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71.
72.
《Surface and interface analysis : SIA》2018,50(3):304-310
In this paper, the effect of coupling agent surface treatment of wood fiber on tensile and tribological property of wood fiber‐reinforced thermoplastic polyimide (PI) composites was experimentally investigated. Experimental results revealed that coupling agent surface treatment could effectively improve the interfacial adhesion between wood fiber and PI matrix. Compared with the untreated wood fiber/PI composite, the coupling agent‐treated composite had better interfacial adhesion. The fracture surfaces and worn surface of samples were investigated by scanning electronic microscopy to analyze the effects of surface treatment methods. 相似文献
73.
S. Borysiak 《Journal of Thermal Analysis and Calorimetry》2007,88(2):455-462
Composites
made from an isotactic polypropylene matrix and wood (pine or beech) have
been prepared and tested. To improve adhesion between components, the wood
modification was performed by esterification with maleic, propionic, crotonic,
succinic and phthalic anhydrides. The surface of wood fillers was also modified
by chemical treatment with NaOH as well as by extraction process. Non-isothermal
crystallisation of polypropylene in wood composites is studied by DSC, and
the basic parameters of crystallisation are determined. We discovered that
the composites containing chemical treated wood fillers showed the tendency
reduction the nucleation efficiency of polypropylene. The ability of wood
filler to induce nucleation in polypropylene matrix is dependent on the kind
of chemical modification of surface wood 相似文献
74.
The functional composition of oxidative ammonolysis products obtained from treatment of birch wood with ammoniacal ammonium persulfate using a mechanochemical method was studied. 相似文献
75.
《Comptes Rendus Chimie》2019,22(8):574-584
Microwave-assisted extraction (MAE) at atmospheric pressure has been demonstrated as an efficient technology for the extraction of polymeric hemicelluloses from spruce sawdust. This technology was shown to be more efficient than conventional extraction. MAE leads to a high solubilization of wood and a selective extraction of hemicellulose polymers with high molecular weights. To optimize MAE, different treatment powers (125–573 W) of presoaked spruce sawdust in water and 1 M sodium hydroxide solution for a period of 60 min were tested. The yield of hemicellulose extraction increased with the microwave power in both mediums, but with a clear advantage for presoaked samples in basic medium. The characterization of extracted hemicelluloses has shown high extraction selectivity depending on the medium of impregnation of sawdust before MAE: High-molecular-mass acetylated galactoglucomannans (Mw ∼ 41 kDa) were isolated after presoaking in water and higher molecular mass arabinoglucoronoxylans (Mw ∼ 66 kDa) in basic medium. 相似文献
76.
Lakshmi Sankaranarayanan Erin O. Semmens Curtis W. Noonan 《International journal of environmental analytical chemistry》2016,96(2):137-147
As part of a randomised controlled residential intervention study, levoglucosan (LG) was investigated as a biomarker for wood smoke exposure. This study was conducted among 33 children living in homes that used wood stoves for residential heating. Indoor fine particulate matter (PM2.5) concentrations and corresponding urine samples from participants were collected during pre- and a post-intervention winter sampling periods. Interventions included the installation of an air filtration unit and a wood stove change out. Homes and children assigned to a placebo filter served as the control condition. Results showed a strong reduction in indoor PM2.5 among the air filter homes (≈58% reduction), whereas the wood stove change out homes did not have a significant PM2.5 reduction from pre- to post-intervention observations. Children living in the air filter homes did not show a corresponding reduction in urinary LG concentrations. Further analysis did not show an association between overall changes in indoor PM2.5 concentrations and changes in urinary LG concentrations. These findings suggest that urinary LG is not a reliable indicator of wood smoke exposure in residential wood heating settings. 相似文献
77.
78.
79.
Different capillary electrophoretic techniques were investigated and compared for the separation of low-molecular-mass phenolic
and neutral lignin degradation compounds. Simple capillary zone electrophoresis (CZE) was not suited for this problem. Switching
to micellar electrokinetic capillary chromatography (MEKC) by adding micelle-forming reagents to the carrier electrolyte enhanced
the separation performance considerably. Alternatively, microemulsion electrokinetic chromatography (MEEKC) was investigated.
This is a CE technique in which analytes interact with moving oil droplets present in a microemulsion buffer. Using the optimized
carrier electrolyte systems and a 60 cm×50 μm I.D. bubble cell capillary it was possible to analyse solutions of different
wood digestion procedures and to investigate differences in lignin degradation products during use of different kinds of wood
(eucalyptus, beech, scotch pine and acacia).
Received August 25, 1999. Revision April 13, 2000 相似文献
80.
Jaime Millán-Santiago Rafael Lucena Soledad Cárdenas 《Journal of separation science》2022,45(1):223-232
Lignocellulosic materials have arisen as a sustainable alternative in microextraction techniques during the last 10 years. As they are natural materials, their use fits into some of the principles of Green Analytical Chemistry. Their inherent porosity, narrow shape, and rigidity permit their use in ambient ionization mass spectrometry techniques. In particular, the combination of wooden-based materials and direct analysis gives birth to the so-called wooden-tip electrospray ionization mass spectrometry technique. This approach has been used for the direct analysis of complex samples, and as a streamlined tool for fingerprint quality analysis. Also, wooden-based materials can be superficially modified to boost the interaction with target compounds, allowing their isolation from complex samples. This review describes the potential and applicability of direct analysis using lignocellulosic materials, as well as other alternatives related to their use in microextraction. 相似文献