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131.
We construct on the boundary of a hyperbolic group (in Gromov'ssense) a natural visual measure and a natural crossratio. Weprove that the I-quasiconformal homeomorphisms (in Pansu's sense)between the boundaries of hyperbolic groups are the quasimöbiusmaps (that is, the bijections that almost preserve the crossratios),and that they are the extensions of the quasi-isometries betweenthe groups. We define a barycentre for every probability measureon the boundary without atom, extending the Douady-Earle construction. 相似文献
132.
The preparation and thermal analysis of the metal chelates of N-benzoyl-N-phenylhydroxylamine (BPHA) with Al(III), Cd(II), Co(II), Cr(III), Cu(II), Fe(III), Mn(II), Ni(II) and Zn(II) is discussed. The differential thermal analysis apparatus is described in detail. DTA and TGA curves of BPHA arid the chelates from 25 to 700° in oxygen and in nitrogen are presented. 相似文献
133.
Berthold A Laugere F Schellevis H de Boer CR Laros M Guijt RM Sarro PM Vellekoop MJ 《Electrophoresis》2002,23(20):3511-3519
Glass microdevices for capillary electrophoresis (CE) gained a lot of interest in the development of micrototal analysis systems (microTAS). The fabrication of a microTAS requires integration of sampling, chemical separation and detection systems into a microdevice. The integration of a detection system into a microchannel, however, is hampered by the lack of suitable microfabrication technology. Here, a microfabrication method for integration of insulated microelectrodes inside a leakage-free microchannel in glass is presented. A combination of newly developed technological approaches, such as low-temperature glass-to-glass anodic bonding, channel etching, fabrication of buried metal interconnects, and deposition of thin plasma-enhanced chemical vapour deposition (PECVD) silicon carbide layers, enables the fabrication of a CE microdevice with an integrated contactless conductivity detector. The fabrication method of this CE microdevice with integrated contactless conductivity detector is described in detail. Standard CE separations of three inorganic cations in concentrations down to 5 microM show the viability of the new microCE system. 相似文献
134.
We have studied the formation of water-CO(2) interfaces in the presence of different concentrations of ovalbumin (OVA) by tensiometry and by means of interfacial rheological measurements to obtain some information on the capacity of protein film to stabilize H(2)O in CO(2) emulsion. The formation of pure water-CO(2) interface can be described as a two-step phenomenon.(1) The CO(2) molecules adsorb onto the water surface and then a reorganization of the interface creates a H(2)O-CO(2) cluster network. This organization occurs at a temperature (40 degrees C) higher than the higher temperature limit (10 degrees C) allowing the formation of crystalline structure called CO(2) clathrate.(2) Our results show that ovalbumin adsorption from bulk concentrations higher than 0.0229 g/L inhibits the cluster formation for a CO(2) pressure less than 80 bar. However, for lower concentrations, the more the CO(2) pressure is close to 80 bar, the more OVA adsorption is reduced by the H(2)O-CO(2) cluster network. Moreover, from a pressure of 90 bar, the affinity of OVA for the interface increases and mixed films made of protein molecules and clusters are obtained for the OVA concentrations lower than 1 g/L. 相似文献
135.
Esseiva P Anglada F Dujourdy L Taroni F Margot P Pasquier ED Dawson M Roux C Doble P 《Talanta》2005,67(2):360-367
Artificial neural networks (ANNs) were utilised to validate illicit drug classification in the profiling method used at “Institut de Police Scientifique” of the University of Lausanne (IPS). This method established links between samples using a combination of principal component analysis (PCA) and calculation of a correlation value between samples.Heroin seizures sent to the IPS laboratory were analysed using gas chromatography (GC) to separate the major alkaloids present in illicit heroin. Statistical analysis was then performed on 3371 samples. Initially, PCA was performed as a preliminary screen to identify samples of a similar chemical profile. A correlation value was then calculated for each sample previously identified with PCA. This correlation value was used to determine links between drug samples. These links were then recorded in an Ibase® database. From this database the notion of “chemical class” arises, where samples with similar chemical profiles are grouped together. Currently, about 20 “chemical classes” have been identified.The normalised peak areas of six target compounds were then used to train an ANN to classify each sample into its appropriate class. Four hundred and sixty-eight samples were used as a training data set. Sixty samples were treated as blinds and 370 as non-linked samples. The results show that in 96% of cases the neural network attributed the seizure to the right “chemical class”.The application of a neural network was found to be a useful tool to validate the classification of new drug seizures in existing chemical classes. This tool should be increasingly used in such situations involving profile comparisons and classifications. 相似文献
136.
