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71.
72.
Noah D. Weiss Nicholas J. Nagle Melvin P. Tucker Richard T. Elander 《Applied biochemistry and biotechnology》2009,155(1-3):115-125
Pretreatment experiments were carried out to demonstrate high xylose yields at high solids loadings in two different batch pretreatment reactors under process-relevant conditions. Corn stover was pretreated with dilute sulfuric acid using a 4-l Steam Digester and a 4-l stirred ZipperClave® reactor. Solids were loaded at 45% dry matter (wt/wt) after sulfuric acid catalyst impregnation using nominal particle sizes of either 6 or 18 mm. Pretreatment was carried out at temperatures between 180 and 200 °C at residence times of either 90 or 105 s. Results demonstrate an ability to achieve high xylose yields (>80%) over a range of pretreatment conditions, with performance showing little dependence on particle size or pretreatment reactor type. The high xylose yields are attributed to effective catalyst impregnation and rapid rates of heat transfer during pretreatment. 相似文献
73.
J.F. Nagle S. Tristram-Nagle H. Takahashi I. Hatta 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,1(4):399-400
This comment shows that data recently reported [#!ref1!#] as being seemingly in conflict with earlier data [#!ref2!#] are,
in fact, in excellent agreement. Together, both studies confirm that the kinetics of the subgel phase transformation in dipalmitoylphosphatidylcholine
(DPPC) lipid bilayers obeys Kolmogorov-Avrami (K-A) theory [#!ref3!#,#!ref4!#] with an anomalously low effective dimensionality.
Received: 11 December 1997 / Accepted: 28 January 1998 相似文献
74.
Roberts MN Nagle JK Majewski MB Finden JG Branda NR Wolf MO 《Inorganic chemistry》2011,50(11):4956-4966
The photophysical behavior for two photochromic Pt-terpyridine acetylide complexes containing pendant dithienylethenes (DTEs) bound to the metal through the alkynyl linkage is presented. Selective excitation of the Pt complex with visible light resulted in the metal-sensitized ring closing of the DTE unit. The central purpose of this study was to understand how excited state interactions govern the photophysics by correlating differences in the linkage of the two components with differences in the intramolecular energy transfer processes that occur between the Pt complex and the DTE. A series of model complexes without photochromic ligands were prepared and studied to elucidate the contributions of the triplet metal-to-ligand charge transfer and triplet intraligand states. It is demonstrated that reducing the orbital overlap of the metal-based and intraligand states by lengthening the linkage and eliminating a conjugated pathway is effective at dramatically decreasing the efficiency of intramolecular energy transfer. This is evidenced by the appearance of Pt-terpyridine based phosphorescence and a significant decrease in the observed rate of metal-sensitized ring closing of the DTE. 相似文献
75.
Scully NM Ashu-Arrah BA Nagle AP Omamogho JO O'Sullivan GP Friebolin V Dietrich B Albert K Glennon JD 《Journal of chromatography. A》2011,1218(15):1974-1982
Investigations into the preparation of silica hydride intermediate in supercritical carbon dioxide (sc-CO(2)) that avoids the use of organic solvents such as toluene or dioxane are described. The effects of reaction temperature, pressure and time on the surface coverage of the supercritical fluid generated silica hydride intermediate were studied. Under optimised supercritical conditions of 120°C, 483 bar and 3 h reaction time, silica hydride (Si-H) conversion efficiencies of ca. 40% were achieved for the hydride intermediate prepared from a monofunctional silane reagent (dimethylmethoxysilane). Si-H conversion efficiencies (as determined from (29)Si CP-MAS NMR spectral analysis) for the hydride intermediate prepared from triethoxysilane (TES) in sc-CO(2) were found to be comparable to those obtained using a TES silanisation approach in an organic solvent. (13)C and (29)Si CP-MAS-NMR spectroscopy was employed to provide a complete structural assignment of the silica hydride intermediates. Furthermore, supercritical CO(2) was subsequently employed as a reaction medium for the heterogenous hydrosilation of silica hydride with octadecene and with styrene, in the presence of a free radical initiator. These supercritical fluid generated reversed-phase materials were prepared in a substantially reduced reaction time (3 h) compared to organic solvent based methods (100 h reaction time). Silica functionalisation in sc-CO(2) presents an efficient and clean alternative to organic solvent based methods for the preparation of important silica hydride intermediate and silica bonded stationary phases via a hydrosilation approach. 相似文献
76.
