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91.
Samad Khakshournia 《General Relativity and Gravitation》2008,40(8):1791-1796
Within our thick brane approach previously used to obtain the cosmological evolution equations on a thick brane embedded in
a five-dimensional Schwarzschild Anti-de Sitter spacetime it is explicitly shown that the consistency of these equations with
the energy conservation equation requires that, in general, the thickness of the brane evolves in time. This varying brane
thickness entails the possibility that both Newton’s gravitational constant G and the effective cosmological constant Λ4 are time dependent. 相似文献
92.
The magnetic moments ofb-quark baryons within the framework of five quark models are derived. Also the transition magnetic moments of variousb-quark baryons are calculated. 相似文献
93.
Nadri Samad Habib Kazemi Sayed Nazari Leila 《Journal of Solid State Electrochemistry》2022,26(6):1389-1397
Journal of Solid State Electrochemistry - For TNF detection, a novel electrochemical biosensor based on the PCL-PPY-MWCNT electrospun nanofiber was developed in this study. TNF is a potent... 相似文献
94.
Muhammad Bachal Korai Ghulam Abbas Shar Gul Afshan Soomro Muhammad Aslam Korai Maqsood Ahmed Mirbahar Abdul Samad Nisar Abbas Shar 《印度化学会志》2022,99(4):100360
A simple and rapid spectrophotometric technique has been designed for the trace copper analysis employing 1-(2-Thiazolylazo)-2-naphthol (TAN) reagent in aqueous micellar solution of cetyl trimethylammonium bromide (CTAB) as a surfactant. Copper complexed with 1-(2-Thiazolylazo)-2-naphthol to form bis[1-(2-Thiazolylazo)-2-naphthol]copper. The present spectrophotometric technique was very important since the micellar system was used in place of the toxic, high cost and time-consuming solvent extraction steps. The technique showed an enhanced detection efficiency, specificity, and molar absorptivity. It was found that the molar absorption coefficient and sensitivity of Sandel were ε 2.45 × 104 L mol?1cm?1 and 2.6 ngcm?2 at λmax 578.4 nm. A linear calibration plot in the range 0.12–5.0 μg mL?1 was obtained; a stoichiometric metal ligand ratio [M:L] of 1:2 was found for the formation of Cu-[TAN]2. The complex was formed at pH 9.5 and was stable up to 24 h. The proposed technique has been employed to study copper from different alloys, biological, environmental and pharmaceutical samples. 相似文献
95.
Enhancement of tribological performance of epoxy bulk composites and composite coatings using micro/nano fillers: a review
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Epoxies in the form of bulk and coatings have been used throughout the years for a wide spectrum of applications in various industries ranging from aerospace, oil and gas, petrochemical and marine to several others. Their use in tribological applications, those involving a range of contact conditions and where the requirement is exceptionally low wear and friction coefficient, is often limited by the properties of the pristine epoxy matrix such as low load bearing capacity combined with low thermal conductivity values. These properties have been improved by the addition of nano‐fillers, and numerous studies have been carried out in this regard. This paper presents a detailed review of the works carried out in the recent years where addition of nano‐fillers to formulate epoxy‐based composites and coatings has shown a substantial improvement in wear and friction properties thereby enhancing their potential to be used in demanding tribological applications such as solid lubricant in bearings, as wear‐resistant protective coatings in rotating and stationary equipment and for applications in the construction industry such as floorings and airport runway repairs. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
96.
O. El Samad C. Ardisson M. Hussonnois G. Ardisson 《Journal of Radioanalytical and Nuclear Chemistry》1992,164(3):171-182
233U -decay was reinvestigated using a radiochemically purified source and high efficiency HPGe coaxial detectors; the lowenergy -spectrum was also measured using a LEPS detector. The energy and intensity values of one hundred sixty three -lines were determined, from which forty eight are newly reported with respect to the last study of Canty et al. A revised229Th level scheme was built, using the Ritz combination principle, in which nine levels are newly observed, at 371.3, 381.8, 465.5, 569.2, 584.9, 605.1, 620.8, 656.9 and 749.9 keV. 相似文献
97.
Staggered arrays of dimples printed on opposite surfaces of a cooling channel is formulated numerically and optimized with
hybrid multi-objective evolutionary algorithm and Pareto optimal front. As Pareto optimal front produces a set of optimal
solutions, the trends of objective functions with design variables are predicted by hybrid multi-objective evolutionary algorithm.
