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61.
Das S de Rooy SL Jordan AN Chandler L Negulescu II El-Zahab B Warner IM 《Langmuir : the ACS journal of surfaces and colloids》2012,28(1):757-765
Microstructures of sodium deoxycholate hydrogels were altered considerably in the presence of variable tris(hydroxymethyl)aminomethane (TRIS) concentrations. These observations were confirmed by use of X-ray diffraction, polarized optical microscopy, rheology, and differential scanning calorimetry measurements. Our studies reveal enhanced gel crystallinity and rigidity with increasing TRIS concentrations. The tunable hydrogel microstructures obtained under various conditions have been successfully utilized as templates to synthesize cyanine-based fluorescent nanoGUMBOS (nanoparticles from a group of uniform materials based on organic salts). A systematic variation in size (70-200 nm), with relatively low polydispersity and tunable spectral properties of [HMT][AOT] nanoGUMBOS, was achieved by use of these modified hydrogels. The gel microstructures are observed to direct the size as well as molecular self-assembly of the nanomaterials, thereby tuning their spectral properties. These modified hydrogels were also found to possess other interesting properties such as variable morphologies ranging from fibrous to spherulitic, variable degrees of crystallinity, rigidity, optical activity, and release profiles which can be exploited for a multitude of applications. Hence, this study demonstrates a novel method for modification of sodium deoxycholate hydrogels, their applications as templates for nanomaterials synthesis, as well as their potential applications in biotechnology and drug delivery. 相似文献
62.
Even though a number of regression techniques have been proposed over the years to handle a large number of regressors, due to the complex nature of data emerging from recent high-throughput experiments, it is unlikely that any single technique will be successful in modeling all data types. Thus, multiple regression algorithms from the collection of modern regression techniques that are capable of handling high dimensional regressors should be entertained for analyzing such data. A novel approach of building a super regression learner is proposed which can be fit with a training data set in order to make future predictions of a continuous outcome. The resulting super regression model is multi-objective in nature and mimics the performances of the best component regression models irrespective of the data type. This is accomplished by combining elements of bootstrap based risk calculation, rank aggregation, and stacking. The utility of this approach is demonstrated through its use on mass spectrometry data. 相似文献
63.
Ramendra Sundar Dey Susmita Gupta Rupankar Paira Shen-Ming Chen C. Retna Raj 《Journal of Solid State Electrochemistry》2012,16(1):173-178
Au electrode modified with the self-assembled monolayer of a heterocyclic thiol, mercaptotriazole (MTz), is used for the electroanalysis
of uric acid (UA) and ascorbic acid (AA). MTz forms a less compact self-assembly on Au electrode. The self-assembly of MTz
on Au electrode favors the oxidation of UA and AA at less positive potential. Significant decrease (∼400 mV) in the overpotential
and enhancement in the peak current for the oxidation of interfering AA with respect to the unmodified electrode is observed.
The negative shift in the oxidation peak potential of AA favors electrochemical sensing of UA without any interference. Two
well-separated voltammetric peaks for AA and UA are observed in their coexistence. The large separation between the two voltammetric
peaks allows the simultaneous or selective sensing of the analytes without compromising the sensitivity. Linear response is
obtained for a wide concentration range. This electrode could sense as low as 1 μM of UA in the presence of 10-fold excess
of interfering AA. No change in the sensitivity (0.012 μA/μM) of the electrode toward UA in the presence and absence of AA
is observed. Reproducible and stable amperometric flow injection response was obtained upon repetitive injection. 相似文献
64.
Adsorption of Ni(II) on clays 总被引:1,自引:0,他引:1
The present work investigates the adsorptive interactions of Ni(II) ions with kaolinite, montmorillonite, and their poly(oxo zirconium) and tetrabutylammonium derivatives in aqueous medium. Batch adsorption studies were carried out with various Ni(II) concentrations, amount of clay adsorbents, pH, agitation time and temperature. The adsorption is strongly dependent on pH of the medium with enhanced adsorption as the pH turns from acidic to alkaline side till precipitation sets in. The process was very fast initially and maximum adsorption was observed within 180 min of agitation. The kinetics of the interactions, tested with pseudo first order Lagergren equation, second order kinetics, Elovich equation, liquid film diffusion model and intra-particle diffusion mechanism, showed better agreement with second order kinetics (k2 = 1.3 x 10(-2) to 5.3 x 10(-2) g/(mg min)). The adsorption data gave good fits with Langmuir and Freundlich isotherms and yielded Langmuir monolayer capacity of 2.75 to 21.14 mg/g and Freundlich adsorption capacity of 0.70 to 3.40 mg(1-1/n) l(1/n)/g for the clay adsorbents. The adsorption process was exothermic with Delta H in the range of -24.0 to -45.1 kJ/mol accompanied by decrease in entropy (DeltaS: -118.2 to -160.5 J/(mol K)) and Gibbs energy (Delta G: -34.6 to -49.5 kJ/mol). The results have shown that montmorillonite has the largest adsorption capacity followed by ZrO-montmorillonite, TBA-montmorillonite, kaolinite, ZrO-kaolinite and TBA-kaolinite. Introduction of ZrO- and TBA- groups into the clays reduced their adsorption capacity by blocking the available adsorption sites. 相似文献
65.