Cholesterol is well known to modulate the physical properties of biomembranes. Using modern x-ray scattering methods, we have studied the effects of cholesterol on the bending modulus K(C), the thickness D(HH), and the orientational order parameter S(xray) of lipid bilayers. We find that the effects are different for at least three classes of phospholipids characterized by different numbers of saturated hydrocarbon chains. Most strikingly, cholesterol strongly increases K(C) when both chains of the phospholipid are fully saturated but not at all when there are two monounsaturated chains. 相似文献
77.
A process economic approach to develop a dilute-acid cellulose hydrolysis process to produce ethanol from biomass 总被引:10,自引:0,他引:10
Successful deployment of a bioethanol process depends on the integration of technologies that can be economically commercialized.
Pretreatment and fermentation operations of the traditional enzymatic bioethanol-production process constitute the largest
portion of the capital and operating costs. Cost reduction in these areas, through improved reactions and reduced capital,
will improve the economic feasibility of a large-scale plant.
A technoeconomic model was developed using the ASPEN PlusTN modeling software package. This model in cluded a two-stage pretreatment operation with a co-current first stage and countercurrent
second stage, a lignin adsorption unit, and a cofermentation unit. Data from kinetic modeling of the pretreatment reactions,
verified by bench-scale experiments, were used to create the ASPEN Plus base model. Results from the initial pretreatment
and fermentation yields of the two-stage system correlated well to the performance targets established by the model. The ASPEN
Plus model determined mass and energy-balance information, which was supplied, to an economic module to determine the required
selling price of the ethanol. Several pretreatment process variables such as glucose yield, liquid: solid ratio, additional
pretreatment stages, and lignin adsorption were varied to determine which parameters had the greatest effect on the process
economics. Optimized values for these key variables became target values for the bench-scale research, either to achieve oridentify
as potential obstacles in the future commercialization process. Results from this modeling and experimentation sequence have
led to the design of an advanced two-stage engineering-scale reactor for a dilute-acid hydrolysis process. 相似文献
78.
Hon M. Chun Carlos E. Padilla Donovan N. Chin Masakatsu Watanabe Valeri I. Karlov Howard E. Alper Keto Soosaar Kim B. Blair Oren M. Becker Leo S. D. Caves Robert Nagle David N. Haney Barry L. Farmer 《Journal of computational chemistry》2000,21(3):159-184
A modeling approach that can significantly speed up the dynamics simulation of large molecular systems is presented herein. A multigranular modeling approach, whereby different parts of the molecule are modeled at different levels of detail, is enabled by substructuring. Substructuring the molecular system is accomplished by collecting groups of atoms into rigid or flexible bodies. Body flexibility is modeled by a truncated set of body‐based modes. This approach allows for the elimination of the high‐frequency harmonic motion while capturing the low‐frequency anharmonic motion of interest. This results in the use of larger integration step sizes, substantially reducing the computational time required for a given dynamic simulation. The method also includes the use of a multiple time scale (MTS) integration scheme. Speed increases of 5‐ to 30‐fold over atomistic simulations have been realized in various applications of the method. © 2000 John Wiley & Sons, Inc. J Comput Chem 21: 159–184, 2000 相似文献
79.
80.
Li XC Ferreira D Jacob MR Zhang Q Khan SI ElSohly HN Nagle DG Smillie TJ Khan IA Walker LA Clark AM 《Journal of the American Chemical Society》2004,126(22):6872-6873
Coruscanones A and B, two new antifungal cyclopentenedione derivatives, have been isolated from Piper coruscans and their structures elucidated by spectroscopic and chemical methods. Coruscanone A exhibits significant antifungal activity against Candida albicans and its azole-resistant strains and may serve as a template for a new class of antifungal agents. 相似文献