The problem is defined by three non-dimensional geometric design variables composed of dimpled channel height, dimple print
diameter, dimple spacing, and dimple depth, to maximize heat transfer rate compromising with pressure drop. Twenty designs
generated by Latin hypercube sampling were evaluated by Reynolds-averaged Navier–Stokes solver and the evaluated objectives
were used to construct Pareto optimal front through hybrid multi-objective evolutionary algorithm. The optimum designs were
grouped by k-means clustering technique and some of the clustered points were evaluated by flow analysis. With increase in dimple depth,
heat transfer rate increases and at the same time pressure drop also increases, while opposite behavior is obtained for the
dimple spacing. The heat transfer performance is related to the vertical motion of the flow and the reattachment length in
the dimple. 相似文献
98.
Nasrin Nouruzi Mohammad Dinari Nazanin Mokhtari Behnam Gholipour Sadegh Rostamnia Samad Khaksar Rana Boluki 《应用有机金属化学》2020,34(8):e5677
A new porous triazine-based covalent organic polymer (Triazine-COP) was prepared through the Schiff-base condensation of 2,4,6-tris(4-formyl phenoxy)-1,3,5-triazine and 4,4′-oxydianiline, under sonication. The synthesized Triazine-COP with a high surface area was stable in water and other organic solvents. In the next step, Au (III) ions were immobilized on the nitrogen-rich Triazine-COP that on the reduction with NaBH4 produced the heterogeneous catalyst of gold clusters in nanosize (Au-NCs@Triazine-COPs). It was applied as an efficient catalyst for the A3 coupling reaction of alkynes, aldehydes with and amines. Both electron-withdrawing/releasing groups produced the corresponding propargylamines with high yields. The high activity of the Au-NCs@Triazine-COPs in this reaction was because of the nanoporous structure of the support that enables the high dispersion and an unhindered open environment for the NCs. The catalyst was reused up to 7 times without significant loss in activity. 相似文献
99.
Electrons and holes as charge carriers appear when a molecular system is exposed to external electric field. For nonsymmetric molecules, the distribution of charge carriers is also nonsymmetric. Although symmetric distribution of charge carriers is expected when the molecular system is symmetric, as the present work shows, they are not symmetric unexpectedly; that is, electrons and holes are not each other's mirror images. In this respect, asymmetric deformation density analysis is introduced to measure the extent of asymmetric distribution of electrons and holes as charge carriers when the symmetric system is exposed to symmetric external potential. Segments of (5,0) carbon nanotubes with different lengths are selected as symmetric systems, and a linear electric field is applied along the principal axis as symmetric potential. Results show that, at high electric fields, electrons tend to localize at the ends, while holes tend to occupy the middle area of carbon nanotube segments. While charge carriers play a vital role in molecular conductivity, asymmetric distribution of electrons and holes in symmetric systems has not yet been reported. 相似文献
100.
Mehdi Rahimi-Nasrabadi Mir Mahdi Zahedi Seied Mahdi Pourmortazavi Rouhollah Heydari Hossein Rai Jalal Jazayeri Abdollah Javidan 《Mikrochimica acta》2012,177(1-2):145-152
Dispersive liquid-liquid microextraction as a rapid, simple and efficient method coupled with high performance liquid chromatography-UV-Vis detection was used for sample preparation and subsequent determination of carbazole, tri nitro carbazole (TrNC) and tetra nitro carbazole in water samples. The influence of several important variables on the extraction efficiency has been evaluated. The methods works best with chloroform as an extractant and acetonitrile as the dispersive solvent. Under optimum conditions, the calibration curve is linear in the range from 0.007 to 1.75?μg?mL?1 for TNC, 0.006 to 1.52?μg?mL?1 for TrNC, and 0.008–2.10?μg?mL?1 for carbazole. The limits of detection (LODs; at a signal-to-noise ratio of 3), range from 1.7 to 1.1?ng?mL?1, for TNC, TrNC and carbazole. Also, the relative standard deviations (RSD, n?=?6) for the extraction of TNC (at 174?ng?mL?1), TrNC (at 151?ng?mL?1) and carbazole (at 84?ng?mL?1) vary between 4.1 and 5.2%. The enrichment factors range from 179 to 186. The method was successfully applied to the determination of TNC, TrNC and carbazole in environmental samples. Figure
Dispersive liquid-liquid microextraction is presented for the determination of carbazole based explosives (tri nitro carbazole (TrTNC) and tetra nitro carbazole (TNC)) using high performance liquid chromatography and UV–vis detection. 相似文献