Dr. Kartik Chandra Mondal Dr. Sudipta Roy Dr. Susmita De Dr. Pattiyil Parameswaran Dr. Birger Dittrich Dr. Fabian Ehret Prof. Dr. Wolfgang Kaim Prof. Dr. Herbert W. Roesky 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(37):11646-11649
Compound (Me2‐cAAC:)2Co0 ( 2 ; Me2‐cAAC:=cyclic (alkyl) amino carbene; :C(CH2)(CMe2)2N‐2,6‐iPr2C6H3) was synthesized by the reduction of the precursor (Me2‐cAAC:)2CoICl ( 1 ) with KC8 in THF. The cyclic voltammogram of 1 exhibited one‐electron reduction, which suggests that synthesis of a bent 2‐metallaallene ( 2 ) from 1 should be possible. Compound 2 contains one cobalt atom in the formal oxidation state zero, which is stabilized by two Me2‐cAAC: ligands. Bond lengths from X‐ray diffraction are 1.871(2) and 1.877(2) Å with a C‐Co‐C bond angle of 170.12(8)°. The EPR spectrum of 2 exhibited a broad resonance attributed to the unique quasi‐linear structure, which favors near degeneracy and gives rise to very rapid relaxation conditions. The cAAC?Co bond in 2 can be considered as a typical Dewar–Chatt–Duncanson type of bonding, which in turn retains 2.5 electron pairs on the Co atom as nonbonding electrons. 相似文献
66.
A highly stereoselective synthesis of 1,6-dichloro-1,3,5-hexatriene derivatives by McMurry coupling of β-chloroacrylaldehydes have been developed. 相似文献
67.
Das S Sylvain MR Fernand VE Losso JN El-Zahab B Warner IM 《Journal of colloid and interface science》2011,363(2):585-594
The interactions of the negatively charged achiral molecular micelle, poly (sodium N-undecanoyl sulfate) (poly-SUS), with four different proteins using intrinsic and extrinsic fluorescence spectroscopic probes, are studied. A comparison of poly-SUS with the conventional surfactant, sodium dodecyl sulfate (SDS), and the monomeric species, SUS, is also reported. In this work, we observed that poly-SUS preferentially binds to acidic proteins, exhibiting positive cooperativity at concentrations less than 1 mM for all proteins studied. Moreover, it appears that the hydrophobic microdomain formed through polymerization of the terminal vinyl group of the monomer, SUS, is largely responsible for the superior binding capacity of poly-SUS. From these results, we conclude that the interactions of poly-SUS with the acidic proteins are predominantly hydrophobic and postulate that poly-SUS would produce superior interactions relative to SDS at low concentrations in polyacrylamide gel electrophoresis (PAGE). As predicted, use of poly-SUS allowed separation of the His-tagged tumor suppressor protein, p53, at sample buffer concentrations as low as 0.08% w/v (2.9 mM), which is 24 times lower than required for SDS in the standard reducing PAGE protocol. This work highlights the use of poly-SUS as an effective surfactant in 1D biochemical analysis. 相似文献
68.
A. Bansil Susmita Basak Hsin Lin J. Nieminen Ilpo Suominen 《Journal of Physics and Chemistry of Solids》2011,72(5):341-346
We discuss a comprehensive scheme for modeling various highly resolved spectroscopies of the cuprates where effects of matrix element, crystal structure, strong electron correlations, and superconductivity are included realistically in material-specific detail. A number of illustrative examples drawn from our recent work are presented. Specific issues in the cuprate physics considered are: (i) Origin of high-energy kink or the waterfall effect; (ii) Dichroic effects in angle-resolved photoemission spectrum; (iii) Asymmetry of the scanning tunneling spectrum between the processes of electron extraction and injection; (iv) Persistence of ‘Mott’ like high-energy features with doping in optical spectra; (v) Magnetic excitations in electron and hole doped cuprates. 相似文献
69.
Let be the set of rooted trees containing an infinite binary subtree starting at the root. This set satisfies the metaproperty that a tree belongs to it if and only if its root has children u and v such that the subtrees rooted at u and v belong to it. Let p be the probability that a Galton‐Watson tree falls in . The metaproperty makes p satisfy a fixed‐point equation, which can have multiple solutions. One of these solutions is p, but what is the meaning of the others? In particular, are they probabilities of the Galton‐Watson tree falling into other sets satisfying the same metaproperty? We create a framework for posing questions of this sort, and we classify solutions to fixed‐point equations according to whether they admit probabilistic interpretations. Our proofs use spine decompositions of Galton‐Watson trees and the analysis of Boolean functions. 相似文献
70.
Susmita Pradhan Mahuya Bhattacharyya Banerjee Dr. Sudip Biswas Dr. Nor Aliya Hamizi Prof. Dipak K. Das Prof. Radhaballabh Bhar Prof. Rajib Bandyopadhyay Prof. Panchanan Pramanik 《Electroanalysis》2021,33(2):383-392
Herein we developed a simple, cost effective, electrochemical sensor based on nanosized copper telluride (nps-CuTe) for simultaneous detection of epinephrine (EP) and uric acid (UA). Voltammetric responses suggests dramatical improvement of electrocatalytic properties of both molecules by incorporating CuTe nps into unmodified graphite paste electrode (bare GP). Differential pulse voltammetric (DPV) measurement depicts large potential separation of 128 mV between EP and UA, allows their simultaneous determination from binary mixture. Under optimized condition, CuTe modified graphite paste electrode (CuTe/GP) manifested linear relationships of EP and UA in the range of 5–60 μM and 5–120 μM with detection limit (S/N=3) of 18 nM and 32 nM respectively. Moreover, CuTe/GP showed satisfactory response towards pharmaceutical and clinical samples for determining EP and UA concentrations. 相似文献