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91.
Two-phase CFD calculations, using a Lagrangian model and commercial code Fluent 6.2.16, were employed to calculate the gas
and droplet flows and film cooling effectiveness with and without mist on a flat plate. Two different three dimensional geometries
are generated and the effects of the geometrical shape, size of droplets, mist concentration in the coolant flow and temperature
of mainstream flow for different blowing ratios are studied. A cylindrical and laterally diffused hole with a streamwise angle
of 30° and spanwise angle of 0° are used. The diameter of film cooling (d) hole, and the hole length to diameter ratio (L/d) for both of geometries are 10 mm and 4, respectively. Also the blowing ratio ranges from 1.0 to 2.0, and the mainstream
Reynolds number based on the mainstream velocity and hole diameter (Re
d) is 6,219. The results are shown for different droplets diameters (1–10 μm), concentrations (1–5%) and mainstream temperatures
(350–500 K). The centreline effectiveness and distribution of effectiveness on the surface of cooling wall are presented. 相似文献
92.
93.
Summary Statistical procedures to test that a life distribution is exponential against the alternative that it is harmonic new better
than used in expectation (HNBUE) are considered. 相似文献
94.
Hadi Ghohari Hassan Ali Zamani Fatemeh Joz-Yarmohammadi Mahmoud Ebrahimi Mohammad Reza Abedi 《Russian Journal of Electrochemistry》2018,54(10):747-754
In the present work, a novel sensitive electrochemical potentiometric sensor for sensing Fe3+ ions based on 1,4-diaminoanthraquinone (DAQ) as a hydrophobic selector element was prepared to implement as an ion selective carbon paste electrode in the aqueous solutions. The adequate amounts of ionophore (5%), paraffin oil (25%) as a binder, Nanosilica (NS: 0.5%) multi-wall carbon nanotubes (MWCNTs: 1%) as a modifier, and graphite powder (68.5%) as an inert matrix was occupied to form the paste. This new FeCP sensor demonstrated a Nernstian slope of 19.7 ± 0.7 mV per decade over widish linear range between 1.0 × 10–8 to 1.0 × 10–2 mol L–1 at working pH range of 1.9–5.0 in the optimized conditions. The average elapsed time to response of electrode was about ~6 s for concentrations from lower (1.0 × 10?8 mol L–1) to higher (1.0 × 10?2 mol L–1) of Fe3+ ion solution. The selectivity of electrode toward Fe3+ ions in comparison with other cations was studied by matched potential method. The making FeCP sensor has been put to use successfully as an indicator electrode in analytical applications such as the potentiometric titration and determination of iron(III) ion in blend of different ions. 相似文献
95.
Vitamin C is known as an essential dietary supplement and implicated in diverse biological processes. We present here a theoretical study on the nature of hydrogen bonding of vitamin C in biological systems. For this reason, the complexes of vitamin C (VC) with neutral and zwitterionic L-alanine (as the simplest chiral amino acid) were studied at the MP2/6-311++G(d,p) level of theory. In the gas phase, neutral L-alanine leads to more stable complexes than the zwitterionic forms while the reverse is true in the aqueous phase. The complexes are formed via two hydrogen bond interactions, which result in a ring-like hydrogen-bonded networks. The nature of H-bonds was characterized in terms of natural bond orbital and quantum theory of atoms in molecule analyses (QTAIM). The H-bonds in the studied complexes were electrostatic in nature; however, in the case of shorter and directional H-bonds and ionic interactions, contributions of covalent character were also non-negligible. Natural energy decomposition analysis of hydrogen-bonded complexes reveals that the charge transfer and electrical components are the largest contributors for the interaction energies of complexes. Natural resonance theory analysis suggests higher resonance weight for charge-assisted interactions of vitamin C---alanine (zwitterionic) complexes, where the total interaction energy is considerably higher than that of neutral alanine. 相似文献
96.
