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91.
92.
Lucimara Mendonça CostaEmerson Schwingel Ribeiro Mariana Gava SegatelliDanielle Raphael do Nascimento Fernanda Midori de OliveiraCésar Ricardo Teixeira Tarley 《Spectrochimica Acta Part B: Atomic Spectroscopy》2011,66(5):329-337
The present study describes the adsorption characteristic of Cd(II) onto Nb2O5/Al2O3 mixed oxide dispersed on silica matrix. The characterization of the adsorbent has been carried out by infrared spectroscopy (IR), scanning electronic microscopy (SEM), energy dispersive spectroscopy (EDS), energy dispersive X-ray fluorescence analysis (EDXRF) and specific surface area (SBET). From batch experiments, adsorption kinetic of Cd(II) was described by a pseudo-second-order kinetic model. The Langmuir linear isotherm fitted to the experimental adsorption isotherm very well, and the maximum adsorption capacity was found to be 17.88 mg g−1. Using the effective material, a method for Cd(II) preconcentration at trace level was developed. The method was based on on-line adsorption of Cd(II) onto SiO2/Al2O3/Nb2O5 at pH 8.64, in which the quantitative desorption occurs with 1.0 mol L−1 hydrochloric acid towards FAAS detector. The experimental parameters related to the system were studied by means of multivariate analysis, using 24 full factorial design and Doehlert matrix. The effect of SO42−, Cu2+, Zn2+ and Ni2+ foreign ions showed no interference at 1:100 analyte:interferent proportion. Under the most favorable experimental conditions, the preconcentration system provided a preconcentration factor of 18.4 times, consumption index of 1.08 mL, sample throughput of 14 h−1, concentration efficiency of 4.35 min−1, linear range from 5.0 up to 35.0 μg L−1 and limits of detection and quantification of 0.19 and 0.65 μg L−1 respectively. The feasibility of the proposed method for Cd(II) determination was assessed by analysis of water samples, cigarette sample and certified reference materials TORT-2 (Lobster hepatopancreas) and DOLT-4 (Dogfish liver). 相似文献
93.
Dietrich PM Horlacher T Girard-Lauriault PL Gross T Lippitz A Min H Wirth T Castelli R Seeberger PH Unger WE 《Langmuir : the ACS journal of surfaces and colloids》2011,27(8):4808-4815
Carbohydrate films on gold based on dimannoside thiols (DMT) were prepared, and a complementary surface chemical analysis was performed in detail by X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), near-edge X-ray absorption fine structure (NEXAFS), FT-IR, and contact angle measurements in order to verify formation of ω-carbohydrate-functionalized alkylthiol films. XPS (C 1s, O 1s, and S 2p) reveals information on carbohydrate specific alkoxy (C-O) and acetal moieties (O-C-O) as well as thiolate species attached to gold. Angle-resolved synchrotron XPS was used for chemical speciation at ultimate surface sensitivity. Angle-resolved XPS analysis suggests the presence of an excess top layer composed of unbound sulfur components combined with alkyl moieties. Further support for DMT attachment on Au is given by ToF-SIMS and FT-IR analysis. Carbon and oxygen K-edge NEXAFS spectra were interpreted by applying the building block model supported by comparison to data of 1-undecanethiol, poly(vinyl alcohol), and polyoxymethylene. No linear dichroism effect was observed in the angle-resolved C K-edge NEXAFS. 相似文献
94.
Riccardo?A.?Siliprandi Stefano?Zanini Elisa?Grimoldi Francesco?S.?Fumagalli Ruggero?BarniEmail author Claudia?Riccardi 《Plasma Chemistry and Plasma Processing》2011,31(2):353-372
An atmospheric pressure dielectric barrier plasma discharge has been used to study a thin film deposition process. The DBD
device is enclosed in a vacuum chamber and one of the electrodes is a rotating cylinder. Thus, this device is able to simulate
continuous processing in arbitrary deposition condition of pressure and atmosphere composition. A deposition process of thin
organosilicon films has been studied reproducing a nitrogen atmosphere with small admixtures of hexamethyldisiloxane (HMDSO)
vapours. The plasma discharge has been characterized with optical emission spectroscopy and voltage-current measurements.
Thin films chemical composition and morphology have been characterized with FTIR spectroscopy, atomic force microscopy (AFM)
and contact angle measurements. A strong dependency of deposit character from the HMDSO concentration has been found and then
compared with the same dependency of a typical low pressure plasma enhanced chemical vapour deposition process. 相似文献
95.
96.
Amorati R Attanasi OA Favi G Menichetti S Pedulli GF Viglianisi C 《Organic & biomolecular chemistry》2011,9(5):1352-1355
Hydrogenated cardanol and cardols, contained in industrial grade cardanol oil and obtained by distillation of the raw "cashew nut shell liquid" (CNSL), are easily transformed into efficient 4-thiaflavane antioxidants bearing a long alkyl chain on A ring and a catechol group on B ring. 相似文献
97.
In recent years fluorescence microscopy has become a widely used tool for tissue imaging and spectroscopy. Optical techniques,
based on both linear and non-linear excitation, have been broadly applied to imaging and characterization of biological tissues.
Among fluorescence techniques used in tissue imaging applications, in recent years two and three-photon excited fluorescence
have gained increased importance because of their high-resolution deep tissue imaging capability inside optically turbid samples.
