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61.
This paper presents a simple yet efficient heuristic for rectilinear Steiner routing. The basic heuristic introduces a new edge into the existing tree for another, costlier edge such that the resulting graph remains a tree. The simplicity of the heuristic led to an O(n2) implementation using basic data structures. Asymptotic time requirement of the heuristic can be further improved to O(n log n) using sophisticated data structures. Due to the generality of the heuristic different cost criteria can be applied to produce routes with different properties. The heuristic has been successfully applied to the problem of minimum-length Steiner routing and minimizing critical-sink Elmore delay. 相似文献
62.
Fabrication of Ruthenium Nanoparticles in Porous Organic Polymers: Towards Advanced Heterogeneous Catalytic Nanoreactors 下载免费PDF全文
Dr. John Mondal Sudipta K. Kundu Dr. Wilson Kwok Hung Ng Ramana Singuru Dr. Parijat Borah Prof. Dr. Hajime Hirao Prof. Dr. Yanli Zhao Prof. Dr. Asim Bhaumik 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(52):19016-19027
A novel strategy has been adopted for the construction of a copolymer of benzene–benzylamine‐1 (BBA‐1), which is a porous organic polymer (POP) with a high BET surface area, through Friedel–Crafts alkylation of benzylamine and benzene by using formaldehyde dimethyl acetal as a cross‐linker and anhydrous FeCl3 as a promoter. Ruthenium nanoparticles (Ru NPs) were successfully distributed in the interior cavities of polymers through NaBH4, ethylene glycol, and hydrothermal reduction routes, which delivered Ru‐A, Ru‐B, and Ru‐C materials, respectively, and avoided aggregation of metal NPs. Homogeneous dispersion, the nanoconfinement effect of the polymer, and the oxidation state of Ru NPs were verified by employing TEM, energy‐dispersive X‐ray spectroscopy mapping, cross polarization magic‐angle spinning 13C NMR spectroscopy, and X‐ray photoelectron spectroscopy analytical tools. These three new Ru‐based POP materials exhibited excellent catalytic performance in the hydrogenation of nitroarenes at RT (with a reaction time of only ≈30 min), with high conversion, selectivity, stability, and recyclability for several catalytic cycles, compared with other traditional materials, such as Ru@C, Ru@SiO2, and Ru@TiO2, but no clear agglomeration or loss of catalytic activity was observed. The high catalytic performance of the ruthenium‐based POP materials is due to the synergetic effect of nanoconfinement and electron donation offered by the 3D POP network. DFT calculations showed that hydrogenation of nitrobenzene over the Ru (0001) catalyst surface through a direct reaction pathway is more favorable than that through an indirect reaction pathway. 相似文献
63.
A simple and inexpensive method for the reductive cleavage of N–O bond of benzofuroxans with bakers' yeast under nonfermenting condition in aqueous media was achieved. The procedure gives excellent yields of aryl-1,2-diamines. 相似文献
64.
In this study, we report the synthesis of several novel dihydroisoxazole-, tetrahydroisoxazole- and dihydropyrazole-fused pyrido[2,3-b]quinolines, α-carbolines, and pyrido[2,3-c]coumarins, respectively, from simple precursors and by exploring intramolecular 1,3-dipolar cycloaddition reactions involving nitrile oxides, nitrones, and nitrile imines as 1,3-dipoles. 相似文献
65.
Joseph Cacaccio Farukh Durrani Ravindra R. Cheruku Ballav Borah Manivannan Ethirajan Walter Tabaczynski Paula Pera Joseph R. Missert Ravindra K. Pandey 《Photochemistry and photobiology》2020,96(3):625-635
To determine the impact of delivery vehicles in photosensitizing efficacy of HPPH, a hydrophobic photosensitizer was dissolved in various formulations: 1% Tween 80/5% dextrose, Pluronic P-123 and Pluronic F-127 in 0.5%, 1% and 2% phosphate buffer solutions (PBS). HPPH was also conjugated to Pluronic F-127, and the resulting conjugate (PL-20) was formulated in PBS. Among the different delivery vehicles, only Pluronic P-123 displayed significant vehicle cytotoxicity, whereas Pluronic F127 was nontoxic. Compared to PL-20, HPPH formulated in Tween80 and Pluronic F-127 showed higher cell-uptake, but lower long-term retention in Colon26 cell compared to PL-20. The higher retention of PL-20 was similarly observed during in vivo uptake with BALB/c mice baring Ct26 tumors. In contrast to the in vitro uptake experiments, PL-20 showed slightly higher uptake compared to HPPH formulated in Tween or Pluronic-F127. A significant difference in pharmacokinetic profile was also observed between the HPPH-Pluronic formulation and PL-20. Under similar in vivo treatment parameters (drug dose 0.47 µmol kg−1, light dose: 135 J cm−2 at 24 h post-injection of PS), HPPH formulated either in Tween or Pluronic F-127 formulation showed similar in vivo PDT efficacy (20–30% tumor cure on day 60), whereas PL-20 showed 40% tumor cure (day 60). 相似文献
66.