[reaction: see text] The copper reagent arising from an optically pure propargylic oxazolidinone was found to react regio- and diastereoselectively with aldehydes, leading, in a one-pot procedure, to the anti homopropargylic amino alcohols derivatives in good yields. 相似文献
137.
Commercial interfaces for multidimensional gas chromatography (MDGC) are based either on a valve or a pneumatic switching between columns. Both exhibit significant drawbacks and only few suppliers exist. An extremely simple interface has been set up to overcome these limitations without requiring any pneumatic control or valves switching. This new MDGC design is based on the cryo-control of the analyte transfer from the first to the second column through two cool strands of a capillary. This technique is simple to implement and does not require any special column connections. Applications involve non-polar/polar phase combinations, as well as chiral analysis, hyphenation to a conventional mass spectrometer, and olfactometric detection. In contrast to conventional MDGC configuration, the present configuration allows the use of a single oven to operate both columns at different temperatures. 相似文献
138.
G. Desrousseaux B. Robrieux A. Renou A. Carlan H. Schaffar M. Gillet 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1989,12(1-4):23-26
The sheet conductance of gold condensates on MgO anda-C is expressed in terms of granulometric quantities. This expression enables us to follow the evolution of metal repartition on its substrate during the gold evaporation. The difference between the growth modes of these gold layers on MgO and ona-C is explained by the predominance of respectively nucleation and coalescence phenomena 相似文献
139.
Thierry Maré Salma Halelfadl Ousmane Sow Patrice Estellé Steven Duret Frederic Bazantay 《Experimental Thermal and Fluid Science》2011,35(8):1535-1543
The objective of this study is to compare experimentally the thermal performances of two types of commercial nanofluids. The first is composed of oxides of alumina (γAl2O3) dispersed in water and the second one is aqueous suspensions of nanotubes of carbons (CNTs). The viscosity of the nanofluids is measured as a function of the temperature between 2 and 10 °C. An experimental device, containing three thermal buckles controlled in temperature and greatly instrumented permits to study the thermal convective transfers. The evolution of the convective coefficient permits to study the convective thermal transfers. The evolution of the convective coefficient is presented according to the Reynolds number, at low temperature from 0 to 10 °C and for the two aforementioned nanofluids. An assessment of the pressure drops in the circuit as well as of the powers of the circulator and outputs is dealt with. 相似文献
140.
Raphaël Frdrick Bernadette Norberg Franois Durant Frederic Ooms Johan Wouters 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(9):o623-o626
The structures of three compounds, namely 7‐methoxy‐2‐[3‐(trifluoromethyl)phenyl]‐9H‐indeno[1,2‐c]pyridazin‐9‐one, C19H11F3N2O2, (Id), 6‐methoxy‐2‐[3‐(trifluoromethyl)phenyl]‐9H‐indeno[1,2‐c]pyridazin‐9‐one, C19H11F3N2O2, (IId), and 2‐methyl‐6‐(4,4,4‐trifluorobutoxy)‐9H‐indeno[1,2‐c]pyridazin‐9‐one, C16H13F3N2O2, (IIf), which are potent reversible type‐B monoamine oxidase (MAO‐B) inhibitors, are presented and discussed. Compounds (Id) and (IId) crystallize in a nearly planar conformation. The crystal structures are stabilized by weak C—H⋯O hydrogen bonds. The packing is dominated by π–π stacking interactions between the heterocyclic central moieties of centrosymmetrically related molecules. In compound (IIf), the trifluoroethyl termination is almost perpendicular to the plane of the ring. 相似文献