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991.
Kłonkowski Andrzej M. Kledzik Krzysztof Wagner-Wysiecka Ewa Biernat Jan F. 《Journal of Sol-Gel Science and Technology》2003,28(2):245-253
Xerogel samples with entrapped series of four optical absorption chemosensors were prepared by sol-gel process. These materials are proposed as chemical recognition elements of an optical chemical sensor. The roles of the chemosensors play proton-dissociable chromogenic azocrown ethers bearing phenol and two azo groups as parts of macrocycles. Occurrence of the alkali ion—receptor interaction is signalled by the chemosensors changing their electronic absorption spectra. By this way chemosensor 4O-CH3 is able to distinguish Li+ ions from other alkali metal ions present in aqueous solution, if the chemosensor is entrapped in Glymo-silica (1:1) xerogel matrix. The proposed recognition element for Li+ has been exposed to the cycles chemisorption—desorption many times. Besides DRIFT spectra of the used xerogel matrices were analyzed. 相似文献
992.
Bobrowski A Baś B Dominik J Niewiara E Szalińska E Vignati D Zare Bski J 《Talanta》2004,63(4):1003-1012
The catalytic adsorptive stripping voltammetry (CAdSV) has been applied to physico-chemical chromium speciation study in the upper Dunajec catchment, severely polluted by the tannery wastewater. The method is based on the adsorptive preconcentration of the Cr(III)-diethylenetriammine-N,N,N′,N″,N″-pentaacetic acid (DTPA) complex and the utilization of the catalytic reaction in the presence of nitrate. Under optimized conditions the CAdSV enables the oxidation state speciation study of Cr content by direct determination of Cr(VI) in the presence of the predominant Cr(III) concentration with the detection limit for chromium(VI) of 0.08 nM and the linearity range from 0.1 to 80 nM obtained for 20 s of accumulation, as well as the determination of total Cr after UV oxidation of Cr(III) to Cr(VI). Due to the difference in the chemical properties of different chromium species the CAdSV method makes possible a speciation study of Cr(III) and Cr(VI) oxidation state. The RSD of the determination of Cr(VI) and Cr(III) varies from 0.5 to 5%. It has been proved that in natural water in which strong complexants of Cr(III) such a humid acids are presented, Cr(VI) can be determined accurately in the presence of high excess of Cr(III). Fractionation of selected water samples with tangential flow filtration (TFF, cut-off 10 and/or 1 kDa) provides insight into physical Cr speciation, i.e. partitioning of the Cr(VI) and Cr(III) between the colloidal and the dissolved fractions. It has been shown that the content of the Cr species in the Dunajec river depends on the season, and is significantly higher in autumn and winter during the most intensive tanneries production processes. The concentration of total Cr exceeds occasionally the legally admissible level. A large fraction of total Cr(III) concentration is associated with the colloidal material, while Cr(VI) occurs solely in the truly dissolved form. 相似文献
993.
Kwaskowska-Chęć Ewa Kubiak Maria Głowiak Tadeusz Ziółkowski Józef J. 《Transition Metal Chemistry》1998,23(5):641-644
Co(NO3)2·6H2O reacts with N,N-bis(1–methylbenzimidazol-2–ylmethyl)methylamine (Me2L) in MeOH/ Et2O solution at ca. 5°C, yielding a novel, penta-coordinate complex, formulated as [Co(NO3)2(Me2L)], which was characterized by means of structural, spectroscopic and magnetic measurements. The Co atom is coordinated in distorted trigonal bipyramidal geometry by three N and two O atoms. The ligand Me2L is coordinated in a facial mode and two coordinated O atoms from the nitrato ligands are in cis-positions. 相似文献
994.
Ewa Schab-Balcerzak Eugenia Grabiec Bożena Jarząbek Łukasz Grobelny Małgorzata Kurcok Zbigniew Mazurak 《Central European Journal of Chemistry》2006,4(4):604-619
A series of aromatic poly(amideimide)s containing 9,9-diphenylfluorene moieties and the amide units in the main chain have
been synthesized by solution polycondensation reaction of newly prepared diamidedianhydride with several aromatic diamines:
1,3-phenylenediamine, 3,3′-dimethoxy-biphenyl-4,4′-diamine, 4,4′-oxydianiline, 4,4′-(1,3-phenylenedioxy)dianiline, 4,4′-(9-fluorenylidene)dianiline
and 1,5-diaminonaphthalene. Molecular structures of the polymers obtained have been characterized using 13C NMR, 1H NMR and FTIR spectroscopies. The polymers prepared are readily soluble in aprotic polar solvents, and form optically transparent
films by solution casting. The resultant poly(amideimide)s have been analyzed by differential scanning calorimetry (DSC),
thermogravimetry (TG) and wide-angle X-ray diffraction measurements. They exhibited high levels of thermal stability, with
decomposition temperatures in the range 452–494 °C, and high glass transition temperatures (181–278 °C). The optical behavior
of these polymers has been investigated in NMP solution as well as in the films. The photoluminescence (PL) spectra of the
free-standing films prepared from the poly(amideimide)s exhibited maximum emission bands around 506–525 nm in the green region. 相似文献
995.