Ehsan Karimi Meisam Habibi Mahdi Ebrahimi Ali Mehrafarin Farahnaz Khalighi-Sigaroodi 《Natural product research》2018,32(16):1991-1995
The antioxidant activities of crude extract fractions using Hexane, Chloroform, Ethyl Acetate, Butanol and Water of Clematis orientalis and Clematis ispahanica were investigated. 1,1-diphenyl-2-picryl-hydrazyl (DPPH) assay and the ferric reducing/antioxidant potential (FRAP) were used to evaluate the antioxidant capacity. The total phenolics were found to be 4.37–9.38 and 1.32–11.37 mg gallic acid equivalents (GAE)/g in different fractions for C. orientalis and C. ispahanica, respectively. The ethyl acetate fraction of C. orientalis and chloroform fraction of C. ispahanica showed the highest DPPH and FRAP activities at a concentration of 300 μg/mL. The predominant phenolic compounds identified by HPLC in C. orientalis were Resorcinol (603.5 μg/g DW) in chloroform fraction and Ellagic acid (811.7 μg/g DW) in chloroform fraction of C. ispahanica. 相似文献
97.
Mir Ali?FarajzadehEmail author Mortaza?Ebrahimi Ali?Ranji Elham?Feyz Vali?Bejani Ramin?Maleki 《Mikrochimica acta》2005,150(2):173-177
This study describes the sample preparation and two chromatographic techniques for determination of Tinuvin 622 in polyethylene. The first part of the two methods consisting of dissolving the polyethylene in boiling xylene is followed by addition of a methanolic solution of potassium hydroxide. The polymeric light stabilizer, Tinuvin 622, is thereby saponified to 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol (diol). Addition of the methanolic solution of the saponification reagent simultaneously precipitates the polyethylene matrix. Then the diol is quantified using either gas chromatography (GC) or high performance liquid chromatography (HPLC). For GC, a Macherey Nagel Optima-17 capillary column (30m×0.25mm ID, film thickness 0.25µm) is used. Nitrogen is used as carrier gas and make-up gas. The detection system is a flame ionization detector. For HPLC, an octadecyl silane (ODS) column (30cm×4mm, particle size 5µm) and a mobile phase methanol: water mixture (3:97, v/v) are used. Detection of analyte is carried out at 215nm. Both methods can be used to determine Tinuvin 622 in polyethylene in the concentration range of 0.02–1%, which represents the usual application concentration. 相似文献
98.
J. Hadian A. Sonboli S. Nejad Ebrahimi M. H. Mirjalili 《Chemistry of Natural Compounds》2006,42(2):175-177
The essential oil of Nepeta satureioides Boiss. from Iran was isolated by hydrodistillation in yield of 0.06% (w/w). The chemical composition of the essential oil
was analyzed by GC and GC-MS. Forty-five compounds accounting for 97.4% of the total oil were identified. The major components
were linalool (23.8%), (Z,E)-farnesol (14.7%), linalyl acetate (11.1%), β-caryophyllene (6.6%), lavandulol acetate (6.6%), caryophyllene oxide (6.4%), and (Z)-β-farnesene (3.4%). Oxygenated terpenoids were the main group of compounds.
Published in Khimiya Prirodnykh Soedinenii, No. 2, pp. 144–145, March–April, 2006. 相似文献
99.
P. Hashemi M. M. Abolghasemi A. R. Fakhari S. N. Ebrahimi S. Ahmadi 《Chromatographia》2007,66(3-4):283-286
A new, simple hydrodistillation–solvent microextraction (HD–SME) technique has been used for analysis of the volatile components
of the aerial parts of Artemisia aucheri. The components were collected in a single microdrop, and this was injected directly for gas chromatographic–mass spectrometric
(GC–MS) analysis. The effects on extraction efficiency of extraction solvent, sample mass, microdrop volume, and extraction
time were optimized by use of a simplex method. The identities of the components of HD–SME extracts were confirmed according
to their retention indexes and mass spectra with those of standards. Forty components were extracted and identified by use
of the method; 1,8-cineol (22.8%), chrysanthenone (18.16%), α-pinene (8.33%), and mesitylene (7.41%) were the major constituents.
The results obtained from the microextraction method were compared with those obtained by conventional hydrodistillation. 相似文献
100.