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1.
Co- and Ni-montmorillonites adsorb in aqueous suspensions up to 13 mmol alizarinate per 100 g clay, onto the broken-bonds
whereas Cu-clay adsorbs up to 25 mmol dye per 100 g clay into the interlayer space. Unloaded Co-, Ni- and Cu-clays and samples
loaded with increasing amounts of alizarinate, were gradually heated in air to 360°C and analyzed by X-ray diffraction. All
diffractograms were curve-fitted. Fitted diffractograms of non-heated samples, showed two peak components labeled C and D,
at<span lang=EN-US style='font-size:10.0pt;font-family:Symbol;mso-bidi-font-family: Symbol;mso-ansi-language:EN-US'>?1.22
and<span lang=EN-US style='font-size:10.0pt;font-family:Symbol;mso-bidi-font-family: Symbol;mso-ansi-language:EN-US'>?1.32
nm, characterizing tactoids with mono- and non-complete bilayers of water, respectively. After heating at 120°C component
D decreased or disappeared and two new components A and B appeared at<span lang=EN-US style='font-size:10.0pt;font-family:Symbol;mso-bidi-font-family:Symbol;
mso-ansi-language:EN-US'>?0.99 and<span lang=EN-US style='font-size:10.0pt;font-family:Symbol;mso-bidi-font-family: Symbol;mso-ansi-language:EN-US'>?1.08
nm, representing collapsed tactoids and tactoids with interlamellar oxy-cations, respectively. At 250°C, C and D decreased
or disappeared but A and B appeared in all fitted diffractograms. Co- and Ni-clay after heating at 360°C did not show C and
D. Components A and B proved that these clays collapsed indicating that initially there was no alizarinate in the interlayers.
At 360°C, C and D persisted in the fitted-diffractograms of Cu-clay, representing tactoids with interlamellar charcoal formed
from the partial oxidation of adsorbed dye initially located in the interlayers. 相似文献
2.
Thermo-XRD analysis of the adsorption of Congo-red by montmorillonite saturated with different cations 总被引:2,自引:0,他引:2
The adsorption of the organic anionic dye Congo red (CR) by montmorillonite saturated with Na+, Cs+, Mg2+, Cu2+, Al3+ and Fe3+ was investigated by XRD of unwashed and washed samples after equilibration at 40% humidity and after heating at 360 and at 420°C. The clay was treated with different amounts of CR, most of which was adsorbed. Clay samples, untreated with CR, after heating showed collapsed interlayer space. Unwashed and washed samples, which contained CR, before heating were characterized by three peaks or shoulders, labeled A (at 0.96-0.99 nm, collapsed interlayers), B (at 1.24-1.36 nm) and C (at 2.10-2.50 nm). Peak B represents adsorbed monolayers of water and dye anions inside the interlayer spaces. Peak C represents interlayer spaces with different orientations of the adsorbed water and organic matter. Diffractograms of samples with small amounts of dye were similar to those without dye showing peak B whereas diffractograms of most samples with high amounts of dye showed an additional peak C. Heated unwashed and washed samples were also characterized by three peaks or shoulders, labeled A' (at 0.96 nm), B' (at 1.10-1.33 nm) and C' (at 1.61-2.10 nm), representing collapsed interlayers, and interlayers with charcoal composed of monolayers or multilayers of carbon. When the samples were heated from 360 to 420°C some of the charcoal monolayers underwent rearrangement to multilayers. In the case of Cu the charcoal decomposed and oxidized. The present results show that most of the adsorbed dye was located inside the interlayer space.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
3.
A De Bruijn torus is a periodicd-dimensionalk-ary array such that eachn
1 × ... ×n
d
k-ary array appears exactly once with the same period. We describe two new methods of constructing such arrays. The first is a type of product that constructs ak
1
k
2
-ary torus from ak
1
-ary torus and ak
2
-ary torus. The second uses a decomposition of ad-dimensional torus to produce ad+1 dimensional torus. Both constructions will produce two dimensionalk-ary tori for which the period is not a power ofk. In particular, for
and for all natural numbers (n
1
, n
2
), we construct 2-dimensionalk-ary De Bruijn tori with order n
1
, n
2
and period
where
.Dedicated to the memory of Tony BrewsterPartially supported by NSF grant DMS-9201467Partially supported by a grant from the Reidler Foundation 相似文献
4.
Dalia Ovadyahu S. Yariv I. Lapides Y. Deutsch 《Journal of Thermal Analysis and Calorimetry》1998,51(2):415-430
The mechanochemical adsorption of phenol by laponite, saponite, montmorillonite, beidellite and vermiculite was studied by IR and X-ray spectroscopy. Mixtures containing phenol and clay in the ratio of 6:10 were manually ground by a mortar and pestle for 1,3,5 and 10 min and the ground mixtures were investigated. Depending on the basicity of the clay mineral and the time of grinding, two different associations between interlay er cations, water and phenol were identified. In these associations phenol can act either as a proton acceptor or donor (Configurations I and II, respectively). The phenol is more acidic than water and in most cases phenol acts as a proton donor. With montmorillonite and beidellite phenol acts as a proton acceptor. In this association the aromatic ring forms π bonds with atoms of the oxygen planes of the tetrahedral sheets which donate electrons to the anti-bonding π orbitals of the phenol. 相似文献
5.