Ewa Krawczyk 《Tetrahedron》2005,61(6):1449-1457
New important organic compounds multifunctionalized cyclic 6-membered and 7-membered allylic amines, azide and phosphonates have been obtained via regio- and diastereoselective reactions of cyclic Baylis-Hillman type adducts 1 with N-nucleophiles and P-nucleophile. We have found that the reactions proceed by SN2 or SN2′ processes exclusively, or by both processes simultaneously. The SN2′ process occurs with anti stereochemistry. 相似文献
996.
Chromium(III)-isonicotinate complexes, cis-[Cr(C2O4)2(N-inic)(H2O)]- and [Cr(C2O4)(H2O)3-OH-Cr(C2O4)2(O-inic)]-(N-inic)(H2 (N-inic = N-bonded and O-inic = O-bonded isonicotinic acid) were obtained and characterized in solution. Kinetics of acid-catalyzed
isonicotinate ligand liberation were studied spectrophotometrically in the 0.1–1.0 m HClO4 range, at I=1.0 m. The dependencies of the pseudo-first order rate constant on [H+] were established: kobs = k0+kHQH[H+] and kobs = kHQH[H+] for the N-inic and O-inic complex, respectively, where k0 and kH are the rate constants of the spontaneous and the acid-catalyzed reaction paths, and QH is the protonation constant of the carboxylic group in isonicotinic ligand. The obtained results indicate that N-bonded isonicotinic
acid liberation occurs mainly via a spontaneous reaction path and is much slower than O-bonded inic liberation. The mechanisms for these processes are proposed. 相似文献
997.
Chat-Wilk Karolina Rudnik Ewa Włoch Grzegorz Osuch Piotr 《Journal of Solid State Electrochemistry》2022,26(8):1715-1731
Journal of Solid State Electrochemistry - The codeposition of zinc and nickel from slightly acidic chloride, sulfate, and chloride-sulfate solutions containing a gluconate complexing agent was... 相似文献
998.
Haupt BJ Osbourn M Spanhoff R de Keijzer S Müller-Taubenberger A Snaar-Jagalska E Schmidt T 《Langmuir : the ACS journal of surfaces and colloids》2007,23(18):9352-9357
In this study we used an AFM to investigate the cytoskeletal properties of live Dictyostelium discoideum cells by measuring the local stiffness across individual living cells. We have examined differences in elastic properties of polarized and unpolarized AX3 wild type and the mutant DAip1- cells, as well as the differences in the front and rear of the cells in relation to organization of the actin cytoskeleton. We found that the average Young's modulus increases upon polarization for the thin regions of the cell and that in polarized cells, the cell front was stiffer than the cell back. We also found that AX3 cells were stiffer than DAip1- cells. This finding suggests that actin polymerization is one of the major determinants of cell motility in Dictyostelium. In addition, a thin agarose film was studied as a model system to examine the influence of the substrate of thin materials probed with the AFM. 相似文献
999.
Rudzińska E Poliwoda A Berlicki Ł Mucha A Dzygiel P Wieczorek PP Kafarski P 《Journal of chromatography. A》2007,1138(1-2):284-290
Capillary electrophoresis was successfully applied for separation of the enantiomers of N-benzyloxycarbonyl-alpha-aminophosphonic and alpha-aminophosphinic acids as well as their ethyl and phenyl monoesters with the use of a range of commercially available cyclodextrins (alpha, beta and hydroxypropyl-gamma-cyclodextrins) as chiral selectors. The dependence of effectiveness of separation on type and concentration of these chiral selectors as well as on pH of background electrolyte was examined in some detail. 相似文献
1000.
Struga M Kossakowski J Kedzierska E Fidecka S Stefańska J 《Chemical & pharmaceutical bulletin》2007,55(5):796-799
A series of nineteen new thiourea and urea derivatives of 10-isopropyl-8-methyl-4-azatricyclo[5.2.2.0(2,6)]undec-8-ene-3,5-dione, 1-isopropyl-7-methyl-4-azatricyclo[5.2.2.0(2,6)]undec-8-ene-3,5-dione and 1,7,8,9,10-pentamethyl-4-azatricyclo[5.2.1.0(2,6)]dec-8-ene-3,5-dione have been prepared and studied by (1)H-NMR. The compound k1a (1-(1,7,8,9,10-pentamethyl-3,5-dioxo-4-aza-tricyclo[5.2.1.0(2,6)]dec-8-en-4-yl)-3-phenyl-urea) was tested for pharmacological activity on animal central nervous system (CNS). The activities of synthesized compounds were evaluated for their cytotoxicity and anti-HIV-1 activity in MT-4 cells. Antimicrobial activity of the newly obtained derivatives was tested against some Gram-positive and Gram-negative bacteria and fungi of the Candida species. 相似文献