucoconjugates is the glucose avidity, and the over-expression of glucose transporters in cancer cells. Here we demonstrate that glycoconjugates are cleaved in vitro by β-glucosidase and these systems exhibit antiproliferative activity against different tumor cell lines in the presence of copper(II) ions. 相似文献
958.
Righi G Silvestri IP Barontini M Crisante F Di Manno A Pelagalli R Bovicelli P 《Natural product research》2012,26(14):1278-1284
Scutellarein is a component of Scutellaria, recently known as a potent cytotoxic agent on human leukaemia cells. The aim of this study was the synthesis of scutellarein and its methylated derivative. The new features are the innovating method to afford flavones from flavanones and the A-ring regioselective bromination step that lead to the target molecule by a facile and high-yielding pathway. 相似文献
959.
V Mirabello M Caporali V Gallo L Gonsalvi D Gudat W Frey A Ienco M Latronico P Mastrorilli M Peruzzini 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(36):11238-11250
The dynamic behavior in solution of eight mono-hapto?tetraphosphorus transition metal-complexes, trans-[Ru(dppm)(2) (H)(η(1) -P(4) )]BF(4) ([1]BF(4) ), trans-[Ru(dppe)(2) (H)(η(1) -P(4) )]BF(4) ([2]BF(4) ), [CpRu(PPh(3) )(2) (η(1) -P(4) )]PF(6) ([3]PF(6) ), [CpOs(PPh(3) )(2) (η(1) -P(4) )]PF(6) ([4]PF(6) ), [Cp*Ru(PPh(3) )(2) (η(1) -P(4) )]PF(6) ([5]PF(6) ), [Cp*Ru(dppe)(η(1) -P(4) )]PF(6) ([6]PF(6) ), [Cp*Fe(dppe)(η(1) -P(4) )]PF(6) ([7]PF(6) ), [(triphos)Re(CO)(2) (η(1) -P(4) )]OTf ([8]OTf), and of three bimetallic Ru(μ,η(1:2) -P(4) )Pt species [{Ru(dppm)(2) (H)}(μ,η(1:2) -P(4) ){Pt(PPh(3) )(2) }]BF(4) ([1-Pt]BF(4) ), [{Ru(dppe)(2) (H)}(μ,η(1:2) -P(4) ){Pt(PPh(3) )(2) }]BF(4) ([2-Pt]BF(4) ), [{CpRu(PPh(3) )(2) )}(μ,η(1:2) -P(4) ){Pt(PPh(3) )(2) }]BF(4) ([3-Pt]BF(4) ), [dppm=bis(diphenylphosphanyl)methane; dppe=1,2-bis(diphenylphosphanyl)ethane; triphos=1,1,1-tris(diphenylphosphanylmethyl)ethane; Cp=η(5) -C(5) H(5) ; Cp*=η(5) -C(5) Me(5) ] was studied by variable-temperature (VT) NMR and (31) P{(1) H} exchange spectroscopy (EXSY). For most of the mononuclear species, NMR spectroscopy allowed to ascertain that the metal-coordinated P(4) molecule experiences a dynamic process consisting, apart from the free rotation about the M?P(4) axis, in a tumbling movement of the P(4) cage while remaining chemically coordinated to the central metal. EXSY and VT (31) P?NMR experiments showed that also the binuclear complex cations [1-Pt](+) -[3-Pt](+) are subjected to molecular motions featured by the shift of each metal from one P to an adjacent one of the P(4) moiety. The relative mobility of the metal fragments (Ru vs. Pt) was found to depend on the co-ligands of the binuclear complexes. For complexes [2]BF(4) and [3]PF(6) , MAS, (31) P?NMR experiments revealed that the dynamic processes observed in solution (i.e., rotation and tumbling) may take place also in the solid state. The activation parameters for the dynamic processes of complexes 1(+) , 2(+) , 3(+) , 4(+) , 6(+) , 8(+) in solution, as well as the X-ray structures of 2(+) , 3(+) , 5(+) , 6(+) are also reported. The data collected suggest that metal-coordinated P(4) should not be considered as a static ligand in solution and in the solid state. 相似文献
960.
Excited tetrabutylammonium decatungstate (TBADT), known to activate a variety of compounds via hydrogen atom transfer (HAT), has now been applied as a photoredox catalyst for the effective oxidative cleavage of benzyl silanes and radical benzylation of reducible olefins occurring in isolated yields from poor to excellent. 相似文献