The main limitation of steady-state fluorescence imaging techniques consists in providing only morphological information;
functional information is not detectable without technical improvements. A spectroscopic approach, based on lifetime measurement
of tissue fluorescence, can provide functional information about tissue conditions, including its environment, red-ox state,
and pH, and hence physiological characterization of the tissue under investigation. Measurement of the fluorescence lifetime
is a very important issue for characterizing a biological tissue. Deviation of this property from a control value can be taken
as an indicator of disorder and/or malignancy in diseased tissues. Even if much work on this topic has still to be done, including
the interpretation of fluorescence lifetime data, we believe that this methodology will gain increasing importance in the
field of biophotonics. In this paper, we review methodologies, potentials and results obtained by using fluorescence lifetime
imaging microscopy for the investigation of biological tissues. 相似文献
98.
César Ricardo Teixeira Tarley Felipe Nascimento Andrade Fernanda Midori de Oliveira Marcela Zanetti Corazza Luiz Fernando Mendes de Azevedo Mariana Gava Segatelli 《Analytica chimica acta》2011,(2):145
A novel ion imprinted polyvinylimidazole-silica hybrid copolymer (IIHC) was synthesized and used as a selective solid sorbent for Pb2+ ions preconcentration using an on-line solid phase extraction (SPE) system coupled to TS-FF-AAS. The ionic hybrid sorbent was prepared using 1-vinylimidazole and 3-(trimethoxysilyl)propylmethacrylate as monomers, Pb2+ ions as template, tetraethoxysilane as reticulating agent and 2,2′-azobis-isobutyronitrile as initiator. The best on-line SPE conditions concerning sorption behavior, including sample pH (6.46), buffer concentration (9.0 mmol L−1), eluent (HNO3) concentration (0.5 mol L−1) and preconcentration flow rate (4.0 mL min−1), were optimized by means of full factorial design and Doehlert matrix. The analytical curve ranged from 2.5 to 65.0 μg L−1 (r = 0.999) with limit of detection of 0.75 μg L−1; the precision (repeatability) calculated as relative standard deviation (n = 10) was 5.0 and 3.6% for Pb2+ concentration of 10.0 and 60.0 μg L−1, respectively. From on-line breakthrough curve, column capacity was 3.5 mg g−1. Preconcentration factor (PF), consumptive index (CI) and concentration efficiency (CE) were 128.0, 0.16 mL and 25.6 min−1, respectively. The selective performance of the sorbent, based on relative selectivity coefficient, was compared to NIC (non imprinted copolymer) for the binary mixture Pb2+/Cd2+, Pb2+/Cu2+ and Pb2+/Zn2+. The results showed that ion imprinted polyvinylimidazole-silica hybrid polymer had higher selectivity for Pb2+ than NIC at 64.9, 16.0 and 8.8 folds. The developed method was successfully applied for highly sensitive and selective Pb2+ determination in different kinds of water samples, parenteral solutions and urine. Accuracy was also assessed by analyzing certified reference fish protein (DORM-3) and marine sediment (MESS-3 and PACS-2) with satisfactory results. 相似文献
99.
Odendaal AY Fiamengo AL Ferdani R Wadas TJ Hill DC Peng Y Heroux KJ Golen JA Rheingold AL Anderson CJ Weisman GR Wong EH 《Inorganic chemistry》2011,50(7):3078-3086
Ethylene cross-bridged tetraamine macrocycles are useful chelators in coordination, catalytic, medicinal, and radiopharmaceutical chemistry. Springborg and co-workers developed trimethylene cross-bridged analogues, although their pendant-armed derivatives received little attention. We report here the synthesis of a bis-carboxymethyl pendant-armed cyclen with a trimethylene cross-bridge (C3B-DO2A) and its isomeric ethylene-cross-bridged homocyclen ligand (CB-TR2A) as well as their copper(II) complexes. The in vitro and in vivo properties of these complexes are compared with respect to their potential application as (64)Cu-radiopharmaceuticals in positron emission tomography (PET imaging). The inertness of Cu-C3B-DO2A to decomplexation is remarkable, exceeding that of Cu-CB-TE2A. Electrochemical reduction of Cu-CB-TR2A is quasi-reversible, whereas that of Cu-C3B-DO2A is irreversible. The reaction conditions for preparing (64)Cu-C3B-DO2A (microwaving at high temperature) are relatively harsh compared to (64)Cu-CB-TR2A (basic ethanol). The in vivo behavior of the (64)Cu complexes was evaluated in normal rats. Rapid and continual clearance of (64)Cu-CB-TR2A through the blood, liver, and kidneys suggests relatively good in vivo stability, albeit inferior to (64)Cu-CB-TE2A. Although (64)Cu-C3B-DO2A clears continually, the initial uptake is high and only about half is excreted within 22 h, suggesting poor stability and transchelation of (64)Cu to proteins in the blood and/or liver. These data suggest that in vitro inertness of a chelator complex may not always be a good indicator of in vivo stability. 相似文献
100.
Surmont R Verniest G De Schrijver M Thuring JW ten Holte P Deroose F De Kimpe N 《The Journal of organic chemistry》2011,76(10):4105-4111
Fluorinated pyrazoles bearing additional functional groups that allow further functionalization are of considerable interest as building blocks in medicinal chemistry. The developed synthetic strategy for new 3-amino-4-fluoropyrazoles consists of a monofluorination of β-methylthio-β-enaminoketones using 1-(chloromethyl)-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (Selectfluor) toward the corresponding monofluorinated enaminoketones, followed by condensation with different hydrazines. 相似文献