We explore a novel possibility for lowering the solar mixing angle (θ
12) from tri-bimaximal mixings, without sacrificing the predictions of maximal atmospheric mixing angle (θ
23 = 45°) and zero reactor angle (θ
13 = 0°) in the inverted and normal hierarchical neutrino mass models having 2–3 symmetry. This can be done through the identification
of a flavour twister term in the texture of neutrino mass matrix and the variation of such term leads to lowering of solar
mixing angle. For the observed ranges of Δm
212 and Δm
232, we calculate the predictions on tan2
θ
12 = 0.5, 0.45, 0.35 for different input values of the parameters in the neutrino mass matrix. We also observe a possible transition
from inverted hierarchical model having even CP parity (Type-IHA) to inverted hierarchical model having odd CP parity (Type-IHB)
in the first two mass eigenvalues, when there is a change in input values of parameters in the same mass matrix. The present
work differs from the conventional approaches for the deviations from tri-bimaximal mixing, where the 2–3 symmetry is broken,
leading to θ
23 ≠ 45° and θ
13 ≠ 0°.
相似文献
67.
Adsorption kinetics, adsorption isotherms and surface complexation of trimesic acid onto alpha-alumina surfaces were investigated. Adsorption kinetics of trimesic acid with an initial concentration of 0.5 mM onto alpha-alumina surfaces were carried out in batch method in presence of 0.05 mM NaCl (aq) at pH 6 and 298.15, 303.15 and 313.15 K. Adsorption isotherms were carried out at 298.15 K, pH 5-9, and 0.05 mM NaCl (aq) by varying trimesic acid concentration from 0.01 to 0.6 mM. Three kinetics equations such as pseudo-first-order, pseudo-second-order and Ho equations were used to estimate the kinetics parameters of the adsorption of trimesic acid on the alpha-alumina surfaces. Ho equation fits the experimental kinetics data significantly better and the estimated equilibrium concentration is in excellent agreement with the experimental value. The adsorption data were fitted to Freundlich and Langmuir adsorption model and the later best fits the adsorption isotherms. Comparison of adsorption density of trimesic acid with that of benzoic and phthalic acids follows the sequence: benzoic acid < trimesic acid < phthalic acid. The negative activation energy and the Gibbs free energy for adsorption indicate that the adsorption of trimesic acid onto alpha-alumina is spontaneous and facile. DRIFT spectroscopic studies reveal that trimesate forms outer-sphere complexes with the surface hydroxyl groups that are generated onto alpha-alumina surfaces in the pH range of the study. 相似文献
68.
A simple and efficient catalytic system based on Pd complex of tetradentate Schiff base ligands is found to be highly active (up to 99% isolated yield) for Suzuki–Miyaura reaction of aryl bromides with arylboronic acids in water at room temperature. Further the scope of this protocol has been extended to the Suzuki–Miyaura cross-coupling reaction of aryl chlorides with arylbronic acids in isopropanol. 相似文献
69.
70.
The thermal stability of linear low density polyethylene (LLDPE)/ethylene methyl acrylate (EMA) blends was studied using thermogravimetry.
The blend ratio as well as the presence of compatibilizer has significant effect on thermal stability of the blends. The compatibilization
of the blends using LLDPE-g-MA has increased the degradation temperature. Phase morphology was found to be one of the most
decisive factors that affected the thermal stability of both uncompatibilized and compatibilized blends. Dynamic mechanical
behavior of the blend was studied by dynamic mechanical analysis. The storage modulus of the blends decreased with increase
in EMA content. When compatibilized with LLDPE-g-MA the storage modulus of the blend increases. LLDPE-g-MA is an effective
compatibilizer as it increases the thermal stability and modulus of the blend. 相似文献