Orly Keidar Isaak Lapdes Shlomo Shoval Shmuel Yariv 《Journal of Thermal Analysis and Calorimetry》2014,118(1):177-187
Charcoals formed during the thermo-XRD-analysis of montmorillonite (MONT) complexes with the dye 1,4-diaminoanthraquinone (DAAQ) were investigated by using curve-fitting calculations. Five saturated dye solutions were prepared (i) in distilled water and (ii–v) in 0.1, 0.5, 1.0, and 2.0 molar HCl. Two series of dye-clay complexes were prepared by using clay suspensions of 0.6 %and of 0.006 % labeled first and second series, respectively. Five dye-clay complexes were prepared of each series by adding 25 mL of dye solution to 25 mL of clay suspension. There is no free dye in complexes of the first series, but those of the second series, which were synthesized with a high ratio between dye and clay, contain non-adsorbed dye even after five washings. Complexes of the first series are loaded with very small amounts of molecular and protonated DAAQ (5–24 mmol DAAQ per 100 g clay), and their spacings are 1.25–1.54 nm suggesting the presence of tactoids with protonated or molecular DAAQ lying parallel to the clay layers. No carbon analyses were performed to the second series complexes. In addition to tactoids with spacing of 1.32 nm, they contain tactoids with spacings of 1.81–1.96 nm, suggesting that intercalated DAAQ are lying perpendicular to the clay layers. Three types of intercalated charcoal are identified in both series during the thermal analysis, one type with a low thermal stability and two types with high thermal stabilities. Charcoals of the second series complexes preserve the geometry of the original complexes up to high temperatures. 相似文献
6.
7.
Calcination of sepiolite and of two sepiolite/CsCl mixtures, unground and air-ground was investigated by thermo-XRD-analysis.
At 200 °C sepiolite, neat, mixed or air-ground with CsCl lost interparticle and zeolitic water. The framework of sepiolite
persisted during the dehydration but became defected, mainly in the air-ground mixture, less in the unground mixture and little
in the neat clay. At 500 °C, with the loss of bound water, the neat clay was folded and transformed into sepiolite anhydride.
In sepiolite/CsCl mixtures the dehydrated variety persisted but the degree of crystal-imperfection increased in the air-ground
mixture more than in the unground mixture. At 700 °C the neat clay remained crystallized, but the CsCl mixtures became amorphous.
Some crystalline dehydrated sepiolite or sepiolite anhydride persisted in the unground and air-ground CsCl mixtures, respectively.
At 850 °C, the neat clay crystallized into protoenstatite with some enstatite and clinoenstatite. The amorphous fraction of
sepiolite in the unground sepiolite/CsCl mixtures crystallized into pollucite and forsterite and the crystalline fraction
was transformed into enstatite, protoenstatite, and clinoenstatite. In the air-ground mixture, the amorphous phase was transformed
into pollucite with some forsterite and the crystalline fraction into enstatite. 相似文献
8.
F. Burstein M. Borisover I. Lapides S. Yariv 《Journal of Thermal Analysis and Calorimetry》2008,92(1):35-42
In the present research we studied the effect of the solvent used, whether it was polar water or a non-polar organic solvent
(n-hexane or n-hexadecane), on the basal-spacing and bulk structure of the sorbate-sorbent complexes obtained by the secondary adsorption
of nitrobenzene and m-nitrophenol by two types of organo-montmorillonites. X-ray measured basal spacings before and after thermal treatments up
to 360°C. The organo-clays were synthesized, with 41 and 90% replacement of the exchangeable Na+ by hexadecyltrimethylammonium (HDTMA), with mono-and bilayers of HDTMA cations in the interlayer space, labelled OC-41 and
OC-90, respectively. After heating at 360°C both organo-clays showed spacing at 1.25–1.28 nm, due to the presence of interlayer-charcoal,
indicating that in the preheated organo-clays the HDTMA was located in the interlayer.
The thermo-XRD-analysis of Na-clay complexes showed that from organic solvents both sorbates were adsorbed on the external
surface but from water they were intercalated. m-Nitrophenol complexes of both organo-clays obtained in aqueous suspensions contain water molecules. Spacings of nitrobenzene
complexes of OC-41 and OC-90 and those of nitrophenol complexes of OC-41 showed that the adsorbed molecules were imbedded
in cavities in the HDTMA layers. Adsorption of m-nitrophenol by OC-90 from water and n-hexane resulted in an increase of basal spacing (0.21 and 0.29 nm, respectively) suggesting the existence of a layer of nitrophenol
molecules sandwiched between two parallel HDTMA layers. 相似文献
9.
Troitsky A. V. Osharin A. M. Korolev A. V. Strapp W. Isaak G. 《Radiophysics and Quantum Electronics》2001,44(12):935-948
We present the results of spectral studies of thermal microwave emission from a cloudy atmosphere at 37 and 85 GHz. The experimental data are interpreted on the basis of modeling of microwave radiation transfer in the mixed-type clouds containing ice crystals of different shapes and supercooled water drops. All orders of scattering are taken into account. It is shown that polarization radiometric measurements allow one to separately determine ice-water and liquid-water contents of the clouds and also to diagnose the cloud microstructure (crystal shapes and characteristic sizes). 相似文献
10.
Thermal Intercalation of Alkali Halides into Kaolinite 总被引:2,自引:0,他引:2
S. Yariv I. Lapides K.H. Michaelian N. Lahav 《Journal of Thermal Analysis and Calorimetry》1999,56(2):865-884
Solid state intercalation of alkali halides into kaolinite takes place by heating pressed disks of dimethylsulfoxide (DMSO)-kaolinite
complex ground in different alkali halides. This reaction involves diffusion of the DMSO outside the interlayer space and
the alkali halide into the interlayer space. IR and Raman spectroscopy reveal two types of intercalation complexes: (i) almost
non-hydrous, obtained during thermal treatment of the DMSO complex; and (ii) hydrated, obtained by regrinding the disk in
air. The strength of the hydrogen bonds between intercalated water or halide anions and the inner surface hydroxyls decreases
in the order Cl−>Br−>I−. Chlorides penetrate the ditrigonal holes and form hydrogen bonds with the inner OH